/* -*- Mode: C; tab-width: 4 -*- * * Copyright (c) 2002-2006 Apple Computer, Inc. All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * This code is completely 100% portable C. It does not depend on any external header files * from outside the mDNS project -- all the types it expects to find are defined right here. * * The previous point is very important: This file does not depend on any external * header files. It should compile on *any* platform that has a C compiler, without * making *any* assumptions about availability of so-called "standard" C functions, * routines, or types (which may or may not be present on any given platform). * Formatting notes: * This code follows the "Whitesmiths style" C indentation rules. Plenty of discussion * on C indentation can be found on the web, such as , * but for the sake of brevity here I will say just this: Curly braces are not syntactially * part of an "if" statement; they are the beginning and ending markers of a compound statement; * therefore common sense dictates that if they are part of a compound statement then they * should be indented to the same level as everything else in that compound statement. * Indenting curly braces at the same level as the "if" implies that curly braces are * part of the "if", which is false. (This is as misleading as people who write "char* x,y;" * thinking that variables x and y are both of type "char*" -- and anyone who doesn't * understand why variable y is not of type "char*" just proves the point that poor code * layout leads people to unfortunate misunderstandings about how the C language really works.) */ #include "DNSCommon.h" // Defines general DNS untility routines #include "uDNS.h" // Defines entry points into unicast-specific routines // Disable certain benign warnings with Microsoft compilers #if(defined(_MSC_VER)) // Disable "conditional expression is constant" warning for debug macros. // Otherwise, this generates warnings for the perfectly natural construct "while(1)" // If someone knows a variant way of writing "while(1)" that doesn't generate warning messages, please let us know #pragma warning(disable:4127) // Disable "assignment within conditional expression". // Other compilers understand the convention that if you place the assignment expression within an extra pair // of parentheses, this signals to the compiler that you really intended an assignment and no warning is necessary. // The Microsoft compiler doesn't understand this convention, so in the absense of any other way to signal // to the compiler that the assignment is intentional, we have to just turn this warning off completely. #pragma warning(disable:4706) #endif #if APPLE_OSX_mDNSResponder #include #if ! NO_WCF WCFConnection *WCFConnectionNew(void) __attribute__((weak_import)); void WCFConnectionDealloc(WCFConnection* c) __attribute__((weak_import)); // Do we really need to define a macro for "if"? #define CHECK_WCF_FUNCTION(X) if (X) #endif // ! NO_WCF #else #define NO_WCF 1 #endif // APPLE_OSX_mDNSResponder // Forward declarations mDNSlocal void BeginSleepProcessing(mDNS *const m); mDNSlocal void RetrySPSRegistrations(mDNS *const m); mDNSlocal void SendWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *EthAddr, mDNSOpaque48 *password); mDNSlocal mDNSBool CacheRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q); mDNSlocal mDNSBool LocalRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q); mDNSlocal void mDNS_PurgeBeforeResolve(mDNS *const m, DNSQuestion *q); // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - Program Constants #endif #define NO_HINFO 1 // Any records bigger than this are considered 'large' records #define SmallRecordLimit 1024 #define kMaxUpdateCredits 10 #define kUpdateCreditRefreshInterval (mDNSPlatformOneSecond * 6) mDNSexport const char *const mDNS_DomainTypeNames[] = { "b._dns-sd._udp.", // Browse "db._dns-sd._udp.", // Default Browse "lb._dns-sd._udp.", // Automatic Browse "r._dns-sd._udp.", // Registration "dr._dns-sd._udp." // Default Registration }; #ifdef UNICAST_DISABLED #define uDNS_IsActiveQuery(q, u) mDNSfalse #endif // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - General Utility Functions #endif // If there is a authoritative LocalOnly record that answers questions of type A, AAAA and CNAME // this returns true. Main use is to handle /etc/hosts records. #define LORecordAnswersAddressType(rr) ((rr)->ARType == AuthRecordLocalOnly && \ (rr)->resrec.RecordType & kDNSRecordTypeUniqueMask && \ ((rr)->resrec.rrtype == kDNSType_A || (rr)->resrec.rrtype == kDNSType_AAAA || \ (rr)->resrec.rrtype == kDNSType_CNAME)) #define FollowCNAME(q, rr, AddRecord) (AddRecord && (q)->qtype != kDNSType_CNAME && \ (rr)->RecordType != kDNSRecordTypePacketNegative && \ (rr)->rrtype == kDNSType_CNAME) mDNSlocal void SetNextQueryStopTime(mDNS *const m, const DNSQuestion *const q) { if (m->mDNS_busy != m->mDNS_reentrancy+1) LogMsg("SetNextQueryTime: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy); #if ForceAlerts if (m->mDNS_busy != m->mDNS_reentrancy+1) *(long*)0 = 0; #endif if (m->NextScheduledStopTime - q->StopTime > 0) m->NextScheduledStopTime = q->StopTime; } mDNSexport void SetNextQueryTime(mDNS *const m, const DNSQuestion *const q) { if (m->mDNS_busy != m->mDNS_reentrancy+1) LogMsg("SetNextQueryTime: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy); #if ForceAlerts if (m->mDNS_busy != m->mDNS_reentrancy+1) *(long*)0 = 0; #endif if (ActiveQuestion(q)) { // Depending on whether this is a multicast or unicast question we want to set either: // m->NextScheduledQuery = NextQSendTime(q) or // m->NextuDNSEvent = NextQSendTime(q) mDNSs32 *const timer = mDNSOpaque16IsZero(q->TargetQID) ? &m->NextScheduledQuery : &m->NextuDNSEvent; if (*timer - NextQSendTime(q) > 0) *timer = NextQSendTime(q); } } mDNSlocal void ReleaseAuthEntity(AuthHash *r, AuthEntity *e) { #if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING >= 1 unsigned int i; for (i=0; inext = r->rrauth_free; r->rrauth_free = e; r->rrauth_totalused--; } mDNSlocal void ReleaseAuthGroup(AuthHash *r, AuthGroup **cp) { AuthEntity *e = (AuthEntity *)(*cp); LogMsg("ReleaseAuthGroup: Releasing AuthGroup %##s", (*cp)->name->c); if ((*cp)->rrauth_tail != &(*cp)->members) LogMsg("ERROR: (*cp)->members == mDNSNULL but (*cp)->rrauth_tail != &(*cp)->members)"); if ((*cp)->name != (domainname*)((*cp)->namestorage)) mDNSPlatformMemFree((*cp)->name); (*cp)->name = mDNSNULL; *cp = (*cp)->next; // Cut record from list ReleaseAuthEntity(r, e); } mDNSlocal AuthEntity *GetAuthEntity(AuthHash *r, const AuthGroup *const PreserveAG) { AuthEntity *e = mDNSNULL; if (r->rrauth_lock) { LogMsg("GetFreeCacheRR ERROR! Cache already locked!"); return(mDNSNULL); } r->rrauth_lock = 1; if (!r->rrauth_free) { // We allocate just one AuthEntity at a time because we need to be able // free them all individually which normally happens when we parse /etc/hosts into // AuthHash where we add the "new" entries and discard (free) the already added // entries. If we allocate as chunks, we can't free them individually. AuthEntity *storage = mDNSPlatformMemAllocate(sizeof(AuthEntity)); storage->next = mDNSNULL; r->rrauth_free = storage; } // If we still have no free records, recycle all the records we can. // Enumerating the entire auth is moderately expensive, so when we do it, we reclaim all the records we can in one pass. if (!r->rrauth_free) { mDNSu32 oldtotalused = r->rrauth_totalused; mDNSu32 slot; for (slot = 0; slot < AUTH_HASH_SLOTS; slot++) { AuthGroup **cp = &r->rrauth_hash[slot]; while (*cp) { if ((*cp)->members || (*cp)==PreserveAG) cp=&(*cp)->next; else ReleaseAuthGroup(r, cp); } } LogInfo("GetAuthEntity: Recycled %d records to reduce auth cache from %d to %d", oldtotalused - r->rrauth_totalused, oldtotalused, r->rrauth_totalused); } if (r->rrauth_free) // If there are records in the free list, take one { e = r->rrauth_free; r->rrauth_free = e->next; if (++r->rrauth_totalused >= r->rrauth_report) { LogInfo("RR Auth now using %ld objects", r->rrauth_totalused); if (r->rrauth_report < 100) r->rrauth_report += 10; else if (r->rrauth_report < 1000) r->rrauth_report += 100; else r->rrauth_report += 1000; } mDNSPlatformMemZero(e, sizeof(*e)); } r->rrauth_lock = 0; return(e); } mDNSexport AuthGroup *AuthGroupForName(AuthHash *r, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name) { AuthGroup *ag; for (ag = r->rrauth_hash[slot]; ag; ag=ag->next) if (ag->namehash == namehash && SameDomainName(ag->name, name)) break; return(ag); } mDNSexport AuthGroup *AuthGroupForRecord(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr) { return(AuthGroupForName(r, slot, rr->namehash, rr->name)); } mDNSlocal AuthGroup *GetAuthGroup(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr) { mDNSu16 namelen = DomainNameLength(rr->name); AuthGroup *ag = (AuthGroup*)GetAuthEntity(r, mDNSNULL); if (!ag) { LogMsg("GetAuthGroup: Failed to allocate memory for %##s", rr->name->c); return(mDNSNULL); } ag->next = r->rrauth_hash[slot]; ag->namehash = rr->namehash; ag->members = mDNSNULL; ag->rrauth_tail = &ag->members; ag->name = (domainname*)ag->namestorage; ag->NewLocalOnlyRecords = mDNSNULL; if (namelen > InlineCacheGroupNameSize) ag->name = mDNSPlatformMemAllocate(namelen); if (!ag->name) { LogMsg("GetAuthGroup: Failed to allocate name storage for %##s", rr->name->c); ReleaseAuthEntity(r, (AuthEntity*)ag); return(mDNSNULL); } AssignDomainName(ag->name, rr->name); if (AuthGroupForRecord(r, slot, rr)) LogMsg("GetAuthGroup: Already have AuthGroup for %##s", rr->name->c); r->rrauth_hash[slot] = ag; if (AuthGroupForRecord(r, slot, rr) != ag) LogMsg("GetAuthGroup: Not finding AuthGroup for %##s", rr->name->c); return(ag); } // Returns the AuthGroup in which the AuthRecord was inserted mDNSexport AuthGroup *InsertAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr) { AuthGroup *ag; const mDNSu32 slot = AuthHashSlot(rr->resrec.name); ag = AuthGroupForRecord(r, slot, &rr->resrec); if (!ag) ag = GetAuthGroup(r, slot, &rr->resrec); // If we don't have a AuthGroup for this name, make one now if (ag) { LogInfo("InsertAuthRecord: inserting auth record %s from table", ARDisplayString(m, rr)); *(ag->rrauth_tail) = rr; // Append this record to tail of cache slot list ag->rrauth_tail = &(rr->next); // Advance tail pointer } return ag; } mDNSexport AuthGroup *RemoveAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr) { AuthGroup *a; AuthGroup **ag = &a; AuthRecord **rp; const mDNSu32 slot = AuthHashSlot(rr->resrec.name); a = AuthGroupForRecord(r, slot, &rr->resrec); if (!a) { LogMsg("RemoveAuthRecord: ERROR!! AuthGroup not found for %s", ARDisplayString(m, rr)); return mDNSNULL; } rp = &(*ag)->members; while (*rp) { if (*rp != rr) rp=&(*rp)->next; else { // We don't break here, so that we can set the tail below without tracking "prev" pointers LogInfo("RemoveAuthRecord: removing auth record %s from table", ARDisplayString(m, rr)); *rp = (*rp)->next; // Cut record from list } } // TBD: If there are no more members, release authgroup ? (*ag)->rrauth_tail = rp; return a; } mDNSexport CacheGroup *CacheGroupForName(const mDNS *const m, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name) { CacheGroup *cg; for (cg = m->rrcache_hash[slot]; cg; cg=cg->next) if (cg->namehash == namehash && SameDomainName(cg->name, name)) break; return(cg); } mDNSlocal CacheGroup *CacheGroupForRecord(const mDNS *const m, const mDNSu32 slot, const ResourceRecord *const rr) { return(CacheGroupForName(m, slot, rr->namehash, rr->name)); } mDNSexport mDNSBool mDNS_AddressIsLocalSubnet(mDNS *const m, const mDNSInterfaceID InterfaceID, const mDNSAddr *addr) { NetworkInterfaceInfo *intf; if (addr->type == mDNSAddrType_IPv4) { // Normally we resist touching the NotAnInteger fields, but here we're doing tricky bitwise masking so we make an exception if (mDNSv4AddressIsLinkLocal(&addr->ip.v4)) return(mDNStrue); for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->ip.type == addr->type && intf->InterfaceID == InterfaceID && intf->McastTxRx) if (((intf->ip.ip.v4.NotAnInteger ^ addr->ip.v4.NotAnInteger) & intf->mask.ip.v4.NotAnInteger) == 0) return(mDNStrue); } if (addr->type == mDNSAddrType_IPv6) { if (mDNSv6AddressIsLinkLocal(&addr->ip.v6)) return(mDNStrue); for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->ip.type == addr->type && intf->InterfaceID == InterfaceID && intf->McastTxRx) if ((((intf->ip.ip.v6.l[0] ^ addr->ip.v6.l[0]) & intf->mask.ip.v6.l[0]) == 0) && (((intf->ip.ip.v6.l[1] ^ addr->ip.v6.l[1]) & intf->mask.ip.v6.l[1]) == 0) && (((intf->ip.ip.v6.l[2] ^ addr->ip.v6.l[2]) & intf->mask.ip.v6.l[2]) == 0) && (((intf->ip.ip.v6.l[3] ^ addr->ip.v6.l[3]) & intf->mask.ip.v6.l[3]) == 0)) return(mDNStrue); } return(mDNSfalse); } mDNSlocal NetworkInterfaceInfo *FirstInterfaceForID(mDNS *const m, const mDNSInterfaceID InterfaceID) { NetworkInterfaceInfo *intf = m->HostInterfaces; while (intf && intf->InterfaceID != InterfaceID) intf = intf->next; return(intf); } mDNSexport char *InterfaceNameForID(mDNS *const m, const mDNSInterfaceID InterfaceID) { NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID); return(intf ? intf->ifname : mDNSNULL); } // Caller should hold the lock mDNSlocal void GenerateNegativeResponse(mDNS *const m) { DNSQuestion *q; if (!m->CurrentQuestion) { LogMsg("GenerateNegativeResponse: ERROR!! CurrentQuestion not set"); return; } q = m->CurrentQuestion; LogInfo("GenerateNegativeResponse: Generating negative response for question %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); MakeNegativeCacheRecord(m, &m->rec.r, &q->qname, q->qnamehash, q->qtype, q->qclass, 60, mDNSInterface_Any, mDNSNULL); AnswerCurrentQuestionWithResourceRecord(m, &m->rec.r, QC_addnocache); if (m->CurrentQuestion == q) { q->ThisQInterval = 0; } // Deactivate this question // Don't touch the question after this m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } mDNSlocal void AnswerQuestionByFollowingCNAME(mDNS *const m, DNSQuestion *q, ResourceRecord *rr) { const mDNSBool selfref = SameDomainName(&q->qname, &rr->rdata->u.name); if (q->CNAMEReferrals >= 10 || selfref) LogMsg("AnswerQuestionByFollowingCNAME: %p %##s (%s) NOT following CNAME referral %d%s for %s", q, q->qname.c, DNSTypeName(q->qtype), q->CNAMEReferrals, selfref ? " (Self-Referential)" : "", RRDisplayString(m, rr)); else { const mDNSu32 c = q->CNAMEReferrals + 1; // Stash a copy of the new q->CNAMEReferrals value // The SameDomainName check above is to ignore bogus CNAME records that point right back at // themselves. Without that check we can get into a case where we have two duplicate questions, // A and B, and when we stop question A, UpdateQuestionDuplicates copies the value of CNAMEReferrals // from A to B, and then A is re-appended to the end of the list as a duplicate of B (because // the target name is still the same), and then when we stop question B, UpdateQuestionDuplicates // copies the B's value of CNAMEReferrals back to A, and we end up not incrementing CNAMEReferrals // for either of them. This is not a problem for CNAME loops of two or more records because in // those cases the newly re-appended question A has a different target name and therefore cannot be // a duplicate of any other question ('B') which was itself a duplicate of the previous question A. // Right now we just stop and re-use the existing query. If we really wanted to be 100% perfect, // and track CNAMEs coming and going, we should really create a subordinate query here, // which we would subsequently cancel and retract if the CNAME referral record were removed. // In reality this is such a corner case we'll ignore it until someone actually needs it. LogInfo("AnswerQuestionByFollowingCNAME: %p %##s (%s) following CNAME referral %d for %s", q, q->qname.c, DNSTypeName(q->qtype), q->CNAMEReferrals, RRDisplayString(m, rr)); mDNS_StopQuery_internal(m, q); // Stop old query AssignDomainName(&q->qname, &rr->rdata->u.name); // Update qname q->qnamehash = DomainNameHashValue(&q->qname); // and namehash // If a unicast query results in a CNAME that points to a .local, we need to re-try // this as unicast. Setting the mDNSInterface_Unicast tells mDNS_StartQuery_internal // to try this as unicast query even though it is a .local name if (!mDNSOpaque16IsZero(q->TargetQID) && IsLocalDomain(&q->qname)) { LogInfo("AnswerQuestionByFollowingCNAME: Resolving a .local CNAME %p %##s (%s) Record %s", q, q->qname.c, DNSTypeName(q->qtype), RRDisplayString(m, rr)); q->InterfaceID = mDNSInterface_Unicast; } mDNS_StartQuery_internal(m, q); // start new query // Record how many times we've done this. We need to do this *after* mDNS_StartQuery_internal, // because mDNS_StartQuery_internal re-initializes CNAMEReferrals to zero q->CNAMEReferrals = c; } } // For a single given DNSQuestion pointed to by CurrentQuestion, deliver an add/remove result for the single given AuthRecord // Note: All the callers should use the m->CurrentQuestion to see if the question is still valid or not mDNSlocal void AnswerLocalQuestionWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord) { DNSQuestion *q = m->CurrentQuestion; mDNSBool followcname; if (!q) { LogMsg("AnswerLocalQuestionWithLocalAuthRecord: ERROR!! CurrentQuestion NULL while answering with %s", ARDisplayString(m, rr)); return; } followcname = FollowCNAME(q, &rr->resrec, AddRecord); // We should not be delivering results for record types Unregistered, Deregistering, and (unverified) Unique if (!(rr->resrec.RecordType & kDNSRecordTypeActiveMask)) { LogMsg("AnswerLocalQuestionWithLocalAuthRecord: *NOT* delivering %s event for local record type %X %s", AddRecord ? "Add" : "Rmv", rr->resrec.RecordType, ARDisplayString(m, rr)); return; } // Indicate that we've given at least one positive answer for this record, so we should be prepared to send a goodbye for it if (AddRecord) rr->AnsweredLocalQ = mDNStrue; mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback if (q->QuestionCallback && !q->NoAnswer) { q->CurrentAnswers += AddRecord ? 1 : -1; if (LORecordAnswersAddressType(rr)) { if (!followcname || q->ReturnIntermed) { // Don't send this packet on the wire as we answered from /etc/hosts q->ThisQInterval = 0; q->LOAddressAnswers += AddRecord ? 1 : -1; q->QuestionCallback(m, q, &rr->resrec, AddRecord); } mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again // The callback above could have caused the question to stop. Detect that // using m->CurrentQuestion if (followcname && m->CurrentQuestion == q) AnswerQuestionByFollowingCNAME(m, q, &rr->resrec); return; } else q->QuestionCallback(m, q, &rr->resrec, AddRecord); } mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again } mDNSlocal void AnswerInterfaceAnyQuestionsWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord) { if (m->CurrentQuestion) LogMsg("AnswerInterfaceAnyQuestionsWithLocalAuthRecord: ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->Questions; while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) { mDNSBool answered; DNSQuestion *q = m->CurrentQuestion; if (RRAny(rr)) answered = ResourceRecordAnswersQuestion(&rr->resrec, q); else answered = LocalOnlyRecordAnswersQuestion(rr, q); if (answered) AnswerLocalQuestionWithLocalAuthRecord(m, rr, AddRecord); // MUST NOT dereference q again if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now m->CurrentQuestion = q->next; } m->CurrentQuestion = mDNSNULL; } // When a new local AuthRecord is created or deleted, AnswerAllLocalQuestionsWithLocalAuthRecord() // delivers the appropriate add/remove events to listening questions: // 1. It runs though all our LocalOnlyQuestions delivering answers as appropriate, // stopping if it reaches a NewLocalOnlyQuestion -- brand-new questions are handled by AnswerNewLocalOnlyQuestion(). // 2. If the AuthRecord is marked mDNSInterface_LocalOnly or mDNSInterface_P2P, then it also runs though // our main question list, delivering answers to mDNSInterface_Any questions as appropriate, // stopping if it reaches a NewQuestion -- brand-new questions are handled by AnswerNewQuestion(). // // AnswerAllLocalQuestionsWithLocalAuthRecord is used by the m->NewLocalRecords loop in mDNS_Execute(), // and by mDNS_Deregister_internal() mDNSlocal void AnswerAllLocalQuestionsWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord) { if (m->CurrentQuestion) LogMsg("AnswerAllLocalQuestionsWithLocalAuthRecord ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->LocalOnlyQuestions; while (m->CurrentQuestion && m->CurrentQuestion != m->NewLocalOnlyQuestions) { mDNSBool answered; DNSQuestion *q = m->CurrentQuestion; // We are called with both LocalOnly/P2P record or a regular AuthRecord if (RRAny(rr)) answered = ResourceRecordAnswersQuestion(&rr->resrec, q); else answered = LocalOnlyRecordAnswersQuestion(rr, q); if (answered) AnswerLocalQuestionWithLocalAuthRecord(m, rr, AddRecord); // MUST NOT dereference q again if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now m->CurrentQuestion = q->next; } m->CurrentQuestion = mDNSNULL; // If this AuthRecord is marked LocalOnly or P2P, then we want to deliver it to all local 'mDNSInterface_Any' questions if (rr->ARType == AuthRecordLocalOnly || rr->ARType == AuthRecordP2P) AnswerInterfaceAnyQuestionsWithLocalAuthRecord(m, rr, AddRecord); } // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Resource Record Utility Functions #endif #define RRTypeIsAddressType(T) ((T) == kDNSType_A || (T) == kDNSType_AAAA) #define ResourceRecordIsValidAnswer(RR) ( ((RR)-> resrec.RecordType & kDNSRecordTypeActiveMask) && \ ((RR)->Additional1 == mDNSNULL || ((RR)->Additional1->resrec.RecordType & kDNSRecordTypeActiveMask)) && \ ((RR)->Additional2 == mDNSNULL || ((RR)->Additional2->resrec.RecordType & kDNSRecordTypeActiveMask)) && \ ((RR)->DependentOn == mDNSNULL || ((RR)->DependentOn->resrec.RecordType & kDNSRecordTypeActiveMask)) ) #define ResourceRecordIsValidInterfaceAnswer(RR, INTID) \ (ResourceRecordIsValidAnswer(RR) && \ ((RR)->resrec.InterfaceID == mDNSInterface_Any || (RR)->resrec.InterfaceID == (INTID))) #define DefaultProbeCountForTypeUnique ((mDNSu8)3) #define DefaultProbeCountForRecordType(X) ((X) == kDNSRecordTypeUnique ? DefaultProbeCountForTypeUnique : (mDNSu8)0) #define InitialAnnounceCount ((mDNSu8)8) // For goodbye packets we set the count to 3, and for wakeups we set it to 18 // (which will be up to 15 wakeup attempts over the course of 30 seconds, // and then if the machine fails to wake, 3 goodbye packets). #define GoodbyeCount ((mDNSu8)3) #define WakeupCount ((mDNSu8)18) // Number of wakeups we send if WakeOnResolve is set in the question #define InitialWakeOnResolveCount ((mDNSu8)3) // Note that the announce intervals use exponential backoff, doubling each time. The probe intervals do not. // This means that because the announce interval is doubled after sending the first packet, the first // observed on-the-wire inter-packet interval between announcements is actually one second. // The half-second value here may be thought of as a conceptual (non-existent) half-second delay *before* the first packet is sent. #define DefaultProbeIntervalForTypeUnique (mDNSPlatformOneSecond/4) #define DefaultAnnounceIntervalForTypeShared (mDNSPlatformOneSecond/2) #define DefaultAnnounceIntervalForTypeUnique (mDNSPlatformOneSecond/2) #define DefaultAPIntervalForRecordType(X) ((X) & kDNSRecordTypeActiveSharedMask ? DefaultAnnounceIntervalForTypeShared : \ (X) & kDNSRecordTypeUnique ? DefaultProbeIntervalForTypeUnique : \ (X) & kDNSRecordTypeActiveUniqueMask ? DefaultAnnounceIntervalForTypeUnique : 0) #define TimeToAnnounceThisRecord(RR,time) ((RR)->AnnounceCount && (time) - ((RR)->LastAPTime + (RR)->ThisAPInterval) >= 0) #define TimeToSendThisRecord(RR,time) ((TimeToAnnounceThisRecord(RR,time) || (RR)->ImmedAnswer) && ResourceRecordIsValidAnswer(RR)) #define TicksTTL(RR) ((mDNSs32)(RR)->resrec.rroriginalttl * mDNSPlatformOneSecond) #define RRExpireTime(RR) ((RR)->TimeRcvd + TicksTTL(RR)) #define MaxUnansweredQueries 4 // SameResourceRecordSignature returns true if two resources records have the same name, type, and class, and may be sent // (or were received) on the same interface (i.e. if *both* records specify an interface, then it has to match). // TTL and rdata may differ. // This is used for cache flush management: // When sending a unique record, all other records matching "SameResourceRecordSignature" must also be sent // When receiving a unique record, all old cache records matching "SameResourceRecordSignature" are flushed // SameResourceRecordNameClassInterface is functionally the same as SameResourceRecordSignature, except rrtype does not have to match #define SameResourceRecordSignature(A,B) (A)->resrec.rrtype == (B)->resrec.rrtype && SameResourceRecordNameClassInterface((A),(B)) mDNSlocal mDNSBool SameResourceRecordNameClassInterface(const AuthRecord *const r1, const AuthRecord *const r2) { if (!r1) { LogMsg("SameResourceRecordSignature ERROR: r1 is NULL"); return(mDNSfalse); } if (!r2) { LogMsg("SameResourceRecordSignature ERROR: r2 is NULL"); return(mDNSfalse); } if (r1->resrec.InterfaceID && r2->resrec.InterfaceID && r1->resrec.InterfaceID != r2->resrec.InterfaceID) return(mDNSfalse); return(mDNSBool)( r1->resrec.rrclass == r2->resrec.rrclass && r1->resrec.namehash == r2->resrec.namehash && SameDomainName(r1->resrec.name, r2->resrec.name)); } // PacketRRMatchesSignature behaves as SameResourceRecordSignature, except that types may differ if our // authoratative record is unique (as opposed to shared). For unique records, we are supposed to have // complete ownership of *all* types for this name, so *any* record type with the same name is a conflict. // In addition, when probing we send our questions with the wildcard type kDNSQType_ANY, // so a response of any type should match, even if it is not actually the type the client plans to use. // For now, to make it easier to avoid false conflicts, we treat SPS Proxy records like shared records, // and require the rrtypes to match for the rdata to be considered potentially conflicting mDNSlocal mDNSBool PacketRRMatchesSignature(const CacheRecord *const pktrr, const AuthRecord *const authrr) { if (!pktrr) { LogMsg("PacketRRMatchesSignature ERROR: pktrr is NULL"); return(mDNSfalse); } if (!authrr) { LogMsg("PacketRRMatchesSignature ERROR: authrr is NULL"); return(mDNSfalse); } if (pktrr->resrec.InterfaceID && authrr->resrec.InterfaceID && pktrr->resrec.InterfaceID != authrr->resrec.InterfaceID) return(mDNSfalse); if (!(authrr->resrec.RecordType & kDNSRecordTypeUniqueMask) || authrr->WakeUp.HMAC.l[0]) if (pktrr->resrec.rrtype != authrr->resrec.rrtype) return(mDNSfalse); return(mDNSBool)( pktrr->resrec.rrclass == authrr->resrec.rrclass && pktrr->resrec.namehash == authrr->resrec.namehash && SameDomainName(pktrr->resrec.name, authrr->resrec.name)); } // CacheRecord *ka is the CacheRecord from the known answer list in the query. // This is the information that the requester believes to be correct. // AuthRecord *rr is the answer we are proposing to give, if not suppressed. // This is the information that we believe to be correct. // We've already determined that we plan to give this answer on this interface // (either the record is non-specific, or it is specific to this interface) // so now we just need to check the name, type, class, rdata and TTL. mDNSlocal mDNSBool ShouldSuppressKnownAnswer(const CacheRecord *const ka, const AuthRecord *const rr) { // If RR signature is different, or data is different, then don't suppress our answer if (!IdenticalResourceRecord(&ka->resrec, &rr->resrec)) return(mDNSfalse); // If the requester's indicated TTL is less than half the real TTL, // we need to give our answer before the requester's copy expires. // If the requester's indicated TTL is at least half the real TTL, // then we can suppress our answer this time. // If the requester's indicated TTL is greater than the TTL we believe, // then that's okay, and we don't need to do anything about it. // (If two responders on the network are offering the same information, // that's okay, and if they are offering the information with different TTLs, // the one offering the lower TTL should defer to the one offering the higher TTL.) return(mDNSBool)(ka->resrec.rroriginalttl >= rr->resrec.rroriginalttl / 2); } mDNSlocal void SetNextAnnounceProbeTime(mDNS *const m, const AuthRecord *const rr) { if (rr->resrec.RecordType == kDNSRecordTypeUnique) { if ((rr->LastAPTime + rr->ThisAPInterval) - m->timenow > mDNSPlatformOneSecond * 10) { LogMsg("SetNextAnnounceProbeTime: ProbeCount %d Next in %d %s", rr->ProbeCount, (rr->LastAPTime + rr->ThisAPInterval) - m->timenow, ARDisplayString(m, rr)); LogMsg("SetNextAnnounceProbeTime: m->SuppressProbes %d m->timenow %d diff %d", m->SuppressProbes, m->timenow, m->SuppressProbes - m->timenow); } if (m->NextScheduledProbe - (rr->LastAPTime + rr->ThisAPInterval) >= 0) m->NextScheduledProbe = (rr->LastAPTime + rr->ThisAPInterval); // Some defensive code: // If (rr->LastAPTime + rr->ThisAPInterval) happens to be far in the past, we don't want to allow // NextScheduledProbe to be set excessively in the past, because that can cause bad things to happen. // See: mDNS: Sometimes advertising stops working and record interval is set to zero if (m->NextScheduledProbe - m->timenow < 0) m->NextScheduledProbe = m->timenow; } else if (rr->AnnounceCount && (ResourceRecordIsValidAnswer(rr) || rr->resrec.RecordType == kDNSRecordTypeDeregistering)) { if (m->NextScheduledResponse - (rr->LastAPTime + rr->ThisAPInterval) >= 0) m->NextScheduledResponse = (rr->LastAPTime + rr->ThisAPInterval); } if (m->NextScheduledResponse - m->timenow < 0) m->NextScheduledResponse = m->timenow; } mDNSlocal void InitializeLastAPTime(mDNS *const m, AuthRecord *const rr) { // For reverse-mapping Sleep Proxy PTR records, probe interval is one second rr->ThisAPInterval = rr->AddressProxy.type ? mDNSPlatformOneSecond : DefaultAPIntervalForRecordType(rr->resrec.RecordType); // * If this is a record type that's going to probe, then we use the m->SuppressProbes time. // * Otherwise, if it's not going to probe, but m->SuppressProbes is set because we have other // records that are going to probe, then we delay its first announcement so that it will // go out synchronized with the first announcement for the other records that *are* probing. // This is a minor performance tweak that helps keep groups of related records synchronized together. // The addition of "interval / 2" is to make sure that, in the event that any of the probes are // delayed by a few milliseconds, this announcement does not inadvertently go out *before* the probing is complete. // When the probing is complete and those records begin to announce, these records will also be picked up and accelerated, // because they will meet the criterion of being at least half-way to their scheduled announcement time. // * If it's not going to probe and m->SuppressProbes is not already set then we should announce immediately. if (rr->ProbeCount) { // If we have no probe suppression time set, or it is in the past, set it now if (m->SuppressProbes == 0 || m->SuppressProbes - m->timenow < 0) { // To allow us to aggregate probes when a group of services are registered together, // the first probe is delayed 1/4 second. This means the common-case behaviour is: // 1/4 second wait; probe // 1/4 second wait; probe // 1/4 second wait; probe // 1/4 second wait; announce (i.e. service is normally announced exactly one second after being registered) m->SuppressProbes = NonZeroTime(m->timenow + DefaultProbeIntervalForTypeUnique/2 + mDNSRandom(DefaultProbeIntervalForTypeUnique/2)); // If we already have a *probe* scheduled to go out sooner, then use that time to get better aggregation if (m->SuppressProbes - m->NextScheduledProbe >= 0) m->SuppressProbes = NonZeroTime(m->NextScheduledProbe); if (m->SuppressProbes - m->timenow < 0) // Make sure we don't set m->SuppressProbes excessively in the past m->SuppressProbes = m->timenow; // If we already have a *query* scheduled to go out sooner, then use that time to get better aggregation if (m->SuppressProbes - m->NextScheduledQuery >= 0) m->SuppressProbes = NonZeroTime(m->NextScheduledQuery); if (m->SuppressProbes - m->timenow < 0) // Make sure we don't set m->SuppressProbes excessively in the past m->SuppressProbes = m->timenow; // except... don't expect to be able to send before the m->SuppressSending timer fires if (m->SuppressSending && m->SuppressProbes - m->SuppressSending < 0) m->SuppressProbes = NonZeroTime(m->SuppressSending); if (m->SuppressProbes - m->timenow > mDNSPlatformOneSecond * 8) { LogMsg("InitializeLastAPTime ERROR m->SuppressProbes %d m->NextScheduledProbe %d m->NextScheduledQuery %d m->SuppressSending %d %d", m->SuppressProbes - m->timenow, m->NextScheduledProbe - m->timenow, m->NextScheduledQuery - m->timenow, m->SuppressSending, m->SuppressSending - m->timenow); m->SuppressProbes = NonZeroTime(m->timenow + DefaultProbeIntervalForTypeUnique/2 + mDNSRandom(DefaultProbeIntervalForTypeUnique/2)); } } rr->LastAPTime = m->SuppressProbes - rr->ThisAPInterval; } else if (m->SuppressProbes && m->SuppressProbes - m->timenow >= 0) rr->LastAPTime = m->SuppressProbes - rr->ThisAPInterval + DefaultProbeIntervalForTypeUnique * DefaultProbeCountForTypeUnique + rr->ThisAPInterval / 2; else rr->LastAPTime = m->timenow - rr->ThisAPInterval; // For reverse-mapping Sleep Proxy PTR records we don't want to start probing instantly -- we // wait one second to give the client a chance to go to sleep, and then start our ARP/NDP probing. // After three probes one second apart with no answer, we conclude the client is now sleeping // and we can begin broadcasting our announcements to take over ownership of that IP address. // If we don't wait for the client to go to sleep, then when the client sees our ARP Announcements there's a risk // (depending on the OS and networking stack it's using) that it might interpret it as a conflict and change its IP address. if (rr->AddressProxy.type) rr->LastAPTime = m->timenow; // Unsolicited Neighbor Advertisements (RFC 2461 Section 7.2.6) give us fast address cache updating, // but some older IPv6 clients get confused by them, so for now we don't send them. Without Unsolicited // Neighbor Advertisements we have to rely on Neighbor Unreachability Detection instead, which is slower. // Given this, we'll do our best to wake for existing IPv6 connections, but we don't want to encourage // new ones for sleeping clients, so we'll we send deletions for our SPS clients' AAAA records. if (m->KnownBugs & mDNS_KnownBug_LimitedIPv6) if (rr->WakeUp.HMAC.l[0] && rr->resrec.rrtype == kDNSType_AAAA) rr->LastAPTime = m->timenow - rr->ThisAPInterval + mDNSPlatformOneSecond * 10; // Set LastMCTime to now, to inhibit multicast responses // (no need to send additional multicast responses when we're announcing anyway) rr->LastMCTime = m->timenow; rr->LastMCInterface = mDNSInterfaceMark; SetNextAnnounceProbeTime(m, rr); } mDNSlocal const domainname *SetUnicastTargetToHostName(mDNS *const m, AuthRecord *rr) { const domainname *target; if (rr->AutoTarget) { // For autotunnel services pointing at our IPv6 ULA we don't need or want a NAT mapping, but for all other // advertised services referencing our uDNS hostname, we want NAT mappings automatically created as appropriate, // with the port number in our advertised SRV record automatically tracking the external mapped port. DomainAuthInfo *AuthInfo = GetAuthInfoForName_internal(m, rr->resrec.name); if (!AuthInfo || !AuthInfo->AutoTunnel) rr->AutoTarget = Target_AutoHostAndNATMAP; } target = GetServiceTarget(m, rr); if (!target || target->c[0] == 0) { // defer registration until we've got a target LogInfo("SetUnicastTargetToHostName No target for %s", ARDisplayString(m, rr)); rr->state = regState_NoTarget; return mDNSNULL; } else { LogInfo("SetUnicastTargetToHostName target %##s for resource record %s", target->c, ARDisplayString(m,rr)); return target; } } // Right now this only applies to mDNS (.local) services where the target host is always m->MulticastHostname // Eventually we should unify this with GetServiceTarget() in uDNS.c mDNSlocal void SetTargetToHostName(mDNS *const m, AuthRecord *const rr) { domainname *const target = GetRRDomainNameTarget(&rr->resrec); const domainname *newname = &m->MulticastHostname; if (!target) LogInfo("SetTargetToHostName: Don't know how to set the target of rrtype %s", DNSTypeName(rr->resrec.rrtype)); if (!(rr->ForceMCast || rr->ARType == AuthRecordLocalOnly || rr->ARType == AuthRecordP2P || IsLocalDomain(&rr->namestorage))) { const domainname *const n = SetUnicastTargetToHostName(m, rr); if (n) newname = n; else { target->c[0] = 0; SetNewRData(&rr->resrec, mDNSNULL, 0); return; } } if (target && SameDomainName(target, newname)) debugf("SetTargetToHostName: Target of %##s is already %##s", rr->resrec.name->c, target->c); if (target && !SameDomainName(target, newname)) { AssignDomainName(target, newname); SetNewRData(&rr->resrec, mDNSNULL, 0); // Update rdlength, rdestimate, rdatahash // If we're in the middle of probing this record, we need to start again, // because changing its rdata may change the outcome of the tie-breaker. // (If the record type is kDNSRecordTypeUnique (unconfirmed unique) then DefaultProbeCountForRecordType is non-zero.) rr->ProbeCount = DefaultProbeCountForRecordType(rr->resrec.RecordType); // If we've announced this record, we really should send a goodbye packet for the old rdata before // changing to the new rdata. However, in practice, we only do SetTargetToHostName for unique records, // so when we announce them we'll set the kDNSClass_UniqueRRSet and clear any stale data that way. if (rr->RequireGoodbye && rr->resrec.RecordType == kDNSRecordTypeShared) debugf("Have announced shared record %##s (%s) at least once: should have sent a goodbye packet before updating", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); rr->AnnounceCount = InitialAnnounceCount; rr->RequireGoodbye = mDNSfalse; InitializeLastAPTime(m, rr); } } mDNSlocal void AcknowledgeRecord(mDNS *const m, AuthRecord *const rr) { if (rr->RecordCallback) { // CAUTION: MUST NOT do anything more with rr after calling rr->Callback(), because the client's callback function // is allowed to do anything, including starting/stopping queries, registering/deregistering records, etc. rr->Acknowledged = mDNStrue; mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback rr->RecordCallback(m, rr, mStatus_NoError); mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again } } mDNSexport void ActivateUnicastRegistration(mDNS *const m, AuthRecord *const rr) { // Make sure that we don't activate the SRV record and associated service records, if it is in // NoTarget state. First time when a service is being instantiated, SRV record may be in NoTarget state. // We should not activate any of the other reords (PTR, TXT) that are part of the service. When // the target becomes available, the records will be reregistered. if (rr->resrec.rrtype != kDNSType_SRV) { AuthRecord *srvRR = mDNSNULL; if (rr->resrec.rrtype == kDNSType_PTR) srvRR = rr->Additional1; else if (rr->resrec.rrtype == kDNSType_TXT) srvRR = rr->DependentOn; if (srvRR) { if (srvRR->resrec.rrtype != kDNSType_SRV) { LogMsg("ActivateUnicastRegistration: ERROR!! Resource record %s wrong, expecting SRV type", ARDisplayString(m, srvRR)); } else { LogInfo("ActivateUnicastRegistration: Found Service Record %s in state %d for %##s (%s)", ARDisplayString(m, srvRR), srvRR->state, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); rr->state = srvRR->state; } } } if (rr->state == regState_NoTarget) { LogInfo("ActivateUnicastRegistration record %s in regState_NoTarget, not activating", ARDisplayString(m, rr)); return; } // When we wake up from sleep, we call ActivateUnicastRegistration. It is possible that just before we went to sleep, // the service/record was being deregistered. In that case, we should not try to register again. For the cases where // the records are deregistered due to e.g., no target for the SRV record, we would have returned from above if it // was already in NoTarget state. If it was in the process of deregistration but did not complete fully before we went // to sleep, then it is okay to start in Pending state as we will go back to NoTarget state if we don't have a target. if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) { LogInfo("ActivateUnicastRegistration: Resource record %s, current state %d, moving to DeregPending", ARDisplayString(m, rr), rr->state); rr->state = regState_DeregPending; } else { LogInfo("ActivateUnicastRegistration: Resource record %s, current state %d, moving to Pending", ARDisplayString(m, rr), rr->state); rr->state = regState_Pending; } rr->ProbeCount = 0; rr->AnnounceCount = 0; rr->ThisAPInterval = INIT_RECORD_REG_INTERVAL; rr->LastAPTime = m->timenow - rr->ThisAPInterval; rr->expire = 0; // Forget about all the leases, start fresh rr->uselease = mDNStrue; rr->updateid = zeroID; rr->SRVChanged = mDNSfalse; rr->updateError = mStatus_NoError; // RestartRecordGetZoneData calls this function whenever a new interface gets registered with core. // The records might already be registered with the server and hence could have NAT state. if (rr->NATinfo.clientContext) { mDNS_StopNATOperation_internal(m, &rr->NATinfo); rr->NATinfo.clientContext = mDNSNULL; } if (rr->nta) { CancelGetZoneData(m, rr->nta); rr->nta = mDNSNULL; } if (rr->tcp) { DisposeTCPConn(rr->tcp); rr->tcp = mDNSNULL; } if (m->NextuDNSEvent - (rr->LastAPTime + rr->ThisAPInterval) >= 0) m->NextuDNSEvent = (rr->LastAPTime + rr->ThisAPInterval); } // Two records qualify to be local duplicates if: // (a) the RecordTypes are the same, or // (b) one is Unique and the other Verified // (c) either is in the process of deregistering #define RecordLDT(A,B) ((A)->resrec.RecordType == (B)->resrec.RecordType || \ ((A)->resrec.RecordType | (B)->resrec.RecordType) == (kDNSRecordTypeUnique | kDNSRecordTypeVerified) || \ ((A)->resrec.RecordType == kDNSRecordTypeDeregistering || (B)->resrec.RecordType == kDNSRecordTypeDeregistering)) #define RecordIsLocalDuplicate(A,B) \ ((A)->resrec.InterfaceID == (B)->resrec.InterfaceID && RecordLDT((A),(B)) && IdenticalResourceRecord(&(A)->resrec, &(B)->resrec)) mDNSlocal AuthRecord *CheckAuthIdenticalRecord(AuthHash *r, AuthRecord *rr) { AuthGroup *a; AuthGroup **ag = &a; AuthRecord **rp; const mDNSu32 slot = AuthHashSlot(rr->resrec.name); a = AuthGroupForRecord(r, slot, &rr->resrec); if (!a) return mDNSNULL; rp = &(*ag)->members; while (*rp) { if (!RecordIsLocalDuplicate(*rp, rr)) rp=&(*rp)->next; else { if ((*rp)->resrec.RecordType == kDNSRecordTypeDeregistering) { (*rp)->AnnounceCount = 0; rp=&(*rp)->next; } else return *rp; } } return (mDNSNULL); } mDNSlocal mDNSBool CheckAuthRecordConflict(AuthHash *r, AuthRecord *rr) { AuthGroup *a; AuthGroup **ag = &a; AuthRecord **rp; const mDNSu32 slot = AuthHashSlot(rr->resrec.name); a = AuthGroupForRecord(r, slot, &rr->resrec); if (!a) return mDNSfalse; rp = &(*ag)->members; while (*rp) { const AuthRecord *s1 = rr->RRSet ? rr->RRSet : rr; const AuthRecord *s2 = (*rp)->RRSet ? (*rp)->RRSet : *rp; if (s1 != s2 && SameResourceRecordSignature((*rp), rr) && !IdenticalSameNameRecord(&(*rp)->resrec, &rr->resrec)) return mDNStrue; else rp=&(*rp)->next; } return (mDNSfalse); } // checks to see if "rr" is already present mDNSlocal AuthRecord *CheckAuthSameRecord(AuthHash *r, AuthRecord *rr) { AuthGroup *a; AuthGroup **ag = &a; AuthRecord **rp; const mDNSu32 slot = AuthHashSlot(rr->resrec.name); a = AuthGroupForRecord(r, slot, &rr->resrec); if (!a) return mDNSNULL; rp = &(*ag)->members; while (*rp) { if (*rp != rr) rp=&(*rp)->next; else { return *rp; } } return (mDNSNULL); } // Exported so uDNS.c can call this mDNSexport mStatus mDNS_Register_internal(mDNS *const m, AuthRecord *const rr) { domainname *target = GetRRDomainNameTarget(&rr->resrec); AuthRecord *r; AuthRecord **p = &m->ResourceRecords; AuthRecord **d = &m->DuplicateRecords; if ((mDNSs32)rr->resrec.rroriginalttl <= 0) { LogMsg("mDNS_Register_internal: TTL %X should be 1 - 0x7FFFFFFF %s", rr->resrec.rroriginalttl, ARDisplayString(m, rr)); return(mStatus_BadParamErr); } if (!rr->resrec.RecordType) { LogMsg("mDNS_Register_internal: RecordType must be non-zero %s", ARDisplayString(m, rr)); return(mStatus_BadParamErr); } if (m->ShutdownTime) { LogMsg("mDNS_Register_internal: Shutting down, can't register %s", ARDisplayString(m, rr)); return(mStatus_ServiceNotRunning); } if (m->DivertMulticastAdvertisements && !AuthRecord_uDNS(rr)) { mDNSInterfaceID previousID = rr->resrec.InterfaceID; if (rr->resrec.InterfaceID == mDNSInterface_Any || rr->resrec.InterfaceID == mDNSInterface_P2P) { rr->resrec.InterfaceID = mDNSInterface_LocalOnly; rr->ARType = AuthRecordLocalOnly; } if (rr->resrec.InterfaceID != mDNSInterface_LocalOnly) { NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID); if (intf && !intf->Advertise){ rr->resrec.InterfaceID = mDNSInterface_LocalOnly; rr->ARType = AuthRecordLocalOnly; } } if (rr->resrec.InterfaceID != previousID) LogInfo("mDNS_Register_internal: Diverting record to local-only %s", ARDisplayString(m, rr)); } if (RRLocalOnly(rr)) { if (CheckAuthSameRecord(&m->rrauth, rr)) { LogMsg("mDNS_Register_internal: ERROR!! Tried to register LocalOnly AuthRecord %p %##s (%s) that's already in the list", rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); return(mStatus_AlreadyRegistered); } } else { while (*p && *p != rr) p=&(*p)->next; if (*p) { LogMsg("mDNS_Register_internal: ERROR!! Tried to register AuthRecord %p %##s (%s) that's already in the list", rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); return(mStatus_AlreadyRegistered); } } while (*d && *d != rr) d=&(*d)->next; if (*d) { LogMsg("mDNS_Register_internal: ERROR!! Tried to register AuthRecord %p %##s (%s) that's already in the Duplicate list", rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); return(mStatus_AlreadyRegistered); } if (rr->DependentOn) { if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified; else { LogMsg("mDNS_Register_internal: ERROR! %##s (%s): rr->DependentOn && RecordType != kDNSRecordTypeUnique", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); return(mStatus_Invalid); } if (!(rr->DependentOn->resrec.RecordType & (kDNSRecordTypeUnique | kDNSRecordTypeVerified | kDNSRecordTypeKnownUnique))) { LogMsg("mDNS_Register_internal: ERROR! %##s (%s): rr->DependentOn->RecordType bad type %X", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->DependentOn->resrec.RecordType); return(mStatus_Invalid); } } // If this resource record is referencing a specific interface, make sure it exists. // Skip checks for LocalOnly and P2P as they are not valid InterfaceIDs. Also, for scoped // entries in /etc/hosts skip that check as that interface may not be valid at this time. if (rr->resrec.InterfaceID && rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P) { NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID); if (!intf) { debugf("mDNS_Register_internal: Bogus InterfaceID %p in resource record", rr->resrec.InterfaceID); return(mStatus_BadReferenceErr); } } rr->next = mDNSNULL; // Field Group 1: The actual information pertaining to this resource record // Set up by client prior to call // Field Group 2: Persistent metadata for Authoritative Records // rr->Additional1 = set to mDNSNULL in mDNS_SetupResourceRecord; may be overridden by client // rr->Additional2 = set to mDNSNULL in mDNS_SetupResourceRecord; may be overridden by client // rr->DependentOn = set to mDNSNULL in mDNS_SetupResourceRecord; may be overridden by client // rr->RRSet = set to mDNSNULL in mDNS_SetupResourceRecord; may be overridden by client // rr->Callback = already set in mDNS_SetupResourceRecord // rr->Context = already set in mDNS_SetupResourceRecord // rr->RecordType = already set in mDNS_SetupResourceRecord // rr->HostTarget = set to mDNSfalse in mDNS_SetupResourceRecord; may be overridden by client // rr->AllowRemoteQuery = set to mDNSfalse in mDNS_SetupResourceRecord; may be overridden by client // Make sure target is not uninitialized data, or we may crash writing debugging log messages if (rr->AutoTarget && target) target->c[0] = 0; // Field Group 3: Transient state for Authoritative Records rr->Acknowledged = mDNSfalse; rr->ProbeCount = DefaultProbeCountForRecordType(rr->resrec.RecordType); rr->AnnounceCount = InitialAnnounceCount; rr->RequireGoodbye = mDNSfalse; rr->AnsweredLocalQ = mDNSfalse; rr->IncludeInProbe = mDNSfalse; rr->ImmedUnicast = mDNSfalse; rr->SendNSECNow = mDNSNULL; rr->ImmedAnswer = mDNSNULL; rr->ImmedAdditional = mDNSNULL; rr->SendRNow = mDNSNULL; rr->v4Requester = zerov4Addr; rr->v6Requester = zerov6Addr; rr->NextResponse = mDNSNULL; rr->NR_AnswerTo = mDNSNULL; rr->NR_AdditionalTo = mDNSNULL; if (!rr->AutoTarget) InitializeLastAPTime(m, rr); // rr->LastAPTime = Set for us in InitializeLastAPTime() // rr->LastMCTime = Set for us in InitializeLastAPTime() // rr->LastMCInterface = Set for us in InitializeLastAPTime() rr->NewRData = mDNSNULL; rr->newrdlength = 0; rr->UpdateCallback = mDNSNULL; rr->UpdateCredits = kMaxUpdateCredits; rr->NextUpdateCredit = 0; rr->UpdateBlocked = 0; // For records we're holding as proxy (except reverse-mapping PTR records) two announcements is sufficient if (rr->WakeUp.HMAC.l[0] && !rr->AddressProxy.type) rr->AnnounceCount = 2; // Field Group 4: Transient uDNS state for Authoritative Records rr->state = regState_Zero; rr->uselease = 0; rr->expire = 0; rr->Private = 0; rr->updateid = zeroID; rr->zone = rr->resrec.name; rr->nta = mDNSNULL; rr->tcp = mDNSNULL; rr->OrigRData = 0; rr->OrigRDLen = 0; rr->InFlightRData = 0; rr->InFlightRDLen = 0; rr->QueuedRData = 0; rr->QueuedRDLen = 0; //mDNSPlatformMemZero(&rr->NATinfo, sizeof(rr->NATinfo)); // We should be recording the actual internal port for this service record here. Once we initiate our NAT mapping // request we'll subsequently overwrite srv.port with the allocated external NAT port -- potentially multiple // times with different values if the external NAT port changes during the lifetime of the service registration. //if (rr->resrec.rrtype == kDNSType_SRV) rr->NATinfo.IntPort = rr->resrec.rdata->u.srv.port; // rr->resrec.interface = already set in mDNS_SetupResourceRecord // rr->resrec.name->c = MUST be set by client // rr->resrec.rrtype = already set in mDNS_SetupResourceRecord // rr->resrec.rrclass = already set in mDNS_SetupResourceRecord // rr->resrec.rroriginalttl = already set in mDNS_SetupResourceRecord // rr->resrec.rdata = MUST be set by client, unless record type is CNAME or PTR and rr->HostTarget is set // BIND named (name daemon) doesn't allow TXT records with zero-length rdata. This is strictly speaking correct, // since RFC 1035 specifies a TXT record as "One or more s", not "Zero or more s". // Since some legacy apps try to create zero-length TXT records, we'll silently correct it here. if (rr->resrec.rrtype == kDNSType_TXT && rr->resrec.rdlength == 0) { rr->resrec.rdlength = 1; rr->resrec.rdata->u.txt.c[0] = 0; } if (rr->AutoTarget) { SetTargetToHostName(m, rr); // Also sets rdlength and rdestimate for us, and calls InitializeLastAPTime(); #ifndef UNICAST_DISABLED // If we have no target record yet, SetTargetToHostName will set rr->state == regState_NoTarget // In this case we leave the record half-formed in the list, and later we'll remove it from the list and re-add it properly. if (rr->state == regState_NoTarget) { // Initialize the target so that we don't crash while logging etc. domainname *tar = GetRRDomainNameTarget(&rr->resrec); if (tar) tar->c[0] = 0; LogInfo("mDNS_Register_internal: record %s in NoTarget state", ARDisplayString(m, rr)); } #endif } else { rr->resrec.rdlength = GetRDLength(&rr->resrec, mDNSfalse); rr->resrec.rdestimate = GetRDLength(&rr->resrec, mDNStrue); } if (!ValidateDomainName(rr->resrec.name)) { LogMsg("Attempt to register record with invalid name: %s", ARDisplayString(m, rr)); return(mStatus_Invalid); } // Don't do this until *after* we've set rr->resrec.rdlength if (!ValidateRData(rr->resrec.rrtype, rr->resrec.rdlength, rr->resrec.rdata)) { LogMsg("Attempt to register record with invalid rdata: %s", ARDisplayString(m, rr)); return(mStatus_Invalid); } rr->resrec.namehash = DomainNameHashValue(rr->resrec.name); rr->resrec.rdatahash = target ? DomainNameHashValue(target) : RDataHashValue(&rr->resrec); if (RRLocalOnly(rr)) { // If this is supposed to be unique, make sure we don't have any name conflicts. // If we found a conflict, we may still want to insert the record in the list but mark it appropriately // (kDNSRecordTypeDeregistering) so that we deliver RMV events to the application. But this causes more // complications and not clear whether there are any benefits. See rdar:9304275 for details. // Hence, just bail out. if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) { if (CheckAuthRecordConflict(&m->rrauth, rr)) { LogInfo("mDNS_Register_internal: Name conflict %s (%p), InterfaceID %p", ARDisplayString(m, rr), rr, rr->resrec.InterfaceID); return mStatus_NameConflict; } } } // For uDNS records, we don't support duplicate checks at this time. #ifndef UNICAST_DISABLED if (AuthRecord_uDNS(rr)) { if (!m->NewLocalRecords) m->NewLocalRecords = rr; // When we called SetTargetToHostName, it may have caused mDNS_Register_internal to be re-entered, appending new // records to the list, so we now need to update p to advance to the new end to the list before appending our new record. // Note that for AutoTunnel this should never happen, but this check makes the code future-proof. while (*p) p=&(*p)->next; *p = rr; if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified; rr->ProbeCount = 0; rr->AnnounceCount = 0; if (rr->state != regState_NoTarget) ActivateUnicastRegistration(m, rr); return(mStatus_NoError); // <--- Note: For unicast records, code currently bails out at this point } #endif // Now that we've finished building our new record, make sure it's not identical to one we already have if (RRLocalOnly(rr)) { rr->ProbeCount = 0; rr->AnnounceCount = 0; r = CheckAuthIdenticalRecord(&m->rrauth, rr); } else { for (r = m->ResourceRecords; r; r=r->next) if (RecordIsLocalDuplicate(r, rr)) { if (r->resrec.RecordType == kDNSRecordTypeDeregistering) r->AnnounceCount = 0; else break; } } if (r) { debugf("mDNS_Register_internal:Adding to duplicate list %s", ARDisplayString(m,rr)); *d = rr; // If the previous copy of this record is already verified unique, // then indicate that we should move this record promptly to kDNSRecordTypeUnique state. // Setting ProbeCount to zero will cause SendQueries() to advance this record to // kDNSRecordTypeVerified state and call the client callback at the next appropriate time. if (rr->resrec.RecordType == kDNSRecordTypeUnique && r->resrec.RecordType == kDNSRecordTypeVerified) rr->ProbeCount = 0; } else { debugf("mDNS_Register_internal: Adding to active record list %s", ARDisplayString(m,rr)); if (RRLocalOnly(rr)) { AuthGroup *ag; ag = InsertAuthRecord(m, &m->rrauth, rr); if (ag && !ag->NewLocalOnlyRecords) { m->NewLocalOnlyRecords = mDNStrue; ag->NewLocalOnlyRecords = rr; } // No probing for LocalOnly records, Acknowledge them right away if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified; AcknowledgeRecord(m, rr); return(mStatus_NoError); } else { if (!m->NewLocalRecords) m->NewLocalRecords = rr; *p = rr; } } if (!AuthRecord_uDNS(rr)) // This check is superfluous, given that for unicast records we (currently) bail out above { // For records that are not going to probe, acknowledge them right away if (rr->resrec.RecordType != kDNSRecordTypeUnique && rr->resrec.RecordType != kDNSRecordTypeDeregistering) AcknowledgeRecord(m, rr); // Adding a record may affect whether or not we should sleep mDNS_UpdateAllowSleep(m); } return(mStatus_NoError); } mDNSlocal void RecordProbeFailure(mDNS *const m, const AuthRecord *const rr) { m->ProbeFailTime = m->timenow; m->NumFailedProbes++; // If we've had fifteen or more probe failures, rate-limit to one every five seconds. // If a bunch of hosts have all been configured with the same name, then they'll all // conflict and run through the same series of names: name-2, name-3, name-4, etc., // up to name-10. After that they'll start adding random increments in the range 1-100, // so they're more likely to branch out in the available namespace and settle on a set of // unique names quickly. If after five more tries the host is still conflicting, then we // may have a serious problem, so we start rate-limiting so we don't melt down the network. if (m->NumFailedProbes >= 15) { m->SuppressProbes = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 5); LogMsg("Excessive name conflicts (%lu) for %##s (%s); rate limiting in effect", m->NumFailedProbes, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); } } mDNSlocal void CompleteRDataUpdate(mDNS *const m, AuthRecord *const rr) { RData *OldRData = rr->resrec.rdata; mDNSu16 OldRDLen = rr->resrec.rdlength; SetNewRData(&rr->resrec, rr->NewRData, rr->newrdlength); // Update our rdata rr->NewRData = mDNSNULL; // Clear the NewRData pointer ... if (rr->UpdateCallback) rr->UpdateCallback(m, rr, OldRData, OldRDLen); // ... and let the client know } // Note: mDNS_Deregister_internal can call a user callback, which may change the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. // Exported so uDNS.c can call this mDNSexport mStatus mDNS_Deregister_internal(mDNS *const m, AuthRecord *const rr, mDNS_Dereg_type drt) { AuthRecord *r2; mDNSu8 RecordType = rr->resrec.RecordType; AuthRecord **p = &m->ResourceRecords; // Find this record in our list of active records mDNSBool dupList = mDNSfalse; if (RRLocalOnly(rr)) { AuthGroup *a; AuthGroup **ag = &a; AuthRecord **rp; const mDNSu32 slot = AuthHashSlot(rr->resrec.name); a = AuthGroupForRecord(&m->rrauth, slot, &rr->resrec); if (!a) return mDNSfalse; rp = &(*ag)->members; while (*rp && *rp != rr) rp=&(*rp)->next; p = rp; } else { while (*p && *p != rr) p=&(*p)->next; } if (*p) { // We found our record on the main list. See if there are any duplicates that need special handling. if (drt == mDNS_Dereg_conflict) // If this was a conflict, see that all duplicates get the same treatment { // Scan for duplicates of rr, and mark them for deregistration at the end of this routine, after we've finished // deregistering rr. We need to do this scan *before* we give the client the chance to free and reuse the rr memory. for (r2 = m->DuplicateRecords; r2; r2=r2->next) if (RecordIsLocalDuplicate(r2, rr)) r2->ProbeCount = 0xFF; } else { // Before we delete the record (and potentially send a goodbye packet) // first see if we have a record on the duplicate list ready to take over from it. AuthRecord **d = &m->DuplicateRecords; while (*d && !RecordIsLocalDuplicate(*d, rr)) d=&(*d)->next; if (*d) { AuthRecord *dup = *d; debugf("mDNS_Register_internal: Duplicate record %p taking over from %p %##s (%s)", dup, rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); *d = dup->next; // Cut replacement record from DuplicateRecords list if (RRLocalOnly(rr)) { dup->next = mDNSNULL; if (!InsertAuthRecord(m, &m->rrauth, dup)) LogMsg("mDNS_Deregister_internal: ERROR!! cannot insert %s", ARDisplayString(m, dup)); } else { dup->next = rr->next; // And then... rr->next = dup; // ... splice it in right after the record we're about to delete } dup->resrec.RecordType = rr->resrec.RecordType; dup->ProbeCount = rr->ProbeCount; dup->AnnounceCount = rr->AnnounceCount; dup->RequireGoodbye = rr->RequireGoodbye; dup->AnsweredLocalQ = rr->AnsweredLocalQ; dup->ImmedAnswer = rr->ImmedAnswer; dup->ImmedUnicast = rr->ImmedUnicast; dup->ImmedAdditional = rr->ImmedAdditional; dup->v4Requester = rr->v4Requester; dup->v6Requester = rr->v6Requester; dup->ThisAPInterval = rr->ThisAPInterval; dup->LastAPTime = rr->LastAPTime; dup->LastMCTime = rr->LastMCTime; dup->LastMCInterface = rr->LastMCInterface; dup->Private = rr->Private; dup->state = rr->state; rr->RequireGoodbye = mDNSfalse; rr->AnsweredLocalQ = mDNSfalse; } } } else { // We didn't find our record on the main list; try the DuplicateRecords list instead. p = &m->DuplicateRecords; while (*p && *p != rr) p=&(*p)->next; // If we found our record on the duplicate list, then make sure we don't send a goodbye for it if (*p) { rr->RequireGoodbye = mDNSfalse; dupList = mDNStrue; } if (*p) debugf("mDNS_Deregister_internal: Deleting DuplicateRecord %p %##s (%s)", rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); } if (!*p) { // No need to log an error message if we already know this is a potentially repeated deregistration if (drt != mDNS_Dereg_repeat) LogMsg("mDNS_Deregister_internal: Record %p not found in list %s", rr, ARDisplayString(m,rr)); return(mStatus_BadReferenceErr); } // If this is a shared record and we've announced it at least once, // we need to retract that announcement before we delete the record // If this is a record (including mDNSInterface_LocalOnly records) for which we've given local-only answers then // it's tempting to just do "AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse)" here, but that would not not be safe. // The AnswerAllLocalQuestionsWithLocalAuthRecord routine walks the question list invoking client callbacks, using the "m->CurrentQuestion" // mechanism to cope with the client callback modifying the question list while that's happening. // However, mDNS_Deregister could have been called from a client callback (e.g. from the domain enumeration callback FoundDomain) // which means that the "m->CurrentQuestion" mechanism is already in use to protect that list, so we can't use it twice. // More generally, if we invoke callbacks from within a client callback, then those callbacks could deregister other // records, thereby invoking yet more callbacks, without limit. // The solution is to defer delivering the "Remove" events until mDNS_Execute time, just like we do for sending // actual goodbye packets. #ifndef UNICAST_DISABLED if (AuthRecord_uDNS(rr)) { if (rr->RequireGoodbye) { if (rr->tcp) { DisposeTCPConn(rr->tcp); rr->tcp = mDNSNULL; } rr->resrec.RecordType = kDNSRecordTypeDeregistering; m->LocalRemoveEvents = mDNStrue; uDNS_DeregisterRecord(m, rr); // At this point unconditionally we bail out // Either uDNS_DeregisterRecord will have completed synchronously, and called CompleteDeregistration, // which calls us back here with RequireGoodbye set to false, or it will have initiated the deregistration // process and will complete asynchronously. Either way we don't need to do anything more here. return(mStatus_NoError); } // Sometimes the records don't complete proper deregistration i.e., don't wait for a response // from the server. In that case, if the records have been part of a group update, clear the // state here. Some recors e.g., AutoTunnel gets reused without ever being completely initialized rr->updateid = zeroID; // We defer cleaning up NAT state only after sending goodbyes. This is important because // RecordRegistrationGotZoneData guards against creating NAT state if clientContext is non-NULL. // This happens today when we turn on/off interface where we get multiple network transitions // and RestartRecordGetZoneData triggers re-registration of the resource records even though // they may be in Registered state which causes NAT information to be setup multiple times. Defering // the cleanup here keeps clientContext non-NULL and hence prevents that. Note that cleaning up // NAT state here takes care of the case where we did not send goodbyes at all. if (rr->NATinfo.clientContext) { mDNS_StopNATOperation_internal(m, &rr->NATinfo); rr->NATinfo.clientContext = mDNSNULL; } if (rr->nta) { CancelGetZoneData(m, rr->nta); rr->nta = mDNSNULL; } if (rr->tcp) { DisposeTCPConn(rr->tcp); rr->tcp = mDNSNULL; } } #endif // UNICAST_DISABLED if (RecordType == kDNSRecordTypeUnregistered) LogMsg("mDNS_Deregister_internal: %s already marked kDNSRecordTypeUnregistered", ARDisplayString(m, rr)); else if (RecordType == kDNSRecordTypeDeregistering) { LogMsg("mDNS_Deregister_internal: %s already marked kDNSRecordTypeDeregistering", ARDisplayString(m, rr)); return(mStatus_BadReferenceErr); } // Local-only questions don't get remove events for unique records // We may want to consider changing this code so that we generate local-only question "rmv" // events (and maybe goodbye packets too) for unique records as well as for shared records // Note: If we change the logic for this "if" statement, need to ensure that the code in // CompleteDeregistration() sets the appropriate state variables to gaurantee that "else" // clause will execute here and the record will be cut from the list. if (rr->WakeUp.HMAC.l[0] || (RecordType == kDNSRecordTypeShared && (rr->RequireGoodbye || rr->AnsweredLocalQ))) { verbosedebugf("mDNS_Deregister_internal: Starting deregistration for %s", ARDisplayString(m, rr)); rr->resrec.RecordType = kDNSRecordTypeDeregistering; rr->resrec.rroriginalttl = 0; rr->AnnounceCount = rr->WakeUp.HMAC.l[0] ? WakeupCount : (drt == mDNS_Dereg_rapid) ? 1 : GoodbyeCount; rr->ThisAPInterval = mDNSPlatformOneSecond * 2; rr->LastAPTime = m->timenow - rr->ThisAPInterval; m->LocalRemoveEvents = mDNStrue; if (m->NextScheduledResponse - (m->timenow + mDNSPlatformOneSecond/10) >= 0) m->NextScheduledResponse = (m->timenow + mDNSPlatformOneSecond/10); } else { if (!dupList && RRLocalOnly(rr)) { AuthGroup *ag = RemoveAuthRecord(m, &m->rrauth, rr); if (ag->NewLocalOnlyRecords == rr) ag->NewLocalOnlyRecords = rr->next; } else { *p = rr->next; // Cut this record from the list if (m->NewLocalRecords == rr) m->NewLocalRecords = rr->next; } // If someone is about to look at this, bump the pointer forward if (m->CurrentRecord == rr) m->CurrentRecord = rr->next; rr->next = mDNSNULL; // Should we generate local remove events here? // i.e. something like: // if (rr->AnsweredLocalQ) { AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); rr->AnsweredLocalQ = mDNSfalse; } verbosedebugf("mDNS_Deregister_internal: Deleting record for %s", ARDisplayString(m, rr)); rr->resrec.RecordType = kDNSRecordTypeUnregistered; if ((drt == mDNS_Dereg_conflict || drt == mDNS_Dereg_repeat) && RecordType == kDNSRecordTypeShared) debugf("mDNS_Deregister_internal: Cannot have a conflict on a shared record! %##s (%s)", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); // If we have an update queued up which never executed, give the client a chance to free that memory if (rr->NewRData) CompleteRDataUpdate(m, rr); // Update our rdata, clear the NewRData pointer, and return memory to the client // CAUTION: MUST NOT do anything more with rr after calling rr->Callback(), because the client's callback function // is allowed to do anything, including starting/stopping queries, registering/deregistering records, etc. // In this case the likely client action to the mStatus_MemFree message is to free the memory, // so any attempt to touch rr after this is likely to lead to a crash. if (drt != mDNS_Dereg_conflict) { mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback LogInfo("mDNS_Deregister_internal: mStatus_MemFree for %s", ARDisplayString(m, rr)); if (rr->RecordCallback) rr->RecordCallback(m, rr, mStatus_MemFree); // MUST NOT touch rr after this mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again } else { RecordProbeFailure(m, rr); mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback if (rr->RecordCallback) rr->RecordCallback(m, rr, mStatus_NameConflict); // MUST NOT touch rr after this mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again // Now that we've finished deregistering rr, check our DuplicateRecords list for any that we marked previously. // Note that with all the client callbacks going on, by the time we get here all the // records we marked may have been explicitly deregistered by the client anyway. r2 = m->DuplicateRecords; while (r2) { if (r2->ProbeCount != 0xFF) r2 = r2->next; else { mDNS_Deregister_internal(m, r2, mDNS_Dereg_conflict); r2 = m->DuplicateRecords; } } } } mDNS_UpdateAllowSleep(m); return(mStatus_NoError); } // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Packet Sending Functions #endif mDNSlocal void AddRecordToResponseList(AuthRecord ***nrpp, AuthRecord *rr, AuthRecord *add) { if (rr->NextResponse == mDNSNULL && *nrpp != &rr->NextResponse) { **nrpp = rr; // NR_AdditionalTo must point to a record with NR_AnswerTo set (and not NR_AdditionalTo) // If 'add' does not meet this requirement, then follow its NR_AdditionalTo pointer to a record that does // The referenced record will definitely be acceptable (by recursive application of this rule) if (add && add->NR_AdditionalTo) add = add->NR_AdditionalTo; rr->NR_AdditionalTo = add; *nrpp = &rr->NextResponse; } debugf("AddRecordToResponseList: %##s (%s) already in list", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); } mDNSlocal void AddAdditionalsToResponseList(mDNS *const m, AuthRecord *ResponseRecords, AuthRecord ***nrpp, const mDNSInterfaceID InterfaceID) { AuthRecord *rr, *rr2; for (rr=ResponseRecords; rr; rr=rr->NextResponse) // For each record we plan to put { // (Note: This is an "if", not a "while". If we add a record, we'll find it again // later in the "for" loop, and we will follow further "additional" links then.) if (rr->Additional1 && ResourceRecordIsValidInterfaceAnswer(rr->Additional1, InterfaceID)) AddRecordToResponseList(nrpp, rr->Additional1, rr); if (rr->Additional2 && ResourceRecordIsValidInterfaceAnswer(rr->Additional2, InterfaceID)) AddRecordToResponseList(nrpp, rr->Additional2, rr); // For SRV records, automatically add the Address record(s) for the target host if (rr->resrec.rrtype == kDNSType_SRV) { for (rr2=m->ResourceRecords; rr2; rr2=rr2->next) // Scan list of resource records if (RRTypeIsAddressType(rr2->resrec.rrtype) && // For all address records (A/AAAA) ... ResourceRecordIsValidInterfaceAnswer(rr2, InterfaceID) && // ... which are valid for answer ... rr->resrec.rdatahash == rr2->resrec.namehash && // ... whose name is the name of the SRV target SameDomainName(&rr->resrec.rdata->u.srv.target, rr2->resrec.name)) AddRecordToResponseList(nrpp, rr2, rr); } else if (RRTypeIsAddressType(rr->resrec.rrtype)) // For A or AAAA, put counterpart as additional { for (rr2=m->ResourceRecords; rr2; rr2=rr2->next) // Scan list of resource records if (RRTypeIsAddressType(rr2->resrec.rrtype) && // For all address records (A/AAAA) ... ResourceRecordIsValidInterfaceAnswer(rr2, InterfaceID) && // ... which are valid for answer ... rr->resrec.namehash == rr2->resrec.namehash && // ... and have the same name SameDomainName(rr->resrec.name, rr2->resrec.name)) AddRecordToResponseList(nrpp, rr2, rr); } else if (rr->resrec.rrtype == kDNSType_PTR) // For service PTR, see if we want to add DeviceInfo record { if (ResourceRecordIsValidInterfaceAnswer(&m->DeviceInfo, InterfaceID) && SameDomainLabel(rr->resrec.rdata->u.name.c, m->DeviceInfo.resrec.name->c)) AddRecordToResponseList(nrpp, &m->DeviceInfo, rr); } } } mDNSlocal void SendDelayedUnicastResponse(mDNS *const m, const mDNSAddr *const dest, const mDNSInterfaceID InterfaceID) { AuthRecord *rr; AuthRecord *ResponseRecords = mDNSNULL; AuthRecord **nrp = &ResponseRecords; NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID); // Make a list of all our records that need to be unicast to this destination for (rr = m->ResourceRecords; rr; rr=rr->next) { // If we find we can no longer unicast this answer, clear ImmedUnicast if (rr->ImmedAnswer == mDNSInterfaceMark || mDNSSameIPv4Address(rr->v4Requester, onesIPv4Addr) || mDNSSameIPv6Address(rr->v6Requester, onesIPv6Addr) ) rr->ImmedUnicast = mDNSfalse; if (rr->ImmedUnicast && rr->ImmedAnswer == InterfaceID) { if ((dest->type == mDNSAddrType_IPv4 && mDNSSameIPv4Address(rr->v4Requester, dest->ip.v4)) || (dest->type == mDNSAddrType_IPv6 && mDNSSameIPv6Address(rr->v6Requester, dest->ip.v6))) { rr->ImmedAnswer = mDNSNULL; // Clear the state fields rr->ImmedUnicast = mDNSfalse; rr->v4Requester = zerov4Addr; rr->v6Requester = zerov6Addr; // Only sent records registered for P2P over P2P interfaces if (intf && !mDNSPlatformValidRecordForInterface(rr, intf)) { LogInfo("SendDelayedUnicastResponse: Not sending %s, on %s", ARDisplayString(m, rr), InterfaceNameForID(m, InterfaceID)); continue; } if (rr->NextResponse == mDNSNULL && nrp != &rr->NextResponse) // rr->NR_AnswerTo { rr->NR_AnswerTo = (mDNSu8*)~0; *nrp = rr; nrp = &rr->NextResponse; } } } } AddAdditionalsToResponseList(m, ResponseRecords, &nrp, InterfaceID); while (ResponseRecords) { mDNSu8 *responseptr = m->omsg.data; mDNSu8 *newptr; InitializeDNSMessage(&m->omsg.h, zeroID, ResponseFlags); // Put answers in the packet while (ResponseRecords && ResponseRecords->NR_AnswerTo) { rr = ResponseRecords; if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the cache flush bit so PutResourceRecord will set it newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAnswers, &rr->resrec); rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear cache flush bit back to normal state if (!newptr && m->omsg.h.numAnswers) break; // If packet full, send it now if (newptr) responseptr = newptr; ResponseRecords = rr->NextResponse; rr->NextResponse = mDNSNULL; rr->NR_AnswerTo = mDNSNULL; rr->NR_AdditionalTo = mDNSNULL; rr->RequireGoodbye = mDNStrue; } // Add additionals, if there's space while (ResponseRecords && !ResponseRecords->NR_AnswerTo) { rr = ResponseRecords; if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the cache flush bit so PutResourceRecord will set it newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAdditionals, &rr->resrec); rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear cache flush bit back to normal state if (newptr) responseptr = newptr; if (newptr && m->omsg.h.numAnswers) rr->RequireGoodbye = mDNStrue; else if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->ImmedAnswer = mDNSInterfaceMark; ResponseRecords = rr->NextResponse; rr->NextResponse = mDNSNULL; rr->NR_AnswerTo = mDNSNULL; rr->NR_AdditionalTo = mDNSNULL; } if (m->omsg.h.numAnswers) mDNSSendDNSMessage(m, &m->omsg, responseptr, InterfaceID, mDNSNULL, dest, MulticastDNSPort, mDNSNULL, mDNSNULL); } } // CompleteDeregistration guarantees that on exit the record will have been cut from the m->ResourceRecords list // and the client's mStatus_MemFree callback will have been invoked mDNSexport void CompleteDeregistration(mDNS *const m, AuthRecord *rr) { LogInfo("CompleteDeregistration: called for Resource record %s", ARDisplayString(m, rr)); // Clearing rr->RequireGoodbye signals mDNS_Deregister_internal() that // it should go ahead and immediately dispose of this registration rr->resrec.RecordType = kDNSRecordTypeShared; rr->RequireGoodbye = mDNSfalse; rr->WakeUp.HMAC = zeroEthAddr; if (rr->AnsweredLocalQ) { AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); rr->AnsweredLocalQ = mDNSfalse; } mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); // Don't touch rr after this } // DiscardDeregistrations is used on shutdown and sleep to discard (forcibly and immediately) // any deregistering records that remain in the m->ResourceRecords list. // DiscardDeregistrations calls mDNS_Deregister_internal which can call a user callback, // which may change the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSlocal void DiscardDeregistrations(mDNS *const m) { if (m->CurrentRecord) LogMsg("DiscardDeregistrations ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); m->CurrentRecord = m->ResourceRecords; while (m->CurrentRecord) { AuthRecord *rr = m->CurrentRecord; if (!AuthRecord_uDNS(rr) && rr->resrec.RecordType == kDNSRecordTypeDeregistering) CompleteDeregistration(m, rr); // Don't touch rr after this else m->CurrentRecord = rr->next; } } mDNSlocal mStatus GetLabelDecimalValue(const mDNSu8 *const src, mDNSu8 *dst) { int i, val = 0; if (src[0] < 1 || src[0] > 3) return(mStatus_Invalid); for (i=1; i<=src[0]; i++) { if (src[i] < '0' || src[i] > '9') return(mStatus_Invalid); val = val * 10 + src[i] - '0'; } if (val > 255) return(mStatus_Invalid); *dst = (mDNSu8)val; return(mStatus_NoError); } mDNSlocal mStatus GetIPv4FromName(mDNSAddr *const a, const domainname *const name) { int skip = CountLabels(name) - 6; if (skip < 0) { LogMsg("GetIPFromName: Need six labels in IPv4 reverse mapping name %##s", name); return mStatus_Invalid; } if (GetLabelDecimalValue(SkipLeadingLabels(name, skip+3)->c, &a->ip.v4.b[0]) || GetLabelDecimalValue(SkipLeadingLabels(name, skip+2)->c, &a->ip.v4.b[1]) || GetLabelDecimalValue(SkipLeadingLabels(name, skip+1)->c, &a->ip.v4.b[2]) || GetLabelDecimalValue(SkipLeadingLabels(name, skip+0)->c, &a->ip.v4.b[3])) return mStatus_Invalid; a->type = mDNSAddrType_IPv4; return(mStatus_NoError); } #define HexVal(X) ( ((X) >= '0' && (X) <= '9') ? ((X) - '0' ) : \ ((X) >= 'A' && (X) <= 'F') ? ((X) - 'A' + 10) : \ ((X) >= 'a' && (X) <= 'f') ? ((X) - 'a' + 10) : -1) mDNSlocal mStatus GetIPv6FromName(mDNSAddr *const a, const domainname *const name) { int i, h, l; const domainname *n; int skip = CountLabels(name) - 34; if (skip < 0) { LogMsg("GetIPFromName: Need 34 labels in IPv6 reverse mapping name %##s", name); return mStatus_Invalid; } n = SkipLeadingLabels(name, skip); for (i=0; i<16; i++) { if (n->c[0] != 1) return mStatus_Invalid; l = HexVal(n->c[1]); n = (const domainname *)(n->c + 2); if (n->c[0] != 1) return mStatus_Invalid; h = HexVal(n->c[1]); n = (const domainname *)(n->c + 2); if (l<0 || h<0) return mStatus_Invalid; a->ip.v6.b[15-i] = (mDNSu8)((h << 4) | l); } a->type = mDNSAddrType_IPv6; return(mStatus_NoError); } mDNSlocal mDNSs32 ReverseMapDomainType(const domainname *const name) { int skip = CountLabels(name) - 2; if (skip >= 0) { const domainname *suffix = SkipLeadingLabels(name, skip); if (SameDomainName(suffix, (const domainname*)"\x7" "in-addr" "\x4" "arpa")) return mDNSAddrType_IPv4; if (SameDomainName(suffix, (const domainname*)"\x3" "ip6" "\x4" "arpa")) return mDNSAddrType_IPv6; } return(mDNSAddrType_None); } mDNSlocal void SendARP(mDNS *const m, const mDNSu8 op, const AuthRecord *const rr, const mDNSv4Addr *const spa, const mDNSEthAddr *const tha, const mDNSv4Addr *const tpa, const mDNSEthAddr *const dst) { int i; mDNSu8 *ptr = m->omsg.data; NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID); if (!intf) { LogMsg("SendARP: No interface with InterfaceID %p found %s", rr->resrec.InterfaceID, ARDisplayString(m,rr)); return; } // 0x00 Destination address for (i=0; i<6; i++) *ptr++ = dst->b[i]; // 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us) for (i=0; i<6; i++) *ptr++ = intf->MAC.b[0]; // 0x0C ARP Ethertype (0x0806) *ptr++ = 0x08; *ptr++ = 0x06; // 0x0E ARP header *ptr++ = 0x00; *ptr++ = 0x01; // Hardware address space; Ethernet = 1 *ptr++ = 0x08; *ptr++ = 0x00; // Protocol address space; IP = 0x0800 *ptr++ = 6; // Hardware address length *ptr++ = 4; // Protocol address length *ptr++ = 0x00; *ptr++ = op; // opcode; Request = 1, Response = 2 // 0x16 Sender hardware address (our MAC address) for (i=0; i<6; i++) *ptr++ = intf->MAC.b[i]; // 0x1C Sender protocol address for (i=0; i<4; i++) *ptr++ = spa->b[i]; // 0x20 Target hardware address for (i=0; i<6; i++) *ptr++ = tha->b[i]; // 0x26 Target protocol address for (i=0; i<4; i++) *ptr++ = tpa->b[i]; // 0x2A Total ARP Packet length 42 bytes mDNSPlatformSendRawPacket(m->omsg.data, ptr, rr->resrec.InterfaceID); } mDNSlocal mDNSu16 CheckSum(const void *const data, mDNSs32 length, mDNSu32 sum) { const mDNSu16 *ptr = data; while (length > 0) { length -= 2; sum += *ptr++; } sum = (sum & 0xFFFF) + (sum >> 16); sum = (sum & 0xFFFF) + (sum >> 16); return(sum != 0xFFFF ? sum : 0); } mDNSlocal mDNSu16 IPv6CheckSum(const mDNSv6Addr *const src, const mDNSv6Addr *const dst, const mDNSu8 protocol, const void *const data, const mDNSu32 length) { IPv6PseudoHeader ph; ph.src = *src; ph.dst = *dst; ph.len.b[0] = length >> 24; ph.len.b[1] = length >> 16; ph.len.b[2] = length >> 8; ph.len.b[3] = length; ph.pro.b[0] = 0; ph.pro.b[1] = 0; ph.pro.b[2] = 0; ph.pro.b[3] = protocol; return CheckSum(&ph, sizeof(ph), CheckSum(data, length, 0)); } mDNSlocal void SendNDP(mDNS *const m, const mDNSu8 op, const mDNSu8 flags, const AuthRecord *const rr, const mDNSv6Addr *const spa, const mDNSEthAddr *const tha, const mDNSv6Addr *const tpa, const mDNSEthAddr *const dst) { int i; mDNSOpaque16 checksum; mDNSu8 *ptr = m->omsg.data; // Some recipient hosts seem to ignore Neighbor Solicitations if the IPv6-layer destination address is not the // appropriate IPv6 solicited node multicast address, so we use that IPv6-layer destination address, even though // at the Ethernet-layer we unicast the packet to the intended target, to avoid wasting network bandwidth. const mDNSv6Addr mc = { { 0xFF,0x02,0x00,0x00, 0,0,0,0, 0,0,0,1, 0xFF,tpa->b[0xD],tpa->b[0xE],tpa->b[0xF] } }; const mDNSv6Addr *const v6dst = (op == NDP_Sol) ? &mc : tpa; NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID); if (!intf) { LogMsg("SendNDP: No interface with InterfaceID %p found %s", rr->resrec.InterfaceID, ARDisplayString(m,rr)); return; } // 0x00 Destination address for (i=0; i<6; i++) *ptr++ = dst->b[i]; // Right now we only send Neighbor Solicitations to verify whether the host we're proxying for has gone to sleep yet. // Since we know who we're looking for, we send it via Ethernet-layer unicast, rather than bothering every host on the // link with a pointless link-layer multicast. // Should we want to send traditional Neighbor Solicitations in the future, where we really don't know in advance what // Ethernet-layer address we're looking for, we'll need to send to the appropriate Ethernet-layer multicast address: // *ptr++ = 0x33; // *ptr++ = 0x33; // *ptr++ = 0xFF; // *ptr++ = tpa->b[0xD]; // *ptr++ = tpa->b[0xE]; // *ptr++ = tpa->b[0xF]; // 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us) for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i]; // 0x0C IPv6 Ethertype (0x86DD) *ptr++ = 0x86; *ptr++ = 0xDD; // 0x0E IPv6 header *ptr++ = 0x60; *ptr++ = 0x00; *ptr++ = 0x00; *ptr++ = 0x00; // Version, Traffic Class, Flow Label *ptr++ = 0x00; *ptr++ = 0x20; // Length *ptr++ = 0x3A; // Protocol == ICMPv6 *ptr++ = 0xFF; // Hop Limit // 0x16 Sender IPv6 address for (i=0; i<16; i++) *ptr++ = spa->b[i]; // 0x26 Destination IPv6 address for (i=0; i<16; i++) *ptr++ = v6dst->b[i]; // 0x36 NDP header *ptr++ = op; // 0x87 == Neighbor Solicitation, 0x88 == Neighbor Advertisement *ptr++ = 0x00; // Code *ptr++ = 0x00; *ptr++ = 0x00; // Checksum placeholder (0x38, 0x39) *ptr++ = flags; *ptr++ = 0x00; *ptr++ = 0x00; *ptr++ = 0x00; if (op == NDP_Sol) // Neighbor Solicitation. The NDP "target" is the address we seek. { // 0x3E NDP target. for (i=0; i<16; i++) *ptr++ = tpa->b[i]; // 0x4E Source Link-layer Address // // MUST NOT be included when the source IP address is the unspecified address. // Otherwise, on link layers that have addresses this option MUST be included // in multicast solicitations and SHOULD be included in unicast solicitations. if (!mDNSIPv6AddressIsZero(*spa)) { *ptr++ = NDP_SrcLL; // Option Type 1 == Source Link-layer Address *ptr++ = 0x01; // Option length 1 (in units of 8 octets) for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i]; } } else // Neighbor Advertisement. The NDP "target" is the address we're giving information about. { // 0x3E NDP target. for (i=0; i<16; i++) *ptr++ = spa->b[i]; // 0x4E Target Link-layer Address *ptr++ = NDP_TgtLL; // Option Type 2 == Target Link-layer Address *ptr++ = 0x01; // Option length 1 (in units of 8 octets) for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i]; } // 0x4E or 0x56 Total NDP Packet length 78 or 86 bytes m->omsg.data[0x13] = ptr - &m->omsg.data[0x36]; // Compute actual length checksum.NotAnInteger = ~IPv6CheckSum(spa, v6dst, 0x3A, &m->omsg.data[0x36], m->omsg.data[0x13]); m->omsg.data[0x38] = checksum.b[0]; m->omsg.data[0x39] = checksum.b[1]; mDNSPlatformSendRawPacket(m->omsg.data, ptr, rr->resrec.InterfaceID); } mDNSlocal void SetupOwnerOpt(const mDNS *const m, const NetworkInterfaceInfo *const intf, rdataOPT *const owner) { owner->u.owner.vers = 0; owner->u.owner.seq = m->SleepSeqNum; owner->u.owner.HMAC = m->PrimaryMAC; owner->u.owner.IMAC = intf->MAC; owner->u.owner.password = zeroEthAddr; // Don't try to compute the optlen until *after* we've set up the data fields // Right now the DNSOpt_Owner_Space macro does not depend on the owner->u.owner being set up correctly, but in the future it might owner->opt = kDNSOpt_Owner; owner->optlen = DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) - 4; } mDNSlocal void GrantUpdateCredit(AuthRecord *rr) { if (++rr->UpdateCredits >= kMaxUpdateCredits) rr->NextUpdateCredit = 0; else rr->NextUpdateCredit = NonZeroTime(rr->NextUpdateCredit + kUpdateCreditRefreshInterval); } // Note about acceleration of announcements to facilitate automatic coalescing of // multiple independent threads of announcements into a single synchronized thread: // The announcements in the packet may be at different stages of maturity; // One-second interval, two-second interval, four-second interval, and so on. // After we've put in all the announcements that are due, we then consider // whether there are other nearly-due announcements that are worth accelerating. // To be eligible for acceleration, a record MUST NOT be older (further along // its timeline) than the most mature record we've already put in the packet. // In other words, younger records can have their timelines accelerated to catch up // with their elder bretheren; this narrows the age gap and helps them eventually get in sync. // Older records cannot have their timelines accelerated; this would just widen // the gap between them and their younger bretheren and get them even more out of sync. // Note: SendResponses calls mDNS_Deregister_internal which can call a user callback, which may change // the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSlocal void SendResponses(mDNS *const m) { int pktcount = 0; AuthRecord *rr, *r2; mDNSs32 maxExistingAnnounceInterval = 0; const NetworkInterfaceInfo *intf = GetFirstActiveInterface(m->HostInterfaces); m->NextScheduledResponse = m->timenow + 0x78000000; if (m->SleepState == SleepState_Transferring) RetrySPSRegistrations(m); for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->ImmedUnicast) { mDNSAddr v4 = { mDNSAddrType_IPv4, {{{0}}} }; mDNSAddr v6 = { mDNSAddrType_IPv6, {{{0}}} }; v4.ip.v4 = rr->v4Requester; v6.ip.v6 = rr->v6Requester; if (!mDNSIPv4AddressIsZero(rr->v4Requester)) SendDelayedUnicastResponse(m, &v4, rr->ImmedAnswer); if (!mDNSIPv6AddressIsZero(rr->v6Requester)) SendDelayedUnicastResponse(m, &v6, rr->ImmedAnswer); if (rr->ImmedUnicast) { LogMsg("SendResponses: ERROR: rr->ImmedUnicast still set: %s", ARDisplayString(m, rr)); rr->ImmedUnicast = mDNSfalse; } } // *** // *** 1. Setup: Set the SendRNow and ImmedAnswer fields to indicate which interface(s) the records need to be sent on // *** // Run through our list of records, and decide which ones we're going to announce on all interfaces for (rr = m->ResourceRecords; rr; rr=rr->next) { while (rr->NextUpdateCredit && m->timenow - rr->NextUpdateCredit >= 0) GrantUpdateCredit(rr); if (TimeToAnnounceThisRecord(rr, m->timenow)) { if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) { if (!rr->WakeUp.HMAC.l[0]) { if (rr->AnnounceCount) rr->ImmedAnswer = mDNSInterfaceMark; // Send goodbye packet on all interfaces } else { LogSPS("SendResponses: Sending wakeup %2d for %.6a %s", rr->AnnounceCount-3, &rr->WakeUp.IMAC, ARDisplayString(m, rr)); SendWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.IMAC, &rr->WakeUp.password); for (r2 = rr; r2; r2=r2->next) if (r2->AnnounceCount && r2->resrec.InterfaceID == rr->resrec.InterfaceID && mDNSSameEthAddress(&r2->WakeUp.IMAC, &rr->WakeUp.IMAC)) { // For now we only want to send a single Unsolicited Neighbor Advertisement restoring the address to the original // owner, because these packets can cause some IPv6 stacks to falsely conclude that there's an address conflict. if (r2->AddressProxy.type == mDNSAddrType_IPv6 && r2->AnnounceCount == WakeupCount) { LogSPS("NDP Announcement %2d Releasing traffic for H-MAC %.6a I-MAC %.6a %s", r2->AnnounceCount-3, &r2->WakeUp.HMAC, &r2->WakeUp.IMAC, ARDisplayString(m,r2)); SendNDP(m, NDP_Adv, NDP_Override, r2, &r2->AddressProxy.ip.v6, &r2->WakeUp.IMAC, &AllHosts_v6, &AllHosts_v6_Eth); } r2->LastAPTime = m->timenow; // After 15 wakeups without success (maybe host has left the network) send three goodbyes instead if (--r2->AnnounceCount <= GoodbyeCount) r2->WakeUp.HMAC = zeroEthAddr; } } } else if (ResourceRecordIsValidAnswer(rr)) { if (rr->AddressProxy.type) { rr->AnnounceCount--; rr->ThisAPInterval *= 2; rr->LastAPTime = m->timenow; if (rr->AddressProxy.type == mDNSAddrType_IPv4) { LogSPS("ARP Announcement %2d Capturing traffic for H-MAC %.6a I-MAC %.6a %s", rr->AnnounceCount, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr)); SendARP(m, 1, rr, &rr->AddressProxy.ip.v4, &zeroEthAddr, &rr->AddressProxy.ip.v4, &onesEthAddr); } else if (rr->AddressProxy.type == mDNSAddrType_IPv6) { LogSPS("NDP Announcement %2d Capturing traffic for H-MAC %.6a I-MAC %.6a %s", rr->AnnounceCount, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr)); SendNDP(m, NDP_Adv, NDP_Override, rr, &rr->AddressProxy.ip.v6, mDNSNULL, &AllHosts_v6, &AllHosts_v6_Eth); } } else { rr->ImmedAnswer = mDNSInterfaceMark; // Send on all interfaces if (maxExistingAnnounceInterval < rr->ThisAPInterval) maxExistingAnnounceInterval = rr->ThisAPInterval; if (rr->UpdateBlocked) rr->UpdateBlocked = 0; } } } } // Any interface-specific records we're going to send are marked as being sent on all appropriate interfaces (which is just one) // Eligible records that are more than half-way to their announcement time are accelerated for (rr = m->ResourceRecords; rr; rr=rr->next) if ((rr->resrec.InterfaceID && rr->ImmedAnswer) || (rr->ThisAPInterval <= maxExistingAnnounceInterval && TimeToAnnounceThisRecord(rr, m->timenow + rr->ThisAPInterval/2) && !rr->AddressProxy.type && // Don't include ARP Annoucements when considering which records to accelerate ResourceRecordIsValidAnswer(rr))) rr->ImmedAnswer = mDNSInterfaceMark; // Send on all interfaces // When sending SRV records (particularly when announcing a new service) automatically add related Address record(s) as additionals // Note: Currently all address records are interface-specific, so it's safe to set ImmedAdditional to their InterfaceID, // which will be non-null. If by some chance there is an address record that's not interface-specific (should never happen) // then all that means is that it won't get sent -- which would not be the end of the world. for (rr = m->ResourceRecords; rr; rr=rr->next) { if (rr->ImmedAnswer && rr->resrec.rrtype == kDNSType_SRV) for (r2=m->ResourceRecords; r2; r2=r2->next) // Scan list of resource records if (RRTypeIsAddressType(r2->resrec.rrtype) && // For all address records (A/AAAA) ... ResourceRecordIsValidAnswer(r2) && // ... which are valid for answer ... rr->LastMCTime - r2->LastMCTime >= 0 && // ... which we have not sent recently ... rr->resrec.rdatahash == r2->resrec.namehash && // ... whose name is the name of the SRV target SameDomainName(&rr->resrec.rdata->u.srv.target, r2->resrec.name) && (rr->ImmedAnswer == mDNSInterfaceMark || rr->ImmedAnswer == r2->resrec.InterfaceID)) r2->ImmedAdditional = r2->resrec.InterfaceID; // ... then mark this address record for sending too // We also make sure we send the DeviceInfo TXT record too, if necessary // We check for RecordType == kDNSRecordTypeShared because we don't want to tag the // DeviceInfo TXT record onto a goodbye packet (RecordType == kDNSRecordTypeDeregistering). if (rr->ImmedAnswer && rr->resrec.RecordType == kDNSRecordTypeShared && rr->resrec.rrtype == kDNSType_PTR) if (ResourceRecordIsValidAnswer(&m->DeviceInfo) && SameDomainLabel(rr->resrec.rdata->u.name.c, m->DeviceInfo.resrec.name->c)) { if (!m->DeviceInfo.ImmedAnswer) m->DeviceInfo.ImmedAnswer = rr->ImmedAnswer; else m->DeviceInfo.ImmedAnswer = mDNSInterfaceMark; } } // If there's a record which is supposed to be unique that we're going to send, then make sure that we give // the whole RRSet as an atomic unit. That means that if we have any other records with the same name/type/class // then we need to mark them for sending too. Otherwise, if we set the kDNSClass_UniqueRRSet bit on a // record, then other RRSet members that have not been sent recently will get flushed out of client caches. // -- If a record is marked to be sent on a certain interface, make sure the whole set is marked to be sent on that interface // -- If any record is marked to be sent on all interfaces, make sure the whole set is marked to be sent on all interfaces for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) { if (rr->ImmedAnswer) // If we're sending this as answer, see that its whole RRSet is similarly marked { for (r2 = m->ResourceRecords; r2; r2=r2->next) if (ResourceRecordIsValidAnswer(r2)) if (r2->ImmedAnswer != mDNSInterfaceMark && r2->ImmedAnswer != rr->ImmedAnswer && SameResourceRecordSignature(r2, rr)) r2->ImmedAnswer = !r2->ImmedAnswer ? rr->ImmedAnswer : mDNSInterfaceMark; } else if (rr->ImmedAdditional) // If we're sending this as additional, see that its whole RRSet is similarly marked { for (r2 = m->ResourceRecords; r2; r2=r2->next) if (ResourceRecordIsValidAnswer(r2)) if (r2->ImmedAdditional != rr->ImmedAdditional && SameResourceRecordSignature(r2, rr)) r2->ImmedAdditional = rr->ImmedAdditional; } } // Now set SendRNow state appropriately for (rr = m->ResourceRecords; rr; rr=rr->next) { if (rr->ImmedAnswer == mDNSInterfaceMark) // Sending this record on all appropriate interfaces { rr->SendRNow = !intf ? mDNSNULL : (rr->resrec.InterfaceID) ? rr->resrec.InterfaceID : intf->InterfaceID; rr->ImmedAdditional = mDNSNULL; // No need to send as additional if sending as answer rr->LastMCTime = m->timenow; rr->LastMCInterface = rr->ImmedAnswer; // If we're announcing this record, and it's at least half-way to its ordained time, then consider this announcement done if (TimeToAnnounceThisRecord(rr, m->timenow + rr->ThisAPInterval/2)) { rr->AnnounceCount--; if (rr->resrec.RecordType != kDNSRecordTypeDeregistering) rr->ThisAPInterval *= 2; rr->LastAPTime = m->timenow; debugf("Announcing %##s (%s) %d", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->AnnounceCount); } } else if (rr->ImmedAnswer) // Else, just respond to a single query on single interface: { rr->SendRNow = rr->ImmedAnswer; // Just respond on that interface rr->ImmedAdditional = mDNSNULL; // No need to send as additional too rr->LastMCTime = m->timenow; rr->LastMCInterface = rr->ImmedAnswer; } SetNextAnnounceProbeTime(m, rr); //if (rr->SendRNow) LogMsg("%-15.4a %s", &rr->v4Requester, ARDisplayString(m, rr)); } // *** // *** 2. Loop through interface list, sending records as appropriate // *** while (intf) { const int OwnerRecordSpace = (m->AnnounceOwner && intf->MAC.l[0]) ? DNSOpt_Header_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) : 0; int numDereg = 0; int numAnnounce = 0; int numAnswer = 0; mDNSu8 *responseptr = m->omsg.data; mDNSu8 *newptr; InitializeDNSMessage(&m->omsg.h, zeroID, ResponseFlags); // First Pass. Look for: // 1. Deregistering records that need to send their goodbye packet // 2. Updated records that need to retract their old data // 3. Answers and announcements we need to send for (rr = m->ResourceRecords; rr; rr=rr->next) { // Skip this interface if the record InterfaceID is *Any and the record is not // appropriate for the interface type. if ((rr->SendRNow == intf->InterfaceID) && ((rr->resrec.InterfaceID == mDNSInterface_Any) && !mDNSPlatformValidRecordForInterface(rr, intf))) { LogInfo("SendResponses: Not sending %s, on %s", ARDisplayString(m, rr), InterfaceNameForID(m, rr->SendRNow)); rr->SendRNow = GetNextActiveInterfaceID(intf); } else if (rr->SendRNow == intf->InterfaceID) { RData *OldRData = rr->resrec.rdata; mDNSu16 oldrdlength = rr->resrec.rdlength; mDNSu8 active = (mDNSu8) (rr->resrec.RecordType != kDNSRecordTypeDeregistering && (m->SleepState != SleepState_Sleeping || intf->SPSAddr[0].type || intf->SPSAddr[1].type || intf->SPSAddr[2].type)); newptr = mDNSNULL; if (rr->NewRData && active) { // See if we should send a courtesy "goodbye" for the old data before we replace it. if (ResourceRecordIsValidAnswer(rr) && rr->resrec.RecordType == kDNSRecordTypeShared && rr->RequireGoodbye) { newptr = PutRR_OS_TTL(responseptr, &m->omsg.h.numAnswers, &rr->resrec, 0); if (newptr) { responseptr = newptr; numDereg++; rr->RequireGoodbye = mDNSfalse; } else continue; // If this packet is already too full to hold the goodbye for this record, skip it for now and we'll retry later } SetNewRData(&rr->resrec, rr->NewRData, rr->newrdlength); } if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the cache flush bit so PutResourceRecord will set it newptr = PutRR_OS_TTL(responseptr, &m->omsg.h.numAnswers, &rr->resrec, active ? rr->resrec.rroriginalttl : 0); rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear cache flush bit back to normal state if (newptr) { responseptr = newptr; rr->RequireGoodbye = active; if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) numDereg++; else if (rr->LastAPTime == m->timenow) numAnnounce++; else numAnswer++; } if (rr->NewRData && active) SetNewRData(&rr->resrec, OldRData, oldrdlength); // The first time through (pktcount==0), if this record is verified unique // (i.e. typically A, AAAA, SRV, TXT and reverse-mapping PTR), set the flag to add an NSEC too. if (!pktcount && active && (rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && !rr->SendNSECNow) rr->SendNSECNow = mDNSInterfaceMark; if (newptr) // If succeeded in sending, advance to next interface { // If sending on all interfaces, go to next interface; else we're finished now if (rr->ImmedAnswer == mDNSInterfaceMark && rr->resrec.InterfaceID == mDNSInterface_Any) rr->SendRNow = GetNextActiveInterfaceID(intf); else rr->SendRNow = mDNSNULL; } } } // Second Pass. Add additional records, if there's space. newptr = responseptr; for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->ImmedAdditional == intf->InterfaceID) if (ResourceRecordIsValidAnswer(rr)) { // If we have at least one answer already in the packet, then plan to add additionals too mDNSBool SendAdditional = (m->omsg.h.numAnswers > 0); // If we're not planning to send any additionals, but this record is a unique one, then // make sure we haven't already sent any other members of its RRSet -- if we have, then they // will have had the cache flush bit set, so now we need to finish the job and send the rest. if (!SendAdditional && (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)) { const AuthRecord *a; for (a = m->ResourceRecords; a; a=a->next) if (a->LastMCTime == m->timenow && a->LastMCInterface == intf->InterfaceID && SameResourceRecordSignature(a, rr)) { SendAdditional = mDNStrue; break; } } if (!SendAdditional) // If we don't want to send this after all, rr->ImmedAdditional = mDNSNULL; // then cancel its ImmedAdditional field else if (newptr) // Else, try to add it if we can { // The first time through (pktcount==0), if this record is verified unique // (i.e. typically A, AAAA, SRV, TXT and reverse-mapping PTR), set the flag to add an NSEC too. if (!pktcount && (rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && !rr->SendNSECNow) rr->SendNSECNow = mDNSInterfaceMark; if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the cache flush bit so PutResourceRecord will set it newptr = PutRR_OS(newptr, &m->omsg.h.numAdditionals, &rr->resrec); rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear cache flush bit back to normal state if (newptr) { responseptr = newptr; rr->ImmedAdditional = mDNSNULL; rr->RequireGoodbye = mDNStrue; // If we successfully put this additional record in the packet, we record LastMCTime & LastMCInterface. // This matters particularly in the case where we have more than one IPv6 (or IPv4) address, because otherwise, // when we see our own multicast with the cache flush bit set, if we haven't set LastMCTime, then we'll get // all concerned and re-announce our record again to make sure it doesn't get flushed from peer caches. rr->LastMCTime = m->timenow; rr->LastMCInterface = intf->InterfaceID; } } } // Third Pass. Add NSEC records, if there's space. // When we're generating an NSEC record in response to a specify query for that type // (recognized by rr->SendNSECNow == intf->InterfaceID) we should really put the NSEC in the Answer Section, // not Additional Section, but for now it's easier to handle both cases in this Additional Section loop here. for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->SendNSECNow == mDNSInterfaceMark || rr->SendNSECNow == intf->InterfaceID) { AuthRecord nsec; mDNS_SetupResourceRecord(&nsec, mDNSNULL, mDNSInterface_Any, kDNSType_NSEC, rr->resrec.rroriginalttl, kDNSRecordTypeUnique, AuthRecordAny, mDNSNULL, mDNSNULL); nsec.resrec.rrclass |= kDNSClass_UniqueRRSet; AssignDomainName(&nsec.namestorage, rr->resrec.name); mDNSPlatformMemZero(nsec.rdatastorage.u.nsec.bitmap, sizeof(nsec.rdatastorage.u.nsec.bitmap)); for (r2 = m->ResourceRecords; r2; r2=r2->next) if (ResourceRecordIsValidAnswer(r2) && SameResourceRecordNameClassInterface(r2, rr)) { if (r2->resrec.rrtype >= kDNSQType_ANY) { LogMsg("Can't create NSEC for record %s", ARDisplayString(m, r2)); break; } else nsec.rdatastorage.u.nsec.bitmap[r2->resrec.rrtype >> 3] |= 128 >> (r2->resrec.rrtype & 7); } newptr = responseptr; if (!r2) // If we successfully built our NSEC record, add it to the packet now { newptr = PutRR_OS(responseptr, &m->omsg.h.numAdditionals, &nsec.resrec); if (newptr) responseptr = newptr; } // If we successfully put the NSEC record, clear the SendNSECNow flag // If we consider this NSEC optional, then we unconditionally clear the SendNSECNow flag, even if we fail to put this additional record if (newptr || rr->SendNSECNow == mDNSInterfaceMark) { rr->SendNSECNow = mDNSNULL; // Run through remainder of list clearing SendNSECNow flag for all other records which would generate the same NSEC for (r2 = rr->next; r2; r2=r2->next) if (SameResourceRecordNameClassInterface(r2, rr)) if (r2->SendNSECNow == mDNSInterfaceMark || r2->SendNSECNow == intf->InterfaceID) r2->SendNSECNow = mDNSNULL; } } if (m->omsg.h.numAnswers || m->omsg.h.numAdditionals) { // If we have data to send, add OWNER option if necessary, then send packet if (OwnerRecordSpace) { AuthRecord opt; mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL); opt.resrec.rrclass = NormalMaxDNSMessageData; opt.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record opt.resrec.rdestimate = sizeof(rdataOPT); SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[0]); newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAdditionals, &opt.resrec); if (newptr) { responseptr = newptr; LogSPS("SendResponses put %s", ARDisplayString(m, &opt)); } else if (m->omsg.h.numAnswers + m->omsg.h.numAuthorities + m->omsg.h.numAdditionals == 1) LogSPS("SendResponses: No space in packet for Owner OPT record (%d/%d/%d/%d) %s", m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt)); else LogMsg("SendResponses: How did we fail to have space for Owner OPT record (%d/%d/%d/%d) %s", m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt)); } debugf("SendResponses: Sending %d Deregistration%s, %d Announcement%s, %d Answer%s, %d Additional%s on %p", numDereg, numDereg == 1 ? "" : "s", numAnnounce, numAnnounce == 1 ? "" : "s", numAnswer, numAnswer == 1 ? "" : "s", m->omsg.h.numAdditionals, m->omsg.h.numAdditionals == 1 ? "" : "s", intf->InterfaceID); if (intf->IPv4Available) mDNSSendDNSMessage(m, &m->omsg, responseptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v4, MulticastDNSPort, mDNSNULL, mDNSNULL); if (intf->IPv6Available) mDNSSendDNSMessage(m, &m->omsg, responseptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v6, MulticastDNSPort, mDNSNULL, mDNSNULL); if (!m->SuppressSending) m->SuppressSending = NonZeroTime(m->timenow + (mDNSPlatformOneSecond+9)/10); if (++pktcount >= 1000) { LogMsg("SendResponses exceeded loop limit %d: giving up", pktcount); break; } // There might be more things to send on this interface, so go around one more time and try again. } else // Nothing more to send on this interface; go to next { const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next); #if MDNS_DEBUGMSGS && 0 const char *const msg = next ? "SendResponses: Nothing more on %p; moving to %p" : "SendResponses: Nothing more on %p"; debugf(msg, intf, next); #endif intf = next; pktcount = 0; // When we move to a new interface, reset packet count back to zero -- NSEC generation logic uses it } } // *** // *** 3. Cleanup: Now that everything is sent, call client callback functions, and reset state variables // *** if (m->CurrentRecord) LogMsg("SendResponses ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); m->CurrentRecord = m->ResourceRecords; while (m->CurrentRecord) { rr = m->CurrentRecord; m->CurrentRecord = rr->next; if (rr->SendRNow) { if (rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P) LogMsg("SendResponses: No active interface %p to send: %p %02X %s", rr->SendRNow, rr->resrec.InterfaceID, rr->resrec.RecordType, ARDisplayString(m, rr)); rr->SendRNow = mDNSNULL; } if (rr->ImmedAnswer || rr->resrec.RecordType == kDNSRecordTypeDeregistering) { if (rr->NewRData) CompleteRDataUpdate(m, rr); // Update our rdata, clear the NewRData pointer, and return memory to the client if (rr->resrec.RecordType == kDNSRecordTypeDeregistering && rr->AnnounceCount == 0) { // For Unicast, when we get the response from the server, we will call CompleteDeregistration if (!AuthRecord_uDNS(rr)) CompleteDeregistration(m, rr); // Don't touch rr after this } else { rr->ImmedAnswer = mDNSNULL; rr->ImmedUnicast = mDNSfalse; rr->v4Requester = zerov4Addr; rr->v6Requester = zerov6Addr; } } } verbosedebugf("SendResponses: Next in %ld ticks", m->NextScheduledResponse - m->timenow); } // Calling CheckCacheExpiration() is an expensive operation because it has to look at the entire cache, // so we want to be lazy about how frequently we do it. // 1. If a cache record is currently referenced by *no* active questions, // then we don't mind expiring it up to a minute late (who will know?) // 2. Else, if a cache record is due for some of its final expiration queries, // we'll allow them to be late by up to 2% of the TTL // 3. Else, if a cache record has completed all its final expiration queries without success, // and is expiring, and had an original TTL more than ten seconds, we'll allow it to be one second late // 4. Else, it is expiring and had an original TTL of ten seconds or less (includes explicit goodbye packets), // so allow at most 1/10 second lateness // 5. For records with rroriginalttl set to zero, that means we really want to delete them immediately // (we have a new record with DelayDelivery set, waiting for the old record to go away before we can notify clients). #define CacheCheckGracePeriod(RR) ( \ ((RR)->CRActiveQuestion == mDNSNULL ) ? (60 * mDNSPlatformOneSecond) : \ ((RR)->UnansweredQueries < MaxUnansweredQueries) ? (TicksTTL(rr)/50) : \ ((RR)->resrec.rroriginalttl > 10 ) ? (mDNSPlatformOneSecond) : \ ((RR)->resrec.rroriginalttl > 0 ) ? (mDNSPlatformOneSecond/10) : 0) #define NextCacheCheckEvent(RR) ((RR)->NextRequiredQuery + CacheCheckGracePeriod(RR)) mDNSexport void ScheduleNextCacheCheckTime(mDNS *const m, const mDNSu32 slot, const mDNSs32 event) { if (m->rrcache_nextcheck[slot] - event > 0) m->rrcache_nextcheck[slot] = event; if (m->NextCacheCheck - event > 0) m->NextCacheCheck = event; } // Note: MUST call SetNextCacheCheckTimeForRecord any time we change: // rr->TimeRcvd // rr->resrec.rroriginalttl // rr->UnansweredQueries // rr->CRActiveQuestion mDNSlocal void SetNextCacheCheckTimeForRecord(mDNS *const m, CacheRecord *const rr) { rr->NextRequiredQuery = RRExpireTime(rr); // If we have an active question, then see if we want to schedule a refresher query for this record. // Usually we expect to do four queries, at 80-82%, 85-87%, 90-92% and then 95-97% of the TTL. if (rr->CRActiveQuestion && rr->UnansweredQueries < MaxUnansweredQueries) { rr->NextRequiredQuery -= TicksTTL(rr)/20 * (MaxUnansweredQueries - rr->UnansweredQueries); rr->NextRequiredQuery += mDNSRandom((mDNSu32)TicksTTL(rr)/50); verbosedebugf("SetNextCacheCheckTimeForRecord: NextRequiredQuery in %ld sec CacheCheckGracePeriod %d ticks for %s", (rr->NextRequiredQuery - m->timenow) / mDNSPlatformOneSecond, CacheCheckGracePeriod(rr), CRDisplayString(m,rr)); } ScheduleNextCacheCheckTime(m, HashSlot(rr->resrec.name), NextCacheCheckEvent(rr)); } #define kMinimumReconfirmTime ((mDNSu32)mDNSPlatformOneSecond * 5) #define kDefaultReconfirmTimeForWake ((mDNSu32)mDNSPlatformOneSecond * 5) #define kDefaultReconfirmTimeForNoAnswer ((mDNSu32)mDNSPlatformOneSecond * 5) #define kDefaultReconfirmTimeForFlappingInterface ((mDNSu32)mDNSPlatformOneSecond * 30) mDNSlocal mStatus mDNS_Reconfirm_internal(mDNS *const m, CacheRecord *const rr, mDNSu32 interval) { if (interval < kMinimumReconfirmTime) interval = kMinimumReconfirmTime; if (interval > 0x10000000) // Make sure interval doesn't overflow when we multiply by four below interval = 0x10000000; // If the expected expiration time for this record is more than interval+33%, then accelerate its expiration if (RRExpireTime(rr) - m->timenow > (mDNSs32)((interval * 4) / 3)) { // Add a 33% random amount to the interval, to avoid synchronization between multiple hosts // For all the reconfirmations in a given batch, we want to use the same random value // so that the reconfirmation questions can be grouped into a single query packet if (!m->RandomReconfirmDelay) m->RandomReconfirmDelay = 1 + mDNSRandom(0x3FFFFFFF); interval += m->RandomReconfirmDelay % ((interval/3) + 1); rr->TimeRcvd = m->timenow - (mDNSs32)interval * 3; rr->resrec.rroriginalttl = (interval * 4 + mDNSPlatformOneSecond - 1) / mDNSPlatformOneSecond; SetNextCacheCheckTimeForRecord(m, rr); } debugf("mDNS_Reconfirm_internal:%6ld ticks to go for %s %p", RRExpireTime(rr) - m->timenow, CRDisplayString(m, rr), rr->CRActiveQuestion); return(mStatus_NoError); } #define MaxQuestionInterval (3600 * mDNSPlatformOneSecond) // BuildQuestion puts a question into a DNS Query packet and if successful, updates the value of queryptr. // It also appends to the list of known answer records that need to be included, // and updates the forcast for the size of the known answer section. mDNSlocal mDNSBool BuildQuestion(mDNS *const m, DNSMessage *query, mDNSu8 **queryptr, DNSQuestion *q, CacheRecord ***kalistptrptr, mDNSu32 *answerforecast) { mDNSBool ucast = (q->LargeAnswers || q->RequestUnicast) && m->CanReceiveUnicastOn5353; mDNSu16 ucbit = (mDNSu16)(ucast ? kDNSQClass_UnicastResponse : 0); const mDNSu8 *const limit = query->data + NormalMaxDNSMessageData; mDNSu8 *newptr = putQuestion(query, *queryptr, limit - *answerforecast, &q->qname, q->qtype, (mDNSu16)(q->qclass | ucbit)); if (!newptr) { debugf("BuildQuestion: No more space in this packet for question %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); return(mDNSfalse); } else { mDNSu32 forecast = *answerforecast; const mDNSu32 slot = HashSlot(&q->qname); const CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); CacheRecord *rr; CacheRecord **ka = *kalistptrptr; // Make a working copy of the pointer we're going to update for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) // If we have a resource record in our cache, if (rr->resrec.InterfaceID == q->SendQNow && // received on this interface !(rr->resrec.RecordType & kDNSRecordTypeUniqueMask) && // which is a shared (i.e. not unique) record type rr->NextInKAList == mDNSNULL && ka != &rr->NextInKAList && // which is not already in the known answer list rr->resrec.rdlength <= SmallRecordLimit && // which is small enough to sensibly fit in the packet SameNameRecordAnswersQuestion(&rr->resrec, q) && // which answers our question rr->TimeRcvd + TicksTTL(rr)/2 - m->timenow > // and its half-way-to-expiry time is at least 1 second away mDNSPlatformOneSecond) // (also ensures we never include goodbye records with TTL=1) { // We don't want to include unique records in the Known Answer section. The Known Answer section // is intended to suppress floods of shared-record replies from many other devices on the network. // That concept really does not apply to unique records, and indeed if we do send a query for // which we have a unique record already in our cache, then including that unique record as a // Known Answer, so as to suppress the only answer we were expecting to get, makes little sense. *ka = rr; // Link this record into our known answer chain ka = &rr->NextInKAList; // We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n) forecast += 12 + rr->resrec.rdestimate; // If we're trying to put more than one question in this packet, and it doesn't fit // then undo that last question and try again next time if (query->h.numQuestions > 1 && newptr + forecast >= limit) { debugf("BuildQuestion: Retracting question %##s (%s) new forecast total %d", q->qname.c, DNSTypeName(q->qtype), newptr + forecast - query->data); query->h.numQuestions--; ka = *kalistptrptr; // Go back to where we started and retract these answer records while (*ka) { CacheRecord *c = *ka; *ka = mDNSNULL; ka = &c->NextInKAList; } return(mDNSfalse); // Return false, so we'll try again in the next packet } } // Success! Update our state pointers, increment UnansweredQueries as appropriate, and return *queryptr = newptr; // Update the packet pointer *answerforecast = forecast; // Update the forecast *kalistptrptr = ka; // Update the known answer list pointer if (ucast) q->ExpectUnicastResp = NonZeroTime(m->timenow); for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) // For every resource record in our cache, if (rr->resrec.InterfaceID == q->SendQNow && // received on this interface rr->NextInKAList == mDNSNULL && ka != &rr->NextInKAList && // which is not in the known answer list SameNameRecordAnswersQuestion(&rr->resrec, q)) // which answers our question { rr->UnansweredQueries++; // indicate that we're expecting a response rr->LastUnansweredTime = m->timenow; SetNextCacheCheckTimeForRecord(m, rr); } return(mDNStrue); } } // When we have a query looking for a specified name, but there appear to be no answers with // that name, ReconfirmAntecedents() is called with depth=0 to start the reconfirmation process // for any records in our cache that reference the given name (e.g. PTR and SRV records). // For any such cache record we find, we also recursively call ReconfirmAntecedents() for *its* name. // We increment depth each time we recurse, to guard against possible infinite loops, with a limit of 5. // A typical reconfirmation scenario might go like this: // Depth 0: Name "myhost.local" has no address records // Depth 1: SRV "My Service._example._tcp.local." refers to "myhost.local"; may be stale // Depth 2: PTR "_example._tcp.local." refers to "My Service"; may be stale // Depth 3: PTR "_services._dns-sd._udp.local." refers to "_example._tcp.local."; may be stale // Currently depths 4 and 5 are not expected to occur; if we did get to depth 5 we'd reconfim any records we // found referring to the given name, but not recursively descend any further reconfirm *their* antecedents. mDNSlocal void ReconfirmAntecedents(mDNS *const m, const domainname *const name, const mDNSu32 namehash, const int depth) { mDNSu32 slot; CacheGroup *cg; CacheRecord *cr; debugf("ReconfirmAntecedents (depth=%d) for %##s", depth, name->c); FORALL_CACHERECORDS(slot, cg, cr) { domainname *crtarget = GetRRDomainNameTarget(&cr->resrec); if (crtarget && cr->resrec.rdatahash == namehash && SameDomainName(crtarget, name)) { LogInfo("ReconfirmAntecedents: Reconfirming (depth=%d) %s", depth, CRDisplayString(m, cr)); mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer); if (depth < 5) ReconfirmAntecedents(m, cr->resrec.name, cr->resrec.namehash, depth+1); } } } // If we get no answer for a AAAA query, then before doing an automatic implicit ReconfirmAntecedents // we check if we have an address record for the same name. If we do have an IPv4 address for a given // name but not an IPv6 address, that's okay (it just means the device doesn't do IPv6) so the failure // to get a AAAA response is not grounds to doubt the PTR/SRV chain that lead us to that name. mDNSlocal const CacheRecord *CacheHasAddressTypeForName(mDNS *const m, const domainname *const name, const mDNSu32 namehash) { CacheGroup *const cg = CacheGroupForName(m, HashSlot(name), namehash, name); const CacheRecord *cr = cg ? cg->members : mDNSNULL; while (cr && !RRTypeIsAddressType(cr->resrec.rrtype)) cr=cr->next; return(cr); } mDNSlocal const CacheRecord *FindSPSInCache1(mDNS *const m, const DNSQuestion *const q, const CacheRecord *const c0, const CacheRecord *const c1) { CacheGroup *const cg = CacheGroupForName(m, HashSlot(&q->qname), q->qnamehash, &q->qname); const CacheRecord *cr, *bestcr = mDNSNULL; mDNSu32 bestmetric = 1000000; for (cr = cg ? cg->members : mDNSNULL; cr; cr=cr->next) if (cr->resrec.rrtype == kDNSType_PTR && cr->resrec.rdlength >= 6) // If record is PTR type, with long enough name, if (cr != c0 && cr != c1) // that's not one we've seen before, if (SameNameRecordAnswersQuestion(&cr->resrec, q)) // and answers our browse query, if (!IdenticalSameNameRecord(&cr->resrec, &m->SPSRecords.RR_PTR.resrec)) // and is not our own advertised service... { mDNSu32 metric = SPSMetric(cr->resrec.rdata->u.name.c); if (bestmetric > metric) { bestmetric = metric; bestcr = cr; } } return(bestcr); } // Finds the three best Sleep Proxies we currently have in our cache mDNSexport void FindSPSInCache(mDNS *const m, const DNSQuestion *const q, const CacheRecord *sps[3]) { sps[0] = FindSPSInCache1(m, q, mDNSNULL, mDNSNULL); sps[1] = !sps[0] ? mDNSNULL : FindSPSInCache1(m, q, sps[0], mDNSNULL); sps[2] = !sps[1] ? mDNSNULL : FindSPSInCache1(m, q, sps[0], sps[1]); } // Only DupSuppressInfos newer than the specified 'time' are allowed to remain active mDNSlocal void ExpireDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 time) { int i; for (i=0; iIPv4Available; // If this interface doesn't do v4, we don't need to find a v4 duplicate of this query mDNSBool v6 = !intf->IPv6Available; // If this interface doesn't do v6, we don't need to find a v6 duplicate of this query for (i=0; iInterfaceID) { if (ds[i].Type == mDNSAddrType_IPv4) v4 = mDNStrue; else if (ds[i].Type == mDNSAddrType_IPv6) v6 = mDNStrue; if (v4 && v6) return(mDNStrue); } return(mDNSfalse); } mDNSlocal int RecordDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 Time, mDNSInterfaceID InterfaceID, mDNSs32 Type) { int i, j; // See if we have this one in our list somewhere already for (i=0; i= DupSuppressInfoSize) { i = 0; for (j=1; jInterfaceID; domainname *d = &q->qname; // We can't send magic packets without knowing which interface to send it on. if (InterfaceID == mDNSInterface_Any || InterfaceID == mDNSInterface_LocalOnly || InterfaceID == mDNSInterface_P2P) { LogMsg("mDNSSendWakeOnResolve: ERROR!! Invalid InterfaceID %p for question %##s", InterfaceID, q->qname.c); return; } // Split MAC@IPAddress and pass them separately len = d->c[0]; i = 1; cnt = 0; for (i = 1; i < len; i++) { if (d->c[i] == '@') { char EthAddr[18]; // ethernet adddress : 12 bytes + 5 ":" + 1 NULL byte char IPAddr[47]; // Max IP address len: 46 bytes (IPv6) + 1 NULL byte if (cnt != 5) { LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed Ethernet address %##s, cnt %d", q->qname.c, cnt); return; } if ((i - 1) > (int) (sizeof(EthAddr) - 1)) { LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed Ethernet address %##s, length %d", q->qname.c, i - 1); return; } if ((len - i) > (int)(sizeof(IPAddr) - 1)) { LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed IP address %##s, length %d", q->qname.c, len - i); return; } mDNSPlatformMemCopy(EthAddr, &d->c[1], i - 1); EthAddr[i - 1] = 0; mDNSPlatformMemCopy(IPAddr, &d->c[i + 1], len - i); IPAddr[len - i] = 0; mDNSPlatformSendWakeupPacket(m, InterfaceID, EthAddr, IPAddr, InitialWakeOnResolveCount - q->WakeOnResolveCount); return; } else if (d->c[i] == ':') cnt++; } LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed WakeOnResolve name %##s", q->qname.c); } mDNSlocal mDNSBool AccelerateThisQuery(mDNS *const m, DNSQuestion *q) { // If more than 90% of the way to the query time, we should unconditionally accelerate it if (TimeToSendThisQuestion(q, m->timenow + q->ThisQInterval/10)) return(mDNStrue); // If half-way to next scheduled query time, only accelerate if it will add less than 512 bytes to the packet if (TimeToSendThisQuestion(q, m->timenow + q->ThisQInterval/2)) { // We forecast: qname (n) type (2) class (2) mDNSu32 forecast = (mDNSu32)DomainNameLength(&q->qname) + 4; const mDNSu32 slot = HashSlot(&q->qname); const CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); const CacheRecord *rr; for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) // If we have a resource record in our cache, if (rr->resrec.rdlength <= SmallRecordLimit && // which is small enough to sensibly fit in the packet SameNameRecordAnswersQuestion(&rr->resrec, q) && // which answers our question rr->TimeRcvd + TicksTTL(rr)/2 - m->timenow >= 0 && // and it is less than half-way to expiry rr->NextRequiredQuery - (m->timenow + q->ThisQInterval) > 0)// and we'll ask at least once again before NextRequiredQuery { // We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n) forecast += 12 + rr->resrec.rdestimate; if (forecast >= 512) return(mDNSfalse); // If this would add 512 bytes or more to the packet, don't accelerate } return(mDNStrue); } return(mDNSfalse); } // How Standard Queries are generated: // 1. The Question Section contains the question // 2. The Additional Section contains answers we already know, to suppress duplicate responses // How Probe Queries are generated: // 1. The Question Section contains queries for the name we intend to use, with QType=ANY because // if some other host is already using *any* records with this name, we want to know about it. // 2. The Authority Section contains the proposed values we intend to use for one or more // of our records with that name (analogous to the Update section of DNS Update packets) // because if some other host is probing at the same time, we each want to know what the other is // planning, in order to apply the tie-breaking rule to see who gets to use the name and who doesn't. mDNSlocal void SendQueries(mDNS *const m) { mDNSu32 slot; CacheGroup *cg; CacheRecord *cr; AuthRecord *ar; int pktcount = 0; DNSQuestion *q; // For explanation of maxExistingQuestionInterval logic, see comments for maxExistingAnnounceInterval mDNSs32 maxExistingQuestionInterval = 0; const NetworkInterfaceInfo *intf = GetFirstActiveInterface(m->HostInterfaces); CacheRecord *KnownAnswerList = mDNSNULL; // 1. If time for a query, work out what we need to do // We're expecting to send a query anyway, so see if any expiring cache records are close enough // to their NextRequiredQuery to be worth batching them together with this one FORALL_CACHERECORDS(slot, cg, cr) if (cr->CRActiveQuestion && cr->UnansweredQueries < MaxUnansweredQueries) if (m->timenow + TicksTTL(cr)/50 - cr->NextRequiredQuery >= 0) { debugf("Sending %d%% cache expiration query for %s", 80 + 5 * cr->UnansweredQueries, CRDisplayString(m, cr)); q = cr->CRActiveQuestion; ExpireDupSuppressInfoOnInterface(q->DupSuppress, m->timenow - TicksTTL(cr)/20, cr->resrec.InterfaceID); // For uDNS queries (TargetQID non-zero) we adjust LastQTime, // and bump UnansweredQueries so that we don't spin trying to send the same cache expiration query repeatedly if (q->Target.type) q->SendQNow = mDNSInterfaceMark; // If targeted query, mark it else if (!mDNSOpaque16IsZero(q->TargetQID)) { q->LastQTime = m->timenow - q->ThisQInterval; cr->UnansweredQueries++; } else if (q->SendQNow == mDNSNULL) q->SendQNow = cr->resrec.InterfaceID; else if (q->SendQNow != cr->resrec.InterfaceID) q->SendQNow = mDNSInterfaceMark; } // Scan our list of questions to see which: // *WideArea* queries need to be sent // *unicast* queries need to be sent // *multicast* queries we're definitely going to send if (m->CurrentQuestion) LogMsg("SendQueries ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->Questions; while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) { q = m->CurrentQuestion; if (q->Target.type && (q->SendQNow || TimeToSendThisQuestion(q, m->timenow))) { mDNSu8 *qptr = m->omsg.data; const mDNSu8 *const limit = m->omsg.data + sizeof(m->omsg.data); // If we fail to get a new on-demand socket (should only happen cases of the most extreme resource exhaustion), we'll try again next time if (!q->LocalSocket) q->LocalSocket = mDNSPlatformUDPSocket(m, zeroIPPort); if (q->LocalSocket) { InitializeDNSMessage(&m->omsg.h, q->TargetQID, QueryFlags); qptr = putQuestion(&m->omsg, qptr, limit, &q->qname, q->qtype, q->qclass); mDNSSendDNSMessage(m, &m->omsg, qptr, mDNSInterface_Any, q->LocalSocket, &q->Target, q->TargetPort, mDNSNULL, mDNSNULL); q->ThisQInterval *= QuestionIntervalStep; } if (q->ThisQInterval > MaxQuestionInterval) q->ThisQInterval = MaxQuestionInterval; q->LastQTime = m->timenow; q->LastQTxTime = m->timenow; q->RecentAnswerPkts = 0; q->SendQNow = mDNSNULL; q->ExpectUnicastResp = NonZeroTime(m->timenow); } else if (mDNSOpaque16IsZero(q->TargetQID) && !q->Target.type && TimeToSendThisQuestion(q, m->timenow)) { //LogInfo("Time to send %##s (%s) %d", q->qname.c, DNSTypeName(q->qtype), m->timenow - NextQSendTime(q)); q->SendQNow = mDNSInterfaceMark; // Mark this question for sending on all interfaces if (maxExistingQuestionInterval < q->ThisQInterval) maxExistingQuestionInterval = q->ThisQInterval; } // If m->CurrentQuestion wasn't modified out from under us, advance it now // We can't do this at the start of the loop because uDNS_CheckCurrentQuestion() depends on having // m->CurrentQuestion point to the right question if (q == m->CurrentQuestion) m->CurrentQuestion = m->CurrentQuestion->next; } while (m->CurrentQuestion) { LogInfo("SendQueries question loop 1: Skipping NewQuestion %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->CurrentQuestion->next; } m->CurrentQuestion = mDNSNULL; // Scan our list of questions // (a) to see if there are any more that are worth accelerating, and // (b) to update the state variables for *all* the questions we're going to send // Note: Don't set NextScheduledQuery until here, because uDNS_CheckCurrentQuestion in the loop above can add new questions to the list, // which causes NextScheduledQuery to get (incorrectly) set to m->timenow. Setting it here is the right place, because the very // next thing we do is scan the list and call SetNextQueryTime() for every question we find, so we know we end up with the right value. m->NextScheduledQuery = m->timenow + 0x78000000; for (q = m->Questions; q && q != m->NewQuestions; q=q->next) { if (mDNSOpaque16IsZero(q->TargetQID) && (q->SendQNow || (!q->Target.type && ActiveQuestion(q) && q->ThisQInterval <= maxExistingQuestionInterval && AccelerateThisQuery(m,q)))) { // If at least halfway to next query time, advance to next interval // If less than halfway to next query time, then // treat this as logically a repeat of the last transmission, without advancing the interval if (m->timenow - (q->LastQTime + (q->ThisQInterval/2)) >= 0) { //LogInfo("Accelerating %##s (%s) %d", q->qname.c, DNSTypeName(q->qtype), m->timenow - NextQSendTime(q)); q->SendQNow = mDNSInterfaceMark; // Mark this question for sending on all interfaces debugf("SendQueries: %##s (%s) next interval %d seconds RequestUnicast = %d", q->qname.c, DNSTypeName(q->qtype), q->ThisQInterval / InitialQuestionInterval, q->RequestUnicast); q->ThisQInterval *= QuestionIntervalStep; if (q->ThisQInterval > MaxQuestionInterval) q->ThisQInterval = MaxQuestionInterval; else if (q->CurrentAnswers == 0 && q->ThisQInterval == InitialQuestionInterval * QuestionIntervalStep3 && !q->RequestUnicast && !(RRTypeIsAddressType(q->qtype) && CacheHasAddressTypeForName(m, &q->qname, q->qnamehash))) { // Generally don't need to log this. // It's not especially noteworthy if a query finds no results -- this usually happens for domain // enumeration queries in the LL subdomain (e.g. "db._dns-sd._udp.0.0.254.169.in-addr.arpa") // and when there simply happen to be no instances of the service the client is looking // for (e.g. iTunes is set to look for RAOP devices, and the current network has none). debugf("SendQueries: Zero current answers for %##s (%s); will reconfirm antecedents", q->qname.c, DNSTypeName(q->qtype)); // Sending third query, and no answers yet; time to begin doubting the source ReconfirmAntecedents(m, &q->qname, q->qnamehash, 0); } } // Mark for sending. (If no active interfaces, then don't even try.) q->SendOnAll = (q->SendQNow == mDNSInterfaceMark); if (q->SendOnAll) { q->SendQNow = !intf ? mDNSNULL : (q->InterfaceID) ? q->InterfaceID : intf->InterfaceID; q->LastQTime = m->timenow; } // If we recorded a duplicate suppression for this question less than half an interval ago, // then we consider it recent enough that we don't need to do an identical query ourselves. ExpireDupSuppressInfo(q->DupSuppress, m->timenow - q->ThisQInterval/2); q->LastQTxTime = m->timenow; q->RecentAnswerPkts = 0; if (q->RequestUnicast) q->RequestUnicast--; } // For all questions (not just the ones we're sending) check what the next scheduled event will be // We don't need to consider NewQuestions here because for those we'll set m->NextScheduledQuery in AnswerNewQuestion SetNextQueryTime(m,q); } // 2. Scan our authoritative RR list to see what probes we might need to send m->NextScheduledProbe = m->timenow + 0x78000000; if (m->CurrentRecord) LogMsg("SendQueries ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); m->CurrentRecord = m->ResourceRecords; while (m->CurrentRecord) { ar = m->CurrentRecord; m->CurrentRecord = ar->next; if (!AuthRecord_uDNS(ar) && ar->resrec.RecordType == kDNSRecordTypeUnique) // For all records that are still probing... { // 1. If it's not reached its probe time, just make sure we update m->NextScheduledProbe correctly if (m->timenow - (ar->LastAPTime + ar->ThisAPInterval) < 0) { SetNextAnnounceProbeTime(m, ar); } // 2. else, if it has reached its probe time, mark it for sending and then update m->NextScheduledProbe correctly else if (ar->ProbeCount) { if (ar->AddressProxy.type == mDNSAddrType_IPv4) { LogSPS("SendQueries ARP Probe %d %s %s", ar->ProbeCount, InterfaceNameForID(m, ar->resrec.InterfaceID), ARDisplayString(m,ar)); SendARP(m, 1, ar, &zerov4Addr, &zeroEthAddr, &ar->AddressProxy.ip.v4, &ar->WakeUp.IMAC); } else if (ar->AddressProxy.type == mDNSAddrType_IPv6) { LogSPS("SendQueries NDP Probe %d %s %s", ar->ProbeCount, InterfaceNameForID(m, ar->resrec.InterfaceID), ARDisplayString(m,ar)); // IPv6 source = zero // No target hardware address // IPv6 target address is address we're probing // Ethernet destination address is Ethernet interface address of the Sleep Proxy client we're probing SendNDP(m, NDP_Sol, 0, ar, &zerov6Addr, mDNSNULL, &ar->AddressProxy.ip.v6, &ar->WakeUp.IMAC); } // Mark for sending. (If no active interfaces, then don't even try.) ar->SendRNow = (!intf || ar->WakeUp.HMAC.l[0]) ? mDNSNULL : ar->resrec.InterfaceID ? ar->resrec.InterfaceID : intf->InterfaceID; ar->LastAPTime = m->timenow; // When we have a late conflict that resets a record to probing state we use a special marker value greater // than DefaultProbeCountForTypeUnique. Here we detect that state and reset ar->ProbeCount back to the right value. if (ar->ProbeCount > DefaultProbeCountForTypeUnique) ar->ProbeCount = DefaultProbeCountForTypeUnique; ar->ProbeCount--; SetNextAnnounceProbeTime(m, ar); if (ar->ProbeCount == 0) { // If this is the last probe for this record, then see if we have any matching records // on our duplicate list which should similarly have their ProbeCount cleared to zero... AuthRecord *r2; for (r2 = m->DuplicateRecords; r2; r2=r2->next) if (r2->resrec.RecordType == kDNSRecordTypeUnique && RecordIsLocalDuplicate(r2, ar)) r2->ProbeCount = 0; // ... then acknowledge this record to the client. // We do this optimistically, just as we're about to send the third probe. // This helps clients that both advertise and browse, and want to filter themselves // from the browse results list, because it helps ensure that the registration // confirmation will be delivered 1/4 second *before* the browse "add" event. // A potential downside is that we could deliver a registration confirmation and then find out // moments later that there's a name conflict, but applications have to be prepared to handle // late conflicts anyway (e.g. on connection of network cable, etc.), so this is nothing new. if (!ar->Acknowledged) AcknowledgeRecord(m, ar); } } // else, if it has now finished probing, move it to state Verified, // and update m->NextScheduledResponse so it will be announced else { if (!ar->Acknowledged) AcknowledgeRecord(m, ar); // Defensive, just in case it got missed somehow ar->resrec.RecordType = kDNSRecordTypeVerified; ar->ThisAPInterval = DefaultAnnounceIntervalForTypeUnique; ar->LastAPTime = m->timenow - DefaultAnnounceIntervalForTypeUnique; SetNextAnnounceProbeTime(m, ar); } } } m->CurrentRecord = m->DuplicateRecords; while (m->CurrentRecord) { ar = m->CurrentRecord; m->CurrentRecord = ar->next; if (ar->resrec.RecordType == kDNSRecordTypeUnique && ar->ProbeCount == 0 && !ar->Acknowledged) AcknowledgeRecord(m, ar); } // 3. Now we know which queries and probes we're sending, // go through our interface list sending the appropriate queries on each interface while (intf) { const int OwnerRecordSpace = (m->AnnounceOwner && intf->MAC.l[0]) ? DNSOpt_Header_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) : 0; mDNSu8 *queryptr = m->omsg.data; InitializeDNSMessage(&m->omsg.h, zeroID, QueryFlags); if (KnownAnswerList) verbosedebugf("SendQueries: KnownAnswerList set... Will continue from previous packet"); if (!KnownAnswerList) { // Start a new known-answer list CacheRecord **kalistptr = &KnownAnswerList; mDNSu32 answerforecast = OwnerRecordSpace; // We start by assuming we'll need at least enough space to put the Owner Option // Put query questions in this packet for (q = m->Questions; q && q != m->NewQuestions; q=q->next) { if (mDNSOpaque16IsZero(q->TargetQID) && (q->SendQNow == intf->InterfaceID)) { debugf("SendQueries: %s question for %##s (%s) at %d forecast total %d", SuppressOnThisInterface(q->DupSuppress, intf) ? "Suppressing" : "Putting ", q->qname.c, DNSTypeName(q->qtype), queryptr - m->omsg.data, queryptr + answerforecast - m->omsg.data); // If we're suppressing this question, or we successfully put it, update its SendQNow state if (SuppressOnThisInterface(q->DupSuppress, intf) || BuildQuestion(m, &m->omsg, &queryptr, q, &kalistptr, &answerforecast)) { q->SendQNow = (q->InterfaceID || !q->SendOnAll) ? mDNSNULL : GetNextActiveInterfaceID(intf); if (q->WakeOnResolveCount) { mDNSSendWakeOnResolve(m, q); q->WakeOnResolveCount--; } } } } // Put probe questions in this packet for (ar = m->ResourceRecords; ar; ar=ar->next) if (ar->SendRNow == intf->InterfaceID) { mDNSBool ucast = (ar->ProbeCount >= DefaultProbeCountForTypeUnique-1) && m->CanReceiveUnicastOn5353; mDNSu16 ucbit = (mDNSu16)(ucast ? kDNSQClass_UnicastResponse : 0); const mDNSu8 *const limit = m->omsg.data + (m->omsg.h.numQuestions ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData); // We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n) mDNSu32 forecast = answerforecast + 12 + ar->resrec.rdestimate; mDNSu8 *newptr = putQuestion(&m->omsg, queryptr, limit - forecast, ar->resrec.name, kDNSQType_ANY, (mDNSu16)(ar->resrec.rrclass | ucbit)); if (newptr) { queryptr = newptr; answerforecast = forecast; ar->SendRNow = (ar->resrec.InterfaceID) ? mDNSNULL : GetNextActiveInterfaceID(intf); ar->IncludeInProbe = mDNStrue; verbosedebugf("SendQueries: Put Question %##s (%s) probecount %d", ar->resrec.name->c, DNSTypeName(ar->resrec.rrtype), ar->ProbeCount); } } } // Put our known answer list (either new one from this question or questions, or remainder of old one from last time) while (KnownAnswerList) { CacheRecord *ka = KnownAnswerList; mDNSu32 SecsSinceRcvd = ((mDNSu32)(m->timenow - ka->TimeRcvd)) / mDNSPlatformOneSecond; mDNSu8 *newptr = PutResourceRecordTTLWithLimit(&m->omsg, queryptr, &m->omsg.h.numAnswers, &ka->resrec, ka->resrec.rroriginalttl - SecsSinceRcvd, m->omsg.data + NormalMaxDNSMessageData - OwnerRecordSpace); if (newptr) { verbosedebugf("SendQueries: Put %##s (%s) at %d - %d", ka->resrec.name->c, DNSTypeName(ka->resrec.rrtype), queryptr - m->omsg.data, newptr - m->omsg.data); queryptr = newptr; KnownAnswerList = ka->NextInKAList; ka->NextInKAList = mDNSNULL; } else { // If we ran out of space and we have more than one question in the packet, that's an error -- // we shouldn't have put more than one question if there was a risk of us running out of space. if (m->omsg.h.numQuestions > 1) LogMsg("SendQueries: Put %d answers; No more space for known answers", m->omsg.h.numAnswers); m->omsg.h.flags.b[0] |= kDNSFlag0_TC; break; } } for (ar = m->ResourceRecords; ar; ar=ar->next) if (ar->IncludeInProbe) { mDNSu8 *newptr = PutResourceRecord(&m->omsg, queryptr, &m->omsg.h.numAuthorities, &ar->resrec); ar->IncludeInProbe = mDNSfalse; if (newptr) queryptr = newptr; else LogMsg("SendQueries: How did we fail to have space for the Update record %s", ARDisplayString(m,ar)); } if (queryptr > m->omsg.data) { if (OwnerRecordSpace) { AuthRecord opt; mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL); opt.resrec.rrclass = NormalMaxDNSMessageData; opt.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record opt.resrec.rdestimate = sizeof(rdataOPT); SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[0]); LogSPS("SendQueries putting %s", ARDisplayString(m, &opt)); queryptr = PutResourceRecordTTLWithLimit(&m->omsg, queryptr, &m->omsg.h.numAdditionals, &opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData); if (!queryptr) LogMsg("SendQueries: How did we fail to have space for the OPT record (%d/%d/%d/%d) %s", m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt)); if (queryptr > m->omsg.data + NormalMaxDNSMessageData) if (m->omsg.h.numQuestions != 1 || m->omsg.h.numAnswers != 0 || m->omsg.h.numAuthorities != 1 || m->omsg.h.numAdditionals != 1) LogMsg("SendQueries: Why did we generate oversized packet with OPT record %p %p %p (%d/%d/%d/%d) %s", m->omsg.data, m->omsg.data + NormalMaxDNSMessageData, queryptr, m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt)); } if ((m->omsg.h.flags.b[0] & kDNSFlag0_TC) && m->omsg.h.numQuestions > 1) LogMsg("SendQueries: Should not have more than one question (%d) in a truncated packet", m->omsg.h.numQuestions); debugf("SendQueries: Sending %d Question%s %d Answer%s %d Update%s on %p", m->omsg.h.numQuestions, m->omsg.h.numQuestions == 1 ? "" : "s", m->omsg.h.numAnswers, m->omsg.h.numAnswers == 1 ? "" : "s", m->omsg.h.numAuthorities, m->omsg.h.numAuthorities == 1 ? "" : "s", intf->InterfaceID); if (intf->IPv4Available) mDNSSendDNSMessage(m, &m->omsg, queryptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v4, MulticastDNSPort, mDNSNULL, mDNSNULL); if (intf->IPv6Available) mDNSSendDNSMessage(m, &m->omsg, queryptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v6, MulticastDNSPort, mDNSNULL, mDNSNULL); if (!m->SuppressSending) m->SuppressSending = NonZeroTime(m->timenow + (mDNSPlatformOneSecond+9)/10); if (++pktcount >= 1000) { LogMsg("SendQueries exceeded loop limit %d: giving up", pktcount); break; } // There might be more records left in the known answer list, or more questions to send // on this interface, so go around one more time and try again. } else // Nothing more to send on this interface; go to next { const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next); #if MDNS_DEBUGMSGS && 0 const char *const msg = next ? "SendQueries: Nothing more on %p; moving to %p" : "SendQueries: Nothing more on %p"; debugf(msg, intf, next); #endif intf = next; } } // 4. Final housekeeping // 4a. Debugging check: Make sure we announced all our records for (ar = m->ResourceRecords; ar; ar=ar->next) if (ar->SendRNow) { if (ar->ARType != AuthRecordLocalOnly && ar->ARType != AuthRecordP2P) LogMsg("SendQueries: No active interface %p to send probe: %p %s", ar->SendRNow, ar->resrec.InterfaceID, ARDisplayString(m, ar)); ar->SendRNow = mDNSNULL; } // 4b. When we have lingering cache records that we're keeping around for a few seconds in the hope // that their interface which went away might come back again, the logic will want to send queries // for those records, but we can't because their interface isn't here any more, so to keep the // state machine ticking over we just pretend we did so. // If the interface does not come back in time, the cache record will expire naturally FORALL_CACHERECORDS(slot, cg, cr) if (cr->CRActiveQuestion && cr->UnansweredQueries < MaxUnansweredQueries) if (m->timenow + TicksTTL(cr)/50 - cr->NextRequiredQuery >= 0) { cr->UnansweredQueries++; cr->CRActiveQuestion->SendQNow = mDNSNULL; SetNextCacheCheckTimeForRecord(m, cr); } // 4c. Debugging check: Make sure we sent all our planned questions // Do this AFTER the lingering cache records check above, because that will prevent spurious warnings for questions // we legitimately couldn't send because the interface is no longer available for (q = m->Questions; q; q=q->next) if (q->SendQNow) { DNSQuestion *x; for (x = m->NewQuestions; x; x=x->next) if (x == q) break; // Check if this question is a NewQuestion LogMsg("SendQueries: No active interface %p to send %s question: %p %##s (%s)", q->SendQNow, x ? "new" : "old", q->InterfaceID, q->qname.c, DNSTypeName(q->qtype)); q->SendQNow = mDNSNULL; } } mDNSlocal void SendWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *EthAddr, mDNSOpaque48 *password) { int i, j; mDNSu8 *ptr = m->omsg.data; NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID); if (!intf) { LogMsg("SendARP: No interface with InterfaceID %p found", InterfaceID); return; } // 0x00 Destination address for (i=0; i<6; i++) *ptr++ = EthAddr->b[i]; // 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us) for (i=0; i<6; i++) *ptr++ = intf->MAC.b[0]; // 0x0C Ethertype (0x0842) *ptr++ = 0x08; *ptr++ = 0x42; // 0x0E Wakeup sync sequence for (i=0; i<6; i++) *ptr++ = 0xFF; // 0x14 Wakeup data for (j=0; j<16; j++) for (i=0; i<6; i++) *ptr++ = EthAddr->b[i]; // 0x74 Password for (i=0; i<6; i++) *ptr++ = password->b[i]; mDNSPlatformSendRawPacket(m->omsg.data, ptr, InterfaceID); // For Ethernet switches that don't flood-foward packets with unknown unicast destination MAC addresses, // broadcast is the only reliable way to get a wakeup packet to the intended target machine. // For 802.11 WPA networks, where a sleeping target machine may have missed a broadcast/multicast // key rotation, unicast is the only way to get a wakeup packet to the intended target machine. // So, we send one of each, unicast first, then broadcast second. for (i=0; i<6; i++) m->omsg.data[i] = 0xFF; mDNSPlatformSendRawPacket(m->omsg.data, ptr, InterfaceID); } // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - RR List Management & Task Management #endif // Note: AnswerCurrentQuestionWithResourceRecord can call a user callback, which may change the record list and/or question list. // Any code walking either list must use the m->CurrentQuestion (and possibly m->CurrentRecord) mechanism to protect against this. // In fact, to enforce this, the routine will *only* answer the question currently pointed to by m->CurrentQuestion, // which will be auto-advanced (possibly to NULL) if the client callback cancels the question. mDNSexport void AnswerCurrentQuestionWithResourceRecord(mDNS *const m, CacheRecord *const rr, const QC_result AddRecord) { DNSQuestion *const q = m->CurrentQuestion; mDNSBool followcname = FollowCNAME(q, &rr->resrec, AddRecord); verbosedebugf("AnswerCurrentQuestionWithResourceRecord:%4lu %s TTL %d %s", q->CurrentAnswers, AddRecord ? "Add" : "Rmv", rr->resrec.rroriginalttl, CRDisplayString(m, rr)); // Normally we don't send out the unicast query if we have answered using our local only auth records e.g., /etc/hosts. // But if the query for "A" record has a local answer but query for "AAAA" record has no local answer, we might // send the AAAA query out which will come back with CNAME and will also answer the "A" query. To prevent that, // we check to see if that query already has a unique local answer. if (q->LOAddressAnswers) { LogInfo("AnswerCurrentQuestionWithResourceRecord: Question %p %##s (%s) not answering with record %s due to " "LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), ARDisplayString(m, rr), q->LOAddressAnswers); return; } if (QuerySuppressed(q)) { // If the query is suppressed, then we don't want to answer from the cache. But if this query is // supposed to time out, we still want to callback the clients. We do this only for TimeoutQuestions // that are timing out, which we know are answered with Negative cache record when timing out. if (!q->TimeoutQuestion || rr->resrec.RecordType != kDNSRecordTypePacketNegative || (m->timenow - q->StopTime < 0)) return; } // Note: Use caution here. In the case of records with rr->DelayDelivery set, AnswerCurrentQuestionWithResourceRecord(... mDNStrue) // may be called twice, once when the record is received, and again when it's time to notify local clients. // If any counters or similar are added here, care must be taken to ensure that they are not double-incremented by this. rr->LastUsed = m->timenow; if (AddRecord == QC_add && !q->DuplicateOf && rr->CRActiveQuestion != q) { if (!rr->CRActiveQuestion) m->rrcache_active++; // If not previously active, increment rrcache_active count debugf("AnswerCurrentQuestionWithResourceRecord: Updating CRActiveQuestion from %p to %p for cache record %s, CurrentAnswer %d", rr->CRActiveQuestion, q, CRDisplayString(m,rr), q->CurrentAnswers); rr->CRActiveQuestion = q; // We know q is non-null SetNextCacheCheckTimeForRecord(m, rr); } // If this is: // (a) a no-cache add, where we've already done at least one 'QM' query, or // (b) a normal add, where we have at least one unique-type answer, // then there's no need to keep polling the network. // (If we have an answer in the cache, then we'll automatically ask again in time to stop it expiring.) // We do this for mDNS questions and uDNS one-shot questions, but not for // uDNS LongLived questions, because that would mess up our LLQ lease renewal timing. if ((AddRecord == QC_addnocache && !q->RequestUnicast) || (AddRecord == QC_add && (q->ExpectUnique || (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask)))) if (ActiveQuestion(q) && (mDNSOpaque16IsZero(q->TargetQID) || !q->LongLived)) { q->LastQTime = m->timenow; q->LastQTxTime = m->timenow; q->RecentAnswerPkts = 0; q->ThisQInterval = MaxQuestionInterval; q->RequestUnicast = mDNSfalse; debugf("AnswerCurrentQuestionWithResourceRecord: Set MaxQuestionInterval for %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); } if (rr->DelayDelivery) return; // We'll come back later when CacheRecordDeferredAdd() calls us // Only deliver negative answers if client has explicitly requested them if (rr->resrec.RecordType == kDNSRecordTypePacketNegative || (q->qtype != kDNSType_NSEC && RRAssertsNonexistence(&rr->resrec, q->qtype))) if (!AddRecord || !q->ReturnIntermed) return; // For CNAME results to non-CNAME questions, only inform the client if they explicitly requested that if (q->QuestionCallback && !q->NoAnswer && (!followcname || q->ReturnIntermed)) { mDNS_DropLockBeforeCallback(); // Allow client (and us) to legally make mDNS API calls if (q->qtype != kDNSType_NSEC && RRAssertsNonexistence(&rr->resrec, q->qtype)) { CacheRecord neg; MakeNegativeCacheRecord(m, &neg, &q->qname, q->qnamehash, q->qtype, q->qclass, 1, rr->resrec.InterfaceID, q->qDNSServer); q->QuestionCallback(m, q, &neg.resrec, AddRecord); } else q->QuestionCallback(m, q, &rr->resrec, AddRecord); mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again } // Note: Proceed with caution here because client callback function is allowed to do anything, // including starting/stopping queries, registering/deregistering records, etc. if (followcname && m->CurrentQuestion == q) AnswerQuestionByFollowingCNAME(m, q, &rr->resrec); } // New Questions are answered through AnswerNewQuestion. But there may not have been any // matching cache records for the questions when it is called. There are two possibilities. // // 1) There are no cache records // 2) There are cache records but the DNSServers between question and cache record don't match. // // In the case of (1), where there are no cache records and later we add them when we get a response, // CacheRecordAdd/CacheRecordDeferredAdd will take care of adding the cache and delivering the ADD // events to the application. If we already have a cache entry, then no ADD events are delivered // unless the RDATA has changed // // In the case of (2) where we had the cache records and did not answer because of the DNSServer mismatch, // we need to answer them whenever we change the DNSServer. But we can't do it at the instant the DNSServer // changes because when we do the callback, the question can get deleted and the calling function would not // know how to handle it. So, we run this function from mDNS_Execute to handle DNSServer changes on the // question mDNSlocal void AnswerQuestionsForDNSServerChanges(mDNS *const m) { DNSQuestion *q; DNSQuestion *qnext; CacheRecord *rr; mDNSu32 slot; CacheGroup *cg; if (m->CurrentQuestion) LogMsg("AnswerQuestionsForDNSServerChanges: ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); for (q = m->Questions; q && q != m->NewQuestions; q = qnext) { qnext = q->next; // multicast or DNSServers did not change. if (mDNSOpaque16IsZero(q->TargetQID)) continue; if (!q->deliverAddEvents) continue; // We are going to look through the cache for this question since it changed // its DNSserver last time. Reset it so that we don't call them again. Calling // them again will deliver duplicate events to the application q->deliverAddEvents = mDNSfalse; if (QuerySuppressed(q)) continue; m->CurrentQuestion = q; slot = HashSlot(&q->qname); cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) { if (SameNameRecordAnswersQuestion(&rr->resrec, q)) { LogInfo("AnswerQuestionsForDNSServerChanges: Calling AnswerCurrentQuestionWithResourceRecord for question %p %##s using resource record %s", q, q->qname.c, CRDisplayString(m, rr)); // When this question penalizes a DNS server and has no more DNS servers to pick, we normally // deliver a negative cache response and suspend the question for 60 seconds (see uDNS_CheckCurrentQuestion). // But sometimes we may already find the negative cache entry and deliver that here as the process // of changing DNS servers. When the cache entry is about to expire, we will resend the question and // that time, we need to make sure that we have a valid DNS server. Otherwise, we will deliver // a negative cache response without trying the server. if (!q->qDNSServer && !q->DuplicateOf && rr->resrec.RecordType == kDNSRecordTypePacketNegative) { DNSQuestion *qptr; SetValidDNSServers(m, q); q->qDNSServer = GetServerForQuestion(m, q); for (qptr = q->next ; qptr; qptr = qptr->next) if (qptr->DuplicateOf == q) { qptr->validDNSServers = q->validDNSServers; qptr->qDNSServer = q->qDNSServer; } } q->CurrentAnswers++; if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++; if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++; AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add); if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here } } } m->CurrentQuestion = mDNSNULL; } mDNSlocal void CacheRecordDeferredAdd(mDNS *const m, CacheRecord *rr) { rr->DelayDelivery = 0; if (m->CurrentQuestion) LogMsg("CacheRecordDeferredAdd ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->Questions; while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) { DNSQuestion *q = m->CurrentQuestion; if (ResourceRecordAnswersQuestion(&rr->resrec, q)) AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add); if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now m->CurrentQuestion = q->next; } m->CurrentQuestion = mDNSNULL; } mDNSlocal mDNSs32 CheckForSoonToExpireRecords(mDNS *const m, const domainname *const name, const mDNSu32 namehash, const mDNSu32 slot) { const mDNSs32 threshhold = m->timenow + mDNSPlatformOneSecond; // See if there are any records expiring within one second const mDNSs32 start = m->timenow - 0x10000000; mDNSs32 delay = start; CacheGroup *cg = CacheGroupForName(m, slot, namehash, name); const CacheRecord *rr; for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) if (threshhold - RRExpireTime(rr) >= 0) // If we have records about to expire within a second if (delay - RRExpireTime(rr) < 0) // then delay until after they've been deleted delay = RRExpireTime(rr); if (delay - start > 0) return(NonZeroTime(delay)); else return(0); } // CacheRecordAdd is only called from CreateNewCacheEntry, *never* directly as a result of a client API call. // If new questions are created as a result of invoking client callbacks, they will be added to // the end of the question list, and m->NewQuestions will be set to indicate the first new question. // rr is a new CacheRecord just received into our cache // (kDNSRecordTypePacketAns/PacketAnsUnique/PacketAdd/PacketAddUnique). // Note: CacheRecordAdd calls AnswerCurrentQuestionWithResourceRecord which can call a user callback, // which may change the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSlocal void CacheRecordAdd(mDNS *const m, CacheRecord *rr) { DNSQuestion *q; // We stop when we get to NewQuestions -- if we increment their CurrentAnswers/LargeAnswers/UniqueAnswers // counters here we'll end up double-incrementing them when we do it again in AnswerNewQuestion(). for (q = m->Questions; q && q != m->NewQuestions; q=q->next) { if (ResourceRecordAnswersQuestion(&rr->resrec, q)) { // If this question is one that's actively sending queries, and it's received ten answers within one // second of sending the last query packet, then that indicates some radical network topology change, // so reset its exponential backoff back to the start. We must be at least at the eight-second interval // to do this. If we're at the four-second interval, or less, there's not much benefit accelerating // because we will anyway send another query within a few seconds. The first reset query is sent out // randomized over the next four seconds to reduce possible synchronization between machines. if (q->LastAnswerPktNum != m->PktNum) { q->LastAnswerPktNum = m->PktNum; if (mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q) && ++q->RecentAnswerPkts >= 10 && q->ThisQInterval > InitialQuestionInterval * QuestionIntervalStep3 && m->timenow - q->LastQTxTime < mDNSPlatformOneSecond) { LogMsg("CacheRecordAdd: %##s (%s) got immediate answer burst (%d); restarting exponential backoff sequence (%d)", q->qname.c, DNSTypeName(q->qtype), q->RecentAnswerPkts, q->ThisQInterval); q->LastQTime = m->timenow - InitialQuestionInterval + (mDNSs32)mDNSRandom((mDNSu32)mDNSPlatformOneSecond*4); q->ThisQInterval = InitialQuestionInterval; SetNextQueryTime(m,q); } } verbosedebugf("CacheRecordAdd %p %##s (%s) %lu %#a:%d question %p", rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->resrec.rroriginalttl, rr->resrec.rDNSServer ? &rr->resrec.rDNSServer->addr : mDNSNULL, mDNSVal16(rr->resrec.rDNSServer ? rr->resrec.rDNSServer->port : zeroIPPort), q); q->CurrentAnswers++; q->unansweredQueries = 0; if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++; if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++; if (q->CurrentAnswers > 4000) { static int msgcount = 0; if (msgcount++ < 10) LogMsg("CacheRecordAdd: %##s (%s) has %d answers; shedding records to resist DOS attack", q->qname.c, DNSTypeName(q->qtype), q->CurrentAnswers); rr->resrec.rroriginalttl = 0; rr->UnansweredQueries = MaxUnansweredQueries; } } } if (!rr->DelayDelivery) { if (m->CurrentQuestion) LogMsg("CacheRecordAdd ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->Questions; while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) { q = m->CurrentQuestion; if (ResourceRecordAnswersQuestion(&rr->resrec, q)) AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add); if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now m->CurrentQuestion = q->next; } m->CurrentQuestion = mDNSNULL; } SetNextCacheCheckTimeForRecord(m, rr); } // NoCacheAnswer is only called from mDNSCoreReceiveResponse, *never* directly as a result of a client API call. // If new questions are created as a result of invoking client callbacks, they will be added to // the end of the question list, and m->NewQuestions will be set to indicate the first new question. // rr is a new CacheRecord just received from the wire (kDNSRecordTypePacketAns/AnsUnique/Add/AddUnique) // but we don't have any place to cache it. We'll deliver question 'add' events now, but we won't have any // way to deliver 'remove' events in future, nor will we be able to include this in known-answer lists, // so we immediately bump ThisQInterval up to MaxQuestionInterval to avoid pounding the network. // Note: NoCacheAnswer calls AnswerCurrentQuestionWithResourceRecord which can call a user callback, // which may change the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSlocal void NoCacheAnswer(mDNS *const m, CacheRecord *rr) { LogMsg("No cache space: Delivering non-cached result for %##s", m->rec.r.resrec.name->c); if (m->CurrentQuestion) LogMsg("NoCacheAnswer ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->Questions; // We do this for *all* questions, not stopping when we get to m->NewQuestions, // since we're not caching the record and we'll get no opportunity to do this later while (m->CurrentQuestion) { DNSQuestion *q = m->CurrentQuestion; if (ResourceRecordAnswersQuestion(&rr->resrec, q)) AnswerCurrentQuestionWithResourceRecord(m, rr, QC_addnocache); // QC_addnocache means "don't expect remove events for this" if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now m->CurrentQuestion = q->next; } m->CurrentQuestion = mDNSNULL; } // CacheRecordRmv is only called from CheckCacheExpiration, which is called from mDNS_Execute. // Note that CacheRecordRmv is *only* called for records that are referenced by at least one active question. // If new questions are created as a result of invoking client callbacks, they will be added to // the end of the question list, and m->NewQuestions will be set to indicate the first new question. // rr is an existing cache CacheRecord that just expired and is being deleted // (kDNSRecordTypePacketAns/PacketAnsUnique/PacketAdd/PacketAddUnique). // Note: CacheRecordRmv calls AnswerCurrentQuestionWithResourceRecord which can call a user callback, // which may change the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSlocal void CacheRecordRmv(mDNS *const m, CacheRecord *rr) { if (m->CurrentQuestion) LogMsg("CacheRecordRmv ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->Questions; // We stop when we get to NewQuestions -- for new questions their CurrentAnswers/LargeAnswers/UniqueAnswers counters // will all still be zero because we haven't yet gone through the cache counting how many answers we have for them. while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) { DNSQuestion *q = m->CurrentQuestion; // When a question enters suppressed state, we generate RMV events and generate a negative // response. A cache may be present that answers this question e.g., cache entry generated // before the question became suppressed. We need to skip the suppressed questions here as // the RMV event has already been generated. if (!QuerySuppressed(q) && ResourceRecordAnswersQuestion(&rr->resrec, q)) { verbosedebugf("CacheRecordRmv %p %s", rr, CRDisplayString(m, rr)); q->FlappingInterface1 = mDNSNULL; q->FlappingInterface2 = mDNSNULL; // When a question changes DNS server, it is marked with deliverAddEvents if we find any // cache entry corresponding to the new DNS server. Before we deliver the ADD event, the // cache entry may be removed in which case CurrentAnswers can be zero. if (q->deliverAddEvents && !q->CurrentAnswers) { LogInfo("CacheRecordRmv: Question %p %##s (%s) deliverAddEvents set, DNSServer %#a:%d", q, q->qname.c, DNSTypeName(q->qtype), q->qDNSServer ? &q->qDNSServer->addr : mDNSNULL, mDNSVal16(q->qDNSServer ? q->qDNSServer->port : zeroIPPort)); m->CurrentQuestion = q->next; continue; } if (q->CurrentAnswers == 0) LogMsg("CacheRecordRmv ERROR!!: How can CurrentAnswers already be zero for %p %##s (%s) DNSServer %#a:%d", q, q->qname.c, DNSTypeName(q->qtype), q->qDNSServer ? &q->qDNSServer->addr : mDNSNULL, mDNSVal16(q->qDNSServer ? q->qDNSServer->port : zeroIPPort)); else { q->CurrentAnswers--; if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers--; if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers--; } if (rr->resrec.rdata->MaxRDLength) // Never generate "remove" events for negative results { if (q->CurrentAnswers == 0) { LogInfo("CacheRecordRmv: Last answer for %##s (%s) expired from cache; will reconfirm antecedents", q->qname.c, DNSTypeName(q->qtype)); ReconfirmAntecedents(m, &q->qname, q->qnamehash, 0); } AnswerCurrentQuestionWithResourceRecord(m, rr, QC_rmv); } } if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now m->CurrentQuestion = q->next; } m->CurrentQuestion = mDNSNULL; } mDNSlocal void ReleaseCacheEntity(mDNS *const m, CacheEntity *e) { #if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING >= 1 unsigned int i; for (i=0; inext = m->rrcache_free; m->rrcache_free = e; m->rrcache_totalused--; } mDNSlocal void ReleaseCacheGroup(mDNS *const m, CacheGroup **cp) { CacheEntity *e = (CacheEntity *)(*cp); //LogMsg("ReleaseCacheGroup: Releasing CacheGroup for %p, %##s", (*cp)->name->c, (*cp)->name->c); if ((*cp)->rrcache_tail != &(*cp)->members) LogMsg("ERROR: (*cp)->members == mDNSNULL but (*cp)->rrcache_tail != &(*cp)->members)"); //if ((*cp)->name != (domainname*)((*cp)->namestorage)) // LogMsg("ReleaseCacheGroup: %##s, %p %p", (*cp)->name->c, (*cp)->name, (domainname*)((*cp)->namestorage)); if ((*cp)->name != (domainname*)((*cp)->namestorage)) mDNSPlatformMemFree((*cp)->name); (*cp)->name = mDNSNULL; *cp = (*cp)->next; // Cut record from list ReleaseCacheEntity(m, e); } mDNSlocal void ReleaseCacheRecord(mDNS *const m, CacheRecord *r) { //LogMsg("ReleaseCacheRecord: Releasing %s", CRDisplayString(m, r)); if (r->resrec.rdata && r->resrec.rdata != (RData*)&r->smallrdatastorage) mDNSPlatformMemFree(r->resrec.rdata); r->resrec.rdata = mDNSNULL; ReleaseCacheEntity(m, (CacheEntity *)r); } // Note: We want to be careful that we deliver all the CacheRecordRmv calls before delivering // CacheRecordDeferredAdd calls. The in-order nature of the cache lists ensures that all // callbacks for old records are delivered before callbacks for newer records. mDNSlocal void CheckCacheExpiration(mDNS *const m, const mDNSu32 slot, CacheGroup *const cg) { CacheRecord **rp = &cg->members; if (m->lock_rrcache) { LogMsg("CheckCacheExpiration ERROR! Cache already locked!"); return; } m->lock_rrcache = 1; while (*rp) { CacheRecord *const rr = *rp; mDNSs32 event = RRExpireTime(rr); if (m->timenow - event >= 0) // If expired, delete it { *rp = rr->next; // Cut it from the list verbosedebugf("CheckCacheExpiration: Deleting%7d %7d %p %s", m->timenow - rr->TimeRcvd, rr->resrec.rroriginalttl, rr->CRActiveQuestion, CRDisplayString(m, rr)); if (rr->CRActiveQuestion) // If this record has one or more active questions, tell them it's going away { DNSQuestion *q = rr->CRActiveQuestion; // When a cache record is about to expire, we expect to do four queries at 80-82%, 85-87%, 90-92% and // then 95-97% of the TTL. If the DNS server does not respond, then we will remove the cache entry // before we pick a new DNS server. As the question interval is set to MaxQuestionInterval, we may // not send out a query anytime soon. Hence, we need to reset the question interval. If this is // a normal deferred ADD case, then AnswerCurrentQuestionWithResourceRecord will reset it to // MaxQuestionInterval. If we have inactive questions referring to negative cache entries, // don't ressurect them as they will deliver duplicate "No such Record" ADD events if (!mDNSOpaque16IsZero(q->TargetQID) && !q->LongLived && ActiveQuestion(q)) { q->ThisQInterval = InitialQuestionInterval; q->LastQTime = m->timenow - q->ThisQInterval; SetNextQueryTime(m, q); } CacheRecordRmv(m, rr); m->rrcache_active--; } ReleaseCacheRecord(m, rr); } else // else, not expired; see if we need to query { // If waiting to delay delivery, do nothing until then if (rr->DelayDelivery && rr->DelayDelivery - m->timenow > 0) event = rr->DelayDelivery; else { if (rr->DelayDelivery) CacheRecordDeferredAdd(m, rr); if (rr->CRActiveQuestion && rr->UnansweredQueries < MaxUnansweredQueries) { if (m->timenow - rr->NextRequiredQuery < 0) // If not yet time for next query event = NextCacheCheckEvent(rr); // then just record when we want the next query else // else trigger our question to go out now { // Set NextScheduledQuery to timenow so that SendQueries() will run. // SendQueries() will see that we have records close to expiration, and send FEQs for them. m->NextScheduledQuery = m->timenow; // After sending the query we'll increment UnansweredQueries and call SetNextCacheCheckTimeForRecord(), // which will correctly update m->NextCacheCheck for us. event = m->timenow + 0x3FFFFFFF; } } } verbosedebugf("CheckCacheExpiration:%6d %5d %s", (event - m->timenow) / mDNSPlatformOneSecond, CacheCheckGracePeriod(rr), CRDisplayString(m, rr)); if (m->rrcache_nextcheck[slot] - event > 0) m->rrcache_nextcheck[slot] = event; rp = &rr->next; } } if (cg->rrcache_tail != rp) verbosedebugf("CheckCacheExpiration: Updating CacheGroup tail from %p to %p", cg->rrcache_tail, rp); cg->rrcache_tail = rp; m->lock_rrcache = 0; } mDNSlocal void AnswerNewQuestion(mDNS *const m) { mDNSBool ShouldQueryImmediately = mDNStrue; DNSQuestion *const q = m->NewQuestions; // Grab the question we're going to answer mDNSu32 slot = HashSlot(&q->qname); CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); AuthRecord *lr; AuthGroup *ag; mDNSBool AnsweredFromCache = mDNSfalse; verbosedebugf("AnswerNewQuestion: Answering %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); if (cg) CheckCacheExpiration(m, slot, cg); if (m->NewQuestions != q) { LogInfo("AnswerNewQuestion: Question deleted while doing CheckCacheExpiration"); goto exit; } m->NewQuestions = q->next; // Advance NewQuestions to the next *after* calling CheckCacheExpiration, because if we advance it first // then CheckCacheExpiration may give this question add/remove callbacks, and it's not yet ready for that. // // Also, CheckCacheExpiration() calls CacheRecordDeferredAdd() and CacheRecordRmv(), which invoke // client callbacks, which may delete their own or any other question. Our mechanism for detecting // whether our current m->NewQuestions question got deleted by one of these callbacks is to store the // value of m->NewQuestions in 'q' before calling CheckCacheExpiration(), and then verify afterwards // that they're still the same. If m->NewQuestions has changed (because mDNS_StopQuery_internal // advanced it), that means the question was deleted, so we no longer need to worry about answering // it (and indeed 'q' is now a dangling pointer, so dereferencing it at all would be bad, and the // values we computed for slot and cg are now stale and relate to a question that no longer exists). // // We can't use the usual m->CurrentQuestion mechanism for this because CacheRecordDeferredAdd() and // CacheRecordRmv() both use that themselves when walking the list of (non-new) questions generating callbacks. // Fortunately mDNS_StopQuery_internal auto-advances both m->CurrentQuestion *AND* m->NewQuestions when // deleting a question, so luckily we have an easy alternative way of detecting if our question got deleted. if (m->lock_rrcache) LogMsg("AnswerNewQuestion ERROR! Cache already locked!"); // This should be safe, because calling the client's question callback may cause the // question list to be modified, but should not ever cause the rrcache list to be modified. // If the client's question callback deletes the question, then m->CurrentQuestion will // be advanced, and we'll exit out of the loop m->lock_rrcache = 1; if (m->CurrentQuestion) LogMsg("AnswerNewQuestion ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = q; // Indicate which question we're answering, so we'll know if it gets deleted if (q->NoAnswer == NoAnswer_Fail) { LogMsg("AnswerNewQuestion: NoAnswer_Fail %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); MakeNegativeCacheRecord(m, &m->rec.r, &q->qname, q->qnamehash, q->qtype, q->qclass, 60, mDNSInterface_Any, q->qDNSServer); q->NoAnswer = NoAnswer_Normal; // Temporarily turn off answer suppression AnswerCurrentQuestionWithResourceRecord(m, &m->rec.r, QC_addnocache); // Don't touch the question if it has been stopped already if (m->CurrentQuestion == q) q->NoAnswer = NoAnswer_Fail; // Restore NoAnswer state m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } if (m->CurrentQuestion != q) { LogInfo("AnswerNewQuestion: Question deleted while generating NoAnswer_Fail response"); goto exit; } // See if we want to tell it about LocalOnly records if (m->CurrentRecord) LogMsg("AnswerNewQuestion ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); slot = AuthHashSlot(&q->qname); ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname); if (ag) { m->CurrentRecord = ag->members; while (m->CurrentRecord && m->CurrentRecord != ag->NewLocalOnlyRecords) { AuthRecord *rr = m->CurrentRecord; m->CurrentRecord = rr->next; // // If the question is mDNSInterface_LocalOnly, all records local to the machine should be used // to answer the query. This is handled in AnswerNewLocalOnlyQuestion. // // We handle mDNSInterface_Any and scoped questions here. See LocalOnlyRecordAnswersQuestion for more // details on how we handle this case. For P2P we just handle "Interface_Any" questions. For LocalOnly // we handle both mDNSInterface_Any and scoped questions. if (rr->ARType == AuthRecordLocalOnly || (rr->ARType == AuthRecordP2P && q->InterfaceID == mDNSInterface_Any)) if (LocalOnlyRecordAnswersQuestion(rr, q)) { AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue); if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here } } } m->CurrentRecord = mDNSNULL; if (m->CurrentQuestion != q) { LogInfo("AnswerNewQuestion: Question deleted while while giving LocalOnly record answers"); goto exit; } if (q->LOAddressAnswers) { LogInfo("AnswerNewQuestion: Question %p %##s (%s) answered using local auth records LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), q->LOAddressAnswers); goto exit; } // Before we go check the cache and ship this query on the wire, we have to be sure that there are // no local records that could possibly answer this question. As we did not check the NewLocalRecords, we // need to just peek at them to see whether it will answer this question. If it would answer, pretend // that we answered. AnswerAllLocalQuestionsWithLocalAuthRecord will answer shortly. This happens normally // when we add new /etc/hosts entries and restart the question. It is a new question and also a new record. if (ag) { lr = ag->NewLocalOnlyRecords; while (lr) { if (LORecordAnswersAddressType(lr) && LocalOnlyRecordAnswersQuestion(lr, q)) { LogInfo("AnswerNewQuestion: Question %p %##s (%s) will be answered using new local auth records " " LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), q->LOAddressAnswers); goto exit; } lr = lr->next; } } // If we are not supposed to answer this question, generate a negative response. // Temporarily suspend the SuppressQuery so that AnswerCurrentQuestionWithResourceRecord can answer the question if (QuerySuppressed(q)) { q->SuppressQuery = mDNSfalse; GenerateNegativeResponse(m); q->SuppressQuery = mDNStrue; } else { CacheRecord *rr; for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) if (SameNameRecordAnswersQuestion(&rr->resrec, q)) { // SecsSinceRcvd is whole number of elapsed seconds, rounded down mDNSu32 SecsSinceRcvd = ((mDNSu32)(m->timenow - rr->TimeRcvd)) / mDNSPlatformOneSecond; if (rr->resrec.rroriginalttl <= SecsSinceRcvd) { LogMsg("AnswerNewQuestion: How is rr->resrec.rroriginalttl %lu <= SecsSinceRcvd %lu for %s %d %d", rr->resrec.rroriginalttl, SecsSinceRcvd, CRDisplayString(m, rr), m->timenow, rr->TimeRcvd); continue; // Go to next one in loop } // If this record set is marked unique, then that means we can reasonably assume we have the whole set // -- we don't need to rush out on the network and query immediately to see if there are more answers out there if ((rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) || (q->ExpectUnique)) ShouldQueryImmediately = mDNSfalse; q->CurrentAnswers++; if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++; if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++; AnsweredFromCache = mDNStrue; AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add); if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here } else if (RRTypeIsAddressType(rr->resrec.rrtype) && RRTypeIsAddressType(q->qtype)) ShouldQueryImmediately = mDNSfalse; } // We don't use LogInfo for this "Question deleted" message because it happens so routinely that // it's not remotely remarkable, and therefore unlikely to be of much help tracking down bugs. if (m->CurrentQuestion != q) { debugf("AnswerNewQuestion: Question deleted while giving cache answers"); goto exit; } // Neither a local record nor a cache entry could answer this question. If this question need to be retried // with search domains, generate a negative response which will now retry after appending search domains. // If the query was suppressed above, we already generated a negative response. When it gets unsuppressed, // we will retry with search domains. if (!QuerySuppressed(q) && !AnsweredFromCache && q->RetryWithSearchDomains) { LogInfo("AnswerNewQuestion: Generating response for retrying with search domains %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); GenerateNegativeResponse(m); } if (m->CurrentQuestion != q) { debugf("AnswerNewQuestion: Question deleted while giving negative answer"); goto exit; } // Note: When a query gets suppressed or retried with search domains, we de-activate the question. // Hence we don't execute the following block of code for those cases. if (ShouldQueryImmediately && ActiveQuestion(q)) { debugf("AnswerNewQuestion: ShouldQueryImmediately %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); q->ThisQInterval = InitialQuestionInterval; q->LastQTime = m->timenow - q->ThisQInterval; if (mDNSOpaque16IsZero(q->TargetQID)) // For mDNS, spread packets to avoid a burst of simultaneous queries { // Compute random delay in the range 1-6 seconds, then divide by 50 to get 20-120ms if (!m->RandomQueryDelay) m->RandomQueryDelay = (mDNSPlatformOneSecond + mDNSRandom(mDNSPlatformOneSecond*5) - 1) / 50 + 1; q->LastQTime += m->RandomQueryDelay; } } // IN ALL CASES make sure that m->NextScheduledQuery is set appropriately. // In cases where m->NewQuestions->DelayAnswering is set, we may have delayed generating our // answers for this question until *after* its scheduled transmission time, in which case // m->NextScheduledQuery may now be set to 'never', and in that case -- even though we're *not* doing // ShouldQueryImmediately -- we still need to make sure we set m->NextScheduledQuery correctly. SetNextQueryTime(m,q); exit: m->CurrentQuestion = mDNSNULL; m->lock_rrcache = 0; } // When a NewLocalOnlyQuestion is created, AnswerNewLocalOnlyQuestion runs though our ResourceRecords delivering any // appropriate answers, stopping if it reaches a NewLocalOnlyRecord -- these will be handled by AnswerAllLocalQuestionsWithLocalAuthRecord mDNSlocal void AnswerNewLocalOnlyQuestion(mDNS *const m) { mDNSu32 slot; AuthGroup *ag; DNSQuestion *q = m->NewLocalOnlyQuestions; // Grab the question we're going to answer m->NewLocalOnlyQuestions = q->next; // Advance NewLocalOnlyQuestions to the next (if any) debugf("AnswerNewLocalOnlyQuestion: Answering %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); if (m->CurrentQuestion) LogMsg("AnswerNewLocalOnlyQuestion ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = q; // Indicate which question we're answering, so we'll know if it gets deleted if (m->CurrentRecord) LogMsg("AnswerNewLocalOnlyQuestion ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); // 1. First walk the LocalOnly records answering the LocalOnly question // 2. As LocalOnly questions should also be answered by any other Auth records local to the machine, // walk the ResourceRecords list delivering the answers slot = AuthHashSlot(&q->qname); ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname); if (ag) { m->CurrentRecord = ag->members; while (m->CurrentRecord && m->CurrentRecord != ag->NewLocalOnlyRecords) { AuthRecord *rr = m->CurrentRecord; m->CurrentRecord = rr->next; if (LocalOnlyRecordAnswersQuestion(rr, q)) { AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue); if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here } } } if (m->CurrentQuestion == q) { m->CurrentRecord = m->ResourceRecords; while (m->CurrentRecord && m->CurrentRecord != m->NewLocalRecords) { AuthRecord *rr = m->CurrentRecord; m->CurrentRecord = rr->next; if (ResourceRecordAnswersQuestion(&rr->resrec, q)) { AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue); if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here } } } m->CurrentQuestion = mDNSNULL; m->CurrentRecord = mDNSNULL; } mDNSlocal CacheEntity *GetCacheEntity(mDNS *const m, const CacheGroup *const PreserveCG) { CacheEntity *e = mDNSNULL; if (m->lock_rrcache) { LogMsg("GetFreeCacheRR ERROR! Cache already locked!"); return(mDNSNULL); } m->lock_rrcache = 1; // If we have no free records, ask the client layer to give us some more memory if (!m->rrcache_free && m->MainCallback) { if (m->rrcache_totalused != m->rrcache_size) LogMsg("GetFreeCacheRR: count mismatch: m->rrcache_totalused %lu != m->rrcache_size %lu", m->rrcache_totalused, m->rrcache_size); // We don't want to be vulnerable to a malicious attacker flooding us with an infinite // number of bogus records so that we keep growing our cache until the machine runs out of memory. // To guard against this, if our cache grows above 512kB (approx 3168 records at 164 bytes each), // and we're actively using less than 1/32 of that cache, then we purge all the unused records // and recycle them, instead of allocating more memory. if (m->rrcache_size > 5000 && m->rrcache_size / 32 > m->rrcache_active) LogInfo("Possible denial-of-service attack in progress: m->rrcache_size %lu; m->rrcache_active %lu", m->rrcache_size, m->rrcache_active); else { mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback m->MainCallback(m, mStatus_GrowCache); mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again } } // If we still have no free records, recycle all the records we can. // Enumerating the entire cache is moderately expensive, so when we do it, we reclaim all the records we can in one pass. if (!m->rrcache_free) { mDNSu32 oldtotalused = m->rrcache_totalused; mDNSu32 slot; for (slot = 0; slot < CACHE_HASH_SLOTS; slot++) { CacheGroup **cp = &m->rrcache_hash[slot]; while (*cp) { CacheRecord **rp = &(*cp)->members; while (*rp) { // Records that answer still-active questions are not candidates for recycling // Records that are currently linked into the CacheFlushRecords list may not be recycled, or we'll crash if ((*rp)->CRActiveQuestion || (*rp)->NextInCFList) rp=&(*rp)->next; else { CacheRecord *rr = *rp; *rp = (*rp)->next; // Cut record from list ReleaseCacheRecord(m, rr); } } if ((*cp)->rrcache_tail != rp) verbosedebugf("GetFreeCacheRR: Updating rrcache_tail[%lu] from %p to %p", slot, (*cp)->rrcache_tail, rp); (*cp)->rrcache_tail = rp; if ((*cp)->members || (*cp)==PreserveCG) cp=&(*cp)->next; else ReleaseCacheGroup(m, cp); } } LogInfo("GetCacheEntity recycled %d records to reduce cache from %d to %d", oldtotalused - m->rrcache_totalused, oldtotalused, m->rrcache_totalused); } if (m->rrcache_free) // If there are records in the free list, take one { e = m->rrcache_free; m->rrcache_free = e->next; if (++m->rrcache_totalused >= m->rrcache_report) { LogInfo("RR Cache now using %ld objects", m->rrcache_totalused); if (m->rrcache_report < 100) m->rrcache_report += 10; else if (m->rrcache_report < 1000) m->rrcache_report += 100; else m->rrcache_report += 1000; } mDNSPlatformMemZero(e, sizeof(*e)); } m->lock_rrcache = 0; return(e); } mDNSlocal CacheRecord *GetCacheRecord(mDNS *const m, CacheGroup *cg, mDNSu16 RDLength) { CacheRecord *r = (CacheRecord *)GetCacheEntity(m, cg); if (r) { r->resrec.rdata = (RData*)&r->smallrdatastorage; // By default, assume we're usually going to be using local storage if (RDLength > InlineCacheRDSize) // If RDLength is too big, allocate extra storage { r->resrec.rdata = (RData*)mDNSPlatformMemAllocate(sizeofRDataHeader + RDLength); if (r->resrec.rdata) r->resrec.rdata->MaxRDLength = r->resrec.rdlength = RDLength; else { ReleaseCacheEntity(m, (CacheEntity*)r); r = mDNSNULL; } } } return(r); } mDNSlocal CacheGroup *GetCacheGroup(mDNS *const m, const mDNSu32 slot, const ResourceRecord *const rr) { mDNSu16 namelen = DomainNameLength(rr->name); CacheGroup *cg = (CacheGroup*)GetCacheEntity(m, mDNSNULL); if (!cg) { LogMsg("GetCacheGroup: Failed to allocate memory for %##s", rr->name->c); return(mDNSNULL); } cg->next = m->rrcache_hash[slot]; cg->namehash = rr->namehash; cg->members = mDNSNULL; cg->rrcache_tail = &cg->members; cg->name = (domainname*)cg->namestorage; //LogMsg("GetCacheGroup: %-10s %d-byte cache name %##s", // (namelen > InlineCacheGroupNameSize) ? "Allocating" : "Inline", namelen, rr->name->c); if (namelen > InlineCacheGroupNameSize) cg->name = mDNSPlatformMemAllocate(namelen); if (!cg->name) { LogMsg("GetCacheGroup: Failed to allocate name storage for %##s", rr->name->c); ReleaseCacheEntity(m, (CacheEntity*)cg); return(mDNSNULL); } AssignDomainName(cg->name, rr->name); if (CacheGroupForRecord(m, slot, rr)) LogMsg("GetCacheGroup: Already have CacheGroup for %##s", rr->name->c); m->rrcache_hash[slot] = cg; if (CacheGroupForRecord(m, slot, rr) != cg) LogMsg("GetCacheGroup: Not finding CacheGroup for %##s", rr->name->c); return(cg); } mDNSexport void mDNS_PurgeCacheResourceRecord(mDNS *const m, CacheRecord *rr) { if (m->mDNS_busy != m->mDNS_reentrancy+1) LogMsg("mDNS_PurgeCacheResourceRecord: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy); // Make sure we mark this record as thoroughly expired -- we don't ever want to give // a positive answer using an expired record (e.g. from an interface that has gone away). // We don't want to clear CRActiveQuestion here, because that would leave the record subject to // summary deletion without giving the proper callback to any questions that are monitoring it. // By setting UnansweredQueries to MaxUnansweredQueries we ensure it won't trigger any further expiration queries. rr->TimeRcvd = m->timenow - mDNSPlatformOneSecond * 60; rr->UnansweredQueries = MaxUnansweredQueries; rr->resrec.rroriginalttl = 0; SetNextCacheCheckTimeForRecord(m, rr); } mDNSexport mDNSs32 mDNS_TimeNow(const mDNS *const m) { mDNSs32 time; mDNSPlatformLock(m); if (m->mDNS_busy) { LogMsg("mDNS_TimeNow called while holding mDNS lock. This is incorrect. Code protected by lock should just use m->timenow."); if (!m->timenow) LogMsg("mDNS_TimeNow: m->mDNS_busy is %ld but m->timenow not set", m->mDNS_busy); } if (m->timenow) time = m->timenow; else time = mDNS_TimeNow_NoLock(m); mDNSPlatformUnlock(m); return(time); } // To avoid pointless CPU thrash, we use SetSPSProxyListChanged(X) to record the last interface that // had its Sleep Proxy client list change, and defer to actual BPF reconfiguration to mDNS_Execute(). // (GetNextScheduledEvent() returns "now" when m->SPSProxyListChanged is set) #define SetSPSProxyListChanged(X) do { \ if (m->SPSProxyListChanged && m->SPSProxyListChanged != (X)) mDNSPlatformUpdateProxyList(m, m->SPSProxyListChanged); \ m->SPSProxyListChanged = (X); } while(0) // Called from mDNS_Execute() to expire stale proxy records mDNSlocal void CheckProxyRecords(mDNS *const m, AuthRecord *list) { m->CurrentRecord = list; while (m->CurrentRecord) { AuthRecord *rr = m->CurrentRecord; if (rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->WakeUp.HMAC.l[0]) { // If m->SPSSocket is NULL that means we're not acting as a sleep proxy any more, // so we need to cease proxying for *all* records we may have, expired or not. if (m->SPSSocket && m->timenow - rr->TimeExpire < 0) // If proxy record not expired yet, update m->NextScheduledSPS { if (m->NextScheduledSPS - rr->TimeExpire > 0) m->NextScheduledSPS = rr->TimeExpire; } else // else proxy record expired, so remove it { LogSPS("CheckProxyRecords: Removing %d H-MAC %.6a I-MAC %.6a %d %s", m->ProxyRecords, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, rr->WakeUp.seq, ARDisplayString(m, rr)); SetSPSProxyListChanged(rr->resrec.InterfaceID); mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); // Don't touch rr after this -- memory may have been free'd } } // Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because // new records could have been added to the end of the list as a result of that call. if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now m->CurrentRecord = rr->next; } } mDNSlocal void CheckRmvEventsForLocalRecords(mDNS *const m) { while (m->CurrentRecord) { AuthRecord *rr = m->CurrentRecord; if (rr->AnsweredLocalQ && rr->resrec.RecordType == kDNSRecordTypeDeregistering) { debugf("CheckRmvEventsForLocalRecords: Generating local RMV events for %s", ARDisplayString(m, rr)); rr->resrec.RecordType = kDNSRecordTypeShared; AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); if (m->CurrentRecord == rr) // If rr still exists in list, restore its state now { rr->resrec.RecordType = kDNSRecordTypeDeregistering; rr->AnsweredLocalQ = mDNSfalse; // SendResponses normally calls CompleteDeregistration after sending goodbyes. // For LocalOnly records, we don't do that and hence we need to do that here. if (RRLocalOnly(rr)) CompleteDeregistration(m, rr); } } if (m->CurrentRecord == rr) // If m->CurrentRecord was not auto-advanced, do it ourselves now m->CurrentRecord = rr->next; } } mDNSlocal void TimeoutQuestions(mDNS *const m) { m->NextScheduledStopTime = m->timenow + 0x3FFFFFFF; if (m->CurrentQuestion) LogMsg("TimeoutQuestions ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->Questions; while (m->CurrentQuestion) { DNSQuestion *const q = m->CurrentQuestion; if (q->StopTime) { if (m->timenow - q->StopTime >= 0) { LogInfo("TimeoutQuestions: question %##s timed out, time %d", q->qname.c, m->timenow - q->StopTime); GenerateNegativeResponse(m); if (m->CurrentQuestion == q) q->StopTime = 0; } else { if (m->NextScheduledStopTime - q->StopTime > 0) m->NextScheduledStopTime = q->StopTime; } } // If m->CurrentQuestion wasn't modified out from under us, advance it now // We can't do this at the start of the loop because GenerateNegativeResponse // depends on having m->CurrentQuestion point to the right question if (m->CurrentQuestion == q) m->CurrentQuestion = q->next; } m->CurrentQuestion = mDNSNULL; } mDNSexport mDNSs32 mDNS_Execute(mDNS *const m) { mDNS_Lock(m); // Must grab lock before trying to read m->timenow if (m->timenow - m->NextScheduledEvent >= 0) { int i; AuthRecord *head, *tail; mDNSu32 slot; AuthGroup *ag; verbosedebugf("mDNS_Execute"); if (m->CurrentQuestion) LogMsg("mDNS_Execute: ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); if (m->CurrentRecord) LogMsg("mDNS_Execute: ERROR m->CurrentRecord already set: %s", ARDisplayString(m, m->CurrentRecord)); // 1. If we're past the probe suppression time, we can clear it if (m->SuppressProbes && m->timenow - m->SuppressProbes >= 0) m->SuppressProbes = 0; // 2. If it's been more than ten seconds since the last probe failure, we can clear the counter if (m->NumFailedProbes && m->timenow - m->ProbeFailTime >= mDNSPlatformOneSecond * 10) m->NumFailedProbes = 0; // 3. Purge our cache of stale old records if (m->rrcache_size && m->timenow - m->NextCacheCheck >= 0) { mDNSu32 numchecked = 0; m->NextCacheCheck = m->timenow + 0x3FFFFFFF; for (slot = 0; slot < CACHE_HASH_SLOTS; slot++) { if (m->timenow - m->rrcache_nextcheck[slot] >= 0) { CacheGroup **cp = &m->rrcache_hash[slot]; m->rrcache_nextcheck[slot] = m->timenow + 0x3FFFFFFF; while (*cp) { debugf("m->NextCacheCheck %4d Slot %3d %##s", numchecked, slot, *cp ? (*cp)->name : (domainname*)"\x04NULL"); numchecked++; CheckCacheExpiration(m, slot, *cp); if ((*cp)->members) cp=&(*cp)->next; else ReleaseCacheGroup(m, cp); } } // Even if we didn't need to actually check this slot yet, still need to // factor its nextcheck time into our overall NextCacheCheck value if (m->NextCacheCheck - m->rrcache_nextcheck[slot] > 0) m->NextCacheCheck = m->rrcache_nextcheck[slot]; } debugf("m->NextCacheCheck %4d checked, next in %d", numchecked, m->NextCacheCheck - m->timenow); } if (m->timenow - m->NextScheduledSPS >= 0) { m->NextScheduledSPS = m->timenow + 0x3FFFFFFF; CheckProxyRecords(m, m->DuplicateRecords); // Clear m->DuplicateRecords first, then m->ResourceRecords CheckProxyRecords(m, m->ResourceRecords); } SetSPSProxyListChanged(mDNSNULL); // Perform any deferred BPF reconfiguration now // Clear AnnounceOwner if necessary. (Do this *before* SendQueries() and SendResponses().) if (m->AnnounceOwner && m->timenow - m->AnnounceOwner >= 0) m->AnnounceOwner = 0; if (m->DelaySleep && m->timenow - m->DelaySleep >= 0) { m->DelaySleep = 0; if (m->SleepState == SleepState_Transferring) { LogSPS("Re-sleep delay passed; now checking for Sleep Proxy Servers"); BeginSleepProcessing(m); } } // 4. See if we can answer any of our new local questions from the cache for (i=0; m->NewQuestions && i<1000; i++) { if (m->NewQuestions->DelayAnswering && m->timenow - m->NewQuestions->DelayAnswering < 0) break; AnswerNewQuestion(m); } if (i >= 1000) LogMsg("mDNS_Execute: AnswerNewQuestion exceeded loop limit"); // Make sure we deliver *all* local RMV events, and clear the corresponding rr->AnsweredLocalQ flags, *before* // we begin generating *any* new ADD events in the m->NewLocalOnlyQuestions and m->NewLocalRecords loops below. for (i=0; i<1000 && m->LocalRemoveEvents; i++) { m->LocalRemoveEvents = mDNSfalse; m->CurrentRecord = m->ResourceRecords; CheckRmvEventsForLocalRecords(m); // Walk the LocalOnly records and deliver the RMV events for (slot = 0; slot < AUTH_HASH_SLOTS; slot++) for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next) { m->CurrentRecord = ag->members; if (m->CurrentRecord) CheckRmvEventsForLocalRecords(m); } } if (i >= 1000) LogMsg("mDNS_Execute: m->LocalRemoveEvents exceeded loop limit"); for (i=0; m->NewLocalOnlyQuestions && i<1000; i++) AnswerNewLocalOnlyQuestion(m); if (i >= 1000) LogMsg("mDNS_Execute: AnswerNewLocalOnlyQuestion exceeded loop limit"); head = tail = mDNSNULL; for (i=0; i<1000 && m->NewLocalRecords && m->NewLocalRecords != head; i++) { AuthRecord *rr = m->NewLocalRecords; m->NewLocalRecords = m->NewLocalRecords->next; if (LocalRecordReady(rr)) { debugf("mDNS_Execute: Delivering Add event with LocalAuthRecord %s", ARDisplayString(m, rr)); AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNStrue); } else if (!rr->next) { // If we have just one record that is not ready, we don't have to unlink and // reinsert. As the NewLocalRecords will be NULL for this case, the loop will // terminate and set the NewLocalRecords to rr. debugf("mDNS_Execute: Just one LocalAuthRecord %s, breaking out of the loop early", ARDisplayString(m, rr)); if (head != mDNSNULL || m->NewLocalRecords != mDNSNULL) LogMsg("mDNS_Execute: ERROR!!: head %p, NewLocalRecords %p", head, m->NewLocalRecords); head = rr; } else { AuthRecord **p = &m->ResourceRecords; // Find this record in our list of active records debugf("mDNS_Execute: Skipping LocalAuthRecord %s", ARDisplayString(m, rr)); // if this is the first record we are skipping, move to the end of the list. // if we have already skipped records before, append it at the end. while (*p && *p != rr) p=&(*p)->next; if (*p) *p = rr->next; // Cut this record from the list else { LogMsg("mDNS_Execute: ERROR!! Cannot find record %s in ResourceRecords list", ARDisplayString(m, rr)); break; } if (!head) { while (*p) p=&(*p)->next; *p = rr; head = tail = rr; } else { tail->next = rr; tail = rr; } rr->next = mDNSNULL; } } m->NewLocalRecords = head; debugf("mDNS_Execute: Setting NewLocalRecords to %s", (head ? ARDisplayString(m, head) : "NULL")); if (i >= 1000) LogMsg("mDNS_Execute: m->NewLocalRecords exceeded loop limit"); // Check to see if we have any new LocalOnly/P2P records to examine for delivering // to our local questions if (m->NewLocalOnlyRecords) { m->NewLocalOnlyRecords = mDNSfalse; for (slot = 0; slot < AUTH_HASH_SLOTS; slot++) for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next) { for (i=0; i<100 && ag->NewLocalOnlyRecords; i++) { AuthRecord *rr = ag->NewLocalOnlyRecords; ag->NewLocalOnlyRecords = ag->NewLocalOnlyRecords->next; // LocalOnly records should always be ready as they never probe if (LocalRecordReady(rr)) { debugf("mDNS_Execute: Delivering Add event with LocalAuthRecord %s", ARDisplayString(m, rr)); AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNStrue); } else LogMsg("mDNS_Execute: LocalOnlyRecord %s not ready", ARDisplayString(m, rr)); } // We limit about 100 per AuthGroup that can be serviced at a time if (i >= 100) LogMsg("mDNS_Execute: ag->NewLocalOnlyRecords exceeded loop limit"); } } // 5. Some questions may have picked a new DNS server and the cache may answer these questions now. AnswerQuestionsForDNSServerChanges(m); // 6. See what packets we need to send if (m->mDNSPlatformStatus != mStatus_NoError || (m->SleepState == SleepState_Sleeping)) DiscardDeregistrations(m); if (m->mDNSPlatformStatus == mStatus_NoError && (m->SuppressSending == 0 || m->timenow - m->SuppressSending >= 0)) { // If the platform code is ready, and we're not suppressing packet generation right now // then send our responses, probes, and questions. // We check the cache first, because there might be records close to expiring that trigger questions to refresh them. // We send queries next, because there might be final-stage probes that complete their probing here, causing // them to advance to announcing state, and we want those to be included in any announcements we send out. // Finally, we send responses, including the previously mentioned records that just completed probing. m->SuppressSending = 0; // 7. Send Query packets. This may cause some probing records to advance to announcing state if (m->timenow - m->NextScheduledQuery >= 0 || m->timenow - m->NextScheduledProbe >= 0) SendQueries(m); if (m->timenow - m->NextScheduledQuery >= 0) { DNSQuestion *q; LogMsg("mDNS_Execute: SendQueries didn't send all its queries (%d - %d = %d) will try again in one second", m->timenow, m->NextScheduledQuery, m->timenow - m->NextScheduledQuery); m->NextScheduledQuery = m->timenow + mDNSPlatformOneSecond; for (q = m->Questions; q && q != m->NewQuestions; q=q->next) if (ActiveQuestion(q) && m->timenow - NextQSendTime(q) >= 0) LogMsg("mDNS_Execute: SendQueries didn't send %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); } if (m->timenow - m->NextScheduledProbe >= 0) { debugf("mDNS_Execute: SendQueries didn't send all its probes (%d - %d = %d) will try again in one second", m->timenow, m->NextScheduledProbe, m->timenow - m->NextScheduledProbe); m->NextScheduledProbe = m->timenow + mDNSPlatformOneSecond; } // 8. Send Response packets, including probing records just advanced to announcing state if (m->timenow - m->NextScheduledResponse >= 0) SendResponses(m); if (m->timenow - m->NextScheduledResponse >= 0) { debugf("mDNS_Execute: SendResponses didn't send all its responses; will try again in one second"); m->NextScheduledResponse = m->timenow + mDNSPlatformOneSecond; } } // Clear RandomDelay values, ready to pick a new different value next time m->RandomQueryDelay = 0; m->RandomReconfirmDelay = 0; if (m->NextScheduledStopTime && m->timenow - m->NextScheduledStopTime >= 0) TimeoutQuestions(m); #ifndef UNICAST_DISABLED if (m->NextSRVUpdate && m->timenow - m->NextSRVUpdate >= 0) UpdateAllSRVRecords(m); if (m->timenow - m->NextScheduledNATOp >= 0) CheckNATMappings(m); if (m->timenow - m->NextuDNSEvent >= 0) uDNS_Tasks(m); #endif } // Note about multi-threaded systems: // On a multi-threaded system, some other thread could run right after the mDNS_Unlock(), // performing mDNS API operations that change our next scheduled event time. // // On multi-threaded systems (like the current Windows implementation) that have a single main thread // calling mDNS_Execute() (and other threads allowed to call mDNS API routines) it is the responsibility // of the mDNSPlatformUnlock() routine to signal some kind of stateful condition variable that will // signal whatever blocking primitive the main thread is using, so that it will wake up and execute one // more iteration of its loop, and immediately call mDNS_Execute() again. The signal has to be stateful // in the sense that if the main thread has not yet entered its blocking primitive, then as soon as it // does, the state of the signal will be noticed, causing the blocking primitive to return immediately // without blocking. This avoids the race condition between the signal from the other thread arriving // just *before* or just *after* the main thread enters the blocking primitive. // // On multi-threaded systems (like the current Mac OS 9 implementation) that are entirely timer-driven, // with no main mDNS_Execute() thread, it is the responsibility of the mDNSPlatformUnlock() routine to // set the timer according to the m->NextScheduledEvent value, and then when the timer fires, the timer // callback function should call mDNS_Execute() (and ignore the return value, which may already be stale // by the time it gets to the timer callback function). mDNS_Unlock(m); // Calling mDNS_Unlock is what gives m->NextScheduledEvent its new value return(m->NextScheduledEvent); } mDNSlocal void SuspendLLQs(mDNS *m) { DNSQuestion *q; for (q = m->Questions; q; q = q->next) if (ActiveQuestion(q) && !mDNSOpaque16IsZero(q->TargetQID) && q->LongLived && q->state == LLQ_Established) { q->ReqLease = 0; sendLLQRefresh(m, q); } } mDNSlocal mDNSBool QuestionHasLocalAnswers(mDNS *const m, DNSQuestion *q) { AuthRecord *rr; mDNSu32 slot; AuthGroup *ag; slot = AuthHashSlot(&q->qname); ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname); if (ag) { for (rr = ag->members; rr; rr=rr->next) // Filter the /etc/hosts records - LocalOnly, Unique, A/AAAA/CNAME if (LORecordAnswersAddressType(rr) && LocalOnlyRecordAnswersQuestion(rr, q)) { LogInfo("QuestionHasLocalAnswers: Question %p %##s (%s) has local answer %s", q, q->qname.c, DNSTypeName(q->qtype), ARDisplayString(m, rr)); return mDNStrue; } } return mDNSfalse; } // ActivateUnicastQuery() is called from three places: // 1. When a new question is created // 2. On wake from sleep // 3. When the DNS configuration changes // In case 1 we don't want to mess with our established ThisQInterval and LastQTime (ScheduleImmediately is false) // In cases 2 and 3 we do want to cause the question to be resent immediately (ScheduleImmediately is true) mDNSlocal void ActivateUnicastQuery(mDNS *const m, DNSQuestion *const question, mDNSBool ScheduleImmediately) { // For now this AutoTunnel stuff is specific to Mac OS X. // In the future, if there's demand, we may see if we can abstract it out cleanly into the platform layer #if APPLE_OSX_mDNSResponder // Even though BTMM client tunnels are only useful for AAAA queries, we need to treat v4 and v6 queries equally. // Otherwise we can get the situation where the A query completes really fast (with an NXDOMAIN result) and the // caller then gives up waiting for the AAAA result while we're still in the process of setting up the tunnel. // To level the playing field, we block both A and AAAA queries while tunnel setup is in progress, and then // returns results for both at the same time. If we are looking for the _autotunnel6 record, then skip this logic // as this would trigger looking up _autotunnel6._autotunnel6 and end up failing the original query. if (RRTypeIsAddressType(question->qtype) && PrivateQuery(question) && !SameDomainLabel(question->qname.c, (const mDNSu8 *)"\x0c_autotunnel6")&& question->QuestionCallback != AutoTunnelCallback) { question->NoAnswer = NoAnswer_Suspended; AddNewClientTunnel(m, question); return; } #endif // APPLE_OSX_mDNSResponder if (!question->DuplicateOf) { debugf("ActivateUnicastQuery: %##s %s%s%s", question->qname.c, DNSTypeName(question->qtype), PrivateQuery(question) ? " (Private)" : "", ScheduleImmediately ? " ScheduleImmediately" : ""); question->CNAMEReferrals = 0; if (question->nta) { CancelGetZoneData(m, question->nta); question->nta = mDNSNULL; } if (question->LongLived) { question->state = LLQ_InitialRequest; question->id = zeroOpaque64; question->servPort = zeroIPPort; if (question->tcp) { DisposeTCPConn(question->tcp); question->tcp = mDNSNULL; } } // If the question has local answers, then we don't want answers from outside if (ScheduleImmediately && !QuestionHasLocalAnswers(m, question)) { question->ThisQInterval = InitialQuestionInterval; question->LastQTime = m->timenow - question->ThisQInterval; SetNextQueryTime(m, question); } } } // Caller should hold the lock mDNSexport void mDNSCoreRestartAddressQueries(mDNS *const m, mDNSBool SearchDomainsChanged, FlushCache flushCacheRecords, CallbackBeforeStartQuery BeforeStartCallback, void *context) { DNSQuestion *q; DNSQuestion *restart = mDNSNULL; if (!m->mDNS_busy) LogMsg("mDNSCoreRestartAddressQueries: ERROR!! Lock not held"); // 1. Flush the cache records if (flushCacheRecords) flushCacheRecords(m); // 2. Even though we may have purged the cache records above, before it can generate RMV event // we are going to stop the question. Hence we need to deliver the RMV event before we // stop the question. // // CurrentQuestion is used by RmvEventsForQuestion below. While delivering RMV events, the // application callback can potentially stop the current question (detected by CurrentQuestion) or // *any* other question which could be the next one that we may process here. RestartQuestion // points to the "next" question which will be automatically advanced in mDNS_StopQuery_internal // if the "next" question is stopped while the CurrentQuestion is stopped if (m->RestartQuestion) LogMsg("mDNSCoreRestartAddressQueries: ERROR!! m->RestartQuestion already set: %##s (%s)", m->RestartQuestion->qname.c, DNSTypeName(m->RestartQuestion->qtype)); m->RestartQuestion = m->Questions; while (m->RestartQuestion) { q = m->RestartQuestion; m->RestartQuestion = q->next; // GetZoneData questions are referenced by other questions (original query that started the GetZoneData // question) through their "nta" pointer. Normally when the original query stops, it stops the // GetZoneData question and also frees the memory (See CancelGetZoneData). If we stop the GetZoneData // question followed by the original query that refers to this GetZoneData question, we will end up // freeing the GetZoneData question and then start the "freed" question at the end. if (IsGetZoneDataQuestion(q)) { DNSQuestion *refq = q->next; LogInfo("mDNSCoreRestartAddressQueries: Skipping GetZoneDataQuestion %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); // debug stuff, we just try to find the referencing question and don't do much with it while (refq) { if (q == &refq->nta->question) { LogInfo("mDNSCoreRestartAddressQueries: Question %p %##s (%s) referring to GetZoneDataQuestion %p, not stopping", refq, refq->qname.c, DNSTypeName(refq->qtype), q); } refq = refq->next; } continue; } // This function is called when /etc/hosts changes and that could affect A, AAAA and CNAME queries if (q->qtype != kDNSType_A && q->qtype != kDNSType_AAAA && q->qtype != kDNSType_CNAME) continue; // If the search domains did not change, then we restart all the queries. Otherwise, only // for queries for which we "might" have appended search domains ("might" because we may // find results before we apply search domains even though AppendSearchDomains is set to 1) if (!SearchDomainsChanged || q->AppendSearchDomains) { // NOTE: CacheRecordRmvEventsForQuestion will not generate RMV events for queries that have non-zero // LOAddressAnswers. Hence it is important that we call CacheRecordRmvEventsForQuestion before // LocalRecordRmvEventsForQuestion (which decrements LOAddressAnswers). Let us say that // /etc/hosts has an A Record for web.apple.com. Any queries for web.apple.com will be answered locally. // But this can't prevent a CNAME/AAAA query to not to be sent on the wire. When it is sent on the wire, // it could create cache entries. When we are restarting queries, we can't deliver the cache RMV events // for the original query using these cache entries as ADDs were never delivered using these cache // entries and hence this order is needed. // If the query is suppressed, the RMV events won't be delivered if (!CacheRecordRmvEventsForQuestion(m, q)) { LogInfo("mDNSCoreRestartAddressQueries: Question deleted while delivering Cache Record RMV events"); continue; } // SuppressQuery status does not affect questions that are answered using local records if (!LocalRecordRmvEventsForQuestion(m, q)) { LogInfo("mDNSCoreRestartAddressQueries: Question deleted while delivering Local Record RMV events"); continue; } LogInfo("mDNSCoreRestartAddressQueries: Stop question %p %##s (%s), AppendSearchDomains %d, qnameOrig %p", q, q->qname.c, DNSTypeName(q->qtype), q->AppendSearchDomains, q->qnameOrig); mDNS_StopQuery_internal(m, q); // Reset state so that it looks like it was in the beginning i.e it should look at /etc/hosts, cache // and then search domains should be appended. At the beginning, qnameOrig was NULL. if (q->qnameOrig) { LogInfo("mDNSCoreRestartAddressQueries: qnameOrig %##s", q->qnameOrig); AssignDomainName(&q->qname, q->qnameOrig); mDNSPlatformMemFree(q->qnameOrig); q->qnameOrig = mDNSNULL; q->RetryWithSearchDomains = ApplySearchDomainsFirst(q) ? 1 : 0; } q->SearchListIndex = 0; q->next = restart; restart = q; } } // 3. Callback before we start the query if (BeforeStartCallback) BeforeStartCallback(m, context); // 4. Restart all the stopped queries while (restart) { q = restart; restart = restart->next; q->next = mDNSNULL; LogInfo("mDNSCoreRestartAddressQueries: Start question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); mDNS_StartQuery_internal(m, q); } } mDNSexport void mDNSCoreRestartQueries(mDNS *const m) { DNSQuestion *q; #ifndef UNICAST_DISABLED // Retrigger all our uDNS questions if (m->CurrentQuestion) LogMsg("mDNSCoreRestartQueries: ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); m->CurrentQuestion = m->Questions; while (m->CurrentQuestion) { q = m->CurrentQuestion; m->CurrentQuestion = m->CurrentQuestion->next; if (!mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q)) ActivateUnicastQuery(m, q, mDNStrue); } #endif // Retrigger all our mDNS questions for (q = m->Questions; q; q=q->next) // Scan our list of questions if (mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q)) { q->ThisQInterval = InitialQuestionInterval; // MUST be > zero for an active question q->RequestUnicast = 2; // Set to 2 because is decremented once *before* we check it q->LastQTime = m->timenow - q->ThisQInterval; q->RecentAnswerPkts = 0; ExpireDupSuppressInfo(q->DupSuppress, m->timenow); m->NextScheduledQuery = m->timenow; } } // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Power Management (Sleep/Wake) #endif mDNSexport void mDNS_UpdateAllowSleep(mDNS *const m) { #ifndef IDLESLEEPCONTROL_DISABLED mDNSBool allowSleep = mDNStrue; char reason[128]; reason[0] = 0; if (m->SystemSleepOnlyIfWakeOnLAN) { // Don't sleep if we are a proxy for any services if (m->ProxyRecords) { allowSleep = mDNSfalse; mDNS_snprintf(reason, sizeof(reason), "sleep proxy for %d records", m->ProxyRecords); LogInfo("Sleep disabled because we are proxying %d records", m->ProxyRecords); } if (allowSleep && mDNSCoreHaveAdvertisedMulticastServices(m)) { // Scan the list of active interfaces NetworkInterfaceInfo *intf; for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) { if (intf->McastTxRx && !intf->Loopback) { // Disallow sleep if this interface doesn't support NetWake if (!intf->NetWake) { allowSleep = mDNSfalse; mDNS_snprintf(reason, sizeof(reason), "%s does not support NetWake", intf->ifname); LogInfo("Sleep disabled because %s does not support NetWake", intf->ifname); break; } // Disallow sleep if there is no sleep proxy server if (FindSPSInCache1(m, &intf->NetWakeBrowse, mDNSNULL, mDNSNULL) == mDNSNULL) { allowSleep = mDNSfalse; mDNS_snprintf(reason, sizeof(reason), "%s does not support NetWake", intf->ifname); LogInfo("Sleep disabled because %s has no sleep proxy", intf->ifname); break; } } } } } // Call the platform code to enable/disable sleep mDNSPlatformSetAllowSleep(m, allowSleep, reason); #endif /* !defined(IDLESLEEPCONTROL_DISABLED) */ } mDNSlocal void SendSPSRegistrationForOwner(mDNS *const m, NetworkInterfaceInfo *const intf, const mDNSOpaque16 id, const OwnerOptData *const owner) { const int optspace = DNSOpt_Header_Space + DNSOpt_LeaseData_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC); const int sps = intf->NextSPSAttempt / 3; AuthRecord *rr; if (!intf->SPSAddr[sps].type) { intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond; if (m->NextScheduledSPRetry - intf->NextSPSAttemptTime > 0) m->NextScheduledSPRetry = intf->NextSPSAttemptTime; LogSPS("SendSPSRegistration: %s SPS %d (%d) %##s not yet resolved", intf->ifname, intf->NextSPSAttempt, sps, intf->NetWakeResolve[sps].qname.c); goto exit; } // Mark our mDNS records (not unicast records) for transfer to SPS if (mDNSOpaque16IsZero(id)) for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.RecordType > kDNSRecordTypeDeregistering) if (rr->resrec.InterfaceID == intf->InterfaceID || (!rr->resrec.InterfaceID && (rr->ForceMCast || IsLocalDomain(rr->resrec.name)))) if (mDNSPlatformMemSame(owner, &rr->WakeUp, sizeof(*owner))) rr->SendRNow = mDNSInterfaceMark; // mark it now while (1) { mDNSu8 *p = m->omsg.data; // To comply with RFC 2782, PutResourceRecord suppresses name compression for SRV records in unicast updates. // For now we follow that same logic for SPS registrations too. // If we decide to compress SRV records in SPS registrations in the future, we can achieve that by creating our // initial DNSMessage with h.flags set to zero, and then update it to UpdateReqFlags right before sending the packet. InitializeDNSMessage(&m->omsg.h, mDNSOpaque16IsZero(id) ? mDNS_NewMessageID(m) : id, UpdateReqFlags); for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->SendRNow || (!mDNSOpaque16IsZero(id) && !AuthRecord_uDNS(rr) && mDNSSameOpaque16(rr->updateid, id) && m->timenow - (rr->LastAPTime + rr->ThisAPInterval) >= 0)) if (mDNSPlatformMemSame(owner, &rr->WakeUp, sizeof(*owner))) { mDNSu8 *newptr; const mDNSu8 *const limit = m->omsg.data + (m->omsg.h.mDNS_numUpdates ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData) - optspace; if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the 'unique' bit so PutResourceRecord will set it newptr = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.mDNS_numUpdates, &rr->resrec, rr->resrec.rroriginalttl, limit); rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear 'unique' bit back to normal state if (!newptr) LogSPS("SendSPSRegistration put %s FAILED %d/%d %s", intf->ifname, p - m->omsg.data, limit - m->omsg.data, ARDisplayString(m, rr)); else { LogSPS("SendSPSRegistration put %s %s", intf->ifname, ARDisplayString(m, rr)); rr->SendRNow = mDNSNULL; rr->ThisAPInterval = mDNSPlatformOneSecond; rr->LastAPTime = m->timenow; rr->updateid = m->omsg.h.id; if (m->NextScheduledResponse - (rr->LastAPTime + rr->ThisAPInterval) >= 0) m->NextScheduledResponse = (rr->LastAPTime + rr->ThisAPInterval); p = newptr; } } if (!m->omsg.h.mDNS_numUpdates) break; else { AuthRecord opt; mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL); opt.resrec.rrclass = NormalMaxDNSMessageData; opt.resrec.rdlength = sizeof(rdataOPT) * 2; // Two options in this OPT record opt.resrec.rdestimate = sizeof(rdataOPT) * 2; opt.resrec.rdata->u.opt[0].opt = kDNSOpt_Lease; opt.resrec.rdata->u.opt[0].optlen = DNSOpt_LeaseData_Space - 4; opt.resrec.rdata->u.opt[0].u.updatelease = DEFAULT_UPDATE_LEASE; if (!owner->HMAC.l[0]) // If no owner data, SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[1]); // use our own interface information else // otherwise, use the owner data we were given { opt.resrec.rdata->u.opt[1].u.owner = *owner; opt.resrec.rdata->u.opt[1].opt = kDNSOpt_Owner; opt.resrec.rdata->u.opt[1].optlen = DNSOpt_Owner_Space(&owner->HMAC, &owner->IMAC) - 4; } LogSPS("SendSPSRegistration put %s %s", intf->ifname, ARDisplayString(m, &opt)); p = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.numAdditionals, &opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData); if (!p) LogMsg("SendSPSRegistration: Failed to put OPT record (%d updates) %s", m->omsg.h.mDNS_numUpdates, ARDisplayString(m, &opt)); else { mStatus err; LogSPS("SendSPSRegistration: Sending Update %s %d (%d) id %5d with %d records %d bytes to %#a:%d", intf->ifname, intf->NextSPSAttempt, sps, mDNSVal16(m->omsg.h.id), m->omsg.h.mDNS_numUpdates, p - m->omsg.data, &intf->SPSAddr[sps], mDNSVal16(intf->SPSPort[sps])); // if (intf->NextSPSAttempt < 5) m->omsg.h.flags = zeroID; // For simulating packet loss err = mDNSSendDNSMessage(m, &m->omsg, p, intf->InterfaceID, mDNSNULL, &intf->SPSAddr[sps], intf->SPSPort[sps], mDNSNULL, mDNSNULL); if (err) LogSPS("SendSPSRegistration: mDNSSendDNSMessage err %d", err); if (err && intf->SPSAddr[sps].type == mDNSAddrType_IPv6 && intf->NetWakeResolve[sps].ThisQInterval == -1) { LogSPS("SendSPSRegistration %d %##s failed to send to IPv6 address; will try IPv4 instead", sps, intf->NetWakeResolve[sps].qname.c); intf->NetWakeResolve[sps].qtype = kDNSType_A; mDNS_StartQuery_internal(m, &intf->NetWakeResolve[sps]); return; } } } } intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond * 10; // If successful, update NextSPSAttemptTime exit: if (mDNSOpaque16IsZero(id) && intf->NextSPSAttempt < 8) intf->NextSPSAttempt++; } mDNSlocal mDNSBool RecordIsFirstOccurrenceOfOwner(mDNS *const m, const AuthRecord *const rr) { AuthRecord *ar; for (ar = m->ResourceRecords; ar && ar != rr; ar=ar->next) if (mDNSPlatformMemSame(&rr->WakeUp, &ar->WakeUp, sizeof(rr->WakeUp))) return mDNSfalse; return mDNStrue; } mDNSlocal void SendSPSRegistration(mDNS *const m, NetworkInterfaceInfo *const intf, const mDNSOpaque16 id) { AuthRecord *ar; OwnerOptData owner = zeroOwner; SendSPSRegistrationForOwner(m, intf, id, &owner); for (ar = m->ResourceRecords; ar; ar=ar->next) { if (!mDNSPlatformMemSame(&owner, &ar->WakeUp, sizeof(owner)) && RecordIsFirstOccurrenceOfOwner(m, ar)) { owner = ar->WakeUp; SendSPSRegistrationForOwner(m, intf, id, &owner); } } } // RetrySPSRegistrations is called from SendResponses, with the lock held mDNSlocal void RetrySPSRegistrations(mDNS *const m) { AuthRecord *rr; NetworkInterfaceInfo *intf; // First make sure none of our interfaces' NextSPSAttemptTimes are inadvertently set to m->timenow + mDNSPlatformOneSecond * 10 for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) if (intf->NextSPSAttempt && intf->NextSPSAttemptTime == m->timenow + mDNSPlatformOneSecond * 10) intf->NextSPSAttemptTime++; // Retry any record registrations that are due for (rr = m->ResourceRecords; rr; rr=rr->next) if (!AuthRecord_uDNS(rr) && !mDNSOpaque16IsZero(rr->updateid) && m->timenow - (rr->LastAPTime + rr->ThisAPInterval) >= 0) for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) if (!rr->resrec.InterfaceID || rr->resrec.InterfaceID == intf->InterfaceID) { LogSPS("RetrySPSRegistrations: %s", ARDisplayString(m, rr)); SendSPSRegistration(m, intf, rr->updateid); } // For interfaces where we did an SPS registration attempt, increment intf->NextSPSAttempt for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) if (intf->NextSPSAttempt && intf->NextSPSAttemptTime == m->timenow + mDNSPlatformOneSecond * 10 && intf->NextSPSAttempt < 8) intf->NextSPSAttempt++; } mDNSlocal void NetWakeResolve(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord) { NetworkInterfaceInfo *intf = (NetworkInterfaceInfo *)question->QuestionContext; int sps = (int)(question - intf->NetWakeResolve); (void)m; // Unused LogSPS("NetWakeResolve: SPS: %d Add: %d %s", sps, AddRecord, RRDisplayString(m, answer)); if (!AddRecord) return; // Don't care about REMOVE events if (answer->rrtype != question->qtype) return; // Don't care about CNAMEs // if (answer->rrtype == kDNSType_AAAA && sps == 0) return; // To test failing to resolve sleep proxy's address if (answer->rrtype == kDNSType_SRV) { // 1. Got the SRV record; now look up the target host's IPv6 link-local address mDNS_StopQuery(m, question); intf->SPSPort[sps] = answer->rdata->u.srv.port; AssignDomainName(&question->qname, &answer->rdata->u.srv.target); question->qtype = kDNSType_AAAA; mDNS_StartQuery(m, question); } else if (answer->rrtype == kDNSType_AAAA && answer->rdlength == sizeof(mDNSv6Addr) && mDNSv6AddressIsLinkLocal(&answer->rdata->u.ipv6)) { // 2. Got the target host's IPv6 link-local address; record address and initiate an SPS registration if appropriate mDNS_StopQuery(m, question); question->ThisQInterval = -1; intf->SPSAddr[sps].type = mDNSAddrType_IPv6; intf->SPSAddr[sps].ip.v6 = answer->rdata->u.ipv6; mDNS_Lock(m); if (sps == intf->NextSPSAttempt/3) SendSPSRegistration(m, intf, zeroID); // If we're ready for this result, use it now mDNS_Unlock(m); } else if (answer->rrtype == kDNSType_AAAA && answer->rdlength == 0) { // 3. Got negative response -- target host apparently has IPv6 disabled -- so try looking up the target host's IPv4 address(es) instead mDNS_StopQuery(m, question); LogSPS("NetWakeResolve: SPS %d %##s has no IPv6 address, will try IPv4 instead", sps, question->qname.c); question->qtype = kDNSType_A; mDNS_StartQuery(m, question); } else if (answer->rrtype == kDNSType_A && answer->rdlength == sizeof(mDNSv4Addr)) { // 4. Got an IPv4 address for the target host; record address and initiate an SPS registration if appropriate mDNS_StopQuery(m, question); question->ThisQInterval = -1; intf->SPSAddr[sps].type = mDNSAddrType_IPv4; intf->SPSAddr[sps].ip.v4 = answer->rdata->u.ipv4; mDNS_Lock(m); if (sps == intf->NextSPSAttempt/3) SendSPSRegistration(m, intf, zeroID); // If we're ready for this result, use it now mDNS_Unlock(m); } } mDNSexport mDNSBool mDNSCoreHaveAdvertisedMulticastServices(mDNS *const m) { AuthRecord *rr; for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.rrtype == kDNSType_SRV && !AuthRecord_uDNS(rr) && !mDNSSameIPPort(rr->resrec.rdata->u.srv.port, DiscardPort)) return mDNStrue; return mDNSfalse; } mDNSlocal void SendSleepGoodbyes(mDNS *const m) { AuthRecord *rr; m->SleepState = SleepState_Sleeping; #ifndef UNICAST_DISABLED SleepRecordRegistrations(m); // If we have no SPS, need to deregister our uDNS records #endif /* UNICAST_DISABLED */ // Mark all the records we need to deregister and send them for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.RecordType == kDNSRecordTypeShared && rr->RequireGoodbye) rr->ImmedAnswer = mDNSInterfaceMark; SendResponses(m); } // BeginSleepProcessing is called, with the lock held, from either mDNS_Execute or mDNSCoreMachineSleep mDNSlocal void BeginSleepProcessing(mDNS *const m) { mDNSBool SendGoodbyes = mDNStrue; const CacheRecord *sps[3] = { mDNSNULL }; m->NextScheduledSPRetry = m->timenow; if (!m->SystemWakeOnLANEnabled) LogSPS("BeginSleepProcessing: m->SystemWakeOnLANEnabled is false"); else if (!mDNSCoreHaveAdvertisedMulticastServices(m)) LogSPS("BeginSleepProcessing: No advertised services"); else // If we have at least one advertised service { NetworkInterfaceInfo *intf; for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) { if (!intf->NetWake) LogSPS("BeginSleepProcessing: %-6s not capable of magic packet wakeup", intf->ifname); #if APPLE_OSX_mDNSResponder else if (ActivateLocalProxy(m, intf->ifname) == mStatus_NoError) { SendGoodbyes = mDNSfalse; LogSPS("BeginSleepProcessing: %-6s using local proxy", intf->ifname); // This will leave m->SleepState set to SleepState_Transferring, // which is okay because with no outstanding resolves, or updates in flight, // mDNSCoreReadyForSleep() will conclude correctly that all the updates have already completed } #endif // APPLE_OSX_mDNSResponder else { FindSPSInCache(m, &intf->NetWakeBrowse, sps); if (!sps[0]) LogSPS("BeginSleepProcessing: %-6s %#a No Sleep Proxy Server found (Next Browse Q in %d, interval %d)", intf->ifname, &intf->ip, NextQSendTime(&intf->NetWakeBrowse) - m->timenow, intf->NetWakeBrowse.ThisQInterval); else { int i; SendGoodbyes = mDNSfalse; intf->NextSPSAttempt = 0; intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond; // Don't need to set m->NextScheduledSPRetry here because we already set "m->NextScheduledSPRetry = m->timenow" above for (i=0; i<3; i++) { #if ForceAlerts if (intf->SPSAddr[i].type) { LogMsg("BeginSleepProcessing: %s %d intf->SPSAddr[i].type %d", intf->ifname, i, intf->SPSAddr[i].type); *(long*)0 = 0; } if (intf->NetWakeResolve[i].ThisQInterval >= 0) { LogMsg("BeginSleepProcessing: %s %d intf->NetWakeResolve[i].ThisQInterval %d", intf->ifname, i, intf->NetWakeResolve[i].ThisQInterval); *(long*)0 = 0; } #endif intf->SPSAddr[i].type = mDNSAddrType_None; if (intf->NetWakeResolve[i].ThisQInterval >= 0) mDNS_StopQuery(m, &intf->NetWakeResolve[i]); intf->NetWakeResolve[i].ThisQInterval = -1; if (sps[i]) { LogSPS("BeginSleepProcessing: %-6s Found Sleep Proxy Server %d TTL %d %s", intf->ifname, i, sps[i]->resrec.rroriginalttl, CRDisplayString(m, sps[i])); mDNS_SetupQuestion(&intf->NetWakeResolve[i], intf->InterfaceID, &sps[i]->resrec.rdata->u.name, kDNSType_SRV, NetWakeResolve, intf); intf->NetWakeResolve[i].ReturnIntermed = mDNStrue; mDNS_StartQuery_internal(m, &intf->NetWakeResolve[i]); } } } } } } if (SendGoodbyes) // If we didn't find even one Sleep Proxy { LogSPS("BeginSleepProcessing: Not registering with Sleep Proxy Server"); SendSleepGoodbyes(m); } } // Call mDNSCoreMachineSleep(m, mDNStrue) when the machine is about to go to sleep. // Call mDNSCoreMachineSleep(m, mDNSfalse) when the machine is has just woken up. // Normally, the platform support layer below mDNSCore should call this, not the client layer above. mDNSexport void mDNSCoreMachineSleep(mDNS *const m, mDNSBool sleep) { AuthRecord *rr; LogSPS("%s (old state %d) at %ld", sleep ? "Sleeping" : "Waking", m->SleepState, m->timenow); if (sleep && !m->SleepState) // Going to sleep { mDNS_Lock(m); // If we're going to sleep, need to stop advertising that we're a Sleep Proxy Server if (m->SPSSocket) { mDNSu8 oldstate = m->SPSState; mDNS_DropLockBeforeCallback(); // mDNS_DeregisterService expects to be called without the lock held, so we emulate that here m->SPSState = 2; if (oldstate == 1) mDNS_DeregisterService(m, &m->SPSRecords); mDNS_ReclaimLockAfterCallback(); } m->SleepState = SleepState_Transferring; if (m->SystemWakeOnLANEnabled && m->DelaySleep) { // If we just woke up moments ago, allow ten seconds for networking to stabilize before going back to sleep LogSPS("mDNSCoreMachineSleep: Re-sleeping immediately after waking; will delay for %d ticks", m->DelaySleep - m->timenow); m->SleepLimit = NonZeroTime(m->DelaySleep + mDNSPlatformOneSecond * 10); } else { m->DelaySleep = 0; m->SleepLimit = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 10); BeginSleepProcessing(m); } #ifndef UNICAST_DISABLED SuspendLLQs(m); #endif mDNS_Unlock(m); // RemoveAutoTunnel6Record needs to be called outside the lock, as it grabs the lock also. #if APPLE_OSX_mDNSResponder RemoveAutoTunnel6Record(m); #endif LogSPS("mDNSCoreMachineSleep: m->SleepState %d (%s) seq %d", m->SleepState, m->SleepState == SleepState_Transferring ? "Transferring" : m->SleepState == SleepState_Sleeping ? "Sleeping" : "?", m->SleepSeqNum); } else if (!sleep) // Waking up { mDNSu32 slot; CacheGroup *cg; CacheRecord *cr; NetworkInterfaceInfo *intf; mDNS_Lock(m); // Reset SleepLimit back to 0 now that we're awake again. m->SleepLimit = 0; // If we were previously sleeping, but now we're not, increment m->SleepSeqNum to indicate that we're entering a new period of wakefulness if (m->SleepState != SleepState_Awake) { m->SleepState = SleepState_Awake; m->SleepSeqNum++; // If the machine wakes and then immediately tries to sleep again (e.g. a maintenance wake) // then we enforce a minimum delay of 16 seconds before we begin sleep processing. // This is to allow time for the Ethernet link to come up, DHCP to get an address, mDNS to issue queries, etc., // before we make our determination of whether there's a Sleep Proxy out there we should register with. m->DelaySleep = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 16); } if (m->SPSState == 3) { m->SPSState = 0; mDNSCoreBeSleepProxyServer_internal(m, m->SPSType, m->SPSPortability, m->SPSMarginalPower, m->SPSTotalPower); } // In case we gave up waiting and went to sleep before we got an ack from the Sleep Proxy, // on wake we go through our record list and clear updateid back to zero for (rr = m->ResourceRecords; rr; rr=rr->next) rr->updateid = zeroID; // ... and the same for NextSPSAttempt for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) intf->NextSPSAttempt = -1; // Restart unicast and multicast queries mDNSCoreRestartQueries(m); // and reactivtate service registrations m->NextSRVUpdate = NonZeroTime(m->timenow + mDNSPlatformOneSecond); LogInfo("mDNSCoreMachineSleep waking: NextSRVUpdate in %d %d", m->NextSRVUpdate - m->timenow, m->timenow); // 2. Re-validate our cache records FORALL_CACHERECORDS(slot, cg, cr) mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForWake); // 3. Retrigger probing and announcing for all our authoritative records for (rr = m->ResourceRecords; rr; rr=rr->next) if (AuthRecord_uDNS(rr)) { ActivateUnicastRegistration(m, rr); } else { if (rr->resrec.RecordType == kDNSRecordTypeVerified && !rr->DependentOn) rr->resrec.RecordType = kDNSRecordTypeUnique; rr->ProbeCount = DefaultProbeCountForRecordType(rr->resrec.RecordType); rr->AnnounceCount = InitialAnnounceCount; rr->SendNSECNow = mDNSNULL; InitializeLastAPTime(m, rr); } // 4. Refresh NAT mappings // We don't want to have to assume that all hardware can necessarily keep accurate // track of passage of time while asleep, so on wake we refresh our NAT mappings // We typically wake up with no interfaces active, so there's no need to rush to try to find our external address. // When we get a network configuration change, mDNSMacOSXNetworkChanged calls uDNS_SetupDNSConfig, which calls // mDNS_SetPrimaryInterfaceInfo, which then sets m->retryGetAddr to immediately request our external address from the NAT gateway. m->retryIntervalGetAddr = NATMAP_INIT_RETRY; m->retryGetAddr = m->timenow + mDNSPlatformOneSecond * 5; LogInfo("mDNSCoreMachineSleep: retryGetAddr in %d %d", m->retryGetAddr - m->timenow, m->timenow); RecreateNATMappings(m); mDNS_Unlock(m); } } mDNSexport mDNSBool mDNSCoreReadyForSleep(mDNS *m, mDNSs32 now) { DNSQuestion *q; AuthRecord *rr; NetworkInterfaceInfo *intf; mDNS_Lock(m); if (m->DelaySleep) goto notready; // If we've not hit the sleep limit time, and it's not time for our next retry, we can skip these checks if (m->SleepLimit - now > 0 && m->NextScheduledSPRetry - now > 0) goto notready; m->NextScheduledSPRetry = now + 0x40000000UL; // See if we might need to retransmit any lost Sleep Proxy Registrations for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) if (intf->NextSPSAttempt >= 0) { if (now - intf->NextSPSAttemptTime >= 0) { LogSPS("mDNSCoreReadyForSleep: retrying for %s SPS %d try %d", intf->ifname, intf->NextSPSAttempt/3, intf->NextSPSAttempt); SendSPSRegistration(m, intf, zeroID); // Don't need to "goto notready" here, because if we do still have record registrations // that have not been acknowledged yet, we'll catch that in the record list scan below. } else if (m->NextScheduledSPRetry - intf->NextSPSAttemptTime > 0) m->NextScheduledSPRetry = intf->NextSPSAttemptTime; } // Scan list of interfaces, and see if we're still waiting for any sleep proxy resolves to complete for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) { int sps = (intf->NextSPSAttempt == 0) ? 0 : (intf->NextSPSAttempt-1)/3; if (intf->NetWakeResolve[sps].ThisQInterval >= 0) { LogSPS("mDNSCoreReadyForSleep: waiting for SPS Resolve %s %##s (%s)", intf->ifname, intf->NetWakeResolve[sps].qname.c, DNSTypeName(intf->NetWakeResolve[sps].qtype)); goto spsnotready; } } // Scan list of registered records for (rr = m->ResourceRecords; rr; rr = rr->next) if (!AuthRecord_uDNS(rr)) if (!mDNSOpaque16IsZero(rr->updateid)) { LogSPS("mDNSCoreReadyForSleep: waiting for SPS Update ID %d %s", mDNSVal16(rr->updateid), ARDisplayString(m,rr)); goto spsnotready; } // Scan list of private LLQs, and make sure they've all completed their handshake with the server for (q = m->Questions; q; q = q->next) if (!mDNSOpaque16IsZero(q->TargetQID) && q->LongLived && q->ReqLease == 0 && q->tcp) { LogSPS("mDNSCoreReadyForSleep: waiting for LLQ %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); goto notready; } // Scan list of registered records for (rr = m->ResourceRecords; rr; rr = rr->next) if (AuthRecord_uDNS(rr)) { if (rr->state == regState_Refresh && rr->tcp) { LogSPS("mDNSCoreReadyForSleep: waiting for Record Update ID %d %s", mDNSVal16(rr->updateid), ARDisplayString(m,rr)); goto notready; } #if APPLE_OSX_mDNSResponder if (!RecordReadyForSleep(m, rr)) { LogSPS("mDNSCoreReadyForSleep: waiting for %s", ARDisplayString(m, rr)); goto notready; } #endif } mDNS_Unlock(m); return mDNStrue; spsnotready: // If we failed to complete sleep proxy registration within ten seconds, we give up on that // and allow up to ten seconds more to complete wide-area deregistration instead if (now - m->SleepLimit >= 0) { LogMsg("Failed to register with SPS, now sending goodbyes"); for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) if (intf->NetWakeBrowse.ThisQInterval >= 0) { LogSPS("ReadyForSleep mDNS_DeactivateNetWake %s %##s (%s)", intf->ifname, intf->NetWakeResolve[0].qname.c, DNSTypeName(intf->NetWakeResolve[0].qtype)); mDNS_DeactivateNetWake_internal(m, intf); } for (rr = m->ResourceRecords; rr; rr = rr->next) if (!AuthRecord_uDNS(rr)) if (!mDNSOpaque16IsZero(rr->updateid)) { LogSPS("ReadyForSleep clearing updateid for %s", ARDisplayString(m, rr)); rr->updateid = zeroID; } // We'd really like to allow up to ten seconds more here, // but if we don't respond to the sleep notification within 30 seconds // we'll be put back to sleep forcibly without the chance to schedule the next maintenance wake. // Right now we wait 16 sec after wake for all the interfaces to come up, then we wait up to 10 seconds // more for SPS resolves and record registrations to complete, which puts us at 26 seconds. // If we allow just one more second to send our goodbyes, that puts us at 27 seconds. m->SleepLimit = now + mDNSPlatformOneSecond * 1; SendSleepGoodbyes(m); } notready: mDNS_Unlock(m); return mDNSfalse; } mDNSexport mDNSs32 mDNSCoreIntervalToNextWake(mDNS *const m, mDNSs32 now) { AuthRecord *ar; // Even when we have no wake-on-LAN-capable interfaces, or we failed to find a sleep proxy, or we have other // failure scenarios, we still want to wake up in at most 120 minutes, to see if the network environment has changed. // E.g. we might wake up and find no wireless network because the base station got rebooted just at that moment, // and if that happens we don't want to just give up and go back to sleep and never try again. mDNSs32 e = now + (120 * 60 * mDNSPlatformOneSecond); // Sleep for at most 120 minutes NATTraversalInfo *nat; for (nat = m->NATTraversals; nat; nat=nat->next) if (nat->Protocol && nat->ExpiryTime && nat->ExpiryTime - now > mDNSPlatformOneSecond*4) { mDNSs32 t = nat->ExpiryTime - (nat->ExpiryTime - now) / 10; // Wake up when 90% of the way to the expiry time if (e - t > 0) e = t; LogSPS("ComputeWakeTime: %p %s Int %5d Ext %5d Err %d Retry %5d Interval %5d Expire %5d Wake %5d", nat, nat->Protocol == NATOp_MapTCP ? "TCP" : "UDP", mDNSVal16(nat->IntPort), mDNSVal16(nat->ExternalPort), nat->Result, nat->retryPortMap ? (nat->retryPortMap - now) / mDNSPlatformOneSecond : 0, nat->retryInterval / mDNSPlatformOneSecond, nat->ExpiryTime ? (nat->ExpiryTime - now) / mDNSPlatformOneSecond : 0, (t - now) / mDNSPlatformOneSecond); } // This loop checks both the time we need to renew wide-area registrations, // and the time we need to renew Sleep Proxy registrations for (ar = m->ResourceRecords; ar; ar = ar->next) if (ar->expire && ar->expire - now > mDNSPlatformOneSecond*4) { mDNSs32 t = ar->expire - (ar->expire - now) / 10; // Wake up when 90% of the way to the expiry time if (e - t > 0) e = t; LogSPS("ComputeWakeTime: %p Int %7d Next %7d Expire %7d Wake %7d %s", ar, ar->ThisAPInterval / mDNSPlatformOneSecond, (ar->LastAPTime + ar->ThisAPInterval - now) / mDNSPlatformOneSecond, ar->expire ? (ar->expire - now) / mDNSPlatformOneSecond : 0, (t - now) / mDNSPlatformOneSecond, ARDisplayString(m, ar)); } return(e - now); } // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Packet Reception Functions #endif #define MustSendRecord(RR) ((RR)->NR_AnswerTo || (RR)->NR_AdditionalTo) mDNSlocal mDNSu8 *GenerateUnicastResponse(const DNSMessage *const query, const mDNSu8 *const end, const mDNSInterfaceID InterfaceID, mDNSBool LegacyQuery, DNSMessage *const response, AuthRecord *ResponseRecords) { mDNSu8 *responseptr = response->data; const mDNSu8 *const limit = response->data + sizeof(response->data); const mDNSu8 *ptr = query->data; AuthRecord *rr; mDNSu32 maxttl = 0x70000000; int i; // Initialize the response fields so we can answer the questions InitializeDNSMessage(&response->h, query->h.id, ResponseFlags); // *** // *** 1. Write out the list of questions we are actually going to answer with this packet // *** if (LegacyQuery) { maxttl = kStaticCacheTTL; for (i=0; ih.numQuestions; i++) // For each question... { DNSQuestion q; ptr = getQuestion(query, ptr, end, InterfaceID, &q); // get the question... if (!ptr) return(mDNSNULL); for (rr=ResponseRecords; rr; rr=rr->NextResponse) // and search our list of proposed answers { if (rr->NR_AnswerTo == ptr) // If we're going to generate a record answering this question { // then put the question in the question section responseptr = putQuestion(response, responseptr, limit, &q.qname, q.qtype, q.qclass); if (!responseptr) { debugf("GenerateUnicastResponse: Ran out of space for questions!"); return(mDNSNULL); } break; // break out of the ResponseRecords loop, and go on to the next question } } } if (response->h.numQuestions == 0) { LogMsg("GenerateUnicastResponse: ERROR! Why no questions?"); return(mDNSNULL); } } // *** // *** 2. Write Answers // *** for (rr=ResponseRecords; rr; rr=rr->NextResponse) if (rr->NR_AnswerTo) { mDNSu8 *p = PutResourceRecordTTL(response, responseptr, &response->h.numAnswers, &rr->resrec, maxttl < rr->resrec.rroriginalttl ? maxttl : rr->resrec.rroriginalttl); if (p) responseptr = p; else { debugf("GenerateUnicastResponse: Ran out of space for answers!"); response->h.flags.b[0] |= kDNSFlag0_TC; } } // *** // *** 3. Write Additionals // *** for (rr=ResponseRecords; rr; rr=rr->NextResponse) if (rr->NR_AdditionalTo && !rr->NR_AnswerTo) { mDNSu8 *p = PutResourceRecordTTL(response, responseptr, &response->h.numAdditionals, &rr->resrec, maxttl < rr->resrec.rroriginalttl ? maxttl : rr->resrec.rroriginalttl); if (p) responseptr = p; else debugf("GenerateUnicastResponse: No more space for additionals"); } return(responseptr); } // AuthRecord *our is our Resource Record // CacheRecord *pkt is the Resource Record from the response packet we've witnessed on the network // Returns 0 if there is no conflict // Returns +1 if there was a conflict and we won // Returns -1 if there was a conflict and we lost and have to rename mDNSlocal int CompareRData(const AuthRecord *const our, const CacheRecord *const pkt) { mDNSu8 ourdata[256], *ourptr = ourdata, *ourend; mDNSu8 pktdata[256], *pktptr = pktdata, *pktend; if (!our) { LogMsg("CompareRData ERROR: our is NULL"); return(+1); } if (!pkt) { LogMsg("CompareRData ERROR: pkt is NULL"); return(+1); } ourend = putRData(mDNSNULL, ourdata, ourdata + sizeof(ourdata), &our->resrec); pktend = putRData(mDNSNULL, pktdata, pktdata + sizeof(pktdata), &pkt->resrec); while (ourptr < ourend && pktptr < pktend && *ourptr == *pktptr) { ourptr++; pktptr++; } if (ourptr >= ourend && pktptr >= pktend) return(0); // If data identical, not a conflict if (ourptr >= ourend) return(-1); // Our data ran out first; We lost if (pktptr >= pktend) return(+1); // Packet data ran out first; We won if (*pktptr > *ourptr) return(-1); // Our data is numerically lower; We lost if (*pktptr < *ourptr) return(+1); // Packet data is numerically lower; We won LogMsg("CompareRData ERROR: Invalid state"); return(-1); } // See if we have an authoritative record that's identical to this packet record, // whose canonical DependentOn record is the specified master record. // The DependentOn pointer is typically used for the TXT record of service registrations // It indicates that there is no inherent conflict detection for the TXT record // -- it depends on the SRV record to resolve name conflicts // If we find any identical ResourceRecords in our authoritative list, then follow their DependentOn // pointer chain (if any) to make sure we reach the canonical DependentOn record // If the record has no DependentOn, then just return that record's pointer // Returns NULL if we don't have any local RRs that are identical to the one from the packet mDNSlocal mDNSBool MatchDependentOn(const mDNS *const m, const CacheRecord *const pktrr, const AuthRecord *const master) { const AuthRecord *r1; for (r1 = m->ResourceRecords; r1; r1=r1->next) { if (IdenticalResourceRecord(&r1->resrec, &pktrr->resrec)) { const AuthRecord *r2 = r1; while (r2->DependentOn) r2 = r2->DependentOn; if (r2 == master) return(mDNStrue); } } for (r1 = m->DuplicateRecords; r1; r1=r1->next) { if (IdenticalResourceRecord(&r1->resrec, &pktrr->resrec)) { const AuthRecord *r2 = r1; while (r2->DependentOn) r2 = r2->DependentOn; if (r2 == master) return(mDNStrue); } } return(mDNSfalse); } // Find the canonical RRSet pointer for this RR received in a packet. // If we find any identical AuthRecord in our authoritative list, then follow its RRSet // pointers (if any) to make sure we return the canonical member of this name/type/class // Returns NULL if we don't have any local RRs that are identical to the one from the packet mDNSlocal const AuthRecord *FindRRSet(const mDNS *const m, const CacheRecord *const pktrr) { const AuthRecord *rr; for (rr = m->ResourceRecords; rr; rr=rr->next) { if (IdenticalResourceRecord(&rr->resrec, &pktrr->resrec)) { while (rr->RRSet && rr != rr->RRSet) rr = rr->RRSet; return(rr); } } return(mDNSNULL); } // PacketRRConflict is called when we've received an RR (pktrr) which has the same name // as one of our records (our) but different rdata. // 1. If our record is not a type that's supposed to be unique, we don't care. // 2a. If our record is marked as dependent on some other record for conflict detection, ignore this one. // 2b. If the packet rr exactly matches one of our other RRs, and *that* record's DependentOn pointer // points to our record, ignore this conflict (e.g. the packet record matches one of our // TXT records, and that record is marked as dependent on 'our', its SRV record). // 3. If we have some *other* RR that exactly matches the one from the packet, and that record and our record // are members of the same RRSet, then this is not a conflict. mDNSlocal mDNSBool PacketRRConflict(const mDNS *const m, const AuthRecord *const our, const CacheRecord *const pktrr) { // If not supposed to be unique, not a conflict if (!(our->resrec.RecordType & kDNSRecordTypeUniqueMask)) return(mDNSfalse); // If a dependent record, not a conflict if (our->DependentOn || MatchDependentOn(m, pktrr, our)) return(mDNSfalse); else { // If the pktrr matches a member of ourset, not a conflict const AuthRecord *ourset = our->RRSet ? our->RRSet : our; const AuthRecord *pktset = FindRRSet(m, pktrr); if (pktset == ourset) return(mDNSfalse); // For records we're proxying, where we don't know the full // relationship between the records, having any matching record // in our AuthRecords list is sufficient evidence of non-conflict if (our->WakeUp.HMAC.l[0] && pktset) return(mDNSfalse); } // Okay, this is a conflict return(mDNStrue); } // Note: ResolveSimultaneousProbe calls mDNS_Deregister_internal which can call a user callback, which may change // the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSlocal void ResolveSimultaneousProbe(mDNS *const m, const DNSMessage *const query, const mDNSu8 *const end, DNSQuestion *q, AuthRecord *our) { int i; const mDNSu8 *ptr = LocateAuthorities(query, end); mDNSBool FoundUpdate = mDNSfalse; for (i = 0; i < query->h.numAuthorities; i++) { ptr = GetLargeResourceRecord(m, query, ptr, end, q->InterfaceID, kDNSRecordTypePacketAuth, &m->rec); if (!ptr) break; if (m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && ResourceRecordAnswersQuestion(&m->rec.r.resrec, q)) { FoundUpdate = mDNStrue; if (PacketRRConflict(m, our, &m->rec.r)) { int result = (int)our->resrec.rrclass - (int)m->rec.r.resrec.rrclass; if (!result) result = (int)our->resrec.rrtype - (int)m->rec.r.resrec.rrtype; if (!result) result = CompareRData(our, &m->rec.r); if (result) { const char *const msg = (result < 0) ? "lost:" : (result > 0) ? "won: " : "tie: "; LogMsg("ResolveSimultaneousProbe: %p Pkt Record: %08lX %s", q->InterfaceID, m->rec.r.resrec.rdatahash, CRDisplayString(m, &m->rec.r)); LogMsg("ResolveSimultaneousProbe: %p Our Record %d %s %08lX %s", our->resrec.InterfaceID, our->ProbeCount, msg, our->resrec.rdatahash, ARDisplayString(m, our)); } // If we lost the tie-break for simultaneous probes, we don't immediately give up, because we might be seeing stale packets on the network. // Instead we pause for one second, to give the other host (if real) a chance to establish its name, and then try probing again. // If there really is another live host out there with the same name, it will answer our probes and we'll then rename. if (result < 0) { m->SuppressProbes = NonZeroTime(m->timenow + mDNSPlatformOneSecond); our->ProbeCount = DefaultProbeCountForTypeUnique; our->AnnounceCount = InitialAnnounceCount; InitializeLastAPTime(m, our); goto exit; } } #if 0 else { LogMsg("ResolveSimultaneousProbe: %p Pkt Record: %08lX %s", q->InterfaceID, m->rec.r.resrec.rdatahash, CRDisplayString(m, &m->rec.r)); LogMsg("ResolveSimultaneousProbe: %p Our Record %d ign: %08lX %s", our->resrec.InterfaceID, our->ProbeCount, our->resrec.rdatahash, ARDisplayString(m, our)); } #endif } m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } if (!FoundUpdate) LogInfo("ResolveSimultaneousProbe: %##s (%s): No Update Record found", our->resrec.name->c, DNSTypeName(our->resrec.rrtype)); exit: m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } mDNSlocal CacheRecord *FindIdenticalRecordInCache(const mDNS *const m, const ResourceRecord *const pktrr) { mDNSu32 slot = HashSlot(pktrr->name); CacheGroup *cg = CacheGroupForRecord(m, slot, pktrr); CacheRecord *rr; mDNSBool match; for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) { match = !pktrr->InterfaceID ? pktrr->rDNSServer == rr->resrec.rDNSServer : pktrr->InterfaceID == rr->resrec.InterfaceID; if (match && IdenticalSameNameRecord(pktrr, &rr->resrec)) break; } return(rr); } // Called from mDNSCoreReceiveUpdate when we get a sleep proxy registration request, // to check our lists and discard any stale duplicates of this record we already have mDNSlocal void ClearIdenticalProxyRecords(mDNS *const m, const OwnerOptData *const owner, AuthRecord *const thelist) { if (m->CurrentRecord) LogMsg("ClearIdenticalProxyRecords ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); m->CurrentRecord = thelist; while (m->CurrentRecord) { AuthRecord *const rr = m->CurrentRecord; if (m->rec.r.resrec.InterfaceID == rr->resrec.InterfaceID && mDNSSameEthAddress(&owner->HMAC, &rr->WakeUp.HMAC)) if (IdenticalResourceRecord(&rr->resrec, &m->rec.r.resrec)) { LogSPS("ClearIdenticalProxyRecords: Removing %3d H-MAC %.6a I-MAC %.6a %d %d %s", m->ProxyRecords, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, rr->WakeUp.seq, owner->seq, ARDisplayString(m, rr)); rr->WakeUp.HMAC = zeroEthAddr; // Clear HMAC so that mDNS_Deregister_internal doesn't waste packets trying to wake this host rr->RequireGoodbye = mDNSfalse; // and we don't want to send goodbye for it mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); SetSPSProxyListChanged(m->rec.r.resrec.InterfaceID); } // Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because // new records could have been added to the end of the list as a result of that call. if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now m->CurrentRecord = rr->next; } } // Called from ProcessQuery when we get an mDNS packet with an owner record in it mDNSlocal void ClearProxyRecords(mDNS *const m, const OwnerOptData *const owner, AuthRecord *const thelist) { if (m->CurrentRecord) LogMsg("ClearProxyRecords ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); m->CurrentRecord = thelist; while (m->CurrentRecord) { AuthRecord *const rr = m->CurrentRecord; if (m->rec.r.resrec.InterfaceID == rr->resrec.InterfaceID && mDNSSameEthAddress(&owner->HMAC, &rr->WakeUp.HMAC)) if (owner->seq != rr->WakeUp.seq || m->timenow - rr->TimeRcvd > mDNSPlatformOneSecond * 60) { if (rr->AddressProxy.type == mDNSAddrType_IPv6) { // We don't do this here because we know that the host is waking up at this point, so we don't send // Unsolicited Neighbor Advertisements -- even Neighbor Advertisements agreeing with what the host should be // saying itself -- because it can cause some IPv6 stacks to falsely conclude that there's an address conflict. #if MDNS_USE_Unsolicited_Neighbor_Advertisements LogSPS("NDP Announcement -- Releasing traffic for H-MAC %.6a I-MAC %.6a %s", &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr)); SendNDP(m, NDP_Adv, NDP_Override, rr, &rr->AddressProxy.ip.v6, &rr->WakeUp.IMAC, &AllHosts_v6, &AllHosts_v6_Eth); #endif } LogSPS("ClearProxyRecords: Removing %3d AC %2d %02X H-MAC %.6a I-MAC %.6a %d %d %s", m->ProxyRecords, rr->AnnounceCount, rr->resrec.RecordType, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, rr->WakeUp.seq, owner->seq, ARDisplayString(m, rr)); if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) rr->resrec.RecordType = kDNSRecordTypeShared; rr->WakeUp.HMAC = zeroEthAddr; // Clear HMAC so that mDNS_Deregister_internal doesn't waste packets trying to wake this host rr->RequireGoodbye = mDNSfalse; // and we don't want to send goodbye for it, since real host is now back and functional mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); SetSPSProxyListChanged(m->rec.r.resrec.InterfaceID); } // Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because // new records could have been added to the end of the list as a result of that call. if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now m->CurrentRecord = rr->next; } } // ProcessQuery examines a received query to see if we have any answers to give mDNSlocal mDNSu8 *ProcessQuery(mDNS *const m, const DNSMessage *const query, const mDNSu8 *const end, const mDNSAddr *srcaddr, const mDNSInterfaceID InterfaceID, mDNSBool LegacyQuery, mDNSBool QueryWasMulticast, mDNSBool QueryWasLocalUnicast, DNSMessage *const response) { mDNSBool FromLocalSubnet = srcaddr && mDNS_AddressIsLocalSubnet(m, InterfaceID, srcaddr); AuthRecord *ResponseRecords = mDNSNULL; AuthRecord **nrp = &ResponseRecords; CacheRecord *ExpectedAnswers = mDNSNULL; // Records in our cache we expect to see updated CacheRecord **eap = &ExpectedAnswers; DNSQuestion *DupQuestions = mDNSNULL; // Our questions that are identical to questions in this packet DNSQuestion **dqp = &DupQuestions; mDNSs32 delayresponse = 0; mDNSBool SendLegacyResponse = mDNSfalse; const mDNSu8 *ptr; mDNSu8 *responseptr = mDNSNULL; AuthRecord *rr; int i; // *** // *** 1. Look in Additional Section for an OPT record // *** ptr = LocateOptRR(query, end, DNSOpt_OwnerData_ID_Space); if (ptr) { ptr = GetLargeResourceRecord(m, query, ptr, end, InterfaceID, kDNSRecordTypePacketAdd, &m->rec); if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_OPT) { const rdataOPT *opt; const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength]; // Find owner sub-option(s). We verify that the MAC is non-zero, otherwise we could inadvertently // delete all our own AuthRecords (which are identified by having zero MAC tags on them). for (opt = &m->rec.r.resrec.rdata->u.opt[0]; opt < e; opt++) if (opt->opt == kDNSOpt_Owner && opt->u.owner.vers == 0 && opt->u.owner.HMAC.l[0]) { ClearProxyRecords(m, &opt->u.owner, m->DuplicateRecords); ClearProxyRecords(m, &opt->u.owner, m->ResourceRecords); } } m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } // *** // *** 2. Parse Question Section and mark potential answers // *** ptr = query->data; for (i=0; ih.numQuestions; i++) // For each question... { mDNSBool QuestionNeedsMulticastResponse; int NumAnswersForThisQuestion = 0; AuthRecord *NSECAnswer = mDNSNULL; DNSQuestion pktq, *q; ptr = getQuestion(query, ptr, end, InterfaceID, &pktq); // get the question... if (!ptr) goto exit; // The only queries that *need* a multicast response are: // * Queries sent via multicast // * from port 5353 // * that don't have the kDNSQClass_UnicastResponse bit set // These queries need multicast responses because other clients will: // * suppress their own identical questions when they see these questions, and // * expire their cache records if they don't see the expected responses // For other queries, we may still choose to send the occasional multicast response anyway, // to keep our neighbours caches warm, and for ongoing conflict detection. QuestionNeedsMulticastResponse = QueryWasMulticast && !LegacyQuery && !(pktq.qclass & kDNSQClass_UnicastResponse); // Clear the UnicastResponse flag -- don't want to confuse the rest of the code that follows later pktq.qclass &= ~kDNSQClass_UnicastResponse; // Note: We use the m->CurrentRecord mechanism here because calling ResolveSimultaneousProbe // can result in user callbacks which may change the record list and/or question list. // Also note: we just mark potential answer records here, without trying to build the // "ResponseRecords" list, because we don't want to risk user callbacks deleting records // from that list while we're in the middle of trying to build it. if (m->CurrentRecord) LogMsg("ProcessQuery ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); m->CurrentRecord = m->ResourceRecords; while (m->CurrentRecord) { rr = m->CurrentRecord; m->CurrentRecord = rr->next; if (AnyTypeRecordAnswersQuestion(&rr->resrec, &pktq) && (QueryWasMulticast || QueryWasLocalUnicast || rr->AllowRemoteQuery)) { if (RRTypeAnswersQuestionType(&rr->resrec, pktq.qtype)) { if (rr->resrec.RecordType == kDNSRecordTypeUnique) ResolveSimultaneousProbe(m, query, end, &pktq, rr); else if (ResourceRecordIsValidAnswer(rr)) { NumAnswersForThisQuestion++; // Note: We should check here if this is a probe-type query, and if so, generate an immediate // unicast answer back to the source, because timeliness in answering probes is important. // Notes: // NR_AnswerTo pointing into query packet means "answer via immediate legacy unicast" (may *also* choose to multicast) // NR_AnswerTo == (mDNSu8*)~1 means "answer via delayed unicast" (to modern querier; may promote to multicast instead) // NR_AnswerTo == (mDNSu8*)~0 means "definitely answer via multicast" (can't downgrade to unicast later) // If we're not multicasting this record because the kDNSQClass_UnicastResponse bit was set, // but the multicast querier is not on a matching subnet (e.g. because of overlaid subnets on one link) // then we'll multicast it anyway (if we unicast, the receiver will ignore it because it has an apparently non-local source) if (QuestionNeedsMulticastResponse || (!FromLocalSubnet && QueryWasMulticast && !LegacyQuery)) { // We only mark this question for sending if it is at least one second since the last time we multicast it // on this interface. If it is more than a second, or LastMCInterface is different, then we may multicast it. // This is to guard against the case where someone blasts us with queries as fast as they can. if (m->timenow - (rr->LastMCTime + mDNSPlatformOneSecond) >= 0 || (rr->LastMCInterface != mDNSInterfaceMark && rr->LastMCInterface != InterfaceID)) rr->NR_AnswerTo = (mDNSu8*)~0; } else if (!rr->NR_AnswerTo) rr->NR_AnswerTo = LegacyQuery ? ptr : (mDNSu8*)~1; } } else if ((rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && ResourceRecordIsValidAnswer(rr)) { // If we don't have any answers for this question, but we do own another record with the same name, // then we'll want to mark it to generate an NSEC record on this interface if (!NSECAnswer) NSECAnswer = rr; } } } if (NumAnswersForThisQuestion == 0 && NSECAnswer) { NumAnswersForThisQuestion++; NSECAnswer->SendNSECNow = InterfaceID; m->NextScheduledResponse = m->timenow; } // If we couldn't answer this question, someone else might be able to, // so use random delay on response to reduce collisions if (NumAnswersForThisQuestion == 0) delayresponse = mDNSPlatformOneSecond; // Divided by 50 = 20ms #if ENABLE_MULTI_PACKET_QUERY_SNOOPING if (QuestionNeedsMulticastResponse) #else // We only do the following accelerated cache expiration and duplicate question suppression processing // for non-truncated multicast queries with multicast responses. // For any query generating a unicast response we don't do this because we can't assume we will see the response. // For truncated queries we don't do this because a response we're expecting might be suppressed by a subsequent // known-answer packet, and when there's packet loss we can't safely assume we'll receive *all* known-answer packets. if (QuestionNeedsMulticastResponse && !(query->h.flags.b[0] & kDNSFlag0_TC)) #endif { const mDNSu32 slot = HashSlot(&pktq.qname); CacheGroup *cg = CacheGroupForName(m, slot, pktq.qnamehash, &pktq.qname); CacheRecord *cr; // Make a list indicating which of our own cache records we expect to see updated as a result of this query // Note: Records larger than 1K are not habitually multicast, so don't expect those to be updated #if ENABLE_MULTI_PACKET_QUERY_SNOOPING if (!(query->h.flags.b[0] & kDNSFlag0_TC)) #endif for (cr = cg ? cg->members : mDNSNULL; cr; cr=cr->next) if (SameNameRecordAnswersQuestion(&cr->resrec, &pktq) && cr->resrec.rdlength <= SmallRecordLimit) if (!cr->NextInKAList && eap != &cr->NextInKAList) { *eap = cr; eap = &cr->NextInKAList; #if ENABLE_MULTI_PACKET_QUERY_SNOOPING if (cr->MPUnansweredQ == 0 || m->timenow - cr->MPLastUnansweredQT >= mDNSPlatformOneSecond) { // Although MPUnansweredQ is only really used for multi-packet query processing, // we increment it for both single-packet and multi-packet queries, so that it stays in sync // with the MPUnansweredKA value, which by necessity is incremented for both query types. cr->MPUnansweredQ++; cr->MPLastUnansweredQT = m->timenow; cr->MPExpectingKA = mDNStrue; } #endif } // Check if this question is the same as any of mine. // We only do this for non-truncated queries. Right now it would be too complicated to try // to keep track of duplicate suppression state between multiple packets, especially when we // can't guarantee to receive all of the Known Answer packets that go with a particular query. #if ENABLE_MULTI_PACKET_QUERY_SNOOPING if (!(query->h.flags.b[0] & kDNSFlag0_TC)) #endif for (q = m->Questions; q; q=q->next) if (!q->Target.type && ActiveQuestion(q) && m->timenow - q->LastQTxTime > mDNSPlatformOneSecond / 4) if (!q->InterfaceID || q->InterfaceID == InterfaceID) if (q->NextInDQList == mDNSNULL && dqp != &q->NextInDQList) if (q->qtype == pktq.qtype && q->qclass == pktq.qclass && q->qnamehash == pktq.qnamehash && SameDomainName(&q->qname, &pktq.qname)) { *dqp = q; dqp = &q->NextInDQList; } } } // *** // *** 3. Now we can safely build the list of marked answers // *** for (rr = m->ResourceRecords; rr; rr=rr->next) // Now build our list of potential answers if (rr->NR_AnswerTo) // If we marked the record... AddRecordToResponseList(&nrp, rr, mDNSNULL); // ... add it to the list // *** // *** 4. Add additional records // *** AddAdditionalsToResponseList(m, ResponseRecords, &nrp, InterfaceID); // *** // *** 5. Parse Answer Section and cancel any records disallowed by Known-Answer list // *** for (i=0; ih.numAnswers; i++) // For each record in the query's answer section... { // Get the record... CacheRecord *ourcacherr; ptr = GetLargeResourceRecord(m, query, ptr, end, InterfaceID, kDNSRecordTypePacketAns, &m->rec); if (!ptr) goto exit; if (m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative) { // See if this Known-Answer suppresses any of our currently planned answers for (rr=ResponseRecords; rr; rr=rr->NextResponse) if (MustSendRecord(rr) && ShouldSuppressKnownAnswer(&m->rec.r, rr)) { rr->NR_AnswerTo = mDNSNULL; rr->NR_AdditionalTo = mDNSNULL; } // See if this Known-Answer suppresses any previously scheduled answers (for multi-packet KA suppression) for (rr=m->ResourceRecords; rr; rr=rr->next) { // If we're planning to send this answer on this interface, and only on this interface, then allow KA suppression if (rr->ImmedAnswer == InterfaceID && ShouldSuppressKnownAnswer(&m->rec.r, rr)) { if (srcaddr->type == mDNSAddrType_IPv4) { if (mDNSSameIPv4Address(rr->v4Requester, srcaddr->ip.v4)) rr->v4Requester = zerov4Addr; } else if (srcaddr->type == mDNSAddrType_IPv6) { if (mDNSSameIPv6Address(rr->v6Requester, srcaddr->ip.v6)) rr->v6Requester = zerov6Addr; } if (mDNSIPv4AddressIsZero(rr->v4Requester) && mDNSIPv6AddressIsZero(rr->v6Requester)) { rr->ImmedAnswer = mDNSNULL; rr->ImmedUnicast = mDNSfalse; #if MDNS_LOG_ANSWER_SUPPRESSION_TIMES LogMsg("Suppressed after%4d: %s", m->timenow - rr->ImmedAnswerMarkTime, ARDisplayString(m, rr)); #endif } } } ourcacherr = FindIdenticalRecordInCache(m, &m->rec.r.resrec); #if ENABLE_MULTI_PACKET_QUERY_SNOOPING // See if this Known-Answer suppresses any answers we were expecting for our cache records. We do this always, // even if the TC bit is not set (the TC bit will *not* be set in the *last* packet of a multi-packet KA list). if (ourcacherr && ourcacherr->MPExpectingKA && m->timenow - ourcacherr->MPLastUnansweredQT < mDNSPlatformOneSecond) { ourcacherr->MPUnansweredKA++; ourcacherr->MPExpectingKA = mDNSfalse; } #endif // Having built our ExpectedAnswers list from the questions in this packet, we then remove // any records that are suppressed by the Known Answer list in this packet. eap = &ExpectedAnswers; while (*eap) { CacheRecord *cr = *eap; if (cr->resrec.InterfaceID == InterfaceID && IdenticalResourceRecord(&m->rec.r.resrec, &cr->resrec)) { *eap = cr->NextInKAList; cr->NextInKAList = mDNSNULL; } else eap = &cr->NextInKAList; } // See if this Known-Answer is a surprise to us. If so, we shouldn't suppress our own query. if (!ourcacherr) { dqp = &DupQuestions; while (*dqp) { DNSQuestion *q = *dqp; if (ResourceRecordAnswersQuestion(&m->rec.r.resrec, q)) { *dqp = q->NextInDQList; q->NextInDQList = mDNSNULL; } else dqp = &q->NextInDQList; } } } m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } // *** // *** 6. Cancel any additionals that were added because of now-deleted records // *** for (rr=ResponseRecords; rr; rr=rr->NextResponse) if (rr->NR_AdditionalTo && !MustSendRecord(rr->NR_AdditionalTo)) { rr->NR_AnswerTo = mDNSNULL; rr->NR_AdditionalTo = mDNSNULL; } // *** // *** 7. Mark the send flags on the records we plan to send // *** for (rr=ResponseRecords; rr; rr=rr->NextResponse) { if (rr->NR_AnswerTo) { mDNSBool SendMulticastResponse = mDNSfalse; // Send modern multicast response mDNSBool SendUnicastResponse = mDNSfalse; // Send modern unicast response (not legacy unicast response) // If it's been a while since we multicast this, then send a multicast response for conflict detection, etc. if (m->timenow - (rr->LastMCTime + TicksTTL(rr)/4) >= 0) { SendMulticastResponse = mDNStrue; // If this record was marked for modern (delayed) unicast response, then mark it as promoted to // multicast response instead (don't want to end up ALSO setting SendUnicastResponse in the check below). // If this record was marked for legacy unicast response, then we mustn't change the NR_AnswerTo value. if (rr->NR_AnswerTo == (mDNSu8*)~1) rr->NR_AnswerTo = (mDNSu8*)~0; } // If the client insists on a multicast response, then we'd better send one if (rr->NR_AnswerTo == (mDNSu8*)~0) SendMulticastResponse = mDNStrue; else if (rr->NR_AnswerTo == (mDNSu8*)~1) SendUnicastResponse = mDNStrue; else if (rr->NR_AnswerTo) SendLegacyResponse = mDNStrue; if (SendMulticastResponse || SendUnicastResponse) { #if MDNS_LOG_ANSWER_SUPPRESSION_TIMES rr->ImmedAnswerMarkTime = m->timenow; #endif m->NextScheduledResponse = m->timenow; // If we're already planning to send this on another interface, just send it on all interfaces if (rr->ImmedAnswer && rr->ImmedAnswer != InterfaceID) rr->ImmedAnswer = mDNSInterfaceMark; else { rr->ImmedAnswer = InterfaceID; // Record interface to send it on if (SendUnicastResponse) rr->ImmedUnicast = mDNStrue; if (srcaddr->type == mDNSAddrType_IPv4) { if (mDNSIPv4AddressIsZero(rr->v4Requester)) rr->v4Requester = srcaddr->ip.v4; else if (!mDNSSameIPv4Address(rr->v4Requester, srcaddr->ip.v4)) rr->v4Requester = onesIPv4Addr; } else if (srcaddr->type == mDNSAddrType_IPv6) { if (mDNSIPv6AddressIsZero(rr->v6Requester)) rr->v6Requester = srcaddr->ip.v6; else if (!mDNSSameIPv6Address(rr->v6Requester, srcaddr->ip.v6)) rr->v6Requester = onesIPv6Addr; } } } // If TC flag is set, it means we should expect that additional known answers may be coming in another packet, // so we allow roughly half a second before deciding to reply (we've observed inter-packet delays of 100-200ms on 802.11) // else, if record is a shared one, spread responses over 100ms to avoid implosion of simultaneous responses // else, for a simple unique record reply, we can reply immediately; no need for delay if (query->h.flags.b[0] & kDNSFlag0_TC) delayresponse = mDNSPlatformOneSecond * 20; // Divided by 50 = 400ms else if (rr->resrec.RecordType == kDNSRecordTypeShared) delayresponse = mDNSPlatformOneSecond; // Divided by 50 = 20ms } else if (rr->NR_AdditionalTo && rr->NR_AdditionalTo->NR_AnswerTo == (mDNSu8*)~0) { // Since additional records are an optimization anyway, we only ever send them on one interface at a time // If two clients on different interfaces do queries that invoke the same optional additional answer, // then the earlier client is out of luck rr->ImmedAdditional = InterfaceID; // No need to set m->NextScheduledResponse here // We'll send these additional records when we send them, or not, as the case may be } } // *** // *** 8. If we think other machines are likely to answer these questions, set our packet suppression timer // *** if (delayresponse && (!m->SuppressSending || (m->SuppressSending - m->timenow) < (delayresponse + 49) / 50)) { #if MDNS_LOG_ANSWER_SUPPRESSION_TIMES mDNSs32 oldss = m->SuppressSending; if (oldss && delayresponse) LogMsg("Current SuppressSending delay%5ld; require%5ld", m->SuppressSending - m->timenow, (delayresponse + 49) / 50); #endif // Pick a random delay: // We start with the base delay chosen above (typically either 1 second or 20 seconds), // and add a random value in the range 0-5 seconds (making 1-6 seconds or 20-25 seconds). // This is an integer value, with resolution determined by the platform clock rate. // We then divide that by 50 to get the delay value in ticks. We defer the division until last // to get better results on platforms with coarse clock granularity (e.g. ten ticks per second). // The +49 before dividing is to ensure we round up, not down, to ensure that even // on platforms where the native clock rate is less than fifty ticks per second, // we still guarantee that the final calculated delay is at least one platform tick. // We want to make sure we don't ever allow the delay to be zero ticks, // because if that happens we'll fail the Bonjour Conformance Test. // Our final computed delay is 20-120ms for normal delayed replies, // or 400-500ms in the case of multi-packet known-answer lists. m->SuppressSending = m->timenow + (delayresponse + (mDNSs32)mDNSRandom((mDNSu32)mDNSPlatformOneSecond*5) + 49) / 50; if (m->SuppressSending == 0) m->SuppressSending = 1; #if MDNS_LOG_ANSWER_SUPPRESSION_TIMES if (oldss && delayresponse) LogMsg("Set SuppressSending to %5ld", m->SuppressSending - m->timenow); #endif } // *** // *** 9. If query is from a legacy client, or from a new client requesting a unicast reply, then generate a unicast response too // *** if (SendLegacyResponse) responseptr = GenerateUnicastResponse(query, end, InterfaceID, LegacyQuery, response, ResponseRecords); exit: m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it // *** // *** 10. Finally, clear our link chains ready for use next time // *** while (ResponseRecords) { rr = ResponseRecords; ResponseRecords = rr->NextResponse; rr->NextResponse = mDNSNULL; rr->NR_AnswerTo = mDNSNULL; rr->NR_AdditionalTo = mDNSNULL; } while (ExpectedAnswers) { CacheRecord *cr = ExpectedAnswers; ExpectedAnswers = cr->NextInKAList; cr->NextInKAList = mDNSNULL; // For non-truncated queries, we can definitively say that we should expect // to be seeing a response for any records still left in the ExpectedAnswers list if (!(query->h.flags.b[0] & kDNSFlag0_TC)) if (cr->UnansweredQueries == 0 || m->timenow - cr->LastUnansweredTime >= mDNSPlatformOneSecond) { cr->UnansweredQueries++; cr->LastUnansweredTime = m->timenow; #if ENABLE_MULTI_PACKET_QUERY_SNOOPING if (cr->UnansweredQueries > 1) debugf("ProcessQuery: (!TC) UAQ %lu MPQ %lu MPKA %lu %s", cr->UnansweredQueries, cr->MPUnansweredQ, cr->MPUnansweredKA, CRDisplayString(m, cr)); #endif SetNextCacheCheckTimeForRecord(m, cr); } // If we've seen multiple unanswered queries for this record, // then mark it to expire in five seconds if we don't get a response by then. if (cr->UnansweredQueries >= MaxUnansweredQueries) { #if ENABLE_MULTI_PACKET_QUERY_SNOOPING // Only show debugging message if this record was not about to expire anyway if (RRExpireTime(cr) - m->timenow > 4 * mDNSPlatformOneSecond) debugf("ProcessQuery: (Max) UAQ %lu MPQ %lu MPKA %lu mDNS_Reconfirm() for %s", cr->UnansweredQueries, cr->MPUnansweredQ, cr->MPUnansweredKA, CRDisplayString(m, cr)); #endif mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer); } #if ENABLE_MULTI_PACKET_QUERY_SNOOPING // Make a guess, based on the multi-packet query / known answer counts, whether we think we // should have seen an answer for this. (We multiply MPQ by 4 and MPKA by 5, to allow for // possible packet loss of up to 20% of the additional KA packets.) else if (cr->MPUnansweredQ * 4 > cr->MPUnansweredKA * 5 + 8) { // We want to do this conservatively. // If there are so many machines on the network that they have to use multi-packet known-answer lists, // then we don't want them to all hit the network simultaneously with their final expiration queries. // By setting the record to expire in four minutes, we achieve two things: // (a) the 90-95% final expiration queries will be less bunched together // (b) we allow some time for us to witness enough other failed queries that we don't have to do our own mDNSu32 remain = (mDNSu32)(RRExpireTime(cr) - m->timenow) / 4; if (remain > 240 * (mDNSu32)mDNSPlatformOneSecond) remain = 240 * (mDNSu32)mDNSPlatformOneSecond; // Only show debugging message if this record was not about to expire anyway if (RRExpireTime(cr) - m->timenow > 4 * mDNSPlatformOneSecond) debugf("ProcessQuery: (MPQ) UAQ %lu MPQ %lu MPKA %lu mDNS_Reconfirm() for %s", cr->UnansweredQueries, cr->MPUnansweredQ, cr->MPUnansweredKA, CRDisplayString(m, cr)); if (remain <= 60 * (mDNSu32)mDNSPlatformOneSecond) cr->UnansweredQueries++; // Treat this as equivalent to one definite unanswered query cr->MPUnansweredQ = 0; // Clear MPQ/MPKA statistics cr->MPUnansweredKA = 0; cr->MPExpectingKA = mDNSfalse; if (remain < kDefaultReconfirmTimeForNoAnswer) remain = kDefaultReconfirmTimeForNoAnswer; mDNS_Reconfirm_internal(m, cr, remain); } #endif } while (DupQuestions) { DNSQuestion *q = DupQuestions; DupQuestions = q->NextInDQList; q->NextInDQList = mDNSNULL; i = RecordDupSuppressInfo(q->DupSuppress, m->timenow, InterfaceID, srcaddr->type); debugf("ProcessQuery: Recorded DSI for %##s (%s) on %p/%s %d", q->qname.c, DNSTypeName(q->qtype), InterfaceID, srcaddr->type == mDNSAddrType_IPv4 ? "v4" : "v6", i); } return(responseptr); } mDNSlocal void mDNSCoreReceiveQuery(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, mDNSIPPort dstport, const mDNSInterfaceID InterfaceID) { mDNSu8 *responseend = mDNSNULL; mDNSBool QueryWasLocalUnicast = srcaddr && dstaddr && !mDNSAddrIsDNSMulticast(dstaddr) && mDNS_AddressIsLocalSubnet(m, InterfaceID, srcaddr); if (!InterfaceID && dstaddr && mDNSAddrIsDNSMulticast(dstaddr)) { LogMsg("Ignoring Query from %#-15a:%-5d to %#-15a:%-5d on 0x%p with " "%2d Question%s %2d Answer%s %2d Authorit%s %2d Additional%s %d bytes (Multicast, but no InterfaceID)", srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), InterfaceID, msg->h.numQuestions, msg->h.numQuestions == 1 ? ", " : "s,", msg->h.numAnswers, msg->h.numAnswers == 1 ? ", " : "s,", msg->h.numAuthorities, msg->h.numAuthorities == 1 ? "y, " : "ies,", msg->h.numAdditionals, msg->h.numAdditionals == 1 ? " " : "s", end - msg->data); return; } verbosedebugf("Received Query from %#-15a:%-5d to %#-15a:%-5d on 0x%p with " "%2d Question%s %2d Answer%s %2d Authorit%s %2d Additional%s %d bytes", srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), InterfaceID, msg->h.numQuestions, msg->h.numQuestions == 1 ? ", " : "s,", msg->h.numAnswers, msg->h.numAnswers == 1 ? ", " : "s,", msg->h.numAuthorities, msg->h.numAuthorities == 1 ? "y, " : "ies,", msg->h.numAdditionals, msg->h.numAdditionals == 1 ? " " : "s", end - msg->data); responseend = ProcessQuery(m, msg, end, srcaddr, InterfaceID, !mDNSSameIPPort(srcport, MulticastDNSPort), mDNSAddrIsDNSMulticast(dstaddr), QueryWasLocalUnicast, &m->omsg); if (responseend) // If responseend is non-null, that means we built a unicast response packet { debugf("Unicast Response: %d Question%s, %d Answer%s, %d Additional%s to %#-15a:%d on %p/%ld", m->omsg.h.numQuestions, m->omsg.h.numQuestions == 1 ? "" : "s", m->omsg.h.numAnswers, m->omsg.h.numAnswers == 1 ? "" : "s", m->omsg.h.numAdditionals, m->omsg.h.numAdditionals == 1 ? "" : "s", srcaddr, mDNSVal16(srcport), InterfaceID, srcaddr->type); mDNSSendDNSMessage(m, &m->omsg, responseend, InterfaceID, mDNSNULL, srcaddr, srcport, mDNSNULL, mDNSNULL); } } #if 0 mDNSlocal mDNSBool TrustedSource(const mDNS *const m, const mDNSAddr *const srcaddr) { DNSServer *s; (void)m; // Unused (void)srcaddr; // Unused for (s = m->DNSServers; s; s = s->next) if (mDNSSameAddress(srcaddr, &s->addr)) return(mDNStrue); return(mDNSfalse); } #endif struct UDPSocket_struct { mDNSIPPort port; // MUST BE FIRST FIELD -- mDNSCoreReceive expects every UDPSocket_struct to begin with mDNSIPPort port }; mDNSlocal DNSQuestion *ExpectingUnicastResponseForQuestion(const mDNS *const m, const mDNSIPPort port, const mDNSOpaque16 id, const DNSQuestion *const question, mDNSBool tcp) { DNSQuestion *q; for (q = m->Questions; q; q=q->next) { if (!tcp && !q->LocalSocket) continue; if (mDNSSameIPPort(tcp ? q->tcpSrcPort : q->LocalSocket->port, port) && mDNSSameOpaque16(q->TargetQID, id) && q->qtype == question->qtype && q->qclass == question->qclass && q->qnamehash == question->qnamehash && SameDomainName(&q->qname, &question->qname)) return(q); } return(mDNSNULL); } // This function is called when we receive a unicast response. This could be the case of a unicast response from the // DNS server or a response to the QU query. Hence, the cache record's InterfaceId can be both NULL or non-NULL (QU case) mDNSlocal DNSQuestion *ExpectingUnicastResponseForRecord(mDNS *const m, const mDNSAddr *const srcaddr, const mDNSBool SrcLocal, const mDNSIPPort port, const mDNSOpaque16 id, const CacheRecord *const rr, mDNSBool tcp) { DNSQuestion *q; (void)id; (void)srcaddr; for (q = m->Questions; q; q=q->next) { if (!q->DuplicateOf && ResourceRecordAnswersUnicastResponse(&rr->resrec, q)) { if (!mDNSOpaque16IsZero(q->TargetQID)) { debugf("ExpectingUnicastResponseForRecord msg->h.id %d q->TargetQID %d for %s", mDNSVal16(id), mDNSVal16(q->TargetQID), CRDisplayString(m, rr)); if (mDNSSameOpaque16(q->TargetQID, id)) { mDNSIPPort srcp; if (!tcp) { srcp = q->LocalSocket ? q->LocalSocket->port : zeroIPPort; } else { srcp = q->tcpSrcPort; } if (mDNSSameIPPort(srcp, port)) return(q); // if (mDNSSameAddress(srcaddr, &q->Target)) return(mDNStrue); // if (q->LongLived && mDNSSameAddress(srcaddr, &q->servAddr)) return(mDNStrue); Shouldn't need this now that we have LLQType checking // if (TrustedSource(m, srcaddr)) return(mDNStrue); LogInfo("WARNING: Ignoring suspect uDNS response for %##s (%s) [q->Target %#a:%d] from %#a:%d %s", q->qname.c, DNSTypeName(q->qtype), &q->Target, mDNSVal16(srcp), srcaddr, mDNSVal16(port), CRDisplayString(m, rr)); return(mDNSNULL); } } else { if (SrcLocal && q->ExpectUnicastResp && (mDNSu32)(m->timenow - q->ExpectUnicastResp) < (mDNSu32)(mDNSPlatformOneSecond*2)) return(q); } } } return(mDNSNULL); } // Certain data types need more space for in-memory storage than their in-packet rdlength would imply // Currently this applies only to rdata types containing more than one domainname, // or types where the domainname is not the last item in the structure. // In addition, NSEC currently requires less space for in-memory storage than its in-packet representation. mDNSlocal mDNSu16 GetRDLengthMem(const ResourceRecord *const rr) { switch (rr->rrtype) { case kDNSType_SOA: return sizeof(rdataSOA); case kDNSType_RP: return sizeof(rdataRP); case kDNSType_PX: return sizeof(rdataPX); case kDNSType_NSEC:return sizeof(rdataNSEC); default: return rr->rdlength; } } mDNSexport CacheRecord *CreateNewCacheEntry(mDNS *const m, const mDNSu32 slot, CacheGroup *cg, mDNSs32 delay) { CacheRecord *rr = mDNSNULL; mDNSu16 RDLength = GetRDLengthMem(&m->rec.r.resrec); if (!m->rec.r.resrec.InterfaceID) debugf("CreateNewCacheEntry %s", CRDisplayString(m, &m->rec.r)); //if (RDLength > InlineCacheRDSize) // LogInfo("Rdata len %4d > InlineCacheRDSize %d %s", RDLength, InlineCacheRDSize, CRDisplayString(m, &m->rec.r)); if (!cg) cg = GetCacheGroup(m, slot, &m->rec.r.resrec); // If we don't have a CacheGroup for this name, make one now if (cg) rr = GetCacheRecord(m, cg, RDLength); // Make a cache record, being careful not to recycle cg if (!rr) NoCacheAnswer(m, &m->rec.r); else { RData *saveptr = rr->resrec.rdata; // Save the rr->resrec.rdata pointer *rr = m->rec.r; // Block copy the CacheRecord object rr->resrec.rdata = saveptr; // Restore rr->resrec.rdata after the structure assignment rr->resrec.name = cg->name; // And set rr->resrec.name to point into our CacheGroup header rr->DelayDelivery = delay; // If this is an oversized record with external storage allocated, copy rdata to external storage if (rr->resrec.rdata == (RData*)&rr->smallrdatastorage && RDLength > InlineCacheRDSize) LogMsg("rr->resrec.rdata == &rr->rdatastorage but length > InlineCacheRDSize %##s", m->rec.r.resrec.name->c); else if (rr->resrec.rdata != (RData*)&rr->smallrdatastorage && RDLength <= InlineCacheRDSize) LogMsg("rr->resrec.rdata != &rr->rdatastorage but length <= InlineCacheRDSize %##s", m->rec.r.resrec.name->c); if (RDLength > InlineCacheRDSize) mDNSPlatformMemCopy(rr->resrec.rdata, m->rec.r.resrec.rdata, sizeofRDataHeader + RDLength); rr->next = mDNSNULL; // Clear 'next' pointer *(cg->rrcache_tail) = rr; // Append this record to tail of cache slot list cg->rrcache_tail = &(rr->next); // Advance tail pointer CacheRecordAdd(m, rr); // CacheRecordAdd calls SetNextCacheCheckTimeForRecord(m, rr); for us } return(rr); } mDNSlocal void RefreshCacheRecord(mDNS *const m, CacheRecord *rr, mDNSu32 ttl) { rr->TimeRcvd = m->timenow; rr->resrec.rroriginalttl = ttl; rr->UnansweredQueries = 0; #if ENABLE_MULTI_PACKET_QUERY_SNOOPING rr->MPUnansweredQ = 0; rr->MPUnansweredKA = 0; rr->MPExpectingKA = mDNSfalse; #endif SetNextCacheCheckTimeForRecord(m, rr); } mDNSexport void GrantCacheExtensions(mDNS *const m, DNSQuestion *q, mDNSu32 lease) { CacheRecord *rr; const mDNSu32 slot = HashSlot(&q->qname); CacheGroup *cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) if (rr->CRActiveQuestion == q) { //LogInfo("GrantCacheExtensions: new lease %d / %s", lease, CRDisplayString(m, rr)); RefreshCacheRecord(m, rr, lease); } } mDNSlocal mDNSu32 GetEffectiveTTL(const uDNS_LLQType LLQType, mDNSu32 ttl) // TTL in seconds { if (LLQType == uDNS_LLQ_Entire) ttl = kLLQ_DefLease; else if (LLQType == uDNS_LLQ_Events) { // If the TTL is -1 for uDNS LLQ event packet, that means "remove" if (ttl == 0xFFFFFFFF) ttl = 0; else ttl = kLLQ_DefLease; } else // else not LLQ (standard uDNS response) { // The TTL is already capped to a maximum value in GetLargeResourceRecord, but just to be extra safe we // also do this check here to make sure we can't get overflow below when we add a quarter to the TTL if (ttl > 0x60000000UL / mDNSPlatformOneSecond) ttl = 0x60000000UL / mDNSPlatformOneSecond; // Adjustment factor to avoid race condition: // Suppose real record as TTL of 3600, and our local caching server has held it for 3500 seconds, so it returns an aged TTL of 100. // If we do our normal refresh at 80% of the TTL, our local caching server will return 20 seconds, so we'll do another // 80% refresh after 16 seconds, and then the server will return 4 seconds, and so on, in the fashion of Zeno's paradox. // To avoid this, we extend the record's effective TTL to give it a little extra grace period. // We adjust the 100 second TTL to 126. This means that when we do our 80% query at 101 seconds, // the cached copy at our local caching server will already have expired, so the server will be forced // to fetch a fresh copy from the authoritative server, and then return a fresh record with the full TTL of 3600 seconds. ttl += ttl/4 + 2; // For mDNS, TTL zero means "delete this record" // For uDNS, TTL zero means: this data is true at this moment, but don't cache it. // For the sake of network efficiency, we impose a minimum effective TTL of 15 seconds. // This means that we'll do our 80, 85, 90, 95% queries at 12.00, 12.75, 13.50, 14.25 seconds // respectively, and then if we get no response, delete the record from the cache at 15 seconds. // This gives the server up to three seconds to respond between when we send our 80% query at 12 seconds // and when we delete the record at 15 seconds. Allowing cache lifetimes less than 15 seconds would // (with the current code) result in the server having even less than three seconds to respond // before we deleted the record and reported a "remove" event to any active questions. // Furthermore, with the current code, if we were to allow a TTL of less than 2 seconds // then things really break (e.g. we end up making a negative cache entry). // In the future we may want to revisit this and consider properly supporting non-cached (TTL=0) uDNS answers. if (ttl < 15) ttl = 15; } return ttl; } // Note: mDNSCoreReceiveResponse calls mDNS_Deregister_internal which can call a user callback, which may change // the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. // InterfaceID non-NULL tells us the interface this multicast response was received on // InterfaceID NULL tells us this was a unicast response // dstaddr NULL tells us we received this over an outgoing TCP connection we made mDNSlocal void mDNSCoreReceiveResponse(mDNS *const m, const DNSMessage *const response, const mDNSu8 *end, const mDNSAddr *srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, mDNSIPPort dstport, const mDNSInterfaceID InterfaceID) { int i; mDNSBool ResponseMCast = dstaddr && mDNSAddrIsDNSMulticast(dstaddr); mDNSBool ResponseSrcLocal = !srcaddr || mDNS_AddressIsLocalSubnet(m, InterfaceID, srcaddr); DNSQuestion *llqMatch = mDNSNULL; uDNS_LLQType LLQType = uDNS_recvLLQResponse(m, response, end, srcaddr, srcport, &llqMatch); // "(CacheRecord*)1" is a special (non-zero) end-of-list marker // We use this non-zero marker so that records in our CacheFlushRecords list will always have NextInCFList // set non-zero, and that tells GetCacheEntity() that they're not, at this moment, eligible for recycling. CacheRecord *CacheFlushRecords = (CacheRecord*)1; CacheRecord **cfp = &CacheFlushRecords; // All records in a DNS response packet are treated as equally valid statements of truth. If we want // to guard against spoof responses, then the only credible protection against that is cryptographic // security, e.g. DNSSEC., not worring about which section in the spoof packet contained the record int firstauthority = response->h.numAnswers; int firstadditional = firstauthority + response->h.numAuthorities; int totalrecords = firstadditional + response->h.numAdditionals; const mDNSu8 *ptr = response->data; DNSServer *uDNSServer = mDNSNULL; debugf("Received Response from %#-15a addressed to %#-15a on %p with " "%2d Question%s %2d Answer%s %2d Authorit%s %2d Additional%s %d bytes LLQType %d", srcaddr, dstaddr, InterfaceID, response->h.numQuestions, response->h.numQuestions == 1 ? ", " : "s,", response->h.numAnswers, response->h.numAnswers == 1 ? ", " : "s,", response->h.numAuthorities, response->h.numAuthorities == 1 ? "y, " : "ies,", response->h.numAdditionals, response->h.numAdditionals == 1 ? " " : "s", end - response->data, LLQType); // According to RFC 2181 // When a DNS client receives a reply with TC // set, it should ignore that response, and query again, using a // mechanism, such as a TCP connection, that will permit larger replies. // It feels wrong to be throwing away data after the network went to all the trouble of delivering it to us, but // delivering some records of the RRSet first and then the remainder a couple of milliseconds later was causing // failures in our Microsoft Active Directory client, which expects to get the entire set of answers at once. // Can't bind to Active Directory // In addition, if the client immediately canceled its query after getting the initial partial response, then we'll // abort our TCP connection, and not complete the operation, and end up with an incomplete RRSet in our cache. // Next time there's a query for this RRSet we'll see answers in our cache, and assume we have the whole RRSet already, // and not even do the TCP query. // Accordingly, if we get a uDNS reply with kDNSFlag0_TC set, we bail out and wait for the TCP response containing the entire RRSet. if (!InterfaceID && (response->h.flags.b[0] & kDNSFlag0_TC)) return; if (LLQType == uDNS_LLQ_Ignore) return; // 1. We ignore questions (if any) in mDNS response packets // 2. If this is an LLQ response, we handle it much the same // 3. If we get a uDNS UDP response with the TC (truncated) bit set, then we can't treat this // answer as being the authoritative complete RRSet, and respond by deleting all other // matching cache records that don't appear in this packet. // Otherwise, this is a authoritative uDNS answer, so arrange for any stale records to be purged if (ResponseMCast || LLQType == uDNS_LLQ_Events || (response->h.flags.b[0] & kDNSFlag0_TC)) ptr = LocateAnswers(response, end); // Otherwise, for one-shot queries, any answers in our cache that are not also contained // in this response packet are immediately deemed to be invalid. else { mDNSu8 rcode = (mDNSu8)(response->h.flags.b[1] & kDNSFlag1_RC_Mask); mDNSBool failure = !(rcode == kDNSFlag1_RC_NoErr || rcode == kDNSFlag1_RC_NXDomain || rcode == kDNSFlag1_RC_NotAuth); mDNSBool returnEarly = mDNSfalse; // We could possibly combine this with the similar loop at the end of this function -- // instead of tagging cache records here and then rescuing them if we find them in the answer section, // we could instead use the "m->PktNum" mechanism to tag each cache record with the packet number in // which it was received (or refreshed), and then at the end if we find any cache records which // answer questions in this packet's question section, but which aren't tagged with this packet's // packet number, then we deduce they are old and delete them for (i = 0; i < response->h.numQuestions && ptr && ptr < end; i++) { DNSQuestion q, *qptr = mDNSNULL; ptr = getQuestion(response, ptr, end, InterfaceID, &q); if (ptr && (qptr = ExpectingUnicastResponseForQuestion(m, dstport, response->h.id, &q, !dstaddr))) { if (!failure) { CacheRecord *rr; const mDNSu32 slot = HashSlot(&q.qname); CacheGroup *cg = CacheGroupForName(m, slot, q.qnamehash, &q.qname); for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) if (SameNameRecordAnswersQuestion(&rr->resrec, qptr)) { debugf("uDNS marking %p %##s (%s) %p %s", q.InterfaceID, q.qname.c, DNSTypeName(q.qtype), rr->resrec.InterfaceID, CRDisplayString(m, rr)); // Don't want to disturb rroriginalttl here, because code below might need it for the exponential backoff doubling algorithm rr->TimeRcvd = m->timenow - TicksTTL(rr) - 1; rr->UnansweredQueries = MaxUnansweredQueries; } } else { if (qptr) { LogInfo("mDNSCoreReceiveResponse: Server %p responded with code %d to query %##s (%s)", qptr->qDNSServer, rcode, q.qname.c, DNSTypeName(q.qtype)); PenalizeDNSServer(m, qptr); } returnEarly = mDNStrue; } } } if (returnEarly) { LogInfo("Ignoring %2d Answer%s %2d Authorit%s %2d Additional%s", response->h.numAnswers, response->h.numAnswers == 1 ? ", " : "s,", response->h.numAuthorities, response->h.numAuthorities == 1 ? "y, " : "ies,", response->h.numAdditionals, response->h.numAdditionals == 1 ? "" : "s"); // not goto exit because we won't have any CacheFlushRecords and we do not want to // generate negative cache entries (we want to query the next server) return; } } for (i = 0; i < totalrecords && ptr && ptr < end; i++) { // All responses sent via LL multicast are acceptable for caching // All responses received over our outbound TCP connections are acceptable for caching mDNSBool AcceptableResponse = ResponseMCast || !dstaddr || LLQType; // (Note that just because we are willing to cache something, that doesn't necessarily make it a trustworthy answer // to any specific question -- any code reading records from the cache needs to make that determination for itself.) const mDNSu8 RecordType = (i < firstauthority ) ? (mDNSu8)kDNSRecordTypePacketAns : (i < firstadditional) ? (mDNSu8)kDNSRecordTypePacketAuth : (mDNSu8)kDNSRecordTypePacketAdd; ptr = GetLargeResourceRecord(m, response, ptr, end, InterfaceID, RecordType, &m->rec); if (!ptr) goto exit; // Break out of the loop and clean up our CacheFlushRecords list before exiting if (m->rec.r.resrec.RecordType == kDNSRecordTypePacketNegative) { m->rec.r.resrec.RecordType = 0; continue; } // Don't want to cache OPT or TSIG pseudo-RRs if (m->rec.r.resrec.rrtype == kDNSType_TSIG) { m->rec.r.resrec.RecordType = 0; continue; } if (m->rec.r.resrec.rrtype == kDNSType_OPT) { const rdataOPT *opt; const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength]; // Find owner sub-option(s). We verify that the MAC is non-zero, otherwise we could inadvertently // delete all our own AuthRecords (which are identified by having zero MAC tags on them). for (opt = &m->rec.r.resrec.rdata->u.opt[0]; opt < e; opt++) if (opt->opt == kDNSOpt_Owner && opt->u.owner.vers == 0 && opt->u.owner.HMAC.l[0]) { ClearProxyRecords(m, &opt->u.owner, m->DuplicateRecords); ClearProxyRecords(m, &opt->u.owner, m->ResourceRecords); } m->rec.r.resrec.RecordType = 0; continue; } // if a CNAME record points to itself, then don't add it to the cache if ((m->rec.r.resrec.rrtype == kDNSType_CNAME) && SameDomainName(m->rec.r.resrec.name, &m->rec.r.resrec.rdata->u.name)) { LogInfo("mDNSCoreReceiveResponse: CNAME loop domain name %##s", m->rec.r.resrec.name->c); m->rec.r.resrec.RecordType = 0; continue; } // When we receive uDNS LLQ responses, we assume a long cache lifetime -- // In the case of active LLQs, we'll get remove events when the records actually do go away // In the case of polling LLQs, we assume the record remains valid until the next poll if (!mDNSOpaque16IsZero(response->h.id)) m->rec.r.resrec.rroriginalttl = GetEffectiveTTL(LLQType, m->rec.r.resrec.rroriginalttl); // If response was not sent via LL multicast, // then see if it answers a recent query of ours, which would also make it acceptable for caching. if (!ResponseMCast) { if (LLQType) { // For Long Lived queries that are both sent over UDP and Private TCP, LLQType is set. // Even though it is AcceptableResponse, we need a matching DNSServer pointer for the // queries to get ADD/RMV events. To lookup the question, we can't use // ExpectingUnicastResponseForRecord as the port numbers don't match. uDNS_recvLLQRespose // has already matched the question using the 64 bit Id in the packet and we use that here. if (llqMatch != mDNSNULL) m->rec.r.resrec.rDNSServer = uDNSServer = llqMatch->qDNSServer; } else if (!AcceptableResponse || !dstaddr) { // For responses that come over TCP (Responses that can't fit within UDP) or TLS (Private queries // that are not long lived e.g., AAAA lookup in a Private domain), it is indicated by !dstaddr. // Even though it is AcceptableResponse, we still need a DNSServer pointer for the resource records that // we create. DNSQuestion *q = ExpectingUnicastResponseForRecord(m, srcaddr, ResponseSrcLocal, dstport, response->h.id, &m->rec.r, !dstaddr); // Intialize the DNS server on the resource record which will now filter what questions we answer with // this record. // // We could potentially lookup the DNS server based on the source address, but that may not work always // and that's why ExpectingUnicastResponseForRecord does not try to verify whether the response came // from the DNS server that queried. We follow the same logic here. If we can find a matching quetion based // on the "id" and "source port", then this response answers the question and assume the response // came from the same DNS server that we sent the query to. if (q != mDNSNULL) { AcceptableResponse = mDNStrue; if (!InterfaceID) { debugf("mDNSCoreReceiveResponse: InterfaceID %p %##s (%s)", q->InterfaceID, q->qname.c, DNSTypeName(q->qtype)); m->rec.r.resrec.rDNSServer = uDNSServer = q->qDNSServer; } } else { // If we can't find a matching question, we need to see whether we have seen records earlier that matched // the question. The code below does that. So, make this record unacceptable for now if (!InterfaceID) { debugf("mDNSCoreReceiveResponse: Can't find question for record name %##s", m->rec.r.resrec.name->c); AcceptableResponse = mDNSfalse; } } } } // 1. Check that this packet resource record does not conflict with any of ours if (mDNSOpaque16IsZero(response->h.id) && m->rec.r.resrec.rrtype != kDNSType_NSEC) { if (m->CurrentRecord) LogMsg("mDNSCoreReceiveResponse ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); m->CurrentRecord = m->ResourceRecords; while (m->CurrentRecord) { AuthRecord *rr = m->CurrentRecord; m->CurrentRecord = rr->next; // We accept all multicast responses, and unicast responses resulting from queries we issued // For other unicast responses, this code accepts them only for responses with an // (apparently) local source address that pertain to a record of our own that's in probing state if (!AcceptableResponse && !(ResponseSrcLocal && rr->resrec.RecordType == kDNSRecordTypeUnique)) continue; if (PacketRRMatchesSignature(&m->rec.r, rr)) // If interface, name, type (if shared record) and class match... { // ... check to see if type and rdata are identical if (IdenticalSameNameRecord(&m->rec.r.resrec, &rr->resrec)) { // If the RR in the packet is identical to ours, just check they're not trying to lower the TTL on us if (m->rec.r.resrec.rroriginalttl >= rr->resrec.rroriginalttl/2 || m->SleepState) { // If we were planning to send on this -- and only this -- interface, then we don't need to any more if (rr->ImmedAnswer == InterfaceID) { rr->ImmedAnswer = mDNSNULL; rr->ImmedUnicast = mDNSfalse; } } else { if (rr->ImmedAnswer == mDNSNULL) { rr->ImmedAnswer = InterfaceID; m->NextScheduledResponse = m->timenow; } else if (rr->ImmedAnswer != InterfaceID) { rr->ImmedAnswer = mDNSInterfaceMark; m->NextScheduledResponse = m->timenow; } } } // else, the packet RR has different type or different rdata -- check to see if this is a conflict else if (m->rec.r.resrec.rroriginalttl > 0 && PacketRRConflict(m, rr, &m->rec.r)) { LogInfo("mDNSCoreReceiveResponse: Pkt Record: %08lX %s", m->rec.r.resrec.rdatahash, CRDisplayString(m, &m->rec.r)); LogInfo("mDNSCoreReceiveResponse: Our Record: %08lX %s", rr-> resrec.rdatahash, ARDisplayString(m, rr)); // If this record is marked DependentOn another record for conflict detection purposes, // then *that* record has to be bumped back to probing state to resolve the conflict if (rr->DependentOn) { while (rr->DependentOn) rr = rr->DependentOn; LogInfo("mDNSCoreReceiveResponse: Dep Record: %08lX %s", rr-> resrec.rdatahash, ARDisplayString(m, rr)); } // If we've just whacked this record's ProbeCount, don't need to do it again if (rr->ProbeCount > DefaultProbeCountForTypeUnique) LogInfo("mDNSCoreReceiveResponse: Already reset to Probing: %s", ARDisplayString(m, rr)); else if (rr->ProbeCount == DefaultProbeCountForTypeUnique) LogMsg("mDNSCoreReceiveResponse: Ignoring response received before we even began probing: %s", ARDisplayString(m, rr)); else { LogMsg("mDNSCoreReceiveResponse: Received from %#a:%d %s", srcaddr, mDNSVal16(srcport), CRDisplayString(m, &m->rec.r)); // If we'd previously verified this record, put it back to probing state and try again if (rr->resrec.RecordType == kDNSRecordTypeVerified) { LogMsg("mDNSCoreReceiveResponse: Resetting to Probing: %s", ARDisplayString(m, rr)); rr->resrec.RecordType = kDNSRecordTypeUnique; // We set ProbeCount to one more than the usual value so we know we've already touched this record. // This is because our single probe for "example-name.local" could yield a response with (say) two A records and // three AAAA records in it, and we don't want to call RecordProbeFailure() five times and count that as five conflicts. // This special value is recognised and reset to DefaultProbeCountForTypeUnique in SendQueries(). rr->ProbeCount = DefaultProbeCountForTypeUnique + 1; rr->AnnounceCount = InitialAnnounceCount; InitializeLastAPTime(m, rr); RecordProbeFailure(m, rr); // Repeated late conflicts also cause us to back off to the slower probing rate } // If we're probing for this record, we just failed else if (rr->resrec.RecordType == kDNSRecordTypeUnique) { LogMsg("mDNSCoreReceiveResponse: ProbeCount %d; will deregister %s", rr->ProbeCount, ARDisplayString(m, rr)); mDNS_Deregister_internal(m, rr, mDNS_Dereg_conflict); } // We assumed this record must be unique, but we were wrong. (e.g. There are two mDNSResponders on the // same machine giving different answers for the reverse mapping record, or there are two machines on the // network using the same IP address.) This is simply a misconfiguration, and there's nothing we can do // to fix it -- e.g. it's not our job to be trying to change the machine's IP address. We just discard our // record to avoid continued conflicts (as we do for a conflict on our Unique records) and get on with life. else if (rr->resrec.RecordType == kDNSRecordTypeKnownUnique) { LogMsg("mDNSCoreReceiveResponse: Unexpected conflict discarding %s", ARDisplayString(m, rr)); mDNS_Deregister_internal(m, rr, mDNS_Dereg_conflict); } else LogMsg("mDNSCoreReceiveResponse: Unexpected record type %X %s", rr->resrec.RecordType, ARDisplayString(m, rr)); } } // Else, matching signature, different type or rdata, but not a considered a conflict. // If the packet record has the cache-flush bit set, then we check to see if we // have any record(s) of the same type that we should re-assert to rescue them // (see note about "multi-homing and bridged networks" at the end of this function). else if (m->rec.r.resrec.rrtype == rr->resrec.rrtype) if ((m->rec.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask) && m->timenow - rr->LastMCTime > mDNSPlatformOneSecond/2) { rr->ImmedAnswer = mDNSInterfaceMark; m->NextScheduledResponse = m->timenow; } } } } if (!AcceptableResponse) { const CacheRecord *cr; for (cr = CacheFlushRecords; cr != (CacheRecord*)1; cr = cr->NextInCFList) { domainname *target = GetRRDomainNameTarget(&cr->resrec); // When we issue a query for A record, the response might contain both a CNAME and A records. Only the CNAME would // match the question and we already created a cache entry in the previous pass of this loop. Now when we process // the A record, it does not match the question because the record name here is the CNAME. Hence we try to // match with the previous records to make it an AcceptableResponse. We have to be careful about setting the // DNSServer value that we got in the previous pass. This can happen for other record types like SRV also. if (target && cr->resrec.rdatahash == m->rec.r.resrec.namehash && SameDomainName(target, m->rec.r.resrec.name)) { debugf("mDNSCoreReceiveResponse: Found a matching entry for %##s in the CacheFlushRecords", m->rec.r.resrec.name->c); AcceptableResponse = mDNStrue; m->rec.r.resrec.rDNSServer = uDNSServer; break; } } } // 2. See if we want to add this packet resource record to our cache // We only try to cache answers if we have a cache to put them in // Also, we ignore any apparent attempts at cache poisoning unicast to us that do not answer any outstanding active query if (!AcceptableResponse) LogInfo("mDNSCoreReceiveResponse ignoring %s", CRDisplayString(m, &m->rec.r)); if (m->rrcache_size && AcceptableResponse) { const mDNSu32 slot = HashSlot(m->rec.r.resrec.name); CacheGroup *cg = CacheGroupForRecord(m, slot, &m->rec.r.resrec); CacheRecord *rr; // 2a. Check if this packet resource record is already in our cache for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) { mDNSBool match = !InterfaceID ? m->rec.r.resrec.rDNSServer == rr->resrec.rDNSServer : rr->resrec.InterfaceID == InterfaceID; // If we found this exact resource record, refresh its TTL if (match && IdenticalSameNameRecord(&m->rec.r.resrec, &rr->resrec)) { if (m->rec.r.resrec.rdlength > InlineCacheRDSize) verbosedebugf("Found record size %5d interface %p already in cache: %s", m->rec.r.resrec.rdlength, InterfaceID, CRDisplayString(m, &m->rec.r)); if (m->rec.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask) { // If this packet record has the kDNSClass_UniqueRRSet flag set, then add it to our cache flushing list if (rr->NextInCFList == mDNSNULL && cfp != &rr->NextInCFList && LLQType != uDNS_LLQ_Events) { *cfp = rr; cfp = &rr->NextInCFList; *cfp = (CacheRecord*)1; } // If this packet record is marked unique, and our previous cached copy was not, then fix it if (!(rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask)) { DNSQuestion *q; for (q = m->Questions; q; q=q->next) if (ResourceRecordAnswersQuestion(&rr->resrec, q)) q->UniqueAnswers++; rr->resrec.RecordType = m->rec.r.resrec.RecordType; } } if (!SameRDataBody(&m->rec.r.resrec, &rr->resrec.rdata->u, SameDomainNameCS)) { // If the rdata of the packet record differs in name capitalization from the record in our cache // then mDNSPlatformMemSame will detect this. In this case, throw the old record away, so that clients get // a 'remove' event for the record with the old capitalization, and then an 'add' event for the new one. // mDNS -F returns the same domain multiple times with different casing rr->resrec.rroriginalttl = 0; rr->TimeRcvd = m->timenow; rr->UnansweredQueries = MaxUnansweredQueries; SetNextCacheCheckTimeForRecord(m, rr); LogInfo("Discarding due to domainname case change old: %s", CRDisplayString(m,rr)); LogInfo("Discarding due to domainname case change new: %s", CRDisplayString(m,&m->rec.r)); LogInfo("Discarding due to domainname case change in %d slot %3d in %d %d", NextCacheCheckEvent(rr) - m->timenow, slot, m->rrcache_nextcheck[slot] - m->timenow, m->NextCacheCheck - m->timenow); // DO NOT break out here -- we want to continue as if we never found it } else if (m->rec.r.resrec.rroriginalttl > 0) { DNSQuestion *q; //if (rr->resrec.rroriginalttl == 0) LogMsg("uDNS rescuing %s", CRDisplayString(m, rr)); RefreshCacheRecord(m, rr, m->rec.r.resrec.rroriginalttl); // We have to reset the question interval to MaxQuestionInterval so that we don't keep // polling the network once we get a valid response back. For the first time when a new // cache entry is created, AnswerCurrentQuestionWithResourceRecord does that. // Subsequently, if we reissue questions from within the mDNSResponder e.g., DNS server // configuration changed, without flushing the cache, we reset the question interval here. // Currently, we do this for for both multicast and unicast questions as long as the record // type is unique. For unicast, resource record is always unique and for multicast it is // true for records like A etc. but not for PTR. if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) { for (q = m->Questions; q; q=q->next) { if (!q->DuplicateOf && !q->LongLived && ActiveQuestion(q) && ResourceRecordAnswersQuestion(&rr->resrec, q)) { q->LastQTime = m->timenow; q->LastQTxTime = m->timenow; q->RecentAnswerPkts = 0; q->ThisQInterval = MaxQuestionInterval; q->RequestUnicast = mDNSfalse; q->unansweredQueries = 0; debugf("mDNSCoreReceiveResponse: Set MaxQuestionInterval for %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); break; // Why break here? Aren't there other questions we might want to look at?-- SC July 2010 } } } break; } else { // If the packet TTL is zero, that means we're deleting this record. // To give other hosts on the network a chance to protest, we push the deletion // out one second into the future. Also, we set UnansweredQueries to MaxUnansweredQueries. // Otherwise, we'll do final queries for this record at 80% and 90% of its apparent // lifetime (800ms and 900ms from now) which is a pointless waste of network bandwidth. // If record's current expiry time is more than a second from now, we set it to expire in one second. // If the record is already going to expire in less than one second anyway, we leave it alone -- // we don't want to let the goodbye packet *extend* the record's lifetime in our cache. debugf("DE for %s", CRDisplayString(m, rr)); if (RRExpireTime(rr) - m->timenow > mDNSPlatformOneSecond) { rr->resrec.rroriginalttl = 1; rr->TimeRcvd = m->timenow; rr->UnansweredQueries = MaxUnansweredQueries; SetNextCacheCheckTimeForRecord(m, rr); } break; } } } // If packet resource record not in our cache, add it now // (unless it is just a deletion of a record we never had, in which case we don't care) if (!rr && m->rec.r.resrec.rroriginalttl > 0) { const mDNSBool AddToCFList = (m->rec.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask) && (LLQType != uDNS_LLQ_Events); const mDNSs32 delay = AddToCFList ? NonZeroTime(m->timenow + mDNSPlatformOneSecond) : CheckForSoonToExpireRecords(m, m->rec.r.resrec.name, m->rec.r.resrec.namehash, slot); // If unique, assume we may have to delay delivery of this 'add' event. // Below, where we walk the CacheFlushRecords list, we either call CacheRecordDeferredAdd() // to immediately to generate answer callbacks, or we call ScheduleNextCacheCheckTime() // to schedule an mDNS_Execute task at the appropriate time. rr = CreateNewCacheEntry(m, slot, cg, delay); if (rr) { if (AddToCFList) { *cfp = rr; cfp = &rr->NextInCFList; *cfp = (CacheRecord*)1; } else if (rr->DelayDelivery) ScheduleNextCacheCheckTime(m, slot, rr->DelayDelivery); } } } m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } exit: m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it // If we've just received one or more records with their cache flush bits set, // then scan that cache slot to see if there are any old stale records we need to flush while (CacheFlushRecords != (CacheRecord*)1) { CacheRecord *r1 = CacheFlushRecords, *r2; const mDNSu32 slot = HashSlot(r1->resrec.name); const CacheGroup *cg = CacheGroupForRecord(m, slot, &r1->resrec); CacheFlushRecords = CacheFlushRecords->NextInCFList; r1->NextInCFList = mDNSNULL; // Look for records in the cache with the same signature as this new one with the cache flush // bit set, and either (a) if they're fresh, just make sure the whole RRSet has the same TTL // (as required by DNS semantics) or (b) if they're old, mark them for deletion in one second. // We make these TTL adjustments *only* for records that still have *more* than one second // remaining to live. Otherwise, a record that we tagged for deletion half a second ago // (and now has half a second remaining) could inadvertently get its life extended, by either // (a) if we got an explicit goodbye packet half a second ago, the record would be considered // "fresh" and would be incorrectly resurrected back to the same TTL as the rest of the RRSet, // or (b) otherwise, the record would not be fully resurrected, but would be reset to expire // in one second, thereby inadvertently delaying its actual expiration, instead of hastening it. // If this were to happen repeatedly, the record's expiration could be deferred indefinitely. // To avoid this, we need to ensure that the cache flushing operation will only act to // *decrease* a record's remaining lifetime, never *increase* it. for (r2 = cg ? cg->members : mDNSNULL; r2; r2=r2->next) // For Unicast (null InterfaceID) the DNSservers should also match if ((r1->resrec.InterfaceID == r2->resrec.InterfaceID) && (r1->resrec.InterfaceID || (r1->resrec.rDNSServer == r2->resrec.rDNSServer)) && r1->resrec.rrtype == r2->resrec.rrtype && r1->resrec.rrclass == r2->resrec.rrclass) { // If record is recent, just ensure the whole RRSet has the same TTL (as required by DNS semantics) // else, if record is old, mark it to be flushed if (m->timenow - r2->TimeRcvd < mDNSPlatformOneSecond && RRExpireTime(r2) - m->timenow > mDNSPlatformOneSecond) { // If we find mismatched TTLs in an RRSet, correct them. // We only do this for records with a TTL of 2 or higher. It's possible to have a // goodbye announcement with the cache flush bit set (or a case-change on record rdata, // which we treat as a goodbye followed by an addition) and in that case it would be // inappropriate to synchronize all the other records to a TTL of 0 (or 1). // We suppress the message for the specific case of correcting from 240 to 60 for type TXT, // because certain early Bonjour devices are known to have this specific mismatch, and // there's no point filling syslog with messages about something we already know about. // We also don't log this for uDNS responses, since a caching name server is obliged // to give us an aged TTL to correct for how long it has held the record, // so our received TTLs are expected to vary in that case if (r2->resrec.rroriginalttl != r1->resrec.rroriginalttl && r1->resrec.rroriginalttl > 1) { if (!(r2->resrec.rroriginalttl == 240 && r1->resrec.rroriginalttl == 60 && r2->resrec.rrtype == kDNSType_TXT) && mDNSOpaque16IsZero(response->h.id)) LogInfo("Correcting TTL from %4d to %4d for %s", r2->resrec.rroriginalttl, r1->resrec.rroriginalttl, CRDisplayString(m, r2)); r2->resrec.rroriginalttl = r1->resrec.rroriginalttl; } r2->TimeRcvd = m->timenow; } else // else, if record is old, mark it to be flushed { verbosedebugf("Cache flush new %p age %d expire in %d %s", r1, m->timenow - r1->TimeRcvd, RRExpireTime(r1) - m->timenow, CRDisplayString(m, r1)); verbosedebugf("Cache flush old %p age %d expire in %d %s", r2, m->timenow - r2->TimeRcvd, RRExpireTime(r2) - m->timenow, CRDisplayString(m, r2)); // We set stale records to expire in one second. // This gives the owner a chance to rescue it if necessary. // This is important in the case of multi-homing and bridged networks: // Suppose host X is on Ethernet. X then connects to an AirPort base station, which happens to be // bridged onto the same Ethernet. When X announces its AirPort IP address with the cache-flush bit // set, the AirPort packet will be bridged onto the Ethernet, and all other hosts on the Ethernet // will promptly delete their cached copies of the (still valid) Ethernet IP address record. // By delaying the deletion by one second, we give X a change to notice that this bridging has // happened, and re-announce its Ethernet IP address to rescue it from deletion from all our caches. // We set UnansweredQueries to MaxUnansweredQueries to avoid expensive and unnecessary // final expiration queries for this record. // If a record is deleted twice, first with an explicit DE record, then a second time by virtue of the cache // flush bit on the new record replacing it, then we allow the record to be deleted immediately, without the usual // one-second grace period. This improves responsiveness for mDNS_Update(), as used for things like iChat status updates. // Updating TXT records is too slow // We check for "rroriginalttl == 1" because we want to include records tagged by the "packet TTL is zero" check above, // which sets rroriginalttl to 1, but not records tagged by the rdata case-change check, which sets rroriginalttl to 0. if (r2->TimeRcvd == m->timenow && r2->resrec.rroriginalttl == 1 && r2->UnansweredQueries == MaxUnansweredQueries) { LogInfo("Cache flush for DE record %s", CRDisplayString(m, r2)); r2->resrec.rroriginalttl = 0; } else if (RRExpireTime(r2) - m->timenow > mDNSPlatformOneSecond) { // We only set a record to expire in one second if it currently has *more* than a second to live // If it's already due to expire in a second or less, we just leave it alone r2->resrec.rroriginalttl = 1; r2->UnansweredQueries = MaxUnansweredQueries; r2->TimeRcvd = m->timenow - 1; // We use (m->timenow - 1) instead of m->timenow, because we use that to identify records // that we marked for deletion via an explicit DE record } } SetNextCacheCheckTimeForRecord(m, r2); } if (r1->DelayDelivery) // If we were planning to delay delivery of this record, see if we still need to { r1->DelayDelivery = CheckForSoonToExpireRecords(m, r1->resrec.name, r1->resrec.namehash, slot); // If no longer delaying, deliver answer now, else schedule delivery for the appropriate time if (!r1->DelayDelivery) CacheRecordDeferredAdd(m, r1); else ScheduleNextCacheCheckTime(m, slot, r1->DelayDelivery); } } // See if we need to generate negative cache entries for unanswered unicast questions ptr = response->data; for (i = 0; i < response->h.numQuestions && ptr && ptr < end; i++) { DNSQuestion q; DNSQuestion *qptr = mDNSNULL; ptr = getQuestion(response, ptr, end, InterfaceID, &q); if (ptr && (qptr = ExpectingUnicastResponseForQuestion(m, dstport, response->h.id, &q, !dstaddr))) { CacheRecord *rr, *neg = mDNSNULL; mDNSu32 slot = HashSlot(&q.qname); CacheGroup *cg = CacheGroupForName(m, slot, q.qnamehash, &q.qname); for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) if (SameNameRecordAnswersQuestion(&rr->resrec, qptr)) { // 1. If we got a fresh answer to this query, then don't need to generate a negative entry if (RRExpireTime(rr) - m->timenow > 0) break; // 2. If we already had a negative entry, keep track of it so we can resurrect it instead of creating a new one if (rr->resrec.RecordType == kDNSRecordTypePacketNegative) neg = rr; } // When we're doing parallel unicast and multicast queries for dot-local names (for supporting Microsoft // Active Directory sites) we don't want to waste memory making negative cache entries for all the unicast answers. // Otherwise we just fill up our cache with negative entries for just about every single multicast name we ever look up // (since the Microsoft Active Directory server is going to assert that pretty much every single multicast name doesn't exist). // This is not only a waste of memory, but there's also the problem of those negative entries confusing us later -- e.g. we // suppress sending our mDNS query packet because we think we already have a valid (negative) answer to that query in our cache. // The one exception is that we *DO* want to make a negative cache entry for "local. SOA", for the (common) case where we're // *not* on a Microsoft Active Directory network, and there is no authoritative server for "local". Note that this is not // in conflict with the mDNS spec, because that spec says, "Multicast DNS Zones have no SOA record," so it's okay to cache // negative answers for "local. SOA" from a uDNS server, because the mDNS spec already says that such records do not exist :-) // // By suppressing negative responses, it might take longer to timeout a .local question as it might be expecting a // response e.g., we deliver a positive "A" response and suppress negative "AAAA" response and the upper layer may // be waiting longer to get the AAAA response before returning the "A" response to the application. To handle this // case without creating the negative cache entries, we generate a negative response and let the layer above us // do the appropriate thing. This negative response is also needed for appending new search domains. if (!InterfaceID && q.qtype != kDNSType_SOA && IsLocalDomain(&q.qname)) { if (!rr) { LogInfo("mDNSCoreReceiveResponse: Generate negative response for %##s (%s)", q.qname.c, DNSTypeName(q.qtype)); m->CurrentQuestion = qptr; GenerateNegativeResponse(m); m->CurrentQuestion = mDNSNULL; } else LogInfo("mDNSCoreReceiveResponse: Skipping check to see if we need to generate a negative cache entry for %##s (%s)", q.qname.c, DNSTypeName(q.qtype)); } else { if (!rr) { // We start off assuming a negative caching TTL of 60 seconds // but then look to see if we can find an SOA authority record to tell us a better value we should be using mDNSu32 negttl = 60; int repeat = 0; const domainname *name = &q.qname; mDNSu32 hash = q.qnamehash; // Special case for our special Microsoft Active Directory "local SOA" check. // Some cheap home gateways don't include an SOA record in the authority section when // they send negative responses, so we don't know how long to cache the negative result. // Because we don't want to keep hitting the root name servers with our query to find // if we're on a network using Microsoft Active Directory using "local" as a private // internal top-level domain, we make sure to cache the negative result for at least one day. if (q.qtype == kDNSType_SOA && SameDomainName(&q.qname, &localdomain)) negttl = 60 * 60 * 24; // If we're going to make (or update) a negative entry, then look for the appropriate TTL from the SOA record if (response->h.numAuthorities && (ptr = LocateAuthorities(response, end)) != mDNSNULL) { ptr = GetLargeResourceRecord(m, response, ptr, end, InterfaceID, kDNSRecordTypePacketAuth, &m->rec); if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_SOA) { const rdataSOA *const soa = (const rdataSOA *)m->rec.r.resrec.rdata->u.data; mDNSu32 ttl_s = soa->min; // We use the lesser of the SOA.MIN field and the SOA record's TTL, *except* // for the SOA record for ".", where the record is reported as non-cacheable // (TTL zero) for some reason, so in this case we just take the SOA record's TTL as-is if (ttl_s > m->rec.r.resrec.rroriginalttl && m->rec.r.resrec.name->c[0]) ttl_s = m->rec.r.resrec.rroriginalttl; if (negttl < ttl_s) negttl = ttl_s; // Special check for SOA queries: If we queried for a.b.c.d.com, and got no answer, // with an Authority Section SOA record for d.com, then this is a hint that the authority // is d.com, and consequently SOA records b.c.d.com and c.d.com don't exist either. // To do this we set the repeat count so the while loop below will make a series of negative cache entries for us if (q.qtype == kDNSType_SOA) { int qcount = CountLabels(&q.qname); int scount = CountLabels(m->rec.r.resrec.name); if (qcount - 1 > scount) if (SameDomainName(SkipLeadingLabels(&q.qname, qcount - scount), m->rec.r.resrec.name)) repeat = qcount - 1 - scount; } } m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } // If we already had a negative entry in the cache, then we double our existing negative TTL. This is to avoid // the case where the record doesn't exist (e.g. particularly for things like our lb._dns-sd._udp. query), // and the server returns no SOA record (or an SOA record with a small MIN TTL) so we assume a TTL // of 60 seconds, and we end up polling the server every minute for a record that doesn't exist. // With this fix in place, when this happens, we double the effective TTL each time (up to one hour), // so that we back off our polling rate and don't keep hitting the server continually. if (neg) { if (negttl < neg->resrec.rroriginalttl * 2) negttl = neg->resrec.rroriginalttl * 2; if (negttl > 3600) negttl = 3600; } negttl = GetEffectiveTTL(LLQType, negttl); // Add 25% grace period if necessary // If we already had a negative cache entry just update it, else make one or more new negative cache entries if (neg) { debugf("Renewing negative TTL from %d to %d %s", neg->resrec.rroriginalttl, negttl, CRDisplayString(m, neg)); RefreshCacheRecord(m, neg, negttl); } else while (1) { debugf("mDNSCoreReceiveResponse making negative cache entry TTL %d for %##s (%s)", negttl, name->c, DNSTypeName(q.qtype)); MakeNegativeCacheRecord(m, &m->rec.r, name, hash, q.qtype, q.qclass, negttl, mDNSInterface_Any, qptr->qDNSServer); CreateNewCacheEntry(m, slot, cg, 0); // We never need any delivery delay for these generated negative cache records m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it if (!repeat) break; repeat--; name = (const domainname *)(name->c + 1 + name->c[0]); hash = DomainNameHashValue(name); slot = HashSlot(name); cg = CacheGroupForName(m, slot, hash, name); } } } } } } // ScheduleWakeup causes all proxy records with WakeUp.HMAC matching mDNSEthAddr 'e' to be deregistered, causing // multiple wakeup magic packets to be sent if appropriate, and all records to be ultimately freed after a few seconds. // ScheduleWakeup is called on mDNS record conflicts, ARP conflicts, NDP conflicts, or reception of trigger traffic // that warrants waking the sleeping host. // ScheduleWakeup must be called with the lock held (ScheduleWakeupForList uses mDNS_Deregister_internal) mDNSlocal void ScheduleWakeupForList(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *e, AuthRecord *const thelist) { // We don't need to use the m->CurrentRecord mechanism here because the target HMAC is nonzero, // so all we're doing is marking the record to generate a few wakeup packets AuthRecord *rr; if (!e->l[0]) { LogMsg("ScheduleWakeupForList ERROR: Target HMAC is zero"); return; } for (rr = thelist; rr; rr = rr->next) if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering && mDNSSameEthAddress(&rr->WakeUp.HMAC, e)) { LogInfo("ScheduleWakeupForList: Scheduling wakeup packets for %s", ARDisplayString(m, rr)); mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); } } mDNSlocal void ScheduleWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *e) { if (!e->l[0]) { LogMsg("ScheduleWakeup ERROR: Target HMAC is zero"); return; } ScheduleWakeupForList(m, InterfaceID, e, m->DuplicateRecords); ScheduleWakeupForList(m, InterfaceID, e, m->ResourceRecords); } mDNSlocal void SPSRecordCallback(mDNS *const m, AuthRecord *const ar, mStatus result) { if (result && result != mStatus_MemFree) LogInfo("SPS Callback %d %s", result, ARDisplayString(m, ar)); if (result == mStatus_NameConflict) { mDNS_Lock(m); LogMsg("%-7s Conflicting mDNS -- waking %.6a %s", InterfaceNameForID(m, ar->resrec.InterfaceID), &ar->WakeUp.HMAC, ARDisplayString(m, ar)); if (ar->WakeUp.HMAC.l[0]) { SendWakeup(m, ar->resrec.InterfaceID, &ar->WakeUp.IMAC, &ar->WakeUp.password); // Send one wakeup magic packet ScheduleWakeup(m, ar->resrec.InterfaceID, &ar->WakeUp.HMAC); // Schedule all other records with the same owner to be woken } mDNS_Unlock(m); } if (result == mStatus_NameConflict || result == mStatus_MemFree) { m->ProxyRecords--; mDNSPlatformMemFree(ar); mDNS_UpdateAllowSleep(m); } } mDNSlocal void mDNSCoreReceiveUpdate(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *end, const mDNSAddr *srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, mDNSIPPort dstport, const mDNSInterfaceID InterfaceID) { int i; AuthRecord opt; mDNSu8 *p = m->omsg.data; OwnerOptData owner = zeroOwner; // Need to zero this, so we'll know if this Update packet was missing its Owner option mDNSu32 updatelease = 0; const mDNSu8 *ptr; LogSPS("Received Update from %#-15a:%-5d to %#-15a:%-5d on 0x%p with " "%2d Question%s %2d Answer%s %2d Authorit%s %2d Additional%s %d bytes", srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), InterfaceID, msg->h.numQuestions, msg->h.numQuestions == 1 ? ", " : "s,", msg->h.numAnswers, msg->h.numAnswers == 1 ? ", " : "s,", msg->h.numAuthorities, msg->h.numAuthorities == 1 ? "y, " : "ies,", msg->h.numAdditionals, msg->h.numAdditionals == 1 ? " " : "s", end - msg->data); if (!InterfaceID || !m->SPSSocket || !mDNSSameIPPort(dstport, m->SPSSocket->port)) return; if (mDNS_PacketLoggingEnabled) DumpPacket(m, mStatus_NoError, mDNSfalse, "UDP", srcaddr, srcport, dstaddr, dstport, msg, end); ptr = LocateOptRR(msg, end, DNSOpt_LeaseData_Space + DNSOpt_OwnerData_ID_Space); if (ptr) { ptr = GetLargeResourceRecord(m, msg, ptr, end, 0, kDNSRecordTypePacketAdd, &m->rec); if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_OPT) { const rdataOPT *o; const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength]; for (o = &m->rec.r.resrec.rdata->u.opt[0]; o < e; o++) { if (o->opt == kDNSOpt_Lease) updatelease = o->u.updatelease; else if (o->opt == kDNSOpt_Owner && o->u.owner.vers == 0) owner = o->u.owner; } } m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } InitializeDNSMessage(&m->omsg.h, msg->h.id, UpdateRespFlags); if (!updatelease || !owner.HMAC.l[0]) { static int msgs = 0; if (msgs < 100) { msgs++; LogMsg("Refusing sleep proxy registration from %#a:%d:%s%s", srcaddr, mDNSVal16(srcport), !updatelease ? " No lease" : "", !owner.HMAC.l[0] ? " No owner" : ""); } m->omsg.h.flags.b[1] |= kDNSFlag1_RC_FormErr; } else if (m->ProxyRecords + msg->h.mDNS_numUpdates > MAX_PROXY_RECORDS) { static int msgs = 0; if (msgs < 100) { msgs++; LogMsg("Refusing sleep proxy registration from %#a:%d: Too many records %d + %d = %d > %d", srcaddr, mDNSVal16(srcport), m->ProxyRecords, msg->h.mDNS_numUpdates, m->ProxyRecords + msg->h.mDNS_numUpdates, MAX_PROXY_RECORDS); } m->omsg.h.flags.b[1] |= kDNSFlag1_RC_Refused; } else { LogSPS("Received Update for H-MAC %.6a I-MAC %.6a Password %.6a seq %d", &owner.HMAC, &owner.IMAC, &owner.password, owner.seq); if (updatelease > 24 * 60 * 60) updatelease = 24 * 60 * 60; if (updatelease > 0x40000000UL / mDNSPlatformOneSecond) updatelease = 0x40000000UL / mDNSPlatformOneSecond; ptr = LocateAuthorities(msg, end); for (i = 0; i < msg->h.mDNS_numUpdates && ptr && ptr < end; i++) { ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAuth, &m->rec); if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative) { mDNSu16 RDLengthMem = GetRDLengthMem(&m->rec.r.resrec); AuthRecord *ar = mDNSPlatformMemAllocate(sizeof(AuthRecord) - sizeof(RDataBody) + RDLengthMem); if (!ar) { m->omsg.h.flags.b[1] |= kDNSFlag1_RC_Refused; break; } else { mDNSu8 RecordType = m->rec.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask ? kDNSRecordTypeUnique : kDNSRecordTypeShared; m->rec.r.resrec.rrclass &= ~kDNSClass_UniqueRRSet; ClearIdenticalProxyRecords(m, &owner, m->DuplicateRecords); // Make sure we don't have any old stale duplicates of this record ClearIdenticalProxyRecords(m, &owner, m->ResourceRecords); mDNS_SetupResourceRecord(ar, mDNSNULL, InterfaceID, m->rec.r.resrec.rrtype, m->rec.r.resrec.rroriginalttl, RecordType, AuthRecordAny, SPSRecordCallback, ar); AssignDomainName(&ar->namestorage, m->rec.r.resrec.name); ar->resrec.rdlength = GetRDLength(&m->rec.r.resrec, mDNSfalse); ar->resrec.rdata->MaxRDLength = RDLengthMem; mDNSPlatformMemCopy(ar->resrec.rdata->u.data, m->rec.r.resrec.rdata->u.data, RDLengthMem); ar->ForceMCast = mDNStrue; ar->WakeUp = owner; if (m->rec.r.resrec.rrtype == kDNSType_PTR) { mDNSs32 t = ReverseMapDomainType(m->rec.r.resrec.name); if (t == mDNSAddrType_IPv4) GetIPv4FromName(&ar->AddressProxy, m->rec.r.resrec.name); else if (t == mDNSAddrType_IPv6) GetIPv6FromName(&ar->AddressProxy, m->rec.r.resrec.name); debugf("mDNSCoreReceiveUpdate: PTR %d %d %#a %s", t, ar->AddressProxy.type, &ar->AddressProxy, ARDisplayString(m, ar)); if (ar->AddressProxy.type) SetSPSProxyListChanged(InterfaceID); } ar->TimeRcvd = m->timenow; ar->TimeExpire = m->timenow + updatelease * mDNSPlatformOneSecond; if (m->NextScheduledSPS - ar->TimeExpire > 0) m->NextScheduledSPS = ar->TimeExpire; mDNS_Register_internal(m, ar); // Unsolicited Neighbor Advertisements (RFC 2461 Section 7.2.6) give us fast address cache updating, // but some older IPv6 clients get confused by them, so for now we don't send them. Without Unsolicited // Neighbor Advertisements we have to rely on Neighbor Unreachability Detection instead, which is slower. // Given this, we'll do our best to wake for existing IPv6 connections, but we don't want to encourage // new ones for sleeping clients, so we'll we send deletions for our SPS clients' AAAA records. if (m->KnownBugs & mDNS_KnownBug_LimitedIPv6) if (ar->resrec.rrtype == kDNSType_AAAA) ar->resrec.rroriginalttl = 0; m->ProxyRecords++; mDNS_UpdateAllowSleep(m); LogSPS("SPS Registered %4d %X %s", m->ProxyRecords, RecordType, ARDisplayString(m,ar)); } } m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } if (m->omsg.h.flags.b[1] & kDNSFlag1_RC_Mask) { LogMsg("Refusing sleep proxy registration from %#a:%d: Out of memory", srcaddr, mDNSVal16(srcport)); ClearProxyRecords(m, &owner, m->DuplicateRecords); ClearProxyRecords(m, &owner, m->ResourceRecords); } else { mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL); opt.resrec.rrclass = NormalMaxDNSMessageData; opt.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record opt.resrec.rdestimate = sizeof(rdataOPT); opt.resrec.rdata->u.opt[0].opt = kDNSOpt_Lease; opt.resrec.rdata->u.opt[0].u.updatelease = updatelease; p = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.numAdditionals, &opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData); } } if (p) mDNSSendDNSMessage(m, &m->omsg, p, InterfaceID, m->SPSSocket, srcaddr, srcport, mDNSNULL, mDNSNULL); } mDNSlocal void mDNSCoreReceiveUpdateR(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *end, const mDNSInterfaceID InterfaceID) { if (InterfaceID) { mDNSu32 updatelease = 60 * 60; // If SPS fails to indicate lease time, assume one hour const mDNSu8 *ptr = LocateOptRR(msg, end, DNSOpt_LeaseData_Space); if (ptr) { ptr = GetLargeResourceRecord(m, msg, ptr, end, 0, kDNSRecordTypePacketAdd, &m->rec); if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_OPT) { const rdataOPT *o; const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength]; for (o = &m->rec.r.resrec.rdata->u.opt[0]; o < e; o++) if (o->opt == kDNSOpt_Lease) { updatelease = o->u.updatelease; LogSPS("Sleep Proxy granted lease time %4d seconds", updatelease); } } m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it } if (m->CurrentRecord) LogMsg("mDNSCoreReceiveUpdateR ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); m->CurrentRecord = m->ResourceRecords; while (m->CurrentRecord) { AuthRecord *const rr = m->CurrentRecord; if (rr->resrec.InterfaceID == InterfaceID || (!rr->resrec.InterfaceID && (rr->ForceMCast || IsLocalDomain(rr->resrec.name)))) if (mDNSSameOpaque16(rr->updateid, msg->h.id)) { rr->updateid = zeroID; rr->expire = NonZeroTime(m->timenow + updatelease * mDNSPlatformOneSecond); LogSPS("Sleep Proxy %s record %5d %s", rr->WakeUp.HMAC.l[0] ? "transferred" : "registered", updatelease, ARDisplayString(m,rr)); if (rr->WakeUp.HMAC.l[0]) { rr->WakeUp.HMAC = zeroEthAddr; // Clear HMAC so that mDNS_Deregister_internal doesn't waste packets trying to wake this host rr->RequireGoodbye = mDNSfalse; // and we don't want to send goodbye for it mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); } } // Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because // new records could have been added to the end of the list as a result of that call. if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now m->CurrentRecord = rr->next; } } // If we were waiting to go to sleep, then this SPS registration or wide-area record deletion // may have been the thing we were waiting for, so schedule another check to see if we can sleep now. if (m->SleepLimit) m->NextScheduledSPRetry = m->timenow; } mDNSexport void MakeNegativeCacheRecord(mDNS *const m, CacheRecord *const cr, const domainname *const name, const mDNSu32 namehash, const mDNSu16 rrtype, const mDNSu16 rrclass, mDNSu32 ttl_seconds, mDNSInterfaceID InterfaceID, DNSServer *dnsserver) { if (cr == &m->rec.r && m->rec.r.resrec.RecordType) { LogMsg("MakeNegativeCacheRecord: m->rec appears to be already in use for %s", CRDisplayString(m, &m->rec.r)); #if ForceAlerts *(long*)0 = 0; #endif } // Create empty resource record cr->resrec.RecordType = kDNSRecordTypePacketNegative; cr->resrec.InterfaceID = InterfaceID; cr->resrec.rDNSServer = dnsserver; cr->resrec.name = name; // Will be updated to point to cg->name when we call CreateNewCacheEntry cr->resrec.rrtype = rrtype; cr->resrec.rrclass = rrclass; cr->resrec.rroriginalttl = ttl_seconds; cr->resrec.rdlength = 0; cr->resrec.rdestimate = 0; cr->resrec.namehash = namehash; cr->resrec.rdatahash = 0; cr->resrec.rdata = (RData*)&cr->smallrdatastorage; cr->resrec.rdata->MaxRDLength = 0; cr->NextInKAList = mDNSNULL; cr->TimeRcvd = m->timenow; cr->DelayDelivery = 0; cr->NextRequiredQuery = m->timenow; cr->LastUsed = m->timenow; cr->CRActiveQuestion = mDNSNULL; cr->UnansweredQueries = 0; cr->LastUnansweredTime = 0; #if ENABLE_MULTI_PACKET_QUERY_SNOOPING cr->MPUnansweredQ = 0; cr->MPLastUnansweredQT = 0; cr->MPUnansweredKA = 0; cr->MPExpectingKA = mDNSfalse; #endif cr->NextInCFList = mDNSNULL; } mDNSexport void mDNSCoreReceive(mDNS *const m, void *const pkt, const mDNSu8 *const end, const mDNSAddr *const srcaddr, const mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSIPPort dstport, const mDNSInterfaceID InterfaceID) { mDNSInterfaceID ifid = InterfaceID; DNSMessage *msg = (DNSMessage *)pkt; const mDNSu8 StdQ = kDNSFlag0_QR_Query | kDNSFlag0_OP_StdQuery; const mDNSu8 StdR = kDNSFlag0_QR_Response | kDNSFlag0_OP_StdQuery; const mDNSu8 UpdQ = kDNSFlag0_QR_Query | kDNSFlag0_OP_Update; const mDNSu8 UpdR = kDNSFlag0_QR_Response | kDNSFlag0_OP_Update; mDNSu8 QR_OP; mDNSu8 *ptr = mDNSNULL; mDNSBool TLS = (dstaddr == (mDNSAddr *)1); // For debug logs: dstaddr = 0 means TCP; dstaddr = 1 means TLS if (TLS) dstaddr = mDNSNULL; #ifndef UNICAST_DISABLED if (mDNSSameAddress(srcaddr, &m->Router)) { #ifdef _LEGACY_NAT_TRAVERSAL_ if (mDNSSameIPPort(srcport, SSDPPort) || (m->SSDPSocket && mDNSSameIPPort(dstport, m->SSDPSocket->port))) { mDNS_Lock(m); LNT_ConfigureRouterInfo(m, InterfaceID, pkt, (mDNSu16)(end - (mDNSu8 *)pkt)); mDNS_Unlock(m); return; } #endif if (mDNSSameIPPort(srcport, NATPMPPort)) { mDNS_Lock(m); uDNS_ReceiveNATPMPPacket(m, InterfaceID, pkt, (mDNSu16)(end - (mDNSu8 *)pkt)); mDNS_Unlock(m); return; } } #ifdef _LEGACY_NAT_TRAVERSAL_ else if (m->SSDPSocket && mDNSSameIPPort(dstport, m->SSDPSocket->port)) { debugf("Ignoring SSDP response from %#a:%d", srcaddr, mDNSVal16(srcport)); return; } #endif #endif if ((unsigned)(end - (mDNSu8 *)pkt) < sizeof(DNSMessageHeader)) { LogMsg("DNS Message from %#a:%d to %#a:%d length %d too short", srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), end - (mDNSu8 *)pkt); return; } QR_OP = (mDNSu8)(msg->h.flags.b[0] & kDNSFlag0_QROP_Mask); // Read the integer parts which are in IETF byte-order (MSB first, LSB second) ptr = (mDNSu8 *)&msg->h.numQuestions; msg->h.numQuestions = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]); msg->h.numAnswers = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]); msg->h.numAuthorities = (mDNSu16)((mDNSu16)ptr[4] << 8 | ptr[5]); msg->h.numAdditionals = (mDNSu16)((mDNSu16)ptr[6] << 8 | ptr[7]); if (!m) { LogMsg("mDNSCoreReceive ERROR m is NULL"); return; } // We use zero addresses and all-ones addresses at various places in the code to indicate special values like "no address" // If we accept and try to process a packet with zero or all-ones source address, that could really mess things up if (srcaddr && !mDNSAddressIsValid(srcaddr)) { debugf("mDNSCoreReceive ignoring packet from %#a", srcaddr); return; } mDNS_Lock(m); m->PktNum++; #ifndef UNICAST_DISABLED if (!dstaddr || (!mDNSAddressIsAllDNSLinkGroup(dstaddr) && (QR_OP == StdR || QR_OP == UpdR))) if (!mDNSOpaque16IsZero(msg->h.id)) // uDNS_ReceiveMsg only needs to get real uDNS responses, not "QU" mDNS responses { ifid = mDNSInterface_Any; if (mDNS_PacketLoggingEnabled) DumpPacket(m, mStatus_NoError, mDNSfalse, TLS ? "TLS" : !dstaddr ? "TCP" : "UDP", srcaddr, srcport, dstaddr, dstport, msg, end); uDNS_ReceiveMsg(m, msg, end, srcaddr, srcport); // Note: mDNSCore also needs to get access to received unicast responses } #endif if (QR_OP == StdQ) mDNSCoreReceiveQuery (m, msg, end, srcaddr, srcport, dstaddr, dstport, ifid); else if (QR_OP == StdR) mDNSCoreReceiveResponse(m, msg, end, srcaddr, srcport, dstaddr, dstport, ifid); else if (QR_OP == UpdQ) mDNSCoreReceiveUpdate (m, msg, end, srcaddr, srcport, dstaddr, dstport, InterfaceID); else if (QR_OP == UpdR) mDNSCoreReceiveUpdateR (m, msg, end, InterfaceID); else { LogMsg("Unknown DNS packet type %02X%02X from %#-15a:%-5d to %#-15a:%-5d length %d on %p (ignored)", msg->h.flags.b[0], msg->h.flags.b[1], srcaddr, mDNSVal16(srcport), dstaddr, mDNSVal16(dstport), end - (mDNSu8 *)pkt, InterfaceID); if (mDNS_LoggingEnabled) { int i = 0; while (iTarget.type == mDNSAddrType_None && (B)->Target.type == mDNSAddrType_None) || \ (mDNSSameAddress(&(A)->Target, &(B)->Target) && mDNSSameIPPort((A)->TargetPort, (B)->TargetPort))) // Note: We explicitly disallow making a public query be a duplicate of a private one. This is to avoid the // circular deadlock where a client does a query for something like "dns-sd -Q _dns-query-tls._tcp.company.com SRV" // and we have a key for company.com, so we try to locate the private query server for company.com, which necessarily entails // doing a standard DNS query for the _dns-query-tls._tcp SRV record for company.com. If we make the latter (public) query // a duplicate of the former (private) query, then it will block forever waiting for an answer that will never come. // // We keep SuppressUnusable questions separate so that we can return a quick response to them and not get blocked behind // the queries that are not marked SuppressUnusable. But if the query is not suppressed, they are treated the same as // non-SuppressUnusable questions. This should be fine as the goal of SuppressUnusable is to return quickly only if it // is suppressed. If it is not suppressed, we do try all the DNS servers for valid answers like any other question. // The main reason for this design is that cache entries point to a *single* question and that question is responsible // for keeping the cache fresh as long as it is active. Having multiple active question for a single cache entry // breaks this design principle. // If IsLLQ(Q) is true, it means the question is both: // (a) long-lived and // (b) being performed by a unicast DNS long-lived query (either full LLQ, or polling) // for multicast questions, we don't want to treat LongLived as anything special #define IsLLQ(Q) ((Q)->LongLived && !mDNSOpaque16IsZero((Q)->TargetQID)) mDNSlocal DNSQuestion *FindDuplicateQuestion(const mDNS *const m, const DNSQuestion *const question) { DNSQuestion *q; // Note: A question can only be marked as a duplicate of one that occurs *earlier* in the list. // This prevents circular references, where two questions are each marked as a duplicate of the other. // Accordingly, we break out of the loop when we get to 'question', because there's no point searching // further in the list. for (q = m->Questions; q && q != question; q=q->next) // Scan our list for another question if (q->InterfaceID == question->InterfaceID && // with the same InterfaceID, SameQTarget(q, question) && // and same unicast/multicast target settings q->qtype == question->qtype && // type, q->qclass == question->qclass && // class, IsLLQ(q) == IsLLQ(question) && // and long-lived status matches (!q->AuthInfo || question->AuthInfo) && // to avoid deadlock, don't make public query dup of a private one (q->SuppressQuery == question->SuppressQuery) && // Questions that are suppressed/not suppressed q->qnamehash == question->qnamehash && SameDomainName(&q->qname, &question->qname)) // and name return(q); return(mDNSNULL); } // This is called after a question is deleted, in case other identical questions were being suppressed as duplicates mDNSlocal void UpdateQuestionDuplicates(mDNS *const m, DNSQuestion *const question) { DNSQuestion *q; DNSQuestion *first = mDNSNULL; // This is referring to some other question as duplicate. No other question can refer to this // question as a duplicate. if (question->DuplicateOf) { LogInfo("UpdateQuestionDuplicates: question %p %##s (%s) duplicate of %p %##s (%s)", question, question->qname.c, DNSTypeName(question->qtype), question->DuplicateOf, question->DuplicateOf->qname.c, DNSTypeName(question->DuplicateOf->qtype)); return; } for (q = m->Questions; q; q=q->next) // Scan our list of questions if (q->DuplicateOf == question) // To see if any questions were referencing this as their duplicate { q->DuplicateOf = first; if (!first) { first = q; // If q used to be a duplicate, but now is not, // then inherit the state from the question that's going away q->LastQTime = question->LastQTime; q->ThisQInterval = question->ThisQInterval; q->ExpectUnicastResp = question->ExpectUnicastResp; q->LastAnswerPktNum = question->LastAnswerPktNum; q->RecentAnswerPkts = question->RecentAnswerPkts; q->RequestUnicast = question->RequestUnicast; q->LastQTxTime = question->LastQTxTime; q->CNAMEReferrals = question->CNAMEReferrals; q->nta = question->nta; q->servAddr = question->servAddr; q->servPort = question->servPort; q->qDNSServer = question->qDNSServer; q->validDNSServers = question->validDNSServers; q->unansweredQueries = question->unansweredQueries; q->noServerResponse = question->noServerResponse; q->triedAllServersOnce = question->triedAllServersOnce; q->TargetQID = question->TargetQID; q->LocalSocket = question->LocalSocket; q->state = question->state; // q->tcp = question->tcp; q->ReqLease = question->ReqLease; q->expire = question->expire; q->ntries = question->ntries; q->id = question->id; question->LocalSocket = mDNSNULL; question->nta = mDNSNULL; // If we've got a GetZoneData in progress, transfer it to the newly active question // question->tcp = mDNSNULL; if (q->LocalSocket) debugf("UpdateQuestionDuplicates transferred LocalSocket pointer for %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); if (q->nta) { LogInfo("UpdateQuestionDuplicates transferred nta pointer for %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); q->nta->ZoneDataContext = q; } // Need to work out how to safely transfer this state too -- appropriate context pointers need to be updated or the code will crash if (question->tcp) LogInfo("UpdateQuestionDuplicates did not transfer tcp pointer"); if (question->state == LLQ_Established) { LogInfo("UpdateQuestionDuplicates transferred LLQ state for %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); question->state = 0; // Must zero question->state, or mDNS_StopQuery_internal will clean up and cancel our LLQ from the server } SetNextQueryTime(m,q); } } } mDNSexport McastResolver *mDNS_AddMcastResolver(mDNS *const m, const domainname *d, const mDNSInterfaceID interface, mDNSu32 timeout) { McastResolver **p = &m->McastResolvers; McastResolver *tmp = mDNSNULL; if (!d) d = (const domainname *)""; LogInfo("mDNS_AddMcastResolver: Adding %##s, InterfaceID %p, timeout %u", d->c, interface, timeout); if (m->mDNS_busy != m->mDNS_reentrancy+1) LogMsg("mDNS_AddMcastResolver: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy); while (*p) // Check if we already have this {interface, domain} tuple registered { if ((*p)->interface == interface && SameDomainName(&(*p)->domain, d)) { if (!((*p)->flags & DNSServer_FlagDelete)) LogMsg("Note: Mcast Resolver domain %##s (%p) registered more than once", d->c, interface); (*p)->flags &= ~DNSServer_FlagDelete; tmp = *p; *p = tmp->next; tmp->next = mDNSNULL; } else p=&(*p)->next; } if (tmp) *p = tmp; // move to end of list, to ensure ordering from platform layer else { // allocate, add to list *p = mDNSPlatformMemAllocate(sizeof(**p)); if (!*p) LogMsg("mDNS_AddMcastResolver: ERROR!! - malloc"); else { (*p)->interface = interface; (*p)->flags = DNSServer_FlagNew; (*p)->timeout = timeout; AssignDomainName(&(*p)->domain, d); (*p)->next = mDNSNULL; } } return(*p); } mDNSinline mDNSs32 PenaltyTimeForServer(mDNS *m, DNSServer *server) { mDNSs32 ptime = 0; if (server->penaltyTime != 0) { ptime = server->penaltyTime - m->timenow; if (ptime < 0) { // This should always be a positive value between 0 and DNSSERVER_PENALTY_TIME // If it does not get reset in ResetDNSServerPenalties for some reason, we do it // here LogMsg("PenaltyTimeForServer: PenaltyTime negative %d, (server penaltyTime %d, timenow %d) resetting the penalty", ptime, server->penaltyTime, m->timenow); server->penaltyTime = 0; ptime = 0; } } return ptime; } //Checks to see whether the newname is a better match for the name, given the best one we have //seen so far (given in bestcount). //Returns -1 if the newname is not a better match //Returns 0 if the newname is the same as the old match //Returns 1 if the newname is a better match mDNSlocal int BetterMatchForName(const domainname *name, int namecount, const domainname *newname, int newcount, int bestcount) { // If the name contains fewer labels than the new server's domain or the new name // contains fewer labels than the current best, then it can't possibly be a better match if (namecount < newcount || newcount < bestcount) return -1; // If there is no match, return -1 and the caller will skip this newname for // selection // // If we find a match and the number of labels is the same as bestcount, then // we return 0 so that the caller can do additional logic to pick one of // the best based on some other factors e.g., penaltyTime // // If we find a match and the number of labels is more than bestcount, then we // return 1 so that the caller can pick this over the old one. // // Note: newcount can either be equal or greater than bestcount beause of the // check above. if (SameDomainName(SkipLeadingLabels(name, namecount - newcount), newname)) return bestcount == newcount ? 0 : 1; else return -1; } // Normally, we have McastResolvers for .local, in-addr.arpa and ip6.arpa. But there // can be queries that can forced to multicast (ForceMCast) even though they don't end in these // names. In that case, we give a default timeout of 5 seconds #define DEFAULT_MCAST_TIMEOUT 5 mDNSlocal mDNSu32 GetTimeoutForMcastQuestion(mDNS *m, DNSQuestion *question) { McastResolver *curmatch = mDNSNULL; int bestmatchlen = -1, namecount = CountLabels(&question->qname); McastResolver *curr; int bettermatch, currcount; for (curr = m->McastResolvers; curr; curr = curr->next) { currcount = CountLabels(&curr->domain); bettermatch = BetterMatchForName(&question->qname, namecount, &curr->domain, currcount, bestmatchlen); // Take the first best match. If there are multiple equally good matches (bettermatch = 0), we take // the timeout value from the first one if (bettermatch == 1) { curmatch = curr; bestmatchlen = currcount; } } LogInfo("GetTimeoutForMcastQuestion: question %##s curmatch %p, Timeout %d", question->qname.c, curmatch, curmatch ? curmatch->timeout : DEFAULT_MCAST_TIMEOUT); return ( curmatch ? curmatch->timeout : DEFAULT_MCAST_TIMEOUT); } // Sets all the Valid DNS servers for a question mDNSexport mDNSu32 SetValidDNSServers(mDNS *m, DNSQuestion *question) { DNSServer *curmatch = mDNSNULL; int bestmatchlen = -1, namecount = CountLabels(&question->qname); DNSServer *curr; int bettermatch, currcount; int index = 0; mDNSu32 timeout = 0; question->validDNSServers = zeroOpaque64; for (curr = m->DNSServers; curr; curr = curr->next) { debugf("SetValidDNSServers: Parsing DNS server Address %#a (Domain %##s), Scope: %d", &curr->addr, curr->domain.c, curr->scoped); // skip servers that will soon be deleted if (curr->flags & DNSServer_FlagDelete) { debugf("SetValidDNSServers: Delete set for index %d, DNS server %#a (Domain %##s), scoped %d", index, &curr->addr, curr->domain.c, curr->scoped); continue; } // This happens normally when you unplug the interface where we reset the interfaceID to mDNSInterface_Any for all // the DNS servers whose scope match the interfaceID. Few seconds later, we also receive the updated DNS configuration. // But any questions that has mDNSInterface_Any scope that are started/restarted before we receive the update // (e.g., CheckSuppressUnusableQuestions is called when interfaces are deregistered with the core) should not // match the scoped entries by mistake. // // Note: DNS configuration change will help pick the new dns servers but currently it does not affect the timeout if (curr->scoped && curr->interface == mDNSInterface_Any) { debugf("SetValidDNSServers: Scoped DNS server %#a (Domain %##s) with Interface Any", &curr->addr, curr->domain.c); continue; } currcount = CountLabels(&curr->domain); if ((!curr->scoped && (!question->InterfaceID || (question->InterfaceID == mDNSInterface_Unicast))) || (curr->interface == question->InterfaceID)) { bettermatch = BetterMatchForName(&question->qname, namecount, &curr->domain, currcount, bestmatchlen); // If we found a better match (bettermatch == 1) then clear all the bits // corresponding to the old DNSServers that we have may set before and start fresh. // If we find an equal match, then include that DNSServer also by setting the corresponding // bit if ((bettermatch == 1) || (bettermatch == 0)) { curmatch = curr; bestmatchlen = currcount; if (bettermatch) { debugf("SetValidDNSServers: Resetting all the bits"); question->validDNSServers = zeroOpaque64; timeout = 0; } debugf("SetValidDNSServers: question %##s Setting the bit for DNS server Address %#a (Domain %##s), Scoped:%d index %d," " Timeout %d, interface %p", question->qname.c, &curr->addr, curr->domain.c, curr->scoped, index, curr->timeout, curr->interface); timeout += curr->timeout; bit_set_opaque64(question->validDNSServers, index); } } index++; } question->noServerResponse = 0; debugf("SetValidDNSServers: ValidDNSServer bits 0x%x%x for question %p %##s (%s)", question->validDNSServers.l[1], question->validDNSServers.l[0], question, question->qname.c, DNSTypeName(question->qtype)); // If there are no matching resolvers, then use the default value to timeout return (timeout ? timeout : DEFAULT_UDNS_TIMEOUT); } // Get the Best server that matches a name. If you find penalized servers, look for the one // that will come out of the penalty box soon mDNSlocal DNSServer *GetBestServer(mDNS *m, const domainname *name, mDNSInterfaceID InterfaceID, mDNSOpaque64 validBits, int *selected, mDNSBool nameMatch) { DNSServer *curmatch = mDNSNULL; int bestmatchlen = -1, namecount = name ? CountLabels(name) : 0; DNSServer *curr; mDNSs32 bestPenaltyTime, currPenaltyTime; int bettermatch, currcount; int index = 0; int currindex = -1; debugf("GetBestServer: ValidDNSServer bits 0x%x%x", validBits.l[1], validBits.l[0]); bestPenaltyTime = DNSSERVER_PENALTY_TIME + 1; for (curr = m->DNSServers; curr; curr = curr->next) { // skip servers that will soon be deleted if (curr->flags & DNSServer_FlagDelete) { debugf("GetBestServer: Delete set for index %d, DNS server %#a (Domain %##s), scoped %d", index, &curr->addr, curr->domain.c, curr->scoped); continue; } // Check if this is a valid DNSServer if (!bit_get_opaque64(validBits, index)) { debugf("GetBestServer: continuing for index %d", index); index++; continue; } currcount = CountLabels(&curr->domain); currPenaltyTime = PenaltyTimeForServer(m, curr); debugf("GetBestServer: Address %#a (Domain %##s), PenaltyTime(abs) %d, PenaltyTime(rel) %d", &curr->addr, curr->domain.c, curr->penaltyTime, currPenaltyTime); // If there are multiple best servers for a given question, we will pick the first one // if none of them are penalized. If some of them are penalized in that list, we pick // the least penalized one. BetterMatchForName walks through all best matches and // "currPenaltyTime < bestPenaltyTime" check lets us either pick the first best server // in the list when there are no penalized servers and least one among them // when there are some penalized servers // // Notes on InterfaceID matching: // // 1) A DNSServer entry may have an InterfaceID but the scoped flag may not be set. This // is the old way of specifying an InterfaceID option for DNSServer. We recoginize these // entries by "scoped" being false. These are like any other unscoped entries except that // if it is picked e.g., domain match, when the packet is sent out later, the packet will // be sent out on that interface. Theese entries can be matched by either specifying a // zero InterfaceID or non-zero InterfaceID on the question. Specifying an InterfaceID on // the question will cause an extra check on matching the InterfaceID on the question // against the DNSServer. // // 2) A DNSServer may also have both scoped set and InterfaceID non-NULL. This // is the new way of specifying an InterfaceID option for DNSServer. These will be considered // only when the question has non-zero interfaceID. if ((!curr->scoped && !InterfaceID) || (curr->interface == InterfaceID)) { // If we know that all the names are already equally good matches, then skip calling BetterMatchForName. // This happens when we initially walk all the DNS servers and set the validity bit on the question. // Actually we just need PenaltyTime match, but for the sake of readability we just skip the expensive // part and still do some redundant steps e.g., InterfaceID match if (nameMatch) bettermatch = BetterMatchForName(name, namecount, &curr->domain, currcount, bestmatchlen); else bettermatch = 0; // If we found a better match (bettermatch == 1) then we don't need to // compare penalty times. But if we found an equal match, then we compare // the penalty times to pick a better match if ((bettermatch == 1) || ((bettermatch == 0) && currPenaltyTime < bestPenaltyTime)) { currindex = index; curmatch = curr; bestmatchlen = currcount; bestPenaltyTime = currPenaltyTime; } } index++; } if (selected) *selected = currindex; return curmatch; } // Look up a DNS Server, matching by name and InterfaceID mDNSexport DNSServer *GetServerForName(mDNS *m, const domainname *name, mDNSInterfaceID InterfaceID) { DNSServer *curmatch = mDNSNULL; char *ifname = mDNSNULL; // for logging purposes only mDNSOpaque64 allValid; if ((InterfaceID == mDNSInterface_Unicast) || (InterfaceID == mDNSInterface_LocalOnly)) InterfaceID = mDNSNULL; if (InterfaceID) ifname = InterfaceNameForID(m, InterfaceID); // By passing in all ones, we make sure that every DNS server is considered allValid.l[0] = allValid.l[1] = 0xFFFFFFFF; curmatch = GetBestServer(m, name, InterfaceID, allValid, mDNSNULL, mDNStrue); if (curmatch != mDNSNULL) LogInfo("GetServerForName: DNS server %#a:%d (Penalty Time Left %d) (Scope %s:%p) found for name %##s", &curmatch->addr, mDNSVal16(curmatch->port), (curmatch->penaltyTime ? (curmatch->penaltyTime - m->timenow) : 0), ifname ? ifname : "None", InterfaceID, name); else LogInfo("GetServerForName: no DNS server (Scope %s:%p) found for name %##s", ifname ? ifname : "None", InterfaceID, name); return(curmatch); } // Look up a DNS Server for a question within its valid DNSServer bits mDNSexport DNSServer *GetServerForQuestion(mDNS *m, DNSQuestion *question) { DNSServer *curmatch = mDNSNULL; char *ifname = mDNSNULL; // for logging purposes only mDNSInterfaceID InterfaceID = question->InterfaceID; const domainname *name = &question->qname; int currindex; if ((InterfaceID == mDNSInterface_Unicast) || (InterfaceID == mDNSInterface_LocalOnly)) InterfaceID = mDNSNULL; if (InterfaceID) ifname = InterfaceNameForID(m, InterfaceID); if (!mDNSOpaque64IsZero(&question->validDNSServers)) { curmatch = GetBestServer(m, name, InterfaceID, question->validDNSServers, &currindex, mDNSfalse); if (currindex != -1) bit_clr_opaque64(question->validDNSServers, currindex); } if (curmatch != mDNSNULL) LogInfo("GetServerForQuestion: %p DNS server %#a:%d (Penalty Time Left %d) (Scope %s:%p) found for name %##s (%s)", question, &curmatch->addr, mDNSVal16(curmatch->port), (curmatch->penaltyTime ? (curmatch->penaltyTime - m->timenow) : 0), ifname ? ifname : "None", InterfaceID, name, DNSTypeName(question->qtype)); else LogInfo("GetServerForQuestion: %p no DNS server (Scope %s:%p) found for name %##s (%s)", question, ifname ? ifname : "None", InterfaceID, name, DNSTypeName(question->qtype)); return(curmatch); } #define ValidQuestionTarget(Q) (((Q)->Target.type == mDNSAddrType_IPv4 || (Q)->Target.type == mDNSAddrType_IPv6) && \ (mDNSSameIPPort((Q)->TargetPort, UnicastDNSPort) || mDNSSameIPPort((Q)->TargetPort, MulticastDNSPort))) // Called in normal client context (lock not held) mDNSlocal void LLQNATCallback(mDNS *m, NATTraversalInfo *n) { DNSQuestion *q; (void)n; // Unused mDNS_Lock(m); LogInfo("LLQNATCallback external address:port %.4a:%u, NAT result %d", &n->ExternalAddress, mDNSVal16(n->ExternalPort), n->Result); for (q = m->Questions; q; q=q->next) if (ActiveQuestion(q) && !mDNSOpaque16IsZero(q->TargetQID) && q->LongLived) startLLQHandshake(m, q); // If ExternalPort is zero, will do StartLLQPolling instead #if APPLE_OSX_mDNSResponder UpdateAutoTunnelDomainStatuses(m); #endif mDNS_Unlock(m); } mDNSlocal mDNSBool ShouldSuppressQuery(mDNS *const m, domainname *qname, mDNSu16 qtype, mDNSInterfaceID InterfaceID) { NetworkInterfaceInfo *i; mDNSs32 iptype; DomainAuthInfo *AuthInfo; if (qtype == kDNSType_A) iptype = mDNSAddrType_IPv4; else if (qtype == kDNSType_AAAA) iptype = mDNSAddrType_IPv6; else { LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, not A/AAAA type", qname, DNSTypeName(qtype)); return mDNSfalse; } // We still want the ability to be able to listen to the local services and hence // don't fail .local requests. We always have a loopback interface which we don't // check here. if (InterfaceID != mDNSInterface_Unicast && IsLocalDomain(qname)) { LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, Local question", qname, DNSTypeName(qtype)); return mDNSfalse; } // Skip Private domains as we have special addresses to get the hosts in the Private domain AuthInfo = GetAuthInfoForName_internal(m, qname); if (AuthInfo && !AuthInfo->deltime && AuthInfo->AutoTunnel) { LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, Private Domain", qname, DNSTypeName(qtype)); return mDNSfalse; } // Match on Type, Address and InterfaceID // // Check whether we are looking for a name that ends in .local, then presence of a link-local // address on the interface is sufficient. for (i = m->HostInterfaces; i; i = i->next) { if (i->ip.type != iptype) continue; if (!InterfaceID || (InterfaceID == mDNSInterface_LocalOnly) || (InterfaceID == mDNSInterface_P2P) || (InterfaceID == mDNSInterface_Unicast) || (i->InterfaceID == InterfaceID)) { if (iptype == mDNSAddrType_IPv4 && !mDNSv4AddressIsLoopback(&i->ip.ip.v4) && !mDNSv4AddressIsLinkLocal(&i->ip.ip.v4)) { LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, Local Address %.4a found", qname, DNSTypeName(qtype), &i->ip.ip.v4); if (m->SleepState == SleepState_Sleeping) LogInfo("ShouldSuppressQuery: Would have returned true earlier"); return mDNSfalse; } else if (iptype == mDNSAddrType_IPv6 && !mDNSv6AddressIsLoopback(&i->ip.ip.v6) && !mDNSv6AddressIsLinkLocal(&i->ip.ip.v6) && !mDNSSameIPv6Address(i->ip.ip.v6, m->AutoTunnelHostAddr) && !mDNSSameIPv6Address(i->ip.ip.v6, m->AutoTunnelRelayAddrOut)) { LogInfo("ShouldSuppressQuery: Query not suppressed for %##s, qtype %s, Local Address %.16a found", qname, DNSTypeName(qtype), &i->ip.ip.v6); if (m->SleepState == SleepState_Sleeping) LogInfo("ShouldSuppressQuery: Would have returned true earlier"); return mDNSfalse; } } } LogInfo("ShouldSuppressQuery: Query suppressed for %##s, qtype %s, because no matching interface found", qname, DNSTypeName(qtype)); return mDNStrue; } mDNSlocal void CacheRecordRmvEventsForCurrentQuestion(mDNS *const m, DNSQuestion *q) { CacheRecord *rr; mDNSu32 slot; CacheGroup *cg; slot = HashSlot(&q->qname); cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) { // Don't deliver RMV events for negative records if (rr->resrec.RecordType == kDNSRecordTypePacketNegative) { LogInfo("CacheRecordRmvEventsForCurrentQuestion: CacheRecord %s Suppressing RMV events for question %p %##s (%s), CRActiveQuestion %p, CurrentAnswers %d", CRDisplayString(m, rr), q, q->qname.c, DNSTypeName(q->qtype), rr->CRActiveQuestion, q->CurrentAnswers); continue; } if (SameNameRecordAnswersQuestion(&rr->resrec, q)) { LogInfo("CacheRecordRmvEventsForCurrentQuestion: Calling AnswerCurrentQuestionWithResourceRecord (RMV) for question %##s using resource record %s LocalAnswers %d", q->qname.c, CRDisplayString(m, rr), q->LOAddressAnswers); q->CurrentAnswers--; if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers--; if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers--; if (rr->CRActiveQuestion == q) { DNSQuestion *qptr; // If this was the active question for this cache entry, it was the one that was // responsible for keeping the cache entry fresh when the cache entry was reaching // its expiry. We need to handover the responsibility to someone else. Otherwise, // when the cache entry is about to expire, we won't find an active question // (pointed by CRActiveQuestion) to refresh the cache. for (qptr = m->Questions; qptr; qptr=qptr->next) if (qptr != q && ActiveQuestion(qptr) && ResourceRecordAnswersQuestion(&rr->resrec, qptr)) break; if (qptr) LogInfo("CacheRecordRmvEventsForCurrentQuestion: Updating CRActiveQuestion to %p for cache record %s, " "Original question CurrentAnswers %d, new question CurrentAnswers %d, SuppressUnusable %d, SuppressQuery %d", qptr, CRDisplayString(m,rr), q->CurrentAnswers, qptr->CurrentAnswers, qptr->SuppressUnusable, qptr->SuppressQuery); rr->CRActiveQuestion = qptr; // Question used to be active; new value may or may not be null if (!qptr) m->rrcache_active--; // If no longer active, decrement rrcache_active count } AnswerCurrentQuestionWithResourceRecord(m, rr, QC_rmv); if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here } } } mDNSlocal mDNSBool IsQuestionNew(mDNS *const m, DNSQuestion *question) { DNSQuestion *q; for (q = m->NewQuestions; q; q = q->next) if (q == question) return mDNStrue; return mDNSfalse; } mDNSlocal mDNSBool LocalRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q) { AuthRecord *rr; mDNSu32 slot; AuthGroup *ag; if (m->CurrentQuestion) LogMsg("LocalRecordRmvEventsForQuestion: ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); if (IsQuestionNew(m, q)) { LogInfo("LocalRecordRmvEventsForQuestion: New Question %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); return mDNStrue; } m->CurrentQuestion = q; slot = AuthHashSlot(&q->qname); ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname); if (ag) { for (rr = ag->members; rr; rr=rr->next) // Filter the /etc/hosts records - LocalOnly, Unique, A/AAAA/CNAME if (LORecordAnswersAddressType(rr) && LocalOnlyRecordAnswersQuestion(rr, q)) { LogInfo("LocalRecordRmvEventsForQuestion: Delivering possible Rmv events with record %s", ARDisplayString(m, rr)); if (q->CurrentAnswers <= 0 || q->LOAddressAnswers <= 0) { LogMsg("LocalRecordRmvEventsForQuestion: ERROR!! CurrentAnswers or LOAddressAnswers is zero %p %##s" " (%s) CurrentAnswers %d, LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), q->CurrentAnswers, q->LOAddressAnswers); continue; } AnswerLocalQuestionWithLocalAuthRecord(m, rr, QC_rmv); // MUST NOT dereference q again if (m->CurrentQuestion != q) { m->CurrentQuestion = mDNSNULL; return mDNSfalse; } } } m->CurrentQuestion = mDNSNULL; return mDNStrue; } // Returns false if the question got deleted while delivering the RMV events // The caller should handle the case mDNSlocal mDNSBool CacheRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q) { if (m->CurrentQuestion) LogMsg("CacheRecordRmvEventsForQuestion: ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); // If it is a new question, we have not delivered any ADD events yet. So, don't deliver RMV events. // If this question was answered using local auth records, then you can't deliver RMVs using cache if (!IsQuestionNew(m, q) && !q->LOAddressAnswers) { m->CurrentQuestion = q; CacheRecordRmvEventsForCurrentQuestion(m, q); if (m->CurrentQuestion != q) { m->CurrentQuestion = mDNSNULL; return mDNSfalse; } m->CurrentQuestion = mDNSNULL; } else { LogInfo("CacheRecordRmvEventsForQuestion: Question %p %##s (%s) is a new question", q, q->qname.c, DNSTypeName(q->qtype)); } return mDNStrue; } // The caller should hold the lock mDNSexport void CheckSuppressUnusableQuestions(mDNS *const m) { DNSQuestion *q; DNSQuestion *restart = mDNSNULL; // We look through all questions including new questions. During network change events, // we potentially restart questions here in this function that ends up as new questions, // which may be suppressed at this instance. Before it is handled we get another network // event that changes the status e.g., address becomes available. If we did not process // new questions, we would never change its SuppressQuery status. // // CurrentQuestion is used by RmvEventsForQuestion below. While delivering RMV events, the // application callback can potentially stop the current question (detected by CurrentQuestion) or // *any* other question which could be the next one that we may process here. RestartQuestion // points to the "next" question which will be automatically advanced in mDNS_StopQuery_internal // if the "next" question is stopped while the CurrentQuestion is stopped if (m->RestartQuestion) LogMsg("CheckSuppressUnusableQuestions: ERROR!! m->RestartQuestion already set: %##s (%s)", m->RestartQuestion->qname.c, DNSTypeName(m->RestartQuestion->qtype)); m->RestartQuestion = m->Questions; while (m->RestartQuestion) { q = m->RestartQuestion; m->RestartQuestion = q->next; if (!mDNSOpaque16IsZero(q->TargetQID) && q->SuppressUnusable) { mDNSBool old = q->SuppressQuery; q->SuppressQuery = ShouldSuppressQuery(m, &q->qname, q->qtype, q->InterfaceID); if (q->SuppressQuery != old) { // NOTE: CacheRecordRmvEventsForQuestion will not generate RMV events for queries that have non-zero // LOddressAnswers. Hence it is important that we call CacheRecordRmvEventsForQuestion before // LocalRecordRmvEventsForQuestion (which decrements LOAddressAnswers) if (q->SuppressQuery) { // Previously it was not suppressed, Generate RMV events for the ADDs that we might have delivered before // followed by a negative cache response. Temporarily turn off suppression so that // AnswerCurrentQuestionWithResourceRecord can answer the question q->SuppressQuery = mDNSfalse; if (!CacheRecordRmvEventsForQuestion(m, q)) { LogInfo("CheckSuppressUnusableQuestions: Question deleted while delivering RMV events"); continue; } q->SuppressQuery = mDNStrue; } // SuppressUnusable does not affect questions that are answered from the local records (/etc/hosts) // and SuppressQuery status does not mean anything for these questions. As we are going to stop the // question below, we need to deliver the RMV events so that the ADDs that will be delivered during // the restart will not be a duplicate ADD if (!LocalRecordRmvEventsForQuestion(m, q)) { LogInfo("CheckSuppressUnusableQuestions: Question deleted while delivering RMV events"); continue; } // There are two cases here. // // 1. Previously it was suppressed and now it is not suppressed, restart the question so // that it will start as a new question. Note that we can't just call ActivateUnicastQuery // because when we get the response, if we had entries in the cache already, it will not answer // this question if the cache entry did not change. Hence, we need to restart // the query so that it can be answered from the cache. // // 2. Previously it was not suppressed and now it is suppressed. We need to restart the questions // so that we redo the duplicate checks in mDNS_StartQuery_internal. A SuppressUnusable question // is a duplicate of non-SuppressUnusable question if it is not suppressed (SuppressQuery is false). // A SuppressUnusable question is not a duplicate of non-SuppressUnusable question if it is suppressed // (SuppressQuery is true). The reason for this is that when a question is suppressed, we want an // immediate response and not want to be blocked behind a question that is querying DNS servers. When // the question is not suppressed, we don't want two active questions sending packets on the wire. // This affects both efficiency and also the current design where there is only one active question // pointed to from a cache entry. // // We restart queries in a two step process by first calling stop and build a temporary list which we // will restart at the end. The main reason for the two step process is to handle duplicate questions. // If there are duplicate questions, calling stop inherits the values from another question on the list (which // will soon become the real question) including q->ThisQInterval which might be zero if it was // suppressed before. At the end when we have restarted all questions, none of them is active as each // inherits from one another and we need to reactivate one of the questions here which is a little hacky. // // It is much cleaner and less error prone to build a list of questions and restart at the end. LogInfo("CheckSuppressUnusableQuestions: Stop question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); mDNS_StopQuery_internal(m, q); q->next = restart; restart = q; } } } while (restart) { q = restart; restart = restart->next; q->next = mDNSNULL; LogInfo("CheckSuppressUnusableQuestions: Start question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); mDNS_StartQuery_internal(m, q); } } mDNSexport mStatus mDNS_StartQuery_internal(mDNS *const m, DNSQuestion *const question) { if (question->Target.type && !ValidQuestionTarget(question)) { LogMsg("mDNS_StartQuery_internal: Warning! Target.type = %ld port = %u (Client forgot to initialize before calling mDNS_StartQuery? for question %##s)", question->Target.type, mDNSVal16(question->TargetPort), question->qname.c); question->Target.type = mDNSAddrType_None; } if (!question->Target.type) question->TargetPort = zeroIPPort; // If no question->Target specified clear TargetPort question->TargetQID = #ifndef UNICAST_DISABLED (question->Target.type || Question_uDNS(question)) ? mDNS_NewMessageID(m) : #endif // UNICAST_DISABLED zeroID; debugf("mDNS_StartQuery: %##s (%s)", question->qname.c, DNSTypeName(question->qtype)); if (m->rrcache_size == 0) // Can't do queries if we have no cache space allocated return(mStatus_NoCache); else { int i; DNSQuestion **q; if (!ValidateDomainName(&question->qname)) { LogMsg("Attempt to start query with invalid qname %##s (%s)", question->qname.c, DNSTypeName(question->qtype)); return(mStatus_Invalid); } // Note: It important that new questions are appended at the *end* of the list, not prepended at the start q = &m->Questions; if (question->InterfaceID == mDNSInterface_LocalOnly || question->InterfaceID == mDNSInterface_P2P) q = &m->LocalOnlyQuestions; while (*q && *q != question) q=&(*q)->next; if (*q) { LogMsg("Error! Tried to add a question %##s (%s) %p that's already in the active list", question->qname.c, DNSTypeName(question->qtype), question); return(mStatus_AlreadyRegistered); } *q = question; // If this question is referencing a specific interface, verify it exists if (question->InterfaceID && question->InterfaceID != mDNSInterface_LocalOnly && question->InterfaceID != mDNSInterface_Unicast && question->InterfaceID != mDNSInterface_P2P) { NetworkInterfaceInfo *intf = FirstInterfaceForID(m, question->InterfaceID); if (!intf) LogMsg("Note: InterfaceID %p for question %##s (%s) not currently found in active interface list", question->InterfaceID, question->qname.c, DNSTypeName(question->qtype)); } // Note: In the case where we already have the answer to this question in our cache, that may be all the client // wanted, and they may immediately cancel their question. In this case, sending an actual query on the wire would // be a waste. For that reason, we schedule our first query to go out in half a second (InitialQuestionInterval). // If AnswerNewQuestion() finds that we have *no* relevant answers currently in our cache, then it will accelerate // that to go out immediately. question->next = mDNSNULL; question->qnamehash = DomainNameHashValue(&question->qname); // MUST do this before FindDuplicateQuestion() question->DelayAnswering = CheckForSoonToExpireRecords(m, &question->qname, question->qnamehash, HashSlot(&question->qname)); question->LastQTime = m->timenow; question->ThisQInterval = InitialQuestionInterval; // MUST be > zero for an active question question->ExpectUnicastResp = 0; question->LastAnswerPktNum = m->PktNum; question->RecentAnswerPkts = 0; question->CurrentAnswers = 0; question->LargeAnswers = 0; question->UniqueAnswers = 0; question->LOAddressAnswers = 0; question->FlappingInterface1 = mDNSNULL; question->FlappingInterface2 = mDNSNULL; // Must do AuthInfo and SuppressQuery before calling FindDuplicateQuestion() question->AuthInfo = GetAuthInfoForQuestion(m, question); if (question->SuppressUnusable) question->SuppressQuery = ShouldSuppressQuery(m, &question->qname, question->qtype, question->InterfaceID); else question->SuppressQuery = 0; question->DuplicateOf = FindDuplicateQuestion(m, question); question->NextInDQList = mDNSNULL; question->SendQNow = mDNSNULL; question->SendOnAll = mDNSfalse; question->RequestUnicast = 0; question->LastQTxTime = m->timenow; question->CNAMEReferrals = 0; // We'll create our question->LocalSocket on demand, if needed. // We won't need one for duplicate questions, or from questions answered immediately out of the cache. // We also don't need one for LLQs because (when we're using NAT) we want them all to share a single // NAT mapping for receiving inbound add/remove events. question->LocalSocket = mDNSNULL; question->deliverAddEvents = mDNSfalse; question->qDNSServer = mDNSNULL; question->unansweredQueries = 0; question->nta = mDNSNULL; question->servAddr = zeroAddr; question->servPort = zeroIPPort; question->tcp = mDNSNULL; question->NoAnswer = NoAnswer_Normal; question->state = LLQ_InitialRequest; question->ReqLease = 0; question->expire = 0; question->ntries = 0; question->id = zeroOpaque64; question->validDNSServers = zeroOpaque64; question->triedAllServersOnce = 0; question->noServerResponse = 0; question->StopTime = 0; if (question->WakeOnResolve) { question->WakeOnResolveCount = InitialWakeOnResolveCount; mDNS_PurgeBeforeResolve(m, question); } else question->WakeOnResolveCount = 0; if (question->DuplicateOf) question->AuthInfo = question->DuplicateOf->AuthInfo; for (i=0; iDupSuppress[i].InterfaceID = mDNSNULL; debugf("mDNS_StartQuery: Question %##s (%s) Interface %p Now %d Send in %d Answer in %d (%p) %s (%p)", question->qname.c, DNSTypeName(question->qtype), question->InterfaceID, m->timenow, NextQSendTime(question) - m->timenow, question->DelayAnswering ? question->DelayAnswering - m->timenow : 0, question, question->DuplicateOf ? "duplicate of" : "not duplicate", question->DuplicateOf); if (question->DelayAnswering) LogInfo("mDNS_StartQuery_internal: Delaying answering for %d ticks while cache stabilizes for %##s (%s)", question->DelayAnswering - m->timenow, question->qname.c, DNSTypeName(question->qtype)); if (question->InterfaceID == mDNSInterface_LocalOnly || question->InterfaceID == mDNSInterface_P2P) { if (!m->NewLocalOnlyQuestions) m->NewLocalOnlyQuestions = question; } else { if (!m->NewQuestions) m->NewQuestions = question; // If the question's id is non-zero, then it's Wide Area // MUST NOT do this Wide Area setup until near the end of // mDNS_StartQuery_internal -- this code may itself issue queries (e.g. SOA, // NS, etc.) and if we haven't finished setting up our own question and setting // m->NewQuestions if necessary then we could end up recursively re-entering // this routine with the question list data structures in an inconsistent state. if (!mDNSOpaque16IsZero(question->TargetQID)) { // Duplicate questions should have the same DNSServers so that when we find // a matching resource record, all of them get the answers. Calling GetServerForQuestion // for the duplicate question may get a different DNS server from the original question mDNSu32 timeout = SetValidDNSServers(m, question); // We set the timeout whenever mDNS_StartQuery_internal is called. This means if we have // a networking change/search domain change that calls this function again we keep // reinitializing the timeout value which means it may never timeout. If this becomes // a common case in the future, we can easily fix this by adding extra state that // indicates that we have already set the StopTime. if (question->TimeoutQuestion) question->StopTime = NonZeroTime(m->timenow + timeout * mDNSPlatformOneSecond); if (question->DuplicateOf) { question->validDNSServers = question->DuplicateOf->validDNSServers; question->qDNSServer = question->DuplicateOf->qDNSServer; LogInfo("mDNS_StartQuery_internal: Duplicate question %p (%p) %##s (%s), Timeout %d, DNS Server %#a:%d", question, question->DuplicateOf, question->qname.c, DNSTypeName(question->qtype), timeout, question->qDNSServer ? &question->qDNSServer->addr : mDNSNULL, mDNSVal16(question->qDNSServer ? question->qDNSServer->port : zeroIPPort)); } else { question->qDNSServer = GetServerForQuestion(m, question); LogInfo("mDNS_StartQuery_internal: question %p %##s (%s) Timeout %d, DNS Server %#a:%d", question, question->qname.c, DNSTypeName(question->qtype), timeout, question->qDNSServer ? &question->qDNSServer->addr : mDNSNULL, mDNSVal16(question->qDNSServer ? question->qDNSServer->port : zeroIPPort)); } ActivateUnicastQuery(m, question, mDNSfalse); // If long-lived query, and we don't have our NAT mapping active, start it now if (question->LongLived && !m->LLQNAT.clientContext) { m->LLQNAT.Protocol = NATOp_MapUDP; m->LLQNAT.IntPort = m->UnicastPort4; m->LLQNAT.RequestedPort = m->UnicastPort4; m->LLQNAT.clientCallback = LLQNATCallback; m->LLQNAT.clientContext = (void*)1; // Means LLQ NAT Traversal is active mDNS_StartNATOperation_internal(m, &m->LLQNAT); } #if APPLE_OSX_mDNSResponder if (question->LongLived) UpdateAutoTunnelDomainStatuses(m); #endif } else { if (question->TimeoutQuestion) question->StopTime = NonZeroTime(m->timenow + GetTimeoutForMcastQuestion(m, question) * mDNSPlatformOneSecond); } if (question->StopTime) SetNextQueryStopTime(m, question); SetNextQueryTime(m,question); } return(mStatus_NoError); } } // CancelGetZoneData is an internal routine (i.e. must be called with the lock already held) mDNSexport void CancelGetZoneData(mDNS *const m, ZoneData *nta) { debugf("CancelGetZoneData %##s (%s)", nta->question.qname.c, DNSTypeName(nta->question.qtype)); // This function may be called anytime to free the zone information.The question may or may not have stopped. // If it was already stopped, mDNS_StopQuery_internal would have set q->ThisQInterval to -1 and should not // call it again if (nta->question.ThisQInterval != -1) { mDNS_StopQuery_internal(m, &nta->question); if (nta->question.ThisQInterval != -1) LogMsg("CancelGetZoneData: Question %##s (%s) ThisQInterval %d not -1", nta->question.qname.c, DNSTypeName(nta->question.qtype), nta->question.ThisQInterval); } mDNSPlatformMemFree(nta); } mDNSexport mStatus mDNS_StopQuery_internal(mDNS *const m, DNSQuestion *const question) { const mDNSu32 slot = HashSlot(&question->qname); CacheGroup *cg = CacheGroupForName(m, slot, question->qnamehash, &question->qname); CacheRecord *rr; DNSQuestion **qp = &m->Questions; //LogInfo("mDNS_StopQuery_internal %##s (%s)", question->qname.c, DNSTypeName(question->qtype)); if (question->InterfaceID == mDNSInterface_LocalOnly || question->InterfaceID == mDNSInterface_P2P) qp = &m->LocalOnlyQuestions; while (*qp && *qp != question) qp=&(*qp)->next; if (*qp) *qp = (*qp)->next; else { #if !ForceAlerts if (question->ThisQInterval >= 0) // Only log error message if the query was supposed to be active #endif LogMsg("mDNS_StopQuery_internal: Question %##s (%s) not found in active list", question->qname.c, DNSTypeName(question->qtype)); #if ForceAlerts *(long*)0 = 0; #endif return(mStatus_BadReferenceErr); } // Take care to cut question from list *before* calling UpdateQuestionDuplicates UpdateQuestionDuplicates(m, question); // But don't trash ThisQInterval until afterwards. question->ThisQInterval = -1; // If there are any cache records referencing this as their active question, then see if there is any // other question that is also referencing them, else their CRActiveQuestion needs to get set to NULL. for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) { if (rr->CRActiveQuestion == question) { DNSQuestion *q; // Checking for ActiveQuestion filters questions that are suppressed also // as suppressed questions are not active for (q = m->Questions; q; q=q->next) // Scan our list of questions if (ActiveQuestion(q) && ResourceRecordAnswersQuestion(&rr->resrec, q)) break; if (q) debugf("mDNS_StopQuery_internal: Updating CRActiveQuestion to %p for cache record %s, Original question CurrentAnswers %d, new question " "CurrentAnswers %d, SuppressQuery %d", q, CRDisplayString(m,rr), question->CurrentAnswers, q->CurrentAnswers, q->SuppressQuery); rr->CRActiveQuestion = q; // Question used to be active; new value may or may not be null if (!q) m->rrcache_active--; // If no longer active, decrement rrcache_active count } } // If we just deleted the question that CacheRecordAdd() or CacheRecordRmv() is about to look at, // bump its pointer forward one question. if (m->CurrentQuestion == question) { debugf("mDNS_StopQuery_internal: Just deleted the currently active question: %##s (%s)", question->qname.c, DNSTypeName(question->qtype)); m->CurrentQuestion = question->next; } if (m->NewQuestions == question) { debugf("mDNS_StopQuery_internal: Just deleted a new question that wasn't even answered yet: %##s (%s)", question->qname.c, DNSTypeName(question->qtype)); m->NewQuestions = question->next; } if (m->NewLocalOnlyQuestions == question) m->NewLocalOnlyQuestions = question->next; if (m->RestartQuestion == question) { LogMsg("mDNS_StopQuery_internal: Just deleted the current restart question: %##s (%s)", question->qname.c, DNSTypeName(question->qtype)); m->RestartQuestion = question->next; } // Take care not to trash question->next until *after* we've updated m->CurrentQuestion and m->NewQuestions question->next = mDNSNULL; // LogMsg("mDNS_StopQuery_internal: Question %##s (%s) removed", question->qname.c, DNSTypeName(question->qtype)); // And finally, cancel any associated GetZoneData operation that's still running. // Must not do this until last, because there's a good chance the GetZoneData question is the next in the list, // so if we delete it earlier in this routine, we could find that our "question->next" pointer above is already // invalid before we even use it. By making sure that we update m->CurrentQuestion and m->NewQuestions if necessary // *first*, then they're all ready to be updated a second time if necessary when we cancel our GetZoneData query. if (question->tcp) { DisposeTCPConn(question->tcp); question->tcp = mDNSNULL; } if (question->LocalSocket) { mDNSPlatformUDPClose(question->LocalSocket); question->LocalSocket = mDNSNULL; } if (!mDNSOpaque16IsZero(question->TargetQID) && question->LongLived) { // Scan our list to see if any more wide-area LLQs remain. If not, stop our NAT Traversal. DNSQuestion *q; for (q = m->Questions; q; q=q->next) if (!mDNSOpaque16IsZero(q->TargetQID) && q->LongLived) break; if (!q) { if (!m->LLQNAT.clientContext) // Should never happen, but just in case... LogMsg("mDNS_StopQuery ERROR LLQNAT.clientContext NULL"); else { LogInfo("Stopping LLQNAT"); mDNS_StopNATOperation_internal(m, &m->LLQNAT); m->LLQNAT.clientContext = mDNSNULL; // Means LLQ NAT Traversal not running } } // If necessary, tell server it can delete this LLQ state if (question->state == LLQ_Established) { question->ReqLease = 0; sendLLQRefresh(m, question); // If we need need to make a TCP connection to cancel the LLQ, that's going to take a little while. // We clear the tcp->question backpointer so that when the TCP connection completes, it doesn't // crash trying to access our cancelled question, but we don't cancel the TCP operation itself -- // we let that run out its natural course and complete asynchronously. if (question->tcp) { question->tcp->question = mDNSNULL; question->tcp = mDNSNULL; } } #if APPLE_OSX_mDNSResponder UpdateAutoTunnelDomainStatuses(m); #endif } // wait until we send the refresh above which needs the nta if (question->nta) { CancelGetZoneData(m, question->nta); question->nta = mDNSNULL; } return(mStatus_NoError); } mDNSexport mStatus mDNS_StartQuery(mDNS *const m, DNSQuestion *const question) { mStatus status; mDNS_Lock(m); status = mDNS_StartQuery_internal(m, question); mDNS_Unlock(m); return(status); } mDNSexport mStatus mDNS_StopQuery(mDNS *const m, DNSQuestion *const question) { mStatus status; mDNS_Lock(m); status = mDNS_StopQuery_internal(m, question); mDNS_Unlock(m); return(status); } // Note that mDNS_StopQueryWithRemoves() does not currently implement the full generality of the other APIs // Specifically, question callbacks invoked as a result of this call cannot themselves make API calls. // We invoke the callback without using mDNS_DropLockBeforeCallback/mDNS_ReclaimLockAfterCallback // specifically to catch and report if the client callback does try to make API calls mDNSexport mStatus mDNS_StopQueryWithRemoves(mDNS *const m, DNSQuestion *const question) { mStatus status; DNSQuestion *qq; mDNS_Lock(m); // Check if question is new -- don't want to give remove events for a question we haven't even answered yet for (qq = m->NewQuestions; qq; qq=qq->next) if (qq == question) break; status = mDNS_StopQuery_internal(m, question); if (status == mStatus_NoError && !qq) { const CacheRecord *rr; const mDNSu32 slot = HashSlot(&question->qname); CacheGroup *const cg = CacheGroupForName(m, slot, question->qnamehash, &question->qname); LogInfo("Generating terminal removes for %##s (%s)", question->qname.c, DNSTypeName(question->qtype)); for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) if (rr->resrec.RecordType != kDNSRecordTypePacketNegative && SameNameRecordAnswersQuestion(&rr->resrec, question)) { // Don't use mDNS_DropLockBeforeCallback() here, since we don't allow API calls if (question->QuestionCallback) question->QuestionCallback(m, question, &rr->resrec, mDNSfalse); } } mDNS_Unlock(m); return(status); } mDNSexport mStatus mDNS_Reconfirm(mDNS *const m, CacheRecord *const cr) { mStatus status; mDNS_Lock(m); status = mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer); if (status == mStatus_NoError) ReconfirmAntecedents(m, cr->resrec.name, cr->resrec.namehash, 0); mDNS_Unlock(m); return(status); } mDNSexport mStatus mDNS_ReconfirmByValue(mDNS *const m, ResourceRecord *const rr) { mStatus status = mStatus_BadReferenceErr; CacheRecord *cr; mDNS_Lock(m); cr = FindIdenticalRecordInCache(m, rr); debugf("mDNS_ReconfirmByValue: %p %s", cr, RRDisplayString(m, rr)); if (cr) status = mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer); if (status == mStatus_NoError) ReconfirmAntecedents(m, cr->resrec.name, cr->resrec.namehash, 0); mDNS_Unlock(m); return(status); } mDNSlocal mStatus mDNS_StartBrowse_internal(mDNS *const m, DNSQuestion *const question, const domainname *const srv, const domainname *const domain, const mDNSInterfaceID InterfaceID, mDNSBool ForceMCast, mDNSQuestionCallback *Callback, void *Context) { question->InterfaceID = InterfaceID; question->Target = zeroAddr; question->qtype = kDNSType_PTR; question->qclass = kDNSClass_IN; question->LongLived = mDNStrue; question->ExpectUnique = mDNSfalse; question->ForceMCast = ForceMCast; question->ReturnIntermed = mDNSfalse; question->SuppressUnusable = mDNSfalse; question->SearchListIndex = 0; question->AppendSearchDomains = 0; question->RetryWithSearchDomains = mDNSfalse; question->TimeoutQuestion = 0; question->WakeOnResolve = 0; question->qnameOrig = mDNSNULL; question->QuestionCallback = Callback; question->QuestionContext = Context; if (!ConstructServiceName(&question->qname, mDNSNULL, srv, domain)) return(mStatus_BadParamErr); return(mDNS_StartQuery_internal(m, question)); } mDNSexport mStatus mDNS_StartBrowse(mDNS *const m, DNSQuestion *const question, const domainname *const srv, const domainname *const domain, const mDNSInterfaceID InterfaceID, mDNSBool ForceMCast, mDNSQuestionCallback *Callback, void *Context) { mStatus status; mDNS_Lock(m); status = mDNS_StartBrowse_internal(m, question, srv, domain, InterfaceID, ForceMCast, Callback, Context); mDNS_Unlock(m); return(status); } mDNSlocal mDNSBool MachineHasActiveIPv6(mDNS *const m) { NetworkInterfaceInfo *intf; for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->ip.type == mDNSAddrType_IPv6) return(mDNStrue); return(mDNSfalse); } mDNSlocal void FoundServiceInfoSRV(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord) { ServiceInfoQuery *query = (ServiceInfoQuery *)question->QuestionContext; mDNSBool PortChanged = !mDNSSameIPPort(query->info->port, answer->rdata->u.srv.port); if (!AddRecord) return; if (answer->rrtype != kDNSType_SRV) return; query->info->port = answer->rdata->u.srv.port; // If this is our first answer, then set the GotSRV flag and start the address query if (!query->GotSRV) { query->GotSRV = mDNStrue; query->qAv4.InterfaceID = answer->InterfaceID; AssignDomainName(&query->qAv4.qname, &answer->rdata->u.srv.target); query->qAv6.InterfaceID = answer->InterfaceID; AssignDomainName(&query->qAv6.qname, &answer->rdata->u.srv.target); mDNS_StartQuery(m, &query->qAv4); // Only do the AAAA query if this machine actually has IPv6 active if (MachineHasActiveIPv6(m)) mDNS_StartQuery(m, &query->qAv6); } // If this is not our first answer, only re-issue the address query if the target host name has changed else if ((query->qAv4.InterfaceID != query->qSRV.InterfaceID && query->qAv4.InterfaceID != answer->InterfaceID) || !SameDomainName(&query->qAv4.qname, &answer->rdata->u.srv.target)) { mDNS_StopQuery(m, &query->qAv4); if (query->qAv6.ThisQInterval >= 0) mDNS_StopQuery(m, &query->qAv6); if (SameDomainName(&query->qAv4.qname, &answer->rdata->u.srv.target) && !PortChanged) { // If we get here, it means: // 1. This is not our first SRV answer // 2. The interface ID is different, but the target host and port are the same // This implies that we're seeing the exact same SRV record on more than one interface, so we should // make our address queries at least as broad as the original SRV query so that we catch all the answers. query->qAv4.InterfaceID = query->qSRV.InterfaceID; // Will be mDNSInterface_Any, or a specific interface query->qAv6.InterfaceID = query->qSRV.InterfaceID; } else { query->qAv4.InterfaceID = answer->InterfaceID; AssignDomainName(&query->qAv4.qname, &answer->rdata->u.srv.target); query->qAv6.InterfaceID = answer->InterfaceID; AssignDomainName(&query->qAv6.qname, &answer->rdata->u.srv.target); } debugf("FoundServiceInfoSRV: Restarting address queries for %##s (%s)", query->qAv4.qname.c, DNSTypeName(query->qAv4.qtype)); mDNS_StartQuery(m, &query->qAv4); // Only do the AAAA query if this machine actually has IPv6 active if (MachineHasActiveIPv6(m)) mDNS_StartQuery(m, &query->qAv6); } else if (query->ServiceInfoQueryCallback && query->GotADD && query->GotTXT && PortChanged) { if (++query->Answers >= 100) debugf("**** WARNING **** Have given %lu answers for %##s (SRV) %##s %u", query->Answers, query->qSRV.qname.c, answer->rdata->u.srv.target.c, mDNSVal16(answer->rdata->u.srv.port)); query->ServiceInfoQueryCallback(m, query); } // CAUTION: MUST NOT do anything more with query after calling query->Callback(), because the client's // callback function is allowed to do anything, including deleting this query and freeing its memory. } mDNSlocal void FoundServiceInfoTXT(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord) { ServiceInfoQuery *query = (ServiceInfoQuery *)question->QuestionContext; if (!AddRecord) return; if (answer->rrtype != kDNSType_TXT) return; if (answer->rdlength > sizeof(query->info->TXTinfo)) return; query->GotTXT = mDNStrue; query->info->TXTlen = answer->rdlength; query->info->TXTinfo[0] = 0; // In case answer->rdlength is zero mDNSPlatformMemCopy(query->info->TXTinfo, answer->rdata->u.txt.c, answer->rdlength); verbosedebugf("FoundServiceInfoTXT: %##s GotADD=%d", query->info->name.c, query->GotADD); // CAUTION: MUST NOT do anything more with query after calling query->Callback(), because the client's // callback function is allowed to do anything, including deleting this query and freeing its memory. if (query->ServiceInfoQueryCallback && query->GotADD) { if (++query->Answers >= 100) debugf("**** WARNING **** have given %lu answers for %##s (TXT) %#s...", query->Answers, query->qSRV.qname.c, answer->rdata->u.txt.c); query->ServiceInfoQueryCallback(m, query); } } mDNSlocal void FoundServiceInfo(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord) { ServiceInfoQuery *query = (ServiceInfoQuery *)question->QuestionContext; //LogInfo("FoundServiceInfo %d %s", AddRecord, RRDisplayString(m, answer)); if (!AddRecord) return; if (answer->rrtype == kDNSType_A) { query->info->ip.type = mDNSAddrType_IPv4; query->info->ip.ip.v4 = answer->rdata->u.ipv4; } else if (answer->rrtype == kDNSType_AAAA) { query->info->ip.type = mDNSAddrType_IPv6; query->info->ip.ip.v6 = answer->rdata->u.ipv6; } else { debugf("FoundServiceInfo: answer %##s type %d (%s) unexpected", answer->name->c, answer->rrtype, DNSTypeName(answer->rrtype)); return; } query->GotADD = mDNStrue; query->info->InterfaceID = answer->InterfaceID; verbosedebugf("FoundServiceInfo v%ld: %##s GotTXT=%d", query->info->ip.type, query->info->name.c, query->GotTXT); // CAUTION: MUST NOT do anything more with query after calling query->Callback(), because the client's // callback function is allowed to do anything, including deleting this query and freeing its memory. if (query->ServiceInfoQueryCallback && query->GotTXT) { if (++query->Answers >= 100) debugf(answer->rrtype == kDNSType_A ? "**** WARNING **** have given %lu answers for %##s (A) %.4a" : "**** WARNING **** have given %lu answers for %##s (AAAA) %.16a", query->Answers, query->qSRV.qname.c, &answer->rdata->u.data); query->ServiceInfoQueryCallback(m, query); } } // On entry, the client must have set the name and InterfaceID fields of the ServiceInfo structure // If the query is not interface-specific, then InterfaceID may be zero // Each time the Callback is invoked, the remainder of the fields will have been filled in // In addition, InterfaceID will be updated to give the interface identifier corresponding to that response mDNSexport mStatus mDNS_StartResolveService(mDNS *const m, ServiceInfoQuery *query, ServiceInfo *info, mDNSServiceInfoQueryCallback *Callback, void *Context) { mStatus status; mDNS_Lock(m); query->qSRV.ThisQInterval = -1; // So that mDNS_StopResolveService() knows whether to cancel this question query->qSRV.InterfaceID = info->InterfaceID; query->qSRV.Target = zeroAddr; AssignDomainName(&query->qSRV.qname, &info->name); query->qSRV.qtype = kDNSType_SRV; query->qSRV.qclass = kDNSClass_IN; query->qSRV.LongLived = mDNSfalse; query->qSRV.ExpectUnique = mDNStrue; query->qSRV.ForceMCast = mDNSfalse; query->qSRV.ReturnIntermed = mDNSfalse; query->qSRV.SuppressUnusable = mDNSfalse; query->qSRV.SearchListIndex = 0; query->qSRV.AppendSearchDomains = 0; query->qSRV.RetryWithSearchDomains = mDNSfalse; query->qSRV.TimeoutQuestion = 0; query->qSRV.WakeOnResolve = 0; query->qSRV.qnameOrig = mDNSNULL; query->qSRV.QuestionCallback = FoundServiceInfoSRV; query->qSRV.QuestionContext = query; query->qTXT.ThisQInterval = -1; // So that mDNS_StopResolveService() knows whether to cancel this question query->qTXT.InterfaceID = info->InterfaceID; query->qTXT.Target = zeroAddr; AssignDomainName(&query->qTXT.qname, &info->name); query->qTXT.qtype = kDNSType_TXT; query->qTXT.qclass = kDNSClass_IN; query->qTXT.LongLived = mDNSfalse; query->qTXT.ExpectUnique = mDNStrue; query->qTXT.ForceMCast = mDNSfalse; query->qTXT.ReturnIntermed = mDNSfalse; query->qTXT.SuppressUnusable = mDNSfalse; query->qTXT.SearchListIndex = 0; query->qTXT.AppendSearchDomains = 0; query->qTXT.RetryWithSearchDomains = mDNSfalse; query->qTXT.TimeoutQuestion = 0; query->qTXT.WakeOnResolve = 0; query->qTXT.qnameOrig = mDNSNULL; query->qTXT.QuestionCallback = FoundServiceInfoTXT; query->qTXT.QuestionContext = query; query->qAv4.ThisQInterval = -1; // So that mDNS_StopResolveService() knows whether to cancel this question query->qAv4.InterfaceID = info->InterfaceID; query->qAv4.Target = zeroAddr; query->qAv4.qname.c[0] = 0; query->qAv4.qtype = kDNSType_A; query->qAv4.qclass = kDNSClass_IN; query->qAv4.LongLived = mDNSfalse; query->qAv4.ExpectUnique = mDNStrue; query->qAv4.ForceMCast = mDNSfalse; query->qAv4.ReturnIntermed = mDNSfalse; query->qAv4.SuppressUnusable = mDNSfalse; query->qAv4.SearchListIndex = 0; query->qAv4.AppendSearchDomains = 0; query->qAv4.RetryWithSearchDomains = mDNSfalse; query->qAv4.TimeoutQuestion = 0; query->qAv4.WakeOnResolve = 0; query->qAv4.qnameOrig = mDNSNULL; query->qAv4.QuestionCallback = FoundServiceInfo; query->qAv4.QuestionContext = query; query->qAv6.ThisQInterval = -1; // So that mDNS_StopResolveService() knows whether to cancel this question query->qAv6.InterfaceID = info->InterfaceID; query->qAv6.Target = zeroAddr; query->qAv6.qname.c[0] = 0; query->qAv6.qtype = kDNSType_AAAA; query->qAv6.qclass = kDNSClass_IN; query->qAv6.LongLived = mDNSfalse; query->qAv6.ExpectUnique = mDNStrue; query->qAv6.ForceMCast = mDNSfalse; query->qAv6.ReturnIntermed = mDNSfalse; query->qAv6.SuppressUnusable = mDNSfalse; query->qAv6.SearchListIndex = 0; query->qAv6.AppendSearchDomains = 0; query->qAv6.RetryWithSearchDomains = mDNSfalse; query->qAv6.TimeoutQuestion = 0; query->qAv6.WakeOnResolve = 0; query->qAv6.qnameOrig = mDNSNULL; query->qAv6.QuestionCallback = FoundServiceInfo; query->qAv6.QuestionContext = query; query->GotSRV = mDNSfalse; query->GotTXT = mDNSfalse; query->GotADD = mDNSfalse; query->Answers = 0; query->info = info; query->ServiceInfoQueryCallback = Callback; query->ServiceInfoQueryContext = Context; // info->name = Must already be set up by client // info->interface = Must already be set up by client info->ip = zeroAddr; info->port = zeroIPPort; info->TXTlen = 0; // We use mDNS_StartQuery_internal here because we're already holding the lock status = mDNS_StartQuery_internal(m, &query->qSRV); if (status == mStatus_NoError) status = mDNS_StartQuery_internal(m, &query->qTXT); if (status != mStatus_NoError) mDNS_StopResolveService(m, query); mDNS_Unlock(m); return(status); } mDNSexport void mDNS_StopResolveService (mDNS *const m, ServiceInfoQuery *q) { mDNS_Lock(m); // We use mDNS_StopQuery_internal here because we're already holding the lock if (q->qSRV.ThisQInterval >= 0) mDNS_StopQuery_internal(m, &q->qSRV); if (q->qTXT.ThisQInterval >= 0) mDNS_StopQuery_internal(m, &q->qTXT); if (q->qAv4.ThisQInterval >= 0) mDNS_StopQuery_internal(m, &q->qAv4); if (q->qAv6.ThisQInterval >= 0) mDNS_StopQuery_internal(m, &q->qAv6); mDNS_Unlock(m); } mDNSexport mStatus mDNS_GetDomains(mDNS *const m, DNSQuestion *const question, mDNS_DomainType DomainType, const domainname *dom, const mDNSInterfaceID InterfaceID, mDNSQuestionCallback *Callback, void *Context) { question->InterfaceID = InterfaceID; question->Target = zeroAddr; question->qtype = kDNSType_PTR; question->qclass = kDNSClass_IN; question->LongLived = mDNSfalse; question->ExpectUnique = mDNSfalse; question->ForceMCast = mDNSfalse; question->ReturnIntermed = mDNSfalse; question->SuppressUnusable = mDNSfalse; question->SearchListIndex = 0; question->AppendSearchDomains = 0; question->RetryWithSearchDomains = mDNSfalse; question->TimeoutQuestion = 0; question->WakeOnResolve = 0; question->qnameOrig = mDNSNULL; question->QuestionCallback = Callback; question->QuestionContext = Context; if (DomainType > mDNS_DomainTypeMax) return(mStatus_BadParamErr); if (!MakeDomainNameFromDNSNameString(&question->qname, mDNS_DomainTypeNames[DomainType])) return(mStatus_BadParamErr); if (!dom) dom = &localdomain; if (!AppendDomainName(&question->qname, dom)) return(mStatus_BadParamErr); return(mDNS_StartQuery(m, question)); } // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Responder Functions #endif mDNSexport mStatus mDNS_Register(mDNS *const m, AuthRecord *const rr) { mStatus status; mDNS_Lock(m); status = mDNS_Register_internal(m, rr); mDNS_Unlock(m); return(status); } mDNSexport mStatus mDNS_Update(mDNS *const m, AuthRecord *const rr, mDNSu32 newttl, const mDNSu16 newrdlength, RData *const newrdata, mDNSRecordUpdateCallback *Callback) { if (!ValidateRData(rr->resrec.rrtype, newrdlength, newrdata)) { LogMsg("Attempt to update record with invalid rdata: %s", GetRRDisplayString_rdb(&rr->resrec, &newrdata->u, m->MsgBuffer)); return(mStatus_Invalid); } mDNS_Lock(m); // If TTL is unspecified, leave TTL unchanged if (newttl == 0) newttl = rr->resrec.rroriginalttl; // If we already have an update queued up which has not gone through yet, give the client a chance to free that memory if (rr->NewRData) { RData *n = rr->NewRData; rr->NewRData = mDNSNULL; // Clear the NewRData pointer ... if (rr->UpdateCallback) rr->UpdateCallback(m, rr, n, rr->newrdlength); // ...and let the client free this memory, if necessary } rr->NewRData = newrdata; rr->newrdlength = newrdlength; rr->UpdateCallback = Callback; #ifndef UNICAST_DISABLED if (rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P && !IsLocalDomain(rr->resrec.name)) { mStatus status = uDNS_UpdateRecord(m, rr); // The caller frees the memory on error, don't retain stale pointers if (status != mStatus_NoError) { rr->NewRData = mDNSNULL; rr->newrdlength = 0; } mDNS_Unlock(m); return(status); } #endif if (RRLocalOnly(rr) || (rr->resrec.rroriginalttl == newttl && rr->resrec.rdlength == newrdlength && mDNSPlatformMemSame(rr->resrec.rdata->u.data, newrdata->u.data, newrdlength))) CompleteRDataUpdate(m, rr); else { rr->AnnounceCount = InitialAnnounceCount; InitializeLastAPTime(m, rr); while (rr->NextUpdateCredit && m->timenow - rr->NextUpdateCredit >= 0) GrantUpdateCredit(rr); if (!rr->UpdateBlocked && rr->UpdateCredits) rr->UpdateCredits--; if (!rr->NextUpdateCredit) rr->NextUpdateCredit = NonZeroTime(m->timenow + kUpdateCreditRefreshInterval); if (rr->AnnounceCount > rr->UpdateCredits + 1) rr->AnnounceCount = (mDNSu8)(rr->UpdateCredits + 1); if (rr->UpdateCredits <= 5) { mDNSu32 delay = 6 - rr->UpdateCredits; // Delay 1 second, then 2, then 3, etc. up to 6 seconds maximum if (!rr->UpdateBlocked) rr->UpdateBlocked = NonZeroTime(m->timenow + (mDNSs32)delay * mDNSPlatformOneSecond); rr->ThisAPInterval *= 4; rr->LastAPTime = rr->UpdateBlocked - rr->ThisAPInterval; LogMsg("Excessive update rate for %##s; delaying announcement by %ld second%s", rr->resrec.name->c, delay, delay > 1 ? "s" : ""); } rr->resrec.rroriginalttl = newttl; } mDNS_Unlock(m); return(mStatus_NoError); } // Note: mDNS_Deregister calls mDNS_Deregister_internal which can call a user callback, which may change // the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSexport mStatus mDNS_Deregister(mDNS *const m, AuthRecord *const rr) { mStatus status; mDNS_Lock(m); status = mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); mDNS_Unlock(m); return(status); } // Circular reference: AdvertiseInterface references mDNS_HostNameCallback, which calls mDNS_SetFQDN, which call AdvertiseInterface mDNSlocal void mDNS_HostNameCallback(mDNS *const m, AuthRecord *const rr, mStatus result); mDNSlocal NetworkInterfaceInfo *FindFirstAdvertisedInterface(mDNS *const m) { NetworkInterfaceInfo *intf; for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->Advertise) break; return(intf); } mDNSlocal void AdvertiseInterface(mDNS *const m, NetworkInterfaceInfo *set) { char buffer[MAX_REVERSE_MAPPING_NAME]; NetworkInterfaceInfo *primary = FindFirstAdvertisedInterface(m); if (!primary) primary = set; // If no existing advertised interface, this new NetworkInterfaceInfo becomes our new primary // Send dynamic update for non-linklocal IPv4 Addresses mDNS_SetupResourceRecord(&set->RR_A, mDNSNULL, set->InterfaceID, kDNSType_A, kHostNameTTL, kDNSRecordTypeUnique, AuthRecordAny, mDNS_HostNameCallback, set); mDNS_SetupResourceRecord(&set->RR_PTR, mDNSNULL, set->InterfaceID, kDNSType_PTR, kHostNameTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL); mDNS_SetupResourceRecord(&set->RR_HINFO, mDNSNULL, set->InterfaceID, kDNSType_HINFO, kHostNameTTL, kDNSRecordTypeUnique, AuthRecordAny, mDNSNULL, mDNSNULL); #if ANSWER_REMOTE_HOSTNAME_QUERIES set->RR_A .AllowRemoteQuery = mDNStrue; set->RR_PTR .AllowRemoteQuery = mDNStrue; set->RR_HINFO.AllowRemoteQuery = mDNStrue; #endif // 1. Set up Address record to map from host name ("foo.local.") to IP address // 2. Set up reverse-lookup PTR record to map from our address back to our host name AssignDomainName(&set->RR_A.namestorage, &m->MulticastHostname); if (set->ip.type == mDNSAddrType_IPv4) { set->RR_A.resrec.rrtype = kDNSType_A; set->RR_A.resrec.rdata->u.ipv4 = set->ip.ip.v4; // Note: This is reverse order compared to a normal dotted-decimal IP address, so we can't use our customary "%.4a" format code mDNS_snprintf(buffer, sizeof(buffer), "%d.%d.%d.%d.in-addr.arpa.", set->ip.ip.v4.b[3], set->ip.ip.v4.b[2], set->ip.ip.v4.b[1], set->ip.ip.v4.b[0]); } else if (set->ip.type == mDNSAddrType_IPv6) { int i; set->RR_A.resrec.rrtype = kDNSType_AAAA; set->RR_A.resrec.rdata->u.ipv6 = set->ip.ip.v6; for (i = 0; i < 16; i++) { static const char hexValues[] = "0123456789ABCDEF"; buffer[i * 4 ] = hexValues[set->ip.ip.v6.b[15 - i] & 0x0F]; buffer[i * 4 + 1] = '.'; buffer[i * 4 + 2] = hexValues[set->ip.ip.v6.b[15 - i] >> 4]; buffer[i * 4 + 3] = '.'; } mDNS_snprintf(&buffer[64], sizeof(buffer)-64, "ip6.arpa."); } MakeDomainNameFromDNSNameString(&set->RR_PTR.namestorage, buffer); set->RR_PTR.AutoTarget = Target_AutoHost; // Tell mDNS that the target of this PTR is to be kept in sync with our host name set->RR_PTR.ForceMCast = mDNStrue; // This PTR points to our dot-local name, so don't ever try to write it into a uDNS server set->RR_A.RRSet = &primary->RR_A; // May refer to self mDNS_Register_internal(m, &set->RR_A); mDNS_Register_internal(m, &set->RR_PTR); if (!NO_HINFO && m->HIHardware.c[0] > 0 && m->HISoftware.c[0] > 0 && m->HIHardware.c[0] + m->HISoftware.c[0] <= 254) { mDNSu8 *p = set->RR_HINFO.resrec.rdata->u.data; AssignDomainName(&set->RR_HINFO.namestorage, &m->MulticastHostname); set->RR_HINFO.DependentOn = &set->RR_A; mDNSPlatformMemCopy(p, &m->HIHardware, 1 + (mDNSu32)m->HIHardware.c[0]); p += 1 + (int)p[0]; mDNSPlatformMemCopy(p, &m->HISoftware, 1 + (mDNSu32)m->HISoftware.c[0]); mDNS_Register_internal(m, &set->RR_HINFO); } else { debugf("Not creating HINFO record: platform support layer provided no information"); set->RR_HINFO.resrec.RecordType = kDNSRecordTypeUnregistered; } } mDNSlocal void DeadvertiseInterface(mDNS *const m, NetworkInterfaceInfo *set) { NetworkInterfaceInfo *intf; // If we still have address records referring to this one, update them NetworkInterfaceInfo *primary = FindFirstAdvertisedInterface(m); AuthRecord *A = primary ? &primary->RR_A : mDNSNULL; for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->RR_A.RRSet == &set->RR_A) intf->RR_A.RRSet = A; // Unregister these records. // When doing the mDNS_Exit processing, we first call DeadvertiseInterface for each interface, so by the time the platform // support layer gets to call mDNS_DeregisterInterface, the address and PTR records have already been deregistered for it. // Also, in the event of a name conflict, one or more of our records will have been forcibly deregistered. // To avoid unnecessary and misleading warning messages, we check the RecordType before calling mDNS_Deregister_internal(). if (set->RR_A. resrec.RecordType) mDNS_Deregister_internal(m, &set->RR_A, mDNS_Dereg_normal); if (set->RR_PTR. resrec.RecordType) mDNS_Deregister_internal(m, &set->RR_PTR, mDNS_Dereg_normal); if (set->RR_HINFO.resrec.RecordType) mDNS_Deregister_internal(m, &set->RR_HINFO, mDNS_Dereg_normal); } mDNSexport void mDNS_SetFQDN(mDNS *const m) { domainname newmname; NetworkInterfaceInfo *intf; AuthRecord *rr; newmname.c[0] = 0; if (!AppendDomainLabel(&newmname, &m->hostlabel)) { LogMsg("ERROR: mDNS_SetFQDN: Cannot create MulticastHostname"); return; } if (!AppendLiteralLabelString(&newmname, "local")) { LogMsg("ERROR: mDNS_SetFQDN: Cannot create MulticastHostname"); return; } mDNS_Lock(m); if (SameDomainNameCS(&m->MulticastHostname, &newmname)) debugf("mDNS_SetFQDN - hostname unchanged"); else { AssignDomainName(&m->MulticastHostname, &newmname); // 1. Stop advertising our address records on all interfaces for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->Advertise) DeadvertiseInterface(m, intf); // 2. Start advertising our address records using the new name for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->Advertise) AdvertiseInterface(m, intf); } // 3. Make sure that any AutoTarget SRV records (and the like) get updated for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->AutoTarget) SetTargetToHostName(m, rr); for (rr = m->DuplicateRecords; rr; rr=rr->next) if (rr->AutoTarget) SetTargetToHostName(m, rr); mDNS_Unlock(m); } mDNSlocal void mDNS_HostNameCallback(mDNS *const m, AuthRecord *const rr, mStatus result) { (void)rr; // Unused parameter #if MDNS_DEBUGMSGS { char *msg = "Unknown result"; if (result == mStatus_NoError) msg = "Name registered"; else if (result == mStatus_NameConflict) msg = "Name conflict"; debugf("mDNS_HostNameCallback: %##s (%s) %s (%ld)", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), msg, result); } #endif if (result == mStatus_NoError) { // Notify the client that the host name is successfully registered if (m->MainCallback) m->MainCallback(m, mStatus_NoError); } else if (result == mStatus_NameConflict) { domainlabel oldlabel = m->hostlabel; // 1. First give the client callback a chance to pick a new name if (m->MainCallback) m->MainCallback(m, mStatus_NameConflict); // 2. If the client callback didn't do it, add (or increment) an index ourselves // This needs to be case-INSENSITIVE compare, because we need to know that the name has been changed so as to // remedy the conflict, and a name that differs only in capitalization will just suffer the exact same conflict again. if (SameDomainLabel(m->hostlabel.c, oldlabel.c)) IncrementLabelSuffix(&m->hostlabel, mDNSfalse); // 3. Generate the FQDNs from the hostlabel, // and make sure all SRV records, etc., are updated to reference our new hostname mDNS_SetFQDN(m); LogMsg("Local Hostname %#s.local already in use; will try %#s.local instead", oldlabel.c, m->hostlabel.c); } else if (result == mStatus_MemFree) { // .local hostnames do not require goodbyes - we ignore the MemFree (which is sent directly by // mDNS_Deregister_internal), and allow the caller to deallocate immediately following mDNS_DeadvertiseInterface debugf("mDNS_HostNameCallback: MemFree (ignored)"); } else LogMsg("mDNS_HostNameCallback: Unknown error %d for registration of record %s", result, rr->resrec.name->c); } mDNSlocal void UpdateInterfaceProtocols(mDNS *const m, NetworkInterfaceInfo *active) { NetworkInterfaceInfo *intf; active->IPv4Available = mDNSfalse; active->IPv6Available = mDNSfalse; for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->InterfaceID == active->InterfaceID) { if (intf->ip.type == mDNSAddrType_IPv4 && intf->McastTxRx) active->IPv4Available = mDNStrue; if (intf->ip.type == mDNSAddrType_IPv6 && intf->McastTxRx) active->IPv6Available = mDNStrue; } } mDNSlocal void RestartRecordGetZoneData(mDNS * const m) { AuthRecord *rr; LogInfo("RestartRecordGetZoneData: ResourceRecords"); for (rr = m->ResourceRecords; rr; rr=rr->next) if (AuthRecord_uDNS(rr) && rr->state != regState_NoTarget) { debugf("RestartRecordGetZoneData: StartGetZoneData for %##s", rr->resrec.name->c); // Zero out the updateid so that if we have a pending response from the server, it won't // be accepted as a valid response. If we accept the response, we might free the new "nta" if (rr->nta) { rr->updateid = zeroID; CancelGetZoneData(m, rr->nta); } rr->nta = StartGetZoneData(m, rr->resrec.name, ZoneServiceUpdate, RecordRegistrationGotZoneData, rr); } } mDNSlocal void InitializeNetWakeState(mDNS *const m, NetworkInterfaceInfo *set) { int i; set->NetWakeBrowse.ThisQInterval = -1; for (i=0; i<3; i++) { set->NetWakeResolve[i].ThisQInterval = -1; set->SPSAddr[i].type = mDNSAddrType_None; } set->NextSPSAttempt = -1; set->NextSPSAttemptTime = m->timenow; } mDNSexport void mDNS_ActivateNetWake_internal(mDNS *const m, NetworkInterfaceInfo *set) { NetworkInterfaceInfo *p = m->HostInterfaces; while (p && p != set) p=p->next; if (!p) { LogMsg("mDNS_ActivateNetWake_internal: NetworkInterfaceInfo %p not found in active list", set); return; } if (set->InterfaceActive) { LogSPS("ActivateNetWake for %s (%#a)", set->ifname, &set->ip); mDNS_StartBrowse_internal(m, &set->NetWakeBrowse, &SleepProxyServiceType, &localdomain, set->InterfaceID, mDNSfalse, m->SPSBrowseCallback, set); } } mDNSexport void mDNS_DeactivateNetWake_internal(mDNS *const m, NetworkInterfaceInfo *set) { NetworkInterfaceInfo *p = m->HostInterfaces; while (p && p != set) p=p->next; if (!p) { LogMsg("mDNS_DeactivateNetWake_internal: NetworkInterfaceInfo %p not found in active list", set); return; } if (set->NetWakeBrowse.ThisQInterval >= 0) { int i; LogSPS("DeactivateNetWake for %s (%#a)", set->ifname, &set->ip); // Stop our browse and resolve operations mDNS_StopQuery_internal(m, &set->NetWakeBrowse); for (i=0; i<3; i++) if (set->NetWakeResolve[i].ThisQInterval >= 0) mDNS_StopQuery_internal(m, &set->NetWakeResolve[i]); // Make special call to the browse callback to let it know it can to remove all records for this interface if (m->SPSBrowseCallback) { mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback m->SPSBrowseCallback(m, &set->NetWakeBrowse, mDNSNULL, mDNSfalse); mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again } // Reset our variables back to initial state, so we're ready for when NetWake is turned back on // (includes resetting NetWakeBrowse.ThisQInterval back to -1) InitializeNetWakeState(m, set); } } mDNSexport mStatus mDNS_RegisterInterface(mDNS *const m, NetworkInterfaceInfo *set, mDNSBool flapping) { AuthRecord *rr; mDNSBool FirstOfType = mDNStrue; NetworkInterfaceInfo **p = &m->HostInterfaces; if (!set->InterfaceID) { LogMsg("mDNS_RegisterInterface: Error! Tried to register a NetworkInterfaceInfo %#a with zero InterfaceID", &set->ip); return(mStatus_Invalid); } if (!mDNSAddressIsValidNonZero(&set->mask)) { LogMsg("mDNS_RegisterInterface: Error! Tried to register a NetworkInterfaceInfo %#a with invalid mask %#a", &set->ip, &set->mask); return(mStatus_Invalid); } mDNS_Lock(m); // Assume this interface will be active now, unless we find a duplicate already in the list set->InterfaceActive = mDNStrue; set->IPv4Available = (mDNSu8)(set->ip.type == mDNSAddrType_IPv4 && set->McastTxRx); set->IPv6Available = (mDNSu8)(set->ip.type == mDNSAddrType_IPv6 && set->McastTxRx); InitializeNetWakeState(m, set); // Scan list to see if this InterfaceID is already represented while (*p) { if (*p == set) { LogMsg("mDNS_RegisterInterface: Error! Tried to register a NetworkInterfaceInfo that's already in the list"); mDNS_Unlock(m); return(mStatus_AlreadyRegistered); } if ((*p)->InterfaceID == set->InterfaceID) { // This InterfaceID already represented by a different interface in the list, so mark this instance inactive for now set->InterfaceActive = mDNSfalse; if (set->ip.type == (*p)->ip.type) FirstOfType = mDNSfalse; if (set->ip.type == mDNSAddrType_IPv4 && set->McastTxRx) (*p)->IPv4Available = mDNStrue; if (set->ip.type == mDNSAddrType_IPv6 && set->McastTxRx) (*p)->IPv6Available = mDNStrue; } p=&(*p)->next; } set->next = mDNSNULL; *p = set; if (set->Advertise) AdvertiseInterface(m, set); LogInfo("mDNS_RegisterInterface: InterfaceID %p %s (%#a) %s", set->InterfaceID, set->ifname, &set->ip, set->InterfaceActive ? "not represented in list; marking active and retriggering queries" : "already represented in list; marking inactive for now"); if (set->NetWake) mDNS_ActivateNetWake_internal(m, set); // In early versions of OS X the IPv6 address remains on an interface even when the interface is turned off, // giving the false impression that there's an active representative of this interface when there really isn't. // Therefore, when registering an interface, we want to re-trigger our questions and re-probe our Resource Records, // even if we believe that we previously had an active representative of this interface. if (set->McastTxRx && (FirstOfType || set->InterfaceActive)) { DNSQuestion *q; // Normally, after an interface comes up, we pause half a second before beginning probing. // This is to guard against cases where there's rapid interface changes, where we could be confused by // seeing packets we ourselves sent just moments ago (perhaps when this interface had a different address) // which are then echoed back after a short delay by some Ethernet switches and some 802.11 base stations. // We don't want to do a probe, and then see a stale echo of an announcement we ourselves sent, // and think it's a conflicting answer to our probe. // In the case of a flapping interface, we pause for five seconds, and reduce the announcement count to one packet. const mDNSs32 probedelay = flapping ? mDNSPlatformOneSecond * 5 : mDNSPlatformOneSecond / 2; const mDNSu8 numannounce = flapping ? (mDNSu8)1 : InitialAnnounceCount; // Use a small amount of randomness: // In the case of a network administrator turning on an Ethernet hub so that all the // connected machines establish link at exactly the same time, we don't want them all // to go and hit the network with identical queries at exactly the same moment. // We set a random delay of up to InitialQuestionInterval (1/3 second). // We must *never* set m->SuppressSending to more than that (or set it repeatedly in a way // that causes mDNSResponder to remain in a prolonged state of SuppressSending, because // suppressing packet sending for more than about 1/3 second can cause protocol correctness // to start to break down (e.g. we don't answer probes fast enough, and get name conflicts). // See mDNS: m->SuppressSending set too enthusiastically if (!m->SuppressSending) m->SuppressSending = m->timenow + (mDNSs32)mDNSRandom((mDNSu32)InitialQuestionInterval); if (flapping) LogMsg("mDNS_RegisterInterface: Frequent transitions for interface %s (%#a)", set->ifname, &set->ip); LogInfo("mDNS_RegisterInterface: %s (%#a) probedelay %d", set->ifname, &set->ip, probedelay); if (m->SuppressProbes == 0 || m->SuppressProbes - NonZeroTime(m->timenow + probedelay) < 0) m->SuppressProbes = NonZeroTime(m->timenow + probedelay); // Include OWNER option in packets for 60 seconds after connecting to the network. Setting // it here also handles the wake up case as the network link comes UP after waking causing // us to reconnect to the network. If we do this as part of the wake up code, it is possible // that the network link comes UP after 60 seconds and we never set the OWNER option m->AnnounceOwner = NonZeroTime(m->timenow + 60 * mDNSPlatformOneSecond); LogInfo("mDNS_RegisterInterface: Setting AnnounceOwner"); for (q = m->Questions; q; q=q->next) // Scan our list of questions if (mDNSOpaque16IsZero(q->TargetQID)) if (!q->InterfaceID || q->InterfaceID == set->InterfaceID) // If non-specific Q, or Q on this specific interface, { // then reactivate this question // If flapping, delay between first and second queries is nine seconds instead of one second mDNSBool dodelay = flapping && (q->FlappingInterface1 == set->InterfaceID || q->FlappingInterface2 == set->InterfaceID); mDNSs32 initial = dodelay ? InitialQuestionInterval * QuestionIntervalStep2 : InitialQuestionInterval; mDNSs32 qdelay = dodelay ? mDNSPlatformOneSecond * 5 : 0; if (dodelay) LogInfo("No cache records expired for %##s (%s); okay to delay questions a little", q->qname.c, DNSTypeName(q->qtype)); if (!q->ThisQInterval || q->ThisQInterval > initial) { q->ThisQInterval = initial; q->RequestUnicast = 2; // Set to 2 because is decremented once *before* we check it } q->LastQTime = m->timenow - q->ThisQInterval + qdelay; q->RecentAnswerPkts = 0; SetNextQueryTime(m,q); } // For all our non-specific authoritative resource records (and any dormant records specific to this interface) // we now need them to re-probe if necessary, and then re-announce. for (rr = m->ResourceRecords; rr; rr=rr->next) if (!AuthRecord_uDNS(rr)) if (!rr->resrec.InterfaceID || rr->resrec.InterfaceID == set->InterfaceID) { if (rr->resrec.RecordType == kDNSRecordTypeVerified && !rr->DependentOn) rr->resrec.RecordType = kDNSRecordTypeUnique; rr->ProbeCount = DefaultProbeCountForRecordType(rr->resrec.RecordType); if (rr->AnnounceCount < numannounce) rr->AnnounceCount = numannounce; rr->SendNSECNow = mDNSNULL; InitializeLastAPTime(m, rr); } } RestartRecordGetZoneData(m); CheckSuppressUnusableQuestions(m); mDNS_UpdateAllowSleep(m); mDNS_Unlock(m); return(mStatus_NoError); } // Note: mDNS_DeregisterInterface calls mDNS_Deregister_internal which can call a user callback, which may change // the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSexport void mDNS_DeregisterInterface(mDNS *const m, NetworkInterfaceInfo *set, mDNSBool flapping) { NetworkInterfaceInfo **p = &m->HostInterfaces; mDNSBool revalidate = mDNSfalse; mDNS_Lock(m); // Find this record in our list while (*p && *p != set) p=&(*p)->next; if (!*p) { debugf("mDNS_DeregisterInterface: NetworkInterfaceInfo not found in list"); mDNS_Unlock(m); return; } mDNS_DeactivateNetWake_internal(m, set); // Unlink this record from our list *p = (*p)->next; set->next = mDNSNULL; if (!set->InterfaceActive) { // If this interface not the active member of its set, update the v4/v6Available flags for the active member NetworkInterfaceInfo *intf; for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->InterfaceActive && intf->InterfaceID == set->InterfaceID) UpdateInterfaceProtocols(m, intf); } else { NetworkInterfaceInfo *intf = FirstInterfaceForID(m, set->InterfaceID); if (intf) { LogInfo("mDNS_DeregisterInterface: Another representative of InterfaceID %p %s (%#a) exists;" " making it active", set->InterfaceID, set->ifname, &set->ip); if (intf->InterfaceActive) LogMsg("mDNS_DeregisterInterface: ERROR intf->InterfaceActive already set for %s (%#a)", set->ifname, &set->ip); intf->InterfaceActive = mDNStrue; UpdateInterfaceProtocols(m, intf); if (intf->NetWake) mDNS_ActivateNetWake_internal(m, intf); // See if another representative *of the same type* exists. If not, we mave have gone from // dual-stack to v6-only (or v4-only) so we need to reconfirm which records are still valid. for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->InterfaceID == set->InterfaceID && intf->ip.type == set->ip.type) break; if (!intf) revalidate = mDNStrue; } else { mDNSu32 slot; CacheGroup *cg; CacheRecord *rr; DNSQuestion *q; DNSServer *s; LogInfo("mDNS_DeregisterInterface: Last representative of InterfaceID %p %s (%#a) deregistered;" " marking questions etc. dormant", set->InterfaceID, set->ifname, &set->ip); if (set->McastTxRx && flapping) LogMsg("DeregisterInterface: Frequent transitions for interface %s (%#a)", set->ifname, &set->ip); // 1. Deactivate any questions specific to this interface, and tag appropriate questions // so that mDNS_RegisterInterface() knows how swiftly it needs to reactivate them for (q = m->Questions; q; q=q->next) { if (q->InterfaceID == set->InterfaceID) q->ThisQInterval = 0; if (!q->InterfaceID || q->InterfaceID == set->InterfaceID) { q->FlappingInterface2 = q->FlappingInterface1; q->FlappingInterface1 = set->InterfaceID; // Keep history of the last two interfaces to go away } } // 2. Flush any cache records received on this interface revalidate = mDNSfalse; // Don't revalidate if we're flushing the records FORALL_CACHERECORDS(slot, cg, rr) if (rr->resrec.InterfaceID == set->InterfaceID) { // If this interface is deemed flapping, // postpone deleting the cache records in case the interface comes back again if (set->McastTxRx && flapping) { // For a flapping interface we want these record to go away after 30 seconds mDNS_Reconfirm_internal(m, rr, kDefaultReconfirmTimeForFlappingInterface); // We set UnansweredQueries = MaxUnansweredQueries so we don't waste time doing any queries for them -- // if the interface does come back, any relevant questions will be reactivated anyway rr->UnansweredQueries = MaxUnansweredQueries; } else mDNS_PurgeCacheResourceRecord(m, rr); } // 3. Any DNS servers specific to this interface are now unusable for (s = m->DNSServers; s; s = s->next) if (s->interface == set->InterfaceID) { s->interface = mDNSInterface_Any; s->teststate = DNSServer_Disabled; } } } // If we were advertising on this interface, deregister those address and reverse-lookup records now if (set->Advertise) DeadvertiseInterface(m, set); // If we have any cache records received on this interface that went away, then re-verify them. // In some versions of OS X the IPv6 address remains on an interface even when the interface is turned off, // giving the false impression that there's an active representative of this interface when there really isn't. // Don't need to do this when shutting down, because *all* interfaces are about to go away if (revalidate && !m->ShutdownTime) { mDNSu32 slot; CacheGroup *cg; CacheRecord *rr; FORALL_CACHERECORDS(slot, cg, rr) if (rr->resrec.InterfaceID == set->InterfaceID) mDNS_Reconfirm_internal(m, rr, kDefaultReconfirmTimeForFlappingInterface); } CheckSuppressUnusableQuestions(m); mDNS_UpdateAllowSleep(m); mDNS_Unlock(m); } mDNSlocal void ServiceCallback(mDNS *const m, AuthRecord *const rr, mStatus result) { ServiceRecordSet *sr = (ServiceRecordSet *)rr->RecordContext; (void)m; // Unused parameter #if MDNS_DEBUGMSGS { char *msg = "Unknown result"; if (result == mStatus_NoError) msg = "Name Registered"; else if (result == mStatus_NameConflict) msg = "Name Conflict"; else if (result == mStatus_MemFree) msg = "Memory Free"; debugf("ServiceCallback: %##s (%s) %s (%d)", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), msg, result); } #endif // Only pass on the NoError acknowledgement for the SRV record (when it finishes probing) if (result == mStatus_NoError && rr != &sr->RR_SRV) return; // If we got a name conflict on either SRV or TXT, forcibly deregister this service, and record that we did that if (result == mStatus_NameConflict) { sr->Conflict = mDNStrue; // Record that this service set had a conflict mDNS_DeregisterService(m, sr); // Unlink the records from our list return; } if (result == mStatus_MemFree) { // If the SRV/TXT/PTR records, or the _services._dns-sd._udp record, or any of the subtype PTR records, // are still in the process of deregistering, don't pass on the NameConflict/MemFree message until // every record is finished cleaning up. mDNSu32 i; ExtraResourceRecord *e = sr->Extras; if (sr->RR_SRV.resrec.RecordType != kDNSRecordTypeUnregistered) return; if (sr->RR_TXT.resrec.RecordType != kDNSRecordTypeUnregistered) return; if (sr->RR_PTR.resrec.RecordType != kDNSRecordTypeUnregistered) return; if (sr->RR_ADV.resrec.RecordType != kDNSRecordTypeUnregistered) return; for (i=0; iNumSubTypes; i++) if (sr->SubTypes[i].resrec.RecordType != kDNSRecordTypeUnregistered) return; while (e) { if (e->r.resrec.RecordType != kDNSRecordTypeUnregistered) return; e = e->next; } // If this ServiceRecordSet was forcibly deregistered, and now its memory is ready for reuse, // then we can now report the NameConflict to the client if (sr->Conflict) result = mStatus_NameConflict; } LogInfo("ServiceCallback: All records %s for %##s", (result == mStatus_MemFree ? "Unregistered": "Registered"), sr->RR_PTR.resrec.name->c); // CAUTION: MUST NOT do anything more with sr after calling sr->Callback(), because the client's callback // function is allowed to do anything, including deregistering this service and freeing its memory. if (sr->ServiceCallback) sr->ServiceCallback(m, sr, result); } mDNSlocal void NSSCallback(mDNS *const m, AuthRecord *const rr, mStatus result) { ServiceRecordSet *sr = (ServiceRecordSet *)rr->RecordContext; if (sr->ServiceCallback) sr->ServiceCallback(m, sr, result); } // Note: // Name is first label of domain name (any dots in the name are actual dots, not label separators) // Type is service type (e.g. "_ipp._tcp.") // Domain is fully qualified domain name (i.e. ending with a null label) // We always register a TXT, even if it is empty (so that clients are not // left waiting forever looking for a nonexistent record.) // If the host parameter is mDNSNULL or the root domain (ASCII NUL), // then the default host name (m->MulticastHostname) is automatically used // If the optional target host parameter is set, then the storage it points to must remain valid for the lifetime of the service registration mDNSexport mStatus mDNS_RegisterService(mDNS *const m, ServiceRecordSet *sr, const domainlabel *const name, const domainname *const type, const domainname *const domain, const domainname *const host, mDNSIPPort port, const mDNSu8 txtinfo[], mDNSu16 txtlen, AuthRecord *SubTypes, mDNSu32 NumSubTypes, mDNSInterfaceID InterfaceID, mDNSServiceCallback Callback, void *Context, mDNSu32 flags) { mStatus err; mDNSu32 i; mDNSu32 hostTTL; AuthRecType artype; mDNSu8 recordType = (flags & regFlagKnownUnique) ? kDNSRecordTypeKnownUnique : kDNSRecordTypeUnique; sr->ServiceCallback = Callback; sr->ServiceContext = Context; sr->Conflict = mDNSfalse; sr->Extras = mDNSNULL; sr->NumSubTypes = NumSubTypes; sr->SubTypes = SubTypes; if (InterfaceID == mDNSInterface_LocalOnly) artype = AuthRecordLocalOnly; else if (InterfaceID == mDNSInterface_P2P) artype = AuthRecordP2P; else if ((InterfaceID == mDNSInterface_Any) && (flags & regFlagIncludeP2P)) artype = AuthRecordAnyIncludeP2P; else artype = AuthRecordAny; // Initialize the AuthRecord objects to sane values // Need to initialize everything correctly *before* making the decision whether to do a RegisterNoSuchService and bail out mDNS_SetupResourceRecord(&sr->RR_ADV, mDNSNULL, InterfaceID, kDNSType_PTR, kStandardTTL, kDNSRecordTypeAdvisory, artype, ServiceCallback, sr); mDNS_SetupResourceRecord(&sr->RR_PTR, mDNSNULL, InterfaceID, kDNSType_PTR, kStandardTTL, kDNSRecordTypeShared, artype, ServiceCallback, sr); if (SameDomainName(type, (const domainname *) "\x4" "_ubd" "\x4" "_tcp")) hostTTL = kHostNameSmallTTL; else hostTTL = kHostNameTTL; mDNS_SetupResourceRecord(&sr->RR_SRV, mDNSNULL, InterfaceID, kDNSType_SRV, hostTTL, recordType, artype, ServiceCallback, sr); mDNS_SetupResourceRecord(&sr->RR_TXT, mDNSNULL, InterfaceID, kDNSType_TXT, kStandardTTL, kDNSRecordTypeUnique, artype, ServiceCallback, sr); // If port number is zero, that means the client is really trying to do a RegisterNoSuchService if (mDNSIPPortIsZero(port)) return(mDNS_RegisterNoSuchService(m, &sr->RR_SRV, name, type, domain, mDNSNULL, InterfaceID, NSSCallback, sr, (flags & regFlagIncludeP2P))); // If the client is registering an oversized TXT record, // it is the client's responsibility to alloate a ServiceRecordSet structure that is large enough for it if (sr->RR_TXT.resrec.rdata->MaxRDLength < txtlen) sr->RR_TXT.resrec.rdata->MaxRDLength = txtlen; // Set up the record names // For now we only create an advisory record for the main type, not for subtypes // We need to gain some operational experience before we decide if there's a need to create them for subtypes too if (ConstructServiceName(&sr->RR_ADV.namestorage, (const domainlabel*)"\x09_services", (const domainname*)"\x07_dns-sd\x04_udp", domain) == mDNSNULL) return(mStatus_BadParamErr); if (ConstructServiceName(&sr->RR_PTR.namestorage, mDNSNULL, type, domain) == mDNSNULL) return(mStatus_BadParamErr); if (ConstructServiceName(&sr->RR_SRV.namestorage, name, type, domain) == mDNSNULL) return(mStatus_BadParamErr); AssignDomainName(&sr->RR_TXT.namestorage, sr->RR_SRV.resrec.name); // 1. Set up the ADV record rdata to advertise our service type AssignDomainName(&sr->RR_ADV.resrec.rdata->u.name, sr->RR_PTR.resrec.name); // 2. Set up the PTR record rdata to point to our service name // We set up two additionals, so when a client asks for this PTR we automatically send the SRV and the TXT too // Note: uDNS registration code assumes that Additional1 points to the SRV record AssignDomainName(&sr->RR_PTR.resrec.rdata->u.name, sr->RR_SRV.resrec.name); sr->RR_PTR.Additional1 = &sr->RR_SRV; sr->RR_PTR.Additional2 = &sr->RR_TXT; // 2a. Set up any subtype PTRs to point to our service name // If the client is using subtypes, it is the client's responsibility to have // already set the first label of the record name to the subtype being registered for (i=0; iSubTypes[i].resrec.name); st.c[1+st.c[0]] = 0; // Only want the first label, not the whole FQDN (particularly for mDNS_RenameAndReregisterService()) AppendDomainName(&st, type); mDNS_SetupResourceRecord(&sr->SubTypes[i], mDNSNULL, InterfaceID, kDNSType_PTR, kStandardTTL, kDNSRecordTypeShared, artype, ServiceCallback, sr); if (ConstructServiceName(&sr->SubTypes[i].namestorage, mDNSNULL, &st, domain) == mDNSNULL) return(mStatus_BadParamErr); AssignDomainName(&sr->SubTypes[i].resrec.rdata->u.name, &sr->RR_SRV.namestorage); sr->SubTypes[i].Additional1 = &sr->RR_SRV; sr->SubTypes[i].Additional2 = &sr->RR_TXT; } // 3. Set up the SRV record rdata. sr->RR_SRV.resrec.rdata->u.srv.priority = 0; sr->RR_SRV.resrec.rdata->u.srv.weight = 0; sr->RR_SRV.resrec.rdata->u.srv.port = port; // Setting AutoTarget tells DNS that the target of this SRV is to be automatically kept in sync with our host name if (host && host->c[0]) AssignDomainName(&sr->RR_SRV.resrec.rdata->u.srv.target, host); else { sr->RR_SRV.AutoTarget = Target_AutoHost; sr->RR_SRV.resrec.rdata->u.srv.target.c[0] = '\0'; } // 4. Set up the TXT record rdata, // and set DependentOn because we're depending on the SRV record to find and resolve conflicts for us // Note: uDNS registration code assumes that DependentOn points to the SRV record if (txtinfo == mDNSNULL) sr->RR_TXT.resrec.rdlength = 0; else if (txtinfo != sr->RR_TXT.resrec.rdata->u.txt.c) { sr->RR_TXT.resrec.rdlength = txtlen; if (sr->RR_TXT.resrec.rdlength > sr->RR_TXT.resrec.rdata->MaxRDLength) return(mStatus_BadParamErr); mDNSPlatformMemCopy(sr->RR_TXT.resrec.rdata->u.txt.c, txtinfo, txtlen); } sr->RR_TXT.DependentOn = &sr->RR_SRV; mDNS_Lock(m); // It is important that we register SRV first. uDNS assumes that SRV is registered first so // that if the SRV cannot find a target, rest of the records that belong to this service // will not be activated. err = mDNS_Register_internal(m, &sr->RR_SRV); // If we can't register the SRV record due to errors, bail out. It has not been inserted in // any list and hence no need to deregister. We could probably do similar checks for other // records below and bail out. For now, this seems to be sufficient to address rdar://9304275 if (err) { mDNS_Unlock(m); return err; } if (!err) err = mDNS_Register_internal(m, &sr->RR_TXT); // We register the RR_PTR last, because we want to be sure that in the event of a forced call to // mDNS_StartExit, the RR_PTR will be the last one to be forcibly deregistered, since that is what triggers // the mStatus_MemFree callback to ServiceCallback, which in turn passes on the mStatus_MemFree back to // the client callback, which is then at liberty to free the ServiceRecordSet memory at will. We need to // make sure we've deregistered all our records and done any other necessary cleanup before that happens. if (!err) err = mDNS_Register_internal(m, &sr->RR_ADV); for (i=0; iSubTypes[i]); if (!err) err = mDNS_Register_internal(m, &sr->RR_PTR); mDNS_Unlock(m); if (err) mDNS_DeregisterService(m, sr); return(err); } mDNSexport mStatus mDNS_AddRecordToService(mDNS *const m, ServiceRecordSet *sr, ExtraResourceRecord *extra, RData *rdata, mDNSu32 ttl, mDNSu32 includeP2P) { ExtraResourceRecord **e; mStatus status; AuthRecType artype; mDNSInterfaceID InterfaceID = sr->RR_PTR.resrec.InterfaceID; if (InterfaceID == mDNSInterface_LocalOnly) artype = AuthRecordLocalOnly; if (InterfaceID == mDNSInterface_P2P) artype = AuthRecordP2P; else if ((InterfaceID == mDNSInterface_Any) && includeP2P) artype = AuthRecordAnyIncludeP2P; else artype = AuthRecordAny; extra->next = mDNSNULL; mDNS_SetupResourceRecord(&extra->r, rdata, sr->RR_PTR.resrec.InterfaceID, extra->r.resrec.rrtype, ttl, kDNSRecordTypeUnique, artype, ServiceCallback, sr); AssignDomainName(&extra->r.namestorage, sr->RR_SRV.resrec.name); mDNS_Lock(m); e = &sr->Extras; while (*e) e = &(*e)->next; if (ttl == 0) ttl = kStandardTTL; extra->r.DependentOn = &sr->RR_SRV; debugf("mDNS_AddRecordToService adding record to %##s %s %d", extra->r.resrec.name->c, DNSTypeName(extra->r.resrec.rrtype), extra->r.resrec.rdlength); status = mDNS_Register_internal(m, &extra->r); if (status == mStatus_NoError) *e = extra; mDNS_Unlock(m); return(status); } mDNSexport mStatus mDNS_RemoveRecordFromService(mDNS *const m, ServiceRecordSet *sr, ExtraResourceRecord *extra, mDNSRecordCallback MemFreeCallback, void *Context) { ExtraResourceRecord **e; mStatus status; mDNS_Lock(m); e = &sr->Extras; while (*e && *e != extra) e = &(*e)->next; if (!*e) { debugf("mDNS_RemoveRecordFromService failed to remove record from %##s", extra->r.resrec.name->c); status = mStatus_BadReferenceErr; } else { debugf("mDNS_RemoveRecordFromService removing record from %##s", extra->r.resrec.name->c); extra->r.RecordCallback = MemFreeCallback; extra->r.RecordContext = Context; *e = (*e)->next; status = mDNS_Deregister_internal(m, &extra->r, mDNS_Dereg_normal); } mDNS_Unlock(m); return(status); } mDNSexport mStatus mDNS_RenameAndReregisterService(mDNS *const m, ServiceRecordSet *const sr, const domainlabel *newname) { // Note: Don't need to use mDNS_Lock(m) here, because this code is just using public routines // mDNS_RegisterService() and mDNS_AddRecordToService(), which do the right locking internally. domainlabel name1, name2; domainname type, domain; const domainname *host = sr->RR_SRV.AutoTarget ? mDNSNULL : &sr->RR_SRV.resrec.rdata->u.srv.target; ExtraResourceRecord *extras = sr->Extras; mStatus err; DeconstructServiceName(sr->RR_SRV.resrec.name, &name1, &type, &domain); if (!newname) { name2 = name1; IncrementLabelSuffix(&name2, mDNStrue); newname = &name2; } if (SameDomainName(&domain, &localdomain)) debugf("%##s service renamed from \"%#s\" to \"%#s\"", type.c, name1.c, newname->c); else debugf("%##s service (domain %##s) renamed from \"%#s\" to \"%#s\"",type.c, domain.c, name1.c, newname->c); err = mDNS_RegisterService(m, sr, newname, &type, &domain, host, sr->RR_SRV.resrec.rdata->u.srv.port, sr->RR_TXT.resrec.rdata->u.txt.c, sr->RR_TXT.resrec.rdlength, sr->SubTypes, sr->NumSubTypes, sr->RR_PTR.resrec.InterfaceID, sr->ServiceCallback, sr->ServiceContext, 0); // mDNS_RegisterService() just reset sr->Extras to NULL. // Fortunately we already grabbed ourselves a copy of this pointer (above), so we can now run // through the old list of extra records, and re-add them to our freshly created service registration while (!err && extras) { ExtraResourceRecord *e = extras; extras = extras->next; err = mDNS_AddRecordToService(m, sr, e, e->r.resrec.rdata, e->r.resrec.rroriginalttl, 0); } return(err); } // Note: mDNS_DeregisterService calls mDNS_Deregister_internal which can call a user callback, // which may change the record list and/or question list. // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. mDNSexport mStatus mDNS_DeregisterService_drt(mDNS *const m, ServiceRecordSet *sr, mDNS_Dereg_type drt) { // If port number is zero, that means this was actually registered using mDNS_RegisterNoSuchService() if (mDNSIPPortIsZero(sr->RR_SRV.resrec.rdata->u.srv.port)) return(mDNS_DeregisterNoSuchService(m, &sr->RR_SRV)); if (sr->RR_PTR.resrec.RecordType == kDNSRecordTypeUnregistered) { debugf("Service set for %##s already deregistered", sr->RR_SRV.resrec.name->c); return(mStatus_BadReferenceErr); } else if (sr->RR_PTR.resrec.RecordType == kDNSRecordTypeDeregistering) { LogInfo("Service set for %##s already in the process of deregistering", sr->RR_SRV.resrec.name->c); // Avoid race condition: // If a service gets a conflict, then we set the Conflict flag to tell us to generate // an mStatus_NameConflict message when we get the mStatus_MemFree for our PTR record. // If the client happens to deregister the service in the middle of that process, then // we clear the flag back to the normal state, so that we deliver a plain mStatus_MemFree // instead of incorrectly promoting it to mStatus_NameConflict. // This race condition is exposed particularly when the conformance test generates // a whole batch of simultaneous conflicts across a range of services all advertised // using the same system default name, and if we don't take this precaution then // we end up incrementing m->nicelabel multiple times instead of just once. // Bug when auto-renaming Computer Name after name collision sr->Conflict = mDNSfalse; return(mStatus_NoError); } else { mDNSu32 i; mStatus status; ExtraResourceRecord *e; mDNS_Lock(m); e = sr->Extras; // We use mDNS_Dereg_repeat because, in the event of a collision, some or all of the // SRV, TXT, or Extra records could have already been automatically deregistered, and that's okay mDNS_Deregister_internal(m, &sr->RR_SRV, mDNS_Dereg_repeat); mDNS_Deregister_internal(m, &sr->RR_TXT, mDNS_Dereg_repeat); mDNS_Deregister_internal(m, &sr->RR_ADV, drt); // We deregister all of the extra records, but we leave the sr->Extras list intact // in case the client wants to do a RenameAndReregister and reinstate the registration while (e) { mDNS_Deregister_internal(m, &e->r, mDNS_Dereg_repeat); e = e->next; } for (i=0; iNumSubTypes; i++) mDNS_Deregister_internal(m, &sr->SubTypes[i], drt); status = mDNS_Deregister_internal(m, &sr->RR_PTR, drt); mDNS_Unlock(m); return(status); } } // Create a registration that asserts that no such service exists with this name. // This can be useful where there is a given function is available through several protocols. // For example, a printer called "Stuart's Printer" may implement printing via the "pdl-datastream" and "IPP" // protocols, but not via "LPR". In this case it would be prudent for the printer to assert the non-existence of an // "LPR" service called "Stuart's Printer". Without this precaution, another printer than offers only "LPR" printing // could inadvertently advertise its service under the same name "Stuart's Printer", which might be confusing for users. mDNSexport mStatus mDNS_RegisterNoSuchService(mDNS *const m, AuthRecord *const rr, const domainlabel *const name, const domainname *const type, const domainname *const domain, const domainname *const host, const mDNSInterfaceID InterfaceID, mDNSRecordCallback Callback, void *Context, mDNSBool includeP2P) { AuthRecType artype; if (InterfaceID == mDNSInterface_LocalOnly) artype = AuthRecordLocalOnly; else if (InterfaceID == mDNSInterface_P2P) artype = AuthRecordP2P; else if ((InterfaceID == mDNSInterface_Any) && includeP2P) artype = AuthRecordAnyIncludeP2P; else artype = AuthRecordAny; mDNS_SetupResourceRecord(rr, mDNSNULL, InterfaceID, kDNSType_SRV, kHostNameTTL, kDNSRecordTypeUnique, artype, Callback, Context); if (ConstructServiceName(&rr->namestorage, name, type, domain) == mDNSNULL) return(mStatus_BadParamErr); rr->resrec.rdata->u.srv.priority = 0; rr->resrec.rdata->u.srv.weight = 0; rr->resrec.rdata->u.srv.port = zeroIPPort; if (host && host->c[0]) AssignDomainName(&rr->resrec.rdata->u.srv.target, host); else rr->AutoTarget = Target_AutoHost; return(mDNS_Register(m, rr)); } mDNSexport mStatus mDNS_AdvertiseDomains(mDNS *const m, AuthRecord *rr, mDNS_DomainType DomainType, const mDNSInterfaceID InterfaceID, char *domname) { AuthRecType artype; if (InterfaceID == mDNSInterface_LocalOnly) artype = AuthRecordLocalOnly; else if (InterfaceID == mDNSInterface_P2P) artype = AuthRecordP2P; else artype = AuthRecordAny; mDNS_SetupResourceRecord(rr, mDNSNULL, InterfaceID, kDNSType_PTR, kStandardTTL, kDNSRecordTypeShared, artype, mDNSNULL, mDNSNULL); if (!MakeDomainNameFromDNSNameString(&rr->namestorage, mDNS_DomainTypeNames[DomainType])) return(mStatus_BadParamErr); if (!MakeDomainNameFromDNSNameString(&rr->resrec.rdata->u.name, domname)) return(mStatus_BadParamErr); return(mDNS_Register(m, rr)); } mDNSlocal mDNSBool mDNS_IdUsedInResourceRecordsList(mDNS * const m, mDNSOpaque16 id) { AuthRecord *r; for (r = m->ResourceRecords; r; r=r->next) if (mDNSSameOpaque16(id, r->updateid)) return mDNStrue; return mDNSfalse; } mDNSlocal mDNSBool mDNS_IdUsedInQuestionsList(mDNS * const m, mDNSOpaque16 id) { DNSQuestion *q; for (q = m->Questions; q; q=q->next) if (mDNSSameOpaque16(id, q->TargetQID)) return mDNStrue; return mDNSfalse; } mDNSexport mDNSOpaque16 mDNS_NewMessageID(mDNS * const m) { mDNSOpaque16 id; int i; for (i=0; i<10; i++) { id = mDNSOpaque16fromIntVal(1 + (mDNSu16)mDNSRandom(0xFFFE)); if (!mDNS_IdUsedInResourceRecordsList(m, id) && !mDNS_IdUsedInQuestionsList(m, id)) break; } debugf("mDNS_NewMessageID: %5d", mDNSVal16(id)); return id; } // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Sleep Proxy Server #endif mDNSlocal void RestartARPProbing(mDNS *const m, AuthRecord *const rr) { // If we see an ARP from a machine we think is sleeping, then either // (i) the machine has woken, or // (ii) it's just a stray old packet from before the machine slept // To handle the second case, we reset ProbeCount, so we'll suppress our own answers for a while, to avoid // generating ARP conflicts with a waking machine, and set rr->LastAPTime so we'll start probing again in 10 seconds. // If the machine has just woken then we'll discard our records when we see the first new mDNS probe from that machine. // If it was a stray old packet, then after 10 seconds we'll probe again and then start answering ARPs again. In this case we *do* // need to send new ARP Announcements, because the owner's ARP broadcasts will have updated neighboring ARP caches, so we need to // re-assert our (temporary) ownership of that IP address in order to receive subsequent packets addressed to that IPv4 address. rr->resrec.RecordType = kDNSRecordTypeUnique; rr->ProbeCount = DefaultProbeCountForTypeUnique; // If we haven't started announcing yet (and we're not already in ten-second-delay mode) the machine is probably // still going to sleep, so we just reset rr->ProbeCount so we'll continue probing until it stops responding. // If we *have* started announcing, the machine is probably in the process of waking back up, so in that case // we're more cautious and we wait ten seconds before probing it again. We do this because while waking from // sleep, some network interfaces tend to lose or delay inbound packets, and without this delay, if the waking machine // didn't answer our three probes within three seconds then we'd announce and cause it an unnecessary address conflict. if (rr->AnnounceCount == InitialAnnounceCount && m->timenow - rr->LastAPTime >= 0) InitializeLastAPTime(m, rr); else { rr->AnnounceCount = InitialAnnounceCount; rr->ThisAPInterval = mDNSPlatformOneSecond; rr->LastAPTime = m->timenow + mDNSPlatformOneSecond * 9; // Send first packet at rr->LastAPTime + rr->ThisAPInterval, i.e. 10 seconds from now SetNextAnnounceProbeTime(m, rr); } } mDNSlocal void mDNSCoreReceiveRawARP(mDNS *const m, const ARP_EthIP *const arp, const mDNSInterfaceID InterfaceID) { static const mDNSOpaque16 ARP_op_request = { { 0, 1 } }; AuthRecord *rr; NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID); if (!intf) return; mDNS_Lock(m); // Pass 1: // Process ARP Requests and Probes (but not Announcements), and generate an ARP Reply if necessary. // We also process ARPs from our own kernel (and 'answer' them by injecting a local ARP table entry) // We ignore ARP Announcements here -- Announcements are not questions, they're assertions, so we don't need to answer them. // The times we might need to react to an ARP Announcement are: // (i) as an indication that the host in question has not gone to sleep yet (so we should delay beginning to proxy for it) or // (ii) if it's a conflicting Announcement from another host // -- and we check for these in Pass 2 below. if (mDNSSameOpaque16(arp->op, ARP_op_request) && !mDNSSameIPv4Address(arp->spa, arp->tpa)) { for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->AddressProxy.type == mDNSAddrType_IPv4 && mDNSSameIPv4Address(rr->AddressProxy.ip.v4, arp->tpa)) { static const char msg1[] = "ARP Req from owner -- re-probing"; static const char msg2[] = "Ignoring ARP Request from "; static const char msg3[] = "Creating Local ARP Cache entry "; static const char msg4[] = "Answering ARP Request from "; const char *const msg = mDNSSameEthAddress(&arp->sha, &rr->WakeUp.IMAC) ? msg1 : (rr->AnnounceCount == InitialAnnounceCount) ? msg2 : mDNSSameEthAddress(&arp->sha, &intf->MAC) ? msg3 : msg4; LogSPS("%-7s %s %.6a %.4a for %.4a -- H-MAC %.6a I-MAC %.6a %s", intf->ifname, msg, &arp->sha, &arp->spa, &arp->tpa, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, rr)); if (msg == msg1) RestartARPProbing(m, rr); else if (msg == msg3) mDNSPlatformSetLocalAddressCacheEntry(m, &rr->AddressProxy, &rr->WakeUp.IMAC, InterfaceID); else if (msg == msg4) SendARP(m, 2, rr, &arp->tpa, &arp->sha, &arp->spa, &arp->sha); } } // Pass 2: // For all types of ARP packet we check the Sender IP address to make sure it doesn't conflict with any AddressProxy record we're holding. // (Strictly speaking we're only checking Announcement/Request/Reply packets, since ARP Probes have zero Sender IP address, // so by definition (and by design) they can never conflict with any real (i.e. non-zero) IP address). // We ignore ARPs we sent ourselves (Sender MAC address is our MAC address) because our own proxy ARPs do not constitute a conflict that we need to handle. // If we see an apparently conflicting ARP, we check the sender hardware address: // If the sender hardware address is the original owner this is benign, so we just suppress our own proxy answering for a while longer. // If the sender hardware address is *not* the original owner, then this is a conflict, and we need to wake the sleeping machine to handle it. if (mDNSSameEthAddress(&arp->sha, &intf->MAC)) debugf("ARP from self for %.4a", &arp->tpa); else { if (!mDNSSameIPv4Address(arp->spa, zerov4Addr)) for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->AddressProxy.type == mDNSAddrType_IPv4 && mDNSSameIPv4Address(rr->AddressProxy.ip.v4, arp->spa)) { RestartARPProbing(m, rr); if (mDNSSameEthAddress(&arp->sha, &rr->WakeUp.IMAC)) LogSPS("%-7s ARP %s from owner %.6a %.4a for %-15.4a -- re-starting probing for %s", intf->ifname, mDNSSameIPv4Address(arp->spa, arp->tpa) ? "Announcement " : mDNSSameOpaque16(arp->op, ARP_op_request) ? "Request " : "Response ", &arp->sha, &arp->spa, &arp->tpa, ARDisplayString(m, rr)); else { LogMsg("%-7s Conflicting ARP from %.6a %.4a for %.4a -- waking H-MAC %.6a I-MAC %.6a %s", intf->ifname, &arp->sha, &arp->spa, &arp->tpa, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, rr)); ScheduleWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.HMAC); } } } mDNS_Unlock(m); } /* // Option 1 is Source Link Layer Address Option // Option 2 is Target Link Layer Address Option mDNSlocal const mDNSEthAddr *GetLinkLayerAddressOption(const IPv6NDP *const ndp, const mDNSu8 *const end, mDNSu8 op) { const mDNSu8 *options = (mDNSu8 *)(ndp+1); while (options < end) { debugf("NDP Option %02X len %2d %d", options[0], options[1], end - options); if (options[0] == op && options[1] == 1) return (const mDNSEthAddr*)(options+2); options += options[1] * 8; } return mDNSNULL; } */ mDNSlocal void mDNSCoreReceiveRawND(mDNS *const m, const mDNSEthAddr *const sha, const mDNSv6Addr *spa, const IPv6NDP *const ndp, const mDNSu8 *const end, const mDNSInterfaceID InterfaceID) { AuthRecord *rr; NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID); if (!intf) return; mDNS_Lock(m); // Pass 1: Process Neighbor Solicitations, and generate a Neighbor Advertisement if necessary. if (ndp->type == NDP_Sol) { //const mDNSEthAddr *const sha = GetLinkLayerAddressOption(ndp, end, NDP_SrcLL); (void)end; for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->AddressProxy.type == mDNSAddrType_IPv6 && mDNSSameIPv6Address(rr->AddressProxy.ip.v6, ndp->target)) { static const char msg1[] = "NDP Req from owner -- re-probing"; static const char msg2[] = "Ignoring NDP Request from "; static const char msg3[] = "Creating Local NDP Cache entry "; static const char msg4[] = "Answering NDP Request from "; static const char msg5[] = "Answering NDP Probe from "; const char *const msg = sha && mDNSSameEthAddress(sha, &rr->WakeUp.IMAC) ? msg1 : (rr->AnnounceCount == InitialAnnounceCount) ? msg2 : sha && mDNSSameEthAddress(sha, &intf->MAC) ? msg3 : spa && mDNSIPv6AddressIsZero(*spa) ? msg4 : msg5; LogSPS("%-7s %s %.6a %.16a for %.16a -- H-MAC %.6a I-MAC %.6a %s", intf->ifname, msg, sha, spa, &ndp->target, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, rr)); if (msg == msg1) RestartARPProbing(m, rr); else if (msg == msg3) { if (!(m->KnownBugs & mDNS_KnownBug_LimitedIPv6)) mDNSPlatformSetLocalAddressCacheEntry(m, &rr->AddressProxy, &rr->WakeUp.IMAC, InterfaceID); } else if (msg == msg4) SendNDP(m, NDP_Adv, NDP_Solicited, rr, &ndp->target, mDNSNULL, spa, sha ); else if (msg == msg5) SendNDP(m, NDP_Adv, 0, rr, &ndp->target, mDNSNULL, &AllHosts_v6, &AllHosts_v6_Eth); } } // Pass 2: For all types of NDP packet we check the Sender IP address to make sure it doesn't conflict with any AddressProxy record we're holding. if (mDNSSameEthAddress(sha, &intf->MAC)) debugf("NDP from self for %.16a", &ndp->target); else { // For Neighbor Advertisements we check the Target address field, not the actual IPv6 source address. // When a machine has both link-local and routable IPv6 addresses, it may send NDP packets making assertions // about its routable IPv6 address, using its link-local address as the source address for all NDP packets. // Hence it is the NDP target address we care about, not the actual packet source address. if (ndp->type == NDP_Adv) spa = &ndp->target; if (!mDNSSameIPv6Address(*spa, zerov6Addr)) for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->AddressProxy.type == mDNSAddrType_IPv6 && mDNSSameIPv6Address(rr->AddressProxy.ip.v6, *spa)) { RestartARPProbing(m, rr); if (mDNSSameEthAddress(sha, &rr->WakeUp.IMAC)) LogSPS("%-7s NDP %s from owner %.6a %.16a for %.16a -- re-starting probing for %s", intf->ifname, ndp->type == NDP_Sol ? "Solicitation " : "Advertisement", sha, spa, &ndp->target, ARDisplayString(m, rr)); else { LogMsg("%-7s Conflicting NDP from %.6a %.16a for %.16a -- waking H-MAC %.6a I-MAC %.6a %s", intf->ifname, sha, spa, &ndp->target, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, rr)); ScheduleWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.HMAC); } } } mDNS_Unlock(m); } mDNSlocal void mDNSCoreReceiveRawTransportPacket(mDNS *const m, const mDNSEthAddr *const sha, const mDNSAddr *const src, const mDNSAddr *const dst, const mDNSu8 protocol, const mDNSu8 *const p, const TransportLayerPacket *const t, const mDNSu8 *const end, const mDNSInterfaceID InterfaceID, const mDNSu16 len) { const mDNSIPPort port = (protocol == 0x06) ? t->tcp.dst : (protocol == 0x11) ? t->udp.dst : zeroIPPort; mDNSBool wake = mDNSfalse; switch (protocol) { #define XX wake ? "Received" : "Ignoring", end-p case 0x01: LogSPS("Ignoring %d-byte ICMP from %#a to %#a", end-p, src, dst); break; case 0x06: { #define SSH_AsNumber 22 static const mDNSIPPort SSH = { { SSH_AsNumber >> 8, SSH_AsNumber & 0xFF } }; // Plan to wake if // (a) RST is not set, AND // (b) packet is SYN, SYN+FIN, or plain data packet (no SYN or FIN). We won't wake for FIN alone. wake = (!(t->tcp.flags & 4) && (t->tcp.flags & 3) != 1); // For now, to reduce spurious wakeups, we wake only for TCP SYN, // except for ssh connections, where we'll wake for plain data packets too if (!mDNSSameIPPort(port, SSH) && !(t->tcp.flags & 2)) wake = mDNSfalse; LogSPS("%s %d-byte TCP from %#a:%d to %#a:%d%s%s%s", XX, src, mDNSVal16(t->tcp.src), dst, mDNSVal16(port), (t->tcp.flags & 2) ? " SYN" : "", (t->tcp.flags & 1) ? " FIN" : "", (t->tcp.flags & 4) ? " RST" : ""); } break; case 0x11: { #define ARD_AsNumber 3283 static const mDNSIPPort ARD = { { ARD_AsNumber >> 8, ARD_AsNumber & 0xFF } }; const mDNSu16 udplen = (mDNSu16)((mDNSu16)t->bytes[4] << 8 | t->bytes[5]); // Length *including* 8-byte UDP header if (udplen >= sizeof(UDPHeader)) { const mDNSu16 datalen = udplen - sizeof(UDPHeader); wake = mDNStrue; // For Back to My Mac UDP port 4500 (IPSEC) packets, we do some special handling if (mDNSSameIPPort(port, IPSECPort)) { // Specifically ignore NAT keepalive packets if (datalen == 1 && end >= &t->bytes[9] && t->bytes[8] == 0xFF) wake = mDNSfalse; else { // Skip over the Non-ESP Marker if present const mDNSBool NonESP = (end >= &t->bytes[12] && t->bytes[8] == 0 && t->bytes[9] == 0 && t->bytes[10] == 0 && t->bytes[11] == 0); const IKEHeader *const ike = (IKEHeader *)(t + (NonESP ? 12 : 8)); const mDNSu16 ikelen = datalen - (NonESP ? 4 : 0); if (ikelen >= sizeof(IKEHeader) && end >= ((mDNSu8 *)ike) + sizeof(IKEHeader)) if ((ike->Version & 0x10) == 0x10) { // ExchangeType == 5 means 'Informational' // ExchangeType == 34 means 'IKE_SA_INIT' if (ike->ExchangeType == 5 || ike->ExchangeType == 34) wake = mDNSfalse; LogSPS("%s %d-byte IKE ExchangeType %d", XX, ike->ExchangeType); } } } // For now, because we haven't yet worked out a clean elegant way to do this, we just special-case the // Apple Remote Desktop port number -- we ignore all packets to UDP 3283 (the "Net Assistant" port), // except for Apple Remote Desktop's explicit manual wakeup packet, which looks like this: // UDP header (8 bytes) // Payload: 13 88 00 6a 41 4e 41 20 (8 bytes) ffffffffffff (6 bytes) 16xMAC (96 bytes) = 110 bytes total if (mDNSSameIPPort(port, ARD)) wake = (datalen >= 110 && end >= &t->bytes[10] && t->bytes[8] == 0x13 && t->bytes[9] == 0x88); LogSPS("%s %d-byte UDP from %#a:%d to %#a:%d", XX, src, mDNSVal16(t->udp.src), dst, mDNSVal16(port)); } } break; case 0x3A: if (&t->bytes[len] <= end) { mDNSu16 checksum = IPv6CheckSum(&src->ip.v6, &dst->ip.v6, protocol, t->bytes, len); if (!checksum) mDNSCoreReceiveRawND(m, sha, &src->ip.v6, &t->ndp, &t->bytes[len], InterfaceID); else LogInfo("IPv6CheckSum bad %04X %02X%02X from %#a to %#a", checksum, t->bytes[2], t->bytes[3], src, dst); } break; default: LogSPS("Ignoring %d-byte IP packet unknown protocol %d from %#a to %#a", end-p, protocol, src, dst); break; } if (wake) { AuthRecord *rr, *r2; mDNS_Lock(m); for (rr = m->ResourceRecords; rr; rr=rr->next) if (rr->resrec.InterfaceID == InterfaceID && rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->AddressProxy.type && mDNSSameAddress(&rr->AddressProxy, dst)) { const mDNSu8 *const tp = (protocol == 6) ? (const mDNSu8 *)"\x4_tcp" : (const mDNSu8 *)"\x4_udp"; for (r2 = m->ResourceRecords; r2; r2=r2->next) if (r2->resrec.InterfaceID == InterfaceID && mDNSSameEthAddress(&r2->WakeUp.HMAC, &rr->WakeUp.HMAC) && r2->resrec.RecordType != kDNSRecordTypeDeregistering && r2->resrec.rrtype == kDNSType_SRV && mDNSSameIPPort(r2->resrec.rdata->u.srv.port, port) && SameDomainLabel(ThirdLabel(r2->resrec.name)->c, tp)) break; if (!r2 && mDNSSameIPPort(port, IPSECPort)) r2 = rr; // So that we wake for BTMM IPSEC packets, even without a matching SRV record if (r2) { LogMsg("Waking host at %s %#a H-MAC %.6a I-MAC %.6a for %s", InterfaceNameForID(m, rr->resrec.InterfaceID), dst, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m, r2)); ScheduleWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.HMAC); } else LogSPS("Sleeping host at %s %#a %.6a has no service on %#s %d", InterfaceNameForID(m, rr->resrec.InterfaceID), dst, &rr->WakeUp.HMAC, tp, mDNSVal16(port)); } mDNS_Unlock(m); } } mDNSexport void mDNSCoreReceiveRawPacket(mDNS *const m, const mDNSu8 *const p, const mDNSu8 *const end, const mDNSInterfaceID InterfaceID) { static const mDNSOpaque16 Ethertype_ARP = { { 0x08, 0x06 } }; // Ethertype 0x0806 = ARP static const mDNSOpaque16 Ethertype_IPv4 = { { 0x08, 0x00 } }; // Ethertype 0x0800 = IPv4 static const mDNSOpaque16 Ethertype_IPv6 = { { 0x86, 0xDD } }; // Ethertype 0x86DD = IPv6 static const mDNSOpaque16 ARP_hrd_eth = { { 0x00, 0x01 } }; // Hardware address space (Ethernet = 1) static const mDNSOpaque16 ARP_pro_ip = { { 0x08, 0x00 } }; // Protocol address space (IP = 0x0800) // Note: BPF guarantees that the NETWORK LAYER header will be word aligned, not the link-layer header. // In other words, we can safely assume that pkt below (ARP, IPv4 or IPv6) is properly word aligned, // but if pkt is 4-byte aligned, that necessarily means that eth CANNOT also be 4-byte aligned // since it points to a an address 14 bytes before pkt. const EthernetHeader *const eth = (const EthernetHeader *)p; const NetworkLayerPacket *const pkt = (const NetworkLayerPacket *)(eth+1); mDNSAddr src, dst; #define RequiredCapLen(P) ((P)==0x01 ? 4 : (P)==0x06 ? 20 : (P)==0x11 ? 8 : (P)==0x3A ? 24 : 0) // Is ARP? Length must be at least 14 + 28 = 42 bytes if (end >= p+42 && mDNSSameOpaque16(eth->ethertype, Ethertype_ARP) && mDNSSameOpaque16(pkt->arp.hrd, ARP_hrd_eth) && mDNSSameOpaque16(pkt->arp.pro, ARP_pro_ip)) mDNSCoreReceiveRawARP(m, &pkt->arp, InterfaceID); // Is IPv4 with zero fragmentation offset? Length must be at least 14 + 20 = 34 bytes else if (end >= p+34 && mDNSSameOpaque16(eth->ethertype, Ethertype_IPv4) && (pkt->v4.flagsfrags.b[0] & 0x1F) == 0 && pkt->v4.flagsfrags.b[1] == 0) { const mDNSu8 *const trans = p + 14 + (pkt->v4.vlen & 0xF) * 4; debugf("Got IPv4 %02X from %.4a to %.4a", pkt->v4.protocol, &pkt->v4.src, &pkt->v4.dst); src.type = mDNSAddrType_IPv4; src.ip.v4 = pkt->v4.src; dst.type = mDNSAddrType_IPv4; dst.ip.v4 = pkt->v4.dst; if (end >= trans + RequiredCapLen(pkt->v4.protocol)) mDNSCoreReceiveRawTransportPacket(m, ð->src, &src, &dst, pkt->v4.protocol, p, (TransportLayerPacket*)trans, end, InterfaceID, 0); } // Is IPv6? Length must be at least 14 + 28 = 42 bytes else if (end >= p+54 && mDNSSameOpaque16(eth->ethertype, Ethertype_IPv6)) { const mDNSu8 *const trans = p + 54; debugf("Got IPv6 %02X from %.16a to %.16a", pkt->v6.pro, &pkt->v6.src, &pkt->v6.dst); src.type = mDNSAddrType_IPv6; src.ip.v6 = pkt->v6.src; dst.type = mDNSAddrType_IPv6; dst.ip.v6 = pkt->v6.dst; if (end >= trans + RequiredCapLen(pkt->v6.pro)) mDNSCoreReceiveRawTransportPacket(m, ð->src, &src, &dst, pkt->v6.pro, p, (TransportLayerPacket*)trans, end, InterfaceID, (mDNSu16)pkt->bytes[4] << 8 | pkt->bytes[5]); } } mDNSlocal void ConstructSleepProxyServerName(mDNS *const m, domainlabel *name) { name->c[0] = (mDNSu8)mDNS_snprintf((char*)name->c+1, 62, "%d-%d-%d-%d %#s", m->SPSType, m->SPSPortability, m->SPSMarginalPower, m->SPSTotalPower, &m->nicelabel); } mDNSlocal void SleepProxyServerCallback(mDNS *const m, ServiceRecordSet *const srs, mStatus result) { if (result == mStatus_NameConflict) mDNS_RenameAndReregisterService(m, srs, mDNSNULL); else if (result == mStatus_MemFree) { if (m->SleepState) m->SPSState = 3; else { m->SPSState = (mDNSu8)(m->SPSSocket != mDNSNULL); if (m->SPSState) { domainlabel name; ConstructSleepProxyServerName(m, &name); mDNS_RegisterService(m, srs, &name, &SleepProxyServiceType, &localdomain, mDNSNULL, m->SPSSocket->port, // Host, port (mDNSu8 *)"", 1, // TXT data, length mDNSNULL, 0, // Subtypes (none) mDNSInterface_Any, // Interface ID SleepProxyServerCallback, mDNSNULL, 0); // Callback, context, flags } LogSPS("Sleep Proxy Server %#s %s", srs->RR_SRV.resrec.name->c, m->SPSState ? "started" : "stopped"); } } } // Called with lock held mDNSexport void mDNSCoreBeSleepProxyServer_internal(mDNS *const m, mDNSu8 sps, mDNSu8 port, mDNSu8 marginalpower, mDNSu8 totpower) { // This routine uses mDNS_DeregisterService and calls SleepProxyServerCallback, so we execute in user callback context mDNS_DropLockBeforeCallback(); // If turning off SPS, close our socket // (Do this first, BEFORE calling mDNS_DeregisterService below) if (!sps && m->SPSSocket) { mDNSPlatformUDPClose(m->SPSSocket); m->SPSSocket = mDNSNULL; } // If turning off, or changing type, deregister old name if (m->SPSState == 1 && sps != m->SPSType) { m->SPSState = 2; mDNS_DeregisterService_drt(m, &m->SPSRecords, sps ? mDNS_Dereg_rapid : mDNS_Dereg_normal); } // Record our new SPS parameters m->SPSType = sps; m->SPSPortability = port; m->SPSMarginalPower = marginalpower; m->SPSTotalPower = totpower; // If turning on, open socket and advertise service if (sps) { if (!m->SPSSocket) { m->SPSSocket = mDNSPlatformUDPSocket(m, zeroIPPort); if (!m->SPSSocket) { LogMsg("mDNSCoreBeSleepProxyServer: Failed to allocate SPSSocket"); goto fail; } } if (m->SPSState == 0) SleepProxyServerCallback(m, &m->SPSRecords, mStatus_MemFree); } else if (m->SPSState) { LogSPS("mDNSCoreBeSleepProxyServer turning off from state %d; will wake clients", m->SPSState); m->NextScheduledSPS = m->timenow; } fail: mDNS_ReclaimLockAfterCallback(); } // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Startup and Shutdown #endif mDNSlocal void mDNS_GrowCache_internal(mDNS *const m, CacheEntity *storage, mDNSu32 numrecords) { if (storage && numrecords) { mDNSu32 i; debugf("Adding cache storage for %d more records (%d bytes)", numrecords, numrecords*sizeof(CacheEntity)); for (i=0; irrcache_free; m->rrcache_free = storage; m->rrcache_size += numrecords; } } mDNSexport void mDNS_GrowCache(mDNS *const m, CacheEntity *storage, mDNSu32 numrecords) { mDNS_Lock(m); mDNS_GrowCache_internal(m, storage, numrecords); mDNS_Unlock(m); } mDNSexport mStatus mDNS_Init(mDNS *const m, mDNS_PlatformSupport *const p, CacheEntity *rrcachestorage, mDNSu32 rrcachesize, mDNSBool AdvertiseLocalAddresses, mDNSCallback *Callback, void *Context) { mDNSu32 slot; mDNSs32 timenow; mStatus result; if (!rrcachestorage) rrcachesize = 0; m->p = p; m->KnownBugs = 0; m->CanReceiveUnicastOn5353 = mDNSfalse; // Assume we can't receive unicasts on 5353, unless platform layer tells us otherwise m->AdvertiseLocalAddresses = AdvertiseLocalAddresses; m->DivertMulticastAdvertisements = mDNSfalse; m->mDNSPlatformStatus = mStatus_Waiting; m->UnicastPort4 = zeroIPPort; m->UnicastPort6 = zeroIPPort; m->PrimaryMAC = zeroEthAddr; m->MainCallback = Callback; m->MainContext = Context; m->rec.r.resrec.RecordType = 0; // For debugging: To catch and report locking failures m->mDNS_busy = 0; m->mDNS_reentrancy = 0; m->ShutdownTime = 0; m->lock_rrcache = 0; m->lock_Questions = 0; m->lock_Records = 0; // Task Scheduling variables result = mDNSPlatformTimeInit(); if (result != mStatus_NoError) return(result); m->timenow_adjust = (mDNSs32)mDNSRandom(0xFFFFFFFF); timenow = mDNS_TimeNow_NoLock(m); m->timenow = 0; // MUST only be set within mDNS_Lock/mDNS_Unlock section m->timenow_last = timenow; m->NextScheduledEvent = timenow; m->SuppressSending = timenow; m->NextCacheCheck = timenow + 0x78000000; m->NextScheduledQuery = timenow + 0x78000000; m->NextScheduledProbe = timenow + 0x78000000; m->NextScheduledResponse = timenow + 0x78000000; m->NextScheduledNATOp = timenow + 0x78000000; m->NextScheduledSPS = timenow + 0x78000000; m->NextScheduledStopTime = timenow + 0x78000000; m->RandomQueryDelay = 0; m->RandomReconfirmDelay = 0; m->PktNum = 0; m->LocalRemoveEvents = mDNSfalse; m->SleepState = SleepState_Awake; m->SleepSeqNum = 0; m->SystemWakeOnLANEnabled = mDNSfalse; m->AnnounceOwner = NonZeroTime(timenow + 60 * mDNSPlatformOneSecond); m->DelaySleep = 0; m->SleepLimit = 0; // These fields only required for mDNS Searcher... m->Questions = mDNSNULL; m->NewQuestions = mDNSNULL; m->CurrentQuestion = mDNSNULL; m->LocalOnlyQuestions = mDNSNULL; m->NewLocalOnlyQuestions = mDNSNULL; m->RestartQuestion = mDNSNULL; m->rrcache_size = 0; m->rrcache_totalused = 0; m->rrcache_active = 0; m->rrcache_report = 10; m->rrcache_free = mDNSNULL; for (slot = 0; slot < CACHE_HASH_SLOTS; slot++) { m->rrcache_hash[slot] = mDNSNULL; m->rrcache_nextcheck[slot] = timenow + 0x78000000;; } mDNS_GrowCache_internal(m, rrcachestorage, rrcachesize); m->rrauth.rrauth_free = mDNSNULL; for (slot = 0; slot < AUTH_HASH_SLOTS; slot++) m->rrauth.rrauth_hash[slot] = mDNSNULL; // Fields below only required for mDNS Responder... m->hostlabel.c[0] = 0; m->nicelabel.c[0] = 0; m->MulticastHostname.c[0] = 0; m->HIHardware.c[0] = 0; m->HISoftware.c[0] = 0; m->ResourceRecords = mDNSNULL; m->DuplicateRecords = mDNSNULL; m->NewLocalRecords = mDNSNULL; m->NewLocalOnlyRecords = mDNSfalse; m->CurrentRecord = mDNSNULL; m->HostInterfaces = mDNSNULL; m->ProbeFailTime = 0; m->NumFailedProbes = 0; m->SuppressProbes = 0; #ifndef UNICAST_DISABLED m->NextuDNSEvent = timenow + 0x78000000; m->NextSRVUpdate = timenow + 0x78000000; m->DNSServers = mDNSNULL; m->Router = zeroAddr; m->AdvertisedV4 = zeroAddr; m->AdvertisedV6 = zeroAddr; m->AuthInfoList = mDNSNULL; m->ReverseMap.ThisQInterval = -1; m->StaticHostname.c[0] = 0; m->FQDN.c[0] = 0; m->Hostnames = mDNSNULL; m->AutoTunnelHostAddr.b[0] = 0; m->AutoTunnelHostAddrActive = mDNSfalse; m->AutoTunnelLabel.c[0] = 0; m->StartWABQueries = mDNSfalse; m->RegisterAutoTunnel6 = mDNStrue; // NAT traversal fields m->NATTraversals = mDNSNULL; m->CurrentNATTraversal = mDNSNULL; m->retryIntervalGetAddr = 0; // delta between time sent and retry m->retryGetAddr = timenow + 0x78000000; // absolute time when we retry m->ExternalAddress = zerov4Addr; m->NATMcastRecvskt = mDNSNULL; m->LastNATupseconds = 0; m->LastNATReplyLocalTime = timenow; m->LastNATMapResultCode = NATErr_None; m->UPnPInterfaceID = 0; m->SSDPSocket = mDNSNULL; m->SSDPWANPPPConnection = mDNSfalse; m->UPnPRouterPort = zeroIPPort; m->UPnPSOAPPort = zeroIPPort; m->UPnPRouterURL = mDNSNULL; m->UPnPWANPPPConnection = mDNSfalse; m->UPnPSOAPURL = mDNSNULL; m->UPnPRouterAddressString = mDNSNULL; m->UPnPSOAPAddressString = mDNSNULL; m->SPSType = 0; m->SPSPortability = 0; m->SPSMarginalPower = 0; m->SPSTotalPower = 0; m->SPSState = 0; m->SPSProxyListChanged = mDNSNULL; m->SPSSocket = mDNSNULL; m->SPSBrowseCallback = mDNSNULL; m->ProxyRecords = 0; #endif #if APPLE_OSX_mDNSResponder m->TunnelClients = mDNSNULL; #if ! NO_WCF CHECK_WCF_FUNCTION(WCFConnectionNew) { m->WCF = WCFConnectionNew(); if (!m->WCF) { LogMsg("WCFConnectionNew failed"); return -1; } } #endif #endif result = mDNSPlatformInit(m); #ifndef UNICAST_DISABLED // It's better to do this *after* the platform layer has set up the // interface list and security credentials uDNS_SetupDNSConfig(m); // Get initial DNS configuration #endif return(result); } mDNSexport void mDNS_ConfigChanged(mDNS *const m) { if (m->SPSState == 1) { domainlabel name, newname; domainname type, domain; DeconstructServiceName(m->SPSRecords.RR_SRV.resrec.name, &name, &type, &domain); ConstructSleepProxyServerName(m, &newname); if (!SameDomainLabelCS(name.c, newname.c)) { LogSPS("Renaming SPS from “%#s” to “%#s”", name.c, newname.c); // When SleepProxyServerCallback gets the mStatus_MemFree message, // it will reregister the service under the new name m->SPSState = 2; mDNS_DeregisterService_drt(m, &m->SPSRecords, mDNS_Dereg_rapid); } } if (m->MainCallback) m->MainCallback(m, mStatus_ConfigChanged); } mDNSlocal void DynDNSHostNameCallback(mDNS *const m, AuthRecord *const rr, mStatus result) { (void)m; // unused debugf("NameStatusCallback: result %d for registration of name %##s", result, rr->resrec.name->c); mDNSPlatformDynDNSHostNameStatusChanged(rr->resrec.name, result); } mDNSlocal void PurgeOrReconfirmCacheRecord(mDNS *const m, CacheRecord *cr, const DNSServer * const ptr, mDNSBool lameduck) { mDNSBool purge = cr->resrec.RecordType == kDNSRecordTypePacketNegative || cr->resrec.rrtype == kDNSType_A || cr->resrec.rrtype == kDNSType_AAAA || cr->resrec.rrtype == kDNSType_SRV; (void) lameduck; (void) ptr; debugf("PurgeOrReconfirmCacheRecord: %s cache record due to %s server %p %#a:%d (%##s): %s", purge ? "purging" : "reconfirming", lameduck ? "lame duck" : "new", ptr, &ptr->addr, mDNSVal16(ptr->port), ptr->domain.c, CRDisplayString(m, cr)); if (purge) { LogInfo("PurgeorReconfirmCacheRecord: Purging Resourcerecord %s, RecordType %x", CRDisplayString(m, cr), cr->resrec.RecordType); mDNS_PurgeCacheResourceRecord(m, cr); } else { LogInfo("PurgeorReconfirmCacheRecord: Reconfirming Resourcerecord %s, RecordType %x", CRDisplayString(m, cr), cr->resrec.RecordType); mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer); } } mDNSlocal void mDNS_PurgeBeforeResolve(mDNS *const m, DNSQuestion *q) { const mDNSu32 slot = HashSlot(&q->qname); CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); CacheRecord *rp; for (rp = cg ? cg->members : mDNSNULL; rp; rp = rp->next) { if (SameNameRecordAnswersQuestion(&rp->resrec, q)) { LogInfo("mDNS_PurgeBeforeResolve: Flushing %s", CRDisplayString(m, rp)); mDNS_PurgeCacheResourceRecord(m, rp); } } } // Check for a positive unicast response to the question but with qtype mDNSexport mDNSBool mDNS_CheckForCacheRecord(mDNS *const m, DNSQuestion *q, mDNSu16 qtype) { DNSQuestion question; const mDNSu32 slot = HashSlot(&q->qname); CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); CacheRecord *rp; // Create an identical question but with qtype mDNS_SetupQuestion(&question, q->InterfaceID, &q->qname, qtype, mDNSNULL, mDNSNULL); question.qDNSServer = q->qDNSServer; for (rp = cg ? cg->members : mDNSNULL; rp; rp = rp->next) { if (!rp->resrec.InterfaceID && rp->resrec.RecordType != kDNSRecordTypePacketNegative && SameNameRecordAnswersQuestion(&rp->resrec, &question)) { LogInfo("mDNS_CheckForCacheRecord: Found %s", CRDisplayString(m, rp)); return mDNStrue; } } return mDNSfalse; } mDNSlocal void CacheRecordResetDNSServer(mDNS *const m, DNSQuestion *q, DNSServer *new) { const mDNSu32 slot = HashSlot(&q->qname); CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); CacheRecord *rp; mDNSBool found = mDNSfalse; mDNSBool foundNew = mDNSfalse; DNSServer *old = q->qDNSServer; mDNSBool newQuestion = IsQuestionNew(m, q); DNSQuestion *qptr; // This function is called when the DNSServer is updated to the new question. There may already be // some cache entries matching the old DNSServer and/or new DNSServer. There are four cases. In the // following table, "Yes" denotes that a cache entry was found for old/new DNSServer. // // old DNSServer new DNSServer // // Case 1 Yes Yes // Case 2 No Yes // Case 3 Yes No // Case 4 No No // // Case 1: There are cache entries for both old and new DNSServer. We handle this case by simply // expiring the old Cache entries, deliver a RMV event (if an ADD event was delivered before) // followed by the ADD event of the cache entries corresponding to the new server. This // case happens when we pick a DNSServer, issue a query and get a valid response and create // cache entries after which it stops responding. Another query (non-duplicate) picks a different // DNSServer and creates identical cache entries (perhaps through records in Additional records). // Now if the first one expires and tries to pick the new DNSServer (the original DNSServer // is not responding) we will find cache entries corresponding to both DNSServers. // // Case 2: There are no cache entries for the old DNSServer but there are some for the new DNSServer. // This means we should deliver an ADD event. Normally ADD events are delivered by // AnswerNewQuestion if it is a new question. So, we check to see if it is a new question // and if so, leave it to AnswerNewQuestion to deliver it. Otherwise, we use // AnswerQuestionsForDNSServerChanges to deliver the ADD event. This case happens when a // question picks a DNS server for which AnswerNewQuestion could not deliver an answer even // though there were potential cache entries but DNSServer did not match. Now when we // pick a new DNSServer, those cache entries may answer this question. // // Case 3: There are the cache entries for the old DNSServer but none for the new. We just move // the old cache entries to point to the new DNSServer and the caller is expected to // do a purge or reconfirm to delete or validate the RDATA. We don't need to do anything // special for delivering ADD events, as it should have been done/will be done by // AnswerNewQuestion. This case happens when we picked a DNSServer, sent the query and // got a response and the cache is expired now and we are reissuing the question but the // original DNSServer does not respond. // // Case 4: There are no cache entries either for the old or for the new DNSServer. There is nothing // much we can do here. // // Case 2 and 3 are the most common while case 4 is possible when no DNSServers are working. Case 1 // is relatively less likely to happen in practice // Temporarily set the DNSServer to look for the matching records for the new DNSServer. q->qDNSServer = new; for (rp = cg ? cg->members : mDNSNULL; rp; rp = rp->next) { if (SameNameRecordAnswersQuestion(&rp->resrec, q)) { LogInfo("CacheRecordResetDNSServer: Found cache record %##s for new DNSServer address: %#a", rp->resrec.name->c, (rp->resrec.rDNSServer != mDNSNULL ? &rp->resrec.rDNSServer->addr : mDNSNULL)); foundNew = mDNStrue; break; } } q->qDNSServer = old; for (rp = cg ? cg->members : mDNSNULL; rp; rp = rp->next) { if (SameNameRecordAnswersQuestion(&rp->resrec, q)) { // Case1 found = mDNStrue; if (foundNew) { LogInfo("CacheRecordResetDNSServer: Flushing Resourcerecord %##s, before:%#a, after:%#a", rp->resrec.name->c, (rp->resrec.rDNSServer != mDNSNULL ? &rp->resrec.rDNSServer->addr : mDNSNULL), (new != mDNSNULL ? &new->addr : mDNSNULL)); mDNS_PurgeCacheResourceRecord(m, rp); if (newQuestion) { // "q" is not a duplicate question. If it is a newQuestion, then the CRActiveQuestion can't be // possibly set as it is set only when we deliver the ADD event to the question. if (rp->CRActiveQuestion != mDNSNULL) { LogMsg("CacheRecordResetDNSServer: ERROR!!: CRActiveQuestion %p set, current question %p, name %##s", rp->CRActiveQuestion, q, q->qname.c); rp->CRActiveQuestion = mDNSNULL; } // if this is a new question, then we never delivered an ADD yet, so don't deliver the RMV. continue; } } LogInfo("CacheRecordResetDNSServer: resetting cache record %##s DNSServer address before:%#a," " after:%#a, CRActiveQuestion %p", rp->resrec.name->c, (rp->resrec.rDNSServer != mDNSNULL ? &rp->resrec.rDNSServer->addr : mDNSNULL), (new != mDNSNULL ? &new->addr : mDNSNULL), rp->CRActiveQuestion); // Though we set it to the new DNS server, the caller is *assumed* to do either a purge // or reconfirm or send out questions to the "new" server to verify whether the cached // RDATA is valid rp->resrec.rDNSServer = new; } } // Case 1 and Case 2 if ((found && foundNew) || (!found && foundNew)) { if (newQuestion) LogInfo("CacheRecordResetDNSServer: deliverAddEvents not set for question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); else if (QuerySuppressed(q)) LogInfo("CacheRecordResetDNSServer: deliverAddEvents not set for suppressed question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); else { LogInfo("CacheRecordResetDNSServer: deliverAddEvents set for %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); q->deliverAddEvents = mDNStrue; for (qptr = q->next; qptr; qptr = qptr->next) if (qptr->DuplicateOf == q) qptr->deliverAddEvents = mDNStrue; } return; } // Case 3 and Case 4 return; } mDNSexport void DNSServerChangeForQuestion(mDNS *const m, DNSQuestion *q, DNSServer *new) { DNSQuestion *qptr; // 1. Whenever we change the DNS server, we change the message identifier also so that response // from the old server is not accepted as a response from the new server but only messages // from the new server are accepted as valid responses. We do it irrespective of whether "new" // is NULL or not. It is possible that we send two queries, no responses, pick a new DNS server // which is NULL and now the response comes back and will try to penalize the DNS server which // is NULL. By setting the messageID here, we will not accept that as a valid response. q->TargetQID = mDNS_NewMessageID(m); // 2. Move the old cache records to point them at the new DNSServer so that we can deliver the ADD/RMV events // appropriately. At any point in time, we want all the cache records point only to one DNSServer for a given // question. "DNSServer" here is the DNSServer object and not the DNS server itself. It is possible to // have the same DNS server address in two objects, one scoped and another not scoped. But, the cache is per // DNSServer object. By maintaining the question and the cache entries point to the same DNSServer // always, the cache maintenance and delivery of ADD/RMV events becomes simpler. // // CacheRecordResetDNSServer should be called only once for the non-duplicate question as once the cache // entries are moved to point to the new DNSServer, we don't need to call it for the duplicate question // and it is wrong to call for the duplicate question as it's decision to mark deliverAddevents will be // incorrect. if (q->DuplicateOf) LogMsg("DNSServerChangeForQuestion: ERROR: Called for duplicate question %##s", q->qname.c); else CacheRecordResetDNSServer(m, q, new); // 3. Make sure all the duplicate questions point to the same DNSServer so that delivery // of events for all of them are consistent. Duplicates for a question are always inserted // after in the list. q->qDNSServer = new; for (qptr = q->next ; qptr; qptr = qptr->next) { if (qptr->DuplicateOf == q) { qptr->validDNSServers = q->validDNSServers; qptr->qDNSServer = new; } } } mDNSexport mStatus uDNS_SetupDNSConfig(mDNS *const m) { mDNSu32 slot; CacheGroup *cg; CacheRecord *cr; mDNSAddr v4, v6, r; domainname fqdn; DNSServer *ptr, **p = &m->DNSServers; const DNSServer *oldServers = m->DNSServers; DNSQuestion *q; McastResolver *mr, **mres = &m->McastResolvers; debugf("uDNS_SetupDNSConfig: entry"); // Let the platform layer get the current DNS information // The m->StartWABQueries is set when we get the first domain enumeration query (no need to hit the network // with domain enumeration queries until we actually need that information). Even if it is not set, we still // need to setup the search domains so that we can append them to queries that need them. uDNS_SetupSearchDomains(m, m->StartWABQueries ? UDNS_START_WAB_QUERY : 0); mDNS_Lock(m); for (ptr = m->DNSServers; ptr; ptr = ptr->next) { ptr->penaltyTime = 0; ptr->flags |= DNSServer_FlagDelete; } // We handle the mcast resolvers here itself as mDNSPlatformSetDNSConfig looks at // mcast resolvers. Today we get both mcast and ucast configuration using the same // API for (mr = m->McastResolvers; mr; mr = mr->next) mr->flags |= McastResolver_FlagDelete; mDNSPlatformSetDNSConfig(m, mDNStrue, mDNSfalse, &fqdn, mDNSNULL, mDNSNULL); // For now, we just delete the mcast resolvers. We don't deal with cache or // questions here. Neither question nor cache point to mcast resolvers. Questions // do inherit the timeout values from mcast resolvers. But we don't bother // affecting them as they never change. while (*mres) { if (((*mres)->flags & DNSServer_FlagDelete) != 0) { mr = *mres; *mres = (*mres)->next; debugf("uDNS_SetupDNSConfig: Deleting mcast resolver %##s", mr, mr->domain.c); mDNSPlatformMemFree(mr); } else { (*mres)->flags &= ~McastResolver_FlagNew; mres = &(*mres)->next; } } // Mark the records to be flushed that match a new resolver. We need to do this before // we walk the questions below where we change the DNSServer pointer of the cache // record FORALL_CACHERECORDS(slot, cg, cr) { if (cr->resrec.InterfaceID) continue; // We just mark them for purge or reconfirm. We can't affect the DNSServer pointer // here as the code below that calls CacheRecordResetDNSServer relies on this // // The new DNSServer may be a scoped or non-scoped one. We use the active question's // InterfaceID for looking up the right DNS server ptr = GetServerForName(m, cr->resrec.name, cr->CRActiveQuestion ? cr->CRActiveQuestion->InterfaceID : mDNSNULL); // Purge or Reconfirm if this cache entry would use the new DNS server if (ptr && (ptr != cr->resrec.rDNSServer)) { // As the DNSServers for this cache record is not the same anymore, we don't // want any new questions to pick this old value if (cr->CRActiveQuestion == mDNSNULL) { LogInfo("uDNS_SetupDNSConfig: Purging Resourcerecord %s", CRDisplayString(m, cr)); mDNS_PurgeCacheResourceRecord(m, cr); } else { LogInfo("uDNS_SetupDNSConfig: Purging/Reconfirming Resourcerecord %s", CRDisplayString(m, cr)); PurgeOrReconfirmCacheRecord(m, cr, ptr, mDNSfalse); } } } // Update our qDNSServer pointers before we go and free the DNSServer object memory for (q = m->Questions; q; q=q->next) if (!mDNSOpaque16IsZero(q->TargetQID)) { DNSServer *s, *t; DNSQuestion *qptr; if (q->DuplicateOf) continue; SetValidDNSServers(m, q); q->triedAllServersOnce = 0; s = GetServerForQuestion(m, q); t = q->qDNSServer; if (t != s) { // If DNS Server for this question has changed, reactivate it debugf("uDNS_SetupDNSConfig: Updating DNS Server from %p %#a:%d (%##s) to %p %#a:%d (%##s) for %##s (%s)", t, t ? &t->addr : mDNSNULL, mDNSVal16(t ? t->port : zeroIPPort), t ? t->domain.c : (mDNSu8*)"", s, s ? &s->addr : mDNSNULL, mDNSVal16(s ? s->port : zeroIPPort), s ? s->domain.c : (mDNSu8*)"", q->qname.c, DNSTypeName(q->qtype)); // After we reset the DNSServer pointer on the cache records here, three things could happen: // // 1) The query gets sent out and when the actual response comes back later it is possible // that the response has the same RDATA, in which case we update our cache entry. // If the response is different, then the entry will expire and a new entry gets added. // For the latter case to generate a RMV followed by ADD events, we need to reset the DNS // server here to match the question and the cache record. // // 2) We might have marked the cache entries for purge above and for us to be able to generate the RMV // events for the questions, the DNSServer on the question should match the Cache Record // // 3) We might have marked the cache entries for reconfirm above, for which we send the query out which is // the same as the first case above. DNSServerChangeForQuestion(m, q, s); q->unansweredQueries = 0; // We still need to pick a new DNSServer for the questions that have been // suppressed, but it is wrong to activate the query as DNS server change // could not possibly change the status of SuppressUnusable questions if (!QuerySuppressed(q)) { debugf("uDNS_SetupDNSConfig: Activating query %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); ActivateUnicastQuery(m, q, mDNStrue); // ActivateUnicastQuery is called for duplicate questions also as it does something // special for AutoTunnel questions for (qptr = q->next ; qptr; qptr = qptr->next) { if (qptr->DuplicateOf == q) ActivateUnicastQuery(m, qptr, mDNStrue); } } } else { debugf("uDNS_SetupDNSConfig: Not Updating DNS server question %p %##s (%s) DNS server %#a:%d %p %d", q, q->qname.c, DNSTypeName(q->qtype), t ? &t->addr : mDNSNULL, mDNSVal16(t ? t->port : zeroIPPort), q->DuplicateOf, q->SuppressUnusable); for (qptr = q->next ; qptr; qptr = qptr->next) if (qptr->DuplicateOf == q) { qptr->validDNSServers = q->validDNSServers; qptr->qDNSServer = q->qDNSServer; } } } while (*p) { if (((*p)->flags & DNSServer_FlagDelete) != 0) { // Scan our cache, looking for uDNS records that we would have queried this server for. // We reconfirm any records that match, because in this world of split DNS, firewalls, etc. // different DNS servers can give different answers to the same question. ptr = *p; FORALL_CACHERECORDS(slot, cg, cr) { if (cr->resrec.InterfaceID) continue; if (cr->resrec.rDNSServer == ptr) { // If we don't have an active question for this cache record, neither Purge can // generate RMV events nor Reconfirm can send queries out. Just set the DNSServer // pointer on the record NULL so that we don't point to freed memory (We might dereference // DNSServer pointers from resource record for logging purposes). // // If there is an active question, point to its DNSServer as long as it does not point to the // freed one. We already went through the questions above and made them point at either the // new server or NULL if there is no server and also affected the cache entries that match // this question. Hence, whenever we hit a resource record with a DNSServer that is just // about to be deleted, we should never have an active question. The code below just tries to // be careful logging messages if we ever hit this case. if (cr->CRActiveQuestion) { DNSQuestion *qptr = cr->CRActiveQuestion; if (qptr->qDNSServer == mDNSNULL) LogMsg("uDNS_SetupDNSConfig: Cache Record %s match: Active question %##s (%s) with DNSServer Address NULL, Server to be deleted %#a", CRDisplayString(m, cr), qptr->qname.c, DNSTypeName(qptr->qtype), &ptr->addr); else LogMsg("uDNS_SetupDNSConfig: Cache Record %s match: Active question %##s (%s) DNSServer Address %#a, Server to be deleted %#a", CRDisplayString(m, cr), qptr->qname.c, DNSTypeName(qptr->qtype), &qptr->qDNSServer->addr, &ptr->addr); if (qptr->qDNSServer == ptr) { qptr->validDNSServers = zeroOpaque64; qptr->qDNSServer = mDNSNULL; cr->resrec.rDNSServer = mDNSNULL; } else { cr->resrec.rDNSServer = qptr->qDNSServer; } } else { LogInfo("uDNS_SetupDNSConfig: Cache Record %##s has no Active question, Record's DNSServer Address %#a, Server to be deleted %#a", cr->resrec.name, &cr->resrec.rDNSServer->addr, &ptr->addr); cr->resrec.rDNSServer = mDNSNULL; } PurgeOrReconfirmCacheRecord(m, cr, ptr, mDNStrue); } } *p = (*p)->next; debugf("uDNS_SetupDNSConfig: Deleting server %p %#a:%d (%##s)", ptr, &ptr->addr, mDNSVal16(ptr->port), ptr->domain.c); mDNSPlatformMemFree(ptr); NumUnicastDNSServers--; } else { (*p)->flags &= ~DNSServer_FlagNew; p = &(*p)->next; } } // If we now have no DNS servers at all and we used to have some, then immediately purge all unicast cache records (including for LLQs). // This is important for giving prompt remove events when the user disconnects the Ethernet cable or turns off wireless. // Otherwise, stale data lingers for 5-10 seconds, which is not the user-experience people expect from Bonjour. // Similarly, if we now have some DNS servers and we used to have none, we want to purge any fake negative results we may have generated. if ((m->DNSServers != mDNSNULL) != (oldServers != mDNSNULL)) { int count = 0; FORALL_CACHERECORDS(slot, cg, cr) if (!cr->resrec.InterfaceID) { mDNS_PurgeCacheResourceRecord(m, cr); count++; } LogInfo("uDNS_SetupDNSConfig: %s available; purged %d unicast DNS records from cache", m->DNSServers ? "DNS server became" : "No DNS servers", count); // Force anything that needs to get zone data to get that information again RestartRecordGetZoneData(m); } // Did our FQDN change? if (!SameDomainName(&fqdn, &m->FQDN)) { if (m->FQDN.c[0]) mDNS_RemoveDynDNSHostName(m, &m->FQDN); AssignDomainName(&m->FQDN, &fqdn); if (m->FQDN.c[0]) { mDNSPlatformDynDNSHostNameStatusChanged(&m->FQDN, 1); mDNS_AddDynDNSHostName(m, &m->FQDN, DynDNSHostNameCallback, mDNSNULL); } } mDNS_Unlock(m); // handle router and primary interface changes v4 = v6 = r = zeroAddr; v4.type = r.type = mDNSAddrType_IPv4; if (mDNSPlatformGetPrimaryInterface(m, &v4, &v6, &r) == mStatus_NoError && !mDNSv4AddressIsLinkLocal(&v4.ip.v4)) { mDNS_SetPrimaryInterfaceInfo(m, !mDNSIPv4AddressIsZero(v4.ip.v4) ? &v4 : mDNSNULL, !mDNSIPv6AddressIsZero(v6.ip.v6) ? &v6 : mDNSNULL, !mDNSIPv4AddressIsZero(r .ip.v4) ? &r : mDNSNULL); } else { mDNS_SetPrimaryInterfaceInfo(m, mDNSNULL, mDNSNULL, mDNSNULL); if (m->FQDN.c[0]) mDNSPlatformDynDNSHostNameStatusChanged(&m->FQDN, 1); // Set status to 1 to indicate temporary failure } debugf("uDNS_SetupDNSConfig: number of unicast DNS servers %d", NumUnicastDNSServers); return mStatus_NoError; } mDNSexport void mDNSCoreInitComplete(mDNS *const m, mStatus result) { m->mDNSPlatformStatus = result; if (m->MainCallback) { mDNS_Lock(m); mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback m->MainCallback(m, mStatus_NoError); mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again mDNS_Unlock(m); } } mDNSlocal void DeregLoop(mDNS *const m, AuthRecord *const start) { m->CurrentRecord = start; while (m->CurrentRecord) { AuthRecord *rr = m->CurrentRecord; LogInfo("DeregLoop: %s deregistration for %p %02X %s", (rr->resrec.RecordType != kDNSRecordTypeDeregistering) ? "Initiating " : "Accelerating", rr, rr->resrec.RecordType, ARDisplayString(m, rr)); if (rr->resrec.RecordType != kDNSRecordTypeDeregistering) mDNS_Deregister_internal(m, rr, mDNS_Dereg_rapid); else if (rr->AnnounceCount > 1) { rr->AnnounceCount = 1; rr->LastAPTime = m->timenow - rr->ThisAPInterval; } // Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because // new records could have been added to the end of the list as a result of that call. if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now m->CurrentRecord = rr->next; } } mDNSexport void mDNS_StartExit(mDNS *const m) { NetworkInterfaceInfo *intf; AuthRecord *rr; mDNS_Lock(m); LogInfo("mDNS_StartExit"); m->ShutdownTime = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 5); mDNSCoreBeSleepProxyServer_internal(m, 0, 0, 0, 0); #if APPLE_OSX_mDNSResponder #if ! NO_WCF CHECK_WCF_FUNCTION(WCFConnectionDealloc) { if (m->WCF) WCFConnectionDealloc((WCFConnection *)m->WCF); } #endif #endif #ifndef UNICAST_DISABLED { SearchListElem *s; SuspendLLQs(m); // Don't need to do SleepRecordRegistrations() here // because we deregister all records and services later in this routine while (m->Hostnames) mDNS_RemoveDynDNSHostName(m, &m->Hostnames->fqdn); // For each member of our SearchList, deregister any records it may have created, and cut them from the list. // Otherwise they'll be forcibly deregistered for us (without being cut them from the appropriate list) // and we may crash because the list still contains dangling pointers. for (s = SearchList; s; s = s->next) while (s->AuthRecs) { ARListElem *dereg = s->AuthRecs; s->AuthRecs = s->AuthRecs->next; mDNS_Deregister_internal(m, &dereg->ar, mDNS_Dereg_normal); // Memory will be freed in the FreeARElemCallback } } #endif for (intf = m->HostInterfaces; intf; intf = intf->next) if (intf->Advertise) DeadvertiseInterface(m, intf); // Shut down all our active NAT Traversals while (m->NATTraversals) { NATTraversalInfo *t = m->NATTraversals; mDNS_StopNATOperation_internal(m, t); // This will cut 't' from the list, thereby advancing m->NATTraversals in the process // After stopping the NAT Traversal, we zero out the fields. // This has particularly important implications for our AutoTunnel records -- // when we deregister our AutoTunnel records below, we don't want their mStatus_MemFree // handlers to just turn around and attempt to re-register those same records. // Clearing t->ExternalPort/t->RequestedPort will cause the mStatus_MemFree callback handlers // to not do this. t->ExternalAddress = zerov4Addr; t->ExternalPort = zeroIPPort; t->RequestedPort = zeroIPPort; t->Lifetime = 0; t->Result = mStatus_NoError; } // Make sure there are nothing but deregistering records remaining in the list if (m->CurrentRecord) LogMsg("mDNS_StartExit: ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); // We're in the process of shutting down, so queries, etc. are no longer available. // Consequently, determining certain information, e.g. the uDNS update server's IP // address, will not be possible. The records on the main list are more likely to // already contain such information, so we deregister the duplicate records first. LogInfo("mDNS_StartExit: Deregistering duplicate resource records"); DeregLoop(m, m->DuplicateRecords); LogInfo("mDNS_StartExit: Deregistering resource records"); DeregLoop(m, m->ResourceRecords); // If we scheduled a response to send goodbye packets, we set NextScheduledResponse to now. Normally when deregistering records, // we allow up to 100ms delay (to help improve record grouping) but when shutting down we don't want any such delay. if (m->NextScheduledResponse - m->timenow < mDNSPlatformOneSecond) { m->NextScheduledResponse = m->timenow; m->SuppressSending = 0; } if (m->ResourceRecords) LogInfo("mDNS_StartExit: Sending final record deregistrations"); else LogInfo("mDNS_StartExit: No deregistering records remain"); for (rr = m->DuplicateRecords; rr; rr = rr->next) LogMsg("mDNS_StartExit: Should not still have Duplicate Records remaining: %02X %s", rr->resrec.RecordType, ARDisplayString(m, rr)); // If any deregistering records remain, send their deregistration announcements before we exit if (m->mDNSPlatformStatus != mStatus_NoError) DiscardDeregistrations(m); mDNS_Unlock(m); LogInfo("mDNS_StartExit: done"); } mDNSexport void mDNS_FinalExit(mDNS *const m) { mDNSu32 rrcache_active = 0; mDNSu32 rrcache_totalused = 0; mDNSu32 slot; AuthRecord *rr; LogInfo("mDNS_FinalExit: mDNSPlatformClose"); mDNSPlatformClose(m); rrcache_totalused = m->rrcache_totalused; for (slot = 0; slot < CACHE_HASH_SLOTS; slot++) { while (m->rrcache_hash[slot]) { CacheGroup *cg = m->rrcache_hash[slot]; while (cg->members) { CacheRecord *cr = cg->members; cg->members = cg->members->next; if (cr->CRActiveQuestion) rrcache_active++; ReleaseCacheRecord(m, cr); } cg->rrcache_tail = &cg->members; ReleaseCacheGroup(m, &m->rrcache_hash[slot]); } } debugf("mDNS_FinalExit: RR Cache was using %ld records, %lu active", rrcache_totalused, rrcache_active); if (rrcache_active != m->rrcache_active) LogMsg("*** ERROR *** rrcache_active %lu != m->rrcache_active %lu", rrcache_active, m->rrcache_active); for (rr = m->ResourceRecords; rr; rr = rr->next) LogMsg("mDNS_FinalExit failed to send goodbye for: %p %02X %s", rr, rr->resrec.RecordType, ARDisplayString(m, rr)); LogInfo("mDNS_FinalExit: done"); }