/* $NetBSD: driver.c,v 1.11.2.1 2023/08/11 13:43:08 martin Exp $ */ /* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * SPDX-License-Identifier: MPL-2.0 * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ /* * This provides a very simple example of an external loadable DLZ * driver, with update support. */ #include "driver.h" #include #include #include #include #include #include #include #include #include #include #include #include #define CHECK(x) \ do { \ result = (x); \ if (result != ISC_R_SUCCESS) \ goto failure; \ } while (0) #define loginfo(...) \ ({ \ if ((state != NULL) && (state->log != NULL)) \ state->log(ISC_LOG_INFO, __VA_ARGS__); \ }) #define logerr(...) \ ({ \ if ((state != NULL) && (state->log != NULL)) \ state->log(ISC_LOG_ERROR, __VA_ARGS__); \ }) /* For this simple example, use fixed sized strings */ struct record { char name[100]; char type[10]; char data[200]; dns_ttl_t ttl; }; #define MAX_RECORDS 100 typedef void log_t(int level, const char *fmt, ...); struct dlz_example_data { char *zone_name; /* An example driver doesn't need good memory management :-) */ struct record current[MAX_RECORDS]; struct record adds[MAX_RECORDS]; struct record deletes[MAX_RECORDS]; bool transaction_started; /* Helper functions from the dlz_dlopen driver */ log_t *log; dns_sdlz_putrr_t *putrr; dns_sdlz_putnamedrr_t *putnamedrr; dns_dlz_writeablezone_t *writeable_zone; }; static bool single_valued(const char *type) { const char *single[] = { "soa", "cname", NULL }; int i; for (i = 0; single[i]; i++) { if (strcasecmp(single[i], type) == 0) { return (true); } } return (false); } /* * Add a record to a list */ static isc_result_t add_name(struct dlz_example_data *state, struct record *list, const char *name, const char *type, dns_ttl_t ttl, const char *data) { int i; bool single = single_valued(type); int first_empty = -1; for (i = 0; i < MAX_RECORDS; i++) { INSIST(list[i].name != NULL); if (first_empty == -1 && strlen(list[i].name) == 0U) { first_empty = i; } if (strcasecmp(list[i].name, name) != 0) { continue; } if (strcasecmp(list[i].type, type) != 0) { continue; } if (!single && strcasecmp(list[i].data, data) != 0) { continue; } break; } if (i == MAX_RECORDS && first_empty != -1) { i = first_empty; } if (i == MAX_RECORDS) { logerr("dlz_example: out of record space"); return (ISC_R_FAILURE); } if (strlen(name) >= sizeof(list[i].name) || strlen(type) >= sizeof(list[i].type) || strlen(data) >= sizeof(list[i].data)) { return (ISC_R_NOSPACE); } strncpy(list[i].name, name, sizeof(list[i].name) - 1); list[i].name[sizeof(list[i].name) - 1] = '\0'; strncpy(list[i].type, type, sizeof(list[i].type) - 1); list[i].type[sizeof(list[i].type) - 1] = '\0'; strncpy(list[i].data, data, sizeof(list[i].data) - 1); list[i].data[sizeof(list[i].data) - 1] = '\0'; list[i].ttl = ttl; return (ISC_R_SUCCESS); } /* * Delete a record from a list */ static isc_result_t del_name(struct dlz_example_data *state, struct record *list, const char *name, const char *type, dns_ttl_t ttl, const char *data) { int i; UNUSED(state); for (i = 0; i < MAX_RECORDS; i++) { if (strcasecmp(name, list[i].name) == 0 && strcasecmp(type, list[i].type) == 0 && strcasecmp(data, list[i].data) == 0 && ttl == list[i].ttl) { break; } } if (i == MAX_RECORDS) { return (ISC_R_NOTFOUND); } memset(&list[i], 0, sizeof(struct record)); return (ISC_R_SUCCESS); } static isc_result_t fmt_address(isc_sockaddr_t *addr, char *buffer, size_t size) { char addr_buf[INET6_ADDRSTRLEN]; const char *ret; uint16_t port = 0; switch (addr->type.sa.sa_family) { case AF_INET: port = ntohs(addr->type.sin.sin_port); ret = inet_ntop(AF_INET, &addr->type.sin.sin_addr, addr_buf, sizeof(addr_buf)); break; case AF_INET6: port = ntohs(addr->type.sin6.sin6_port); ret = inet_ntop(AF_INET6, &addr->type.sin6.sin6_addr, addr_buf, sizeof(addr_buf)); break; default: return (ISC_R_FAILURE); } if (ret == NULL) { return (ISC_R_FAILURE); } snprintf(buffer, size, "%s#%u", addr_buf, port); return (ISC_R_SUCCESS); } /* * Return the version of the API */ int dlz_version(unsigned int *flags) { UNUSED(flags); return (DLZ_DLOPEN_VERSION); } /* * Remember a helper function from the bind9 dlz_dlopen driver */ static void b9_add_helper(struct dlz_example_data *state, const char *helper_name, void *ptr) { if (strcmp(helper_name, "log") == 0) { state->log = (log_t *)ptr; } if (strcmp(helper_name, "putrr") == 0) { state->putrr = (dns_sdlz_putrr_t *)ptr; } if (strcmp(helper_name, "putnamedrr") == 0) { state->putnamedrr = (dns_sdlz_putnamedrr_t *)ptr; } if (strcmp(helper_name, "writeable_zone") == 0) { state->writeable_zone = (dns_dlz_writeablezone_t *)ptr; } } /* * Called to initialize the driver */ isc_result_t dlz_create(const char *dlzname, unsigned int argc, char *argv[], void **dbdata, ...) { struct dlz_example_data *state; const char *helper_name; va_list ap; char soa_data[sizeof("@ hostmaster.root 123 900 600 86400 3600")]; isc_result_t result; size_t n; UNUSED(dlzname); state = calloc(1, sizeof(struct dlz_example_data)); if (state == NULL) { return (ISC_R_NOMEMORY); } /* Fill in the helper functions */ va_start(ap, dbdata); while ((helper_name = va_arg(ap, const char *)) != NULL) { b9_add_helper(state, helper_name, va_arg(ap, void *)); } va_end(ap); if (argc < 2 || argv[1][0] == '\0') { logerr("dlz_example: please specify a zone name"); dlz_destroy(state); return (ISC_R_FAILURE); } /* Ensure zone name is absolute */ state->zone_name = malloc(strlen(argv[1]) + 2); if (state->zone_name == NULL) { free(state); return (ISC_R_NOMEMORY); } if (argv[1][strlen(argv[1]) - 1] == '.') { strcpy(state->zone_name, argv[1]); } else { sprintf(state->zone_name, "%s.", argv[1]); } /* * Use relative names to trigger ISC_R_NOSPACE in dns_sdlz_putrr. */ if (strcmp(state->zone_name, ".") == 0) { n = strlcpy(soa_data, "@ hostmaster.root 123 900 600 86400 3600", sizeof(soa_data)); } else { n = strlcpy(soa_data, "@ hostmaster 123 900 600 86400 3600", sizeof(soa_data)); } if (n >= sizeof(soa_data)) { CHECK(ISC_R_NOSPACE); } add_name(state, &state->current[0], state->zone_name, "soa", 3600, soa_data); add_name(state, &state->current[0], state->zone_name, "ns", 3600, state->zone_name); add_name(state, &state->current[0], state->zone_name, "a", 1800, "10.53.0.1"); loginfo("dlz_example: started for zone %s", state->zone_name); *dbdata = state; return (ISC_R_SUCCESS); failure: free(state); return (result); } /* * Shut down the backend */ void dlz_destroy(void *dbdata) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; loginfo("dlz_example: shutting down zone %s", state->zone_name); free(state->zone_name); free(state); } /* * See if we handle a given zone */ isc_result_t dlz_findzonedb(void *dbdata, const char *name, dns_clientinfomethods_t *methods, dns_clientinfo_t *clientinfo) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; isc_sockaddr_t *src; char addrbuf[100]; char absolute[1024]; strcpy(addrbuf, "unknown"); if (methods != NULL && methods->sourceip != NULL && methods->version - methods->age <= DNS_CLIENTINFOMETHODS_VERSION && DNS_CLIENTINFOMETHODS_VERSION <= methods->version) { methods->sourceip(clientinfo, &src); fmt_address(src, addrbuf, sizeof(addrbuf)); } loginfo("dlz_example: dlz_findzonedb called with name '%s' " "in zone DB '%s' from %s", name, state->zone_name, addrbuf); /* * Returning ISC_R_NOTFOUND will cause the query logic to * check the database for parent names, looking for zone cuts. * * Returning ISC_R_NOMORE prevents the query logic from doing * this; it will move onto the next database after a single query. */ if (strcasecmp(name, "test.example.com") == 0) { return (ISC_R_NOMORE); } /* * For example.net, only return ISC_R_NOMORE when queried * from 10.53.0.1. */ if (strcasecmp(name, "test.example.net") == 0 && strncmp(addrbuf, "10.53.0.1", 9) == 0) { return (ISC_R_NOMORE); } /* * For bigcname.domain, return success so it appears to be * the zone origin; this regression tests a bug in which * zone origin nodes could fail to return SERVFAIL to the client. */ if (strcasecmp(name, "bigcname.domain") == 0) { return (ISC_R_SUCCESS); } /* * Return success if we have an exact match between the * zone name and the qname */ if (strcasecmp(state->zone_name, name) == 0) { return (ISC_R_SUCCESS); } snprintf(absolute, sizeof(absolute), "%s.", name); if (strcasecmp(state->zone_name, absolute) == 0) { return (ISC_R_SUCCESS); } return (ISC_R_NOTFOUND); } /* * Look up one record in the sample database. * * If the queryname is "source-addr", send back a TXT record containing * the address of the client, to test the use of 'methods' and 'clientinfo' * * If the queryname is "too-long", send back a TXT record that's too long * to process; this should result in a SERVFAIL when queried. */ isc_result_t dlz_lookup(const char *zone, const char *name, void *dbdata, dns_sdlzlookup_t *lookup, dns_clientinfomethods_t *methods, dns_clientinfo_t *clientinfo) { isc_result_t result; struct dlz_example_data *state = (struct dlz_example_data *)dbdata; bool found = false; void *dbversion = NULL; isc_sockaddr_t *src; char full_name[256]; char buf[512]; static char last[256]; static int count = 0; int i, size; UNUSED(zone); if (state->putrr == NULL) { return (ISC_R_NOTIMPLEMENTED); } if (strcmp(name, "@") == 0) { size = snprintf(full_name, sizeof(full_name), "%s", state->zone_name); } else if (strcmp(state->zone_name, ".") == 0) { size = snprintf(full_name, sizeof(full_name), "%s.", name); } else { size = snprintf(full_name, sizeof(full_name), "%s.%s", name, state->zone_name); } if (size < 0 || (size_t)size >= sizeof(full_name) || (size_t)size >= sizeof(last)) { return (ISC_R_NOSPACE); } /* * For test purposes, log all calls to dlz_lookup() */ if (strcasecmp(full_name, last) == 0) { count++; } else { count = 1; memcpy(last, full_name, size + 1); } loginfo("lookup #%d for %s", count, full_name); /* * If we need to know the database version (as set in * the 'newversion' dlz function) we can pick it up from the * clientinfo. * * This allows a lookup to query the correct version of the DNS * data, if the DLZ can differentiate between versions. * * For example, if a new database transaction is created by * 'newversion', the lookup should query within the same * transaction scope if it can. * * If the DLZ only operates on 'live' data, then version * wouldn't necessarily be needed. */ if (clientinfo != NULL && clientinfo->version >= 2) { dbversion = clientinfo->dbversion; if (dbversion != NULL && *(bool *)dbversion) { loginfo("dlz_example: lookup against live transaction"); } } if (strcmp(name, "source-addr") == 0) { char ecsbuf[DNS_ECS_FORMATSIZE] = "not supported"; strncpy(buf, "unknown", sizeof(buf)); if (methods != NULL && methods->sourceip != NULL && (methods->version - methods->age <= DNS_CLIENTINFOMETHODS_VERSION) && DNS_CLIENTINFOMETHODS_VERSION <= methods->version) { methods->sourceip(clientinfo, &src); fmt_address(src, buf, sizeof(buf)); } if (clientinfo != NULL && clientinfo->version >= 3) { if (clientinfo->ecs.addr.family != AF_UNSPEC) { dns_ecs_format(&clientinfo->ecs, ecsbuf, sizeof(ecsbuf)); } else { snprintf(ecsbuf, sizeof(ecsbuf), "%s", "not present"); } } i = strlen(buf); snprintf(buf + i, sizeof(buf) - i - 1, " ECS %s", ecsbuf); loginfo("dlz_example: lookup connection from %s", buf); found = true; result = state->putrr(lookup, "TXT", 0, buf); if (result != ISC_R_SUCCESS) { return (result); } } if (strcmp(name, "too-long") == 0 || strcmp(zone, "bigcname.domain") == 0) { for (i = 0; i < 511; i++) { buf[i] = 'x'; } buf[i] = '\0'; found = true; result = state->putrr(lookup, "TXT", 0, buf); if (result != ISC_R_SUCCESS) { return (result); } } /* Tests for DLZ redirection zones */ if (strcmp(name, "*") == 0 && strcmp(zone, ".") == 0) { result = state->putrr(lookup, "A", 0, "100.100.100.2"); found = true; if (result != ISC_R_SUCCESS) { return (result); } } if (strcmp(name, "long.name.is.not.there") == 0 && strcmp(zone, ".") == 0) { result = state->putrr(lookup, "A", 0, "100.100.100.3"); found = true; if (result != ISC_R_SUCCESS) { return (result); } } /* Answer from current records */ for (i = 0; i < MAX_RECORDS; i++) { if (strcasecmp(state->current[i].name, full_name) == 0) { found = true; result = state->putrr(lookup, state->current[i].type, state->current[i].ttl, state->current[i].data); if (result != ISC_R_SUCCESS) { return (result); } } } if (!found) { return (ISC_R_NOTFOUND); } return (ISC_R_SUCCESS); } /* * See if a zone transfer is allowed */ isc_result_t dlz_allowzonexfr(void *dbdata, const char *name, const char *client) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; isc_result_t result; loginfo("dlz_example: dlz_allowzonexfr called for %s", name); result = dlz_findzonedb(dbdata, name, NULL, NULL); if (result != ISC_R_SUCCESS) { loginfo("dlz_example: findzonedb returned %s", isc_result_totext(result)); return (result); } /* * Exception for "example.org" so we can test the use of * the view ACL. */ if (strcmp(name, "example.org") == 0) { loginfo("dlz_example: use view ACL for example.org"); return (ISC_R_DEFAULT); } /* * Exception for 10.53.0.5 so we can test that allow-transfer * is effective. */ if (strcmp(client, "10.53.0.5") == 0) { loginfo("dlz_example: disallow transfer to 10.53.0.5"); return (ISC_R_NOPERM); } loginfo("dlz_example: transfer allowed for %s", name); return (ISC_R_SUCCESS); } /* * Perform a zone transfer */ isc_result_t dlz_allnodes(const char *zone, void *dbdata, dns_sdlzallnodes_t *allnodes) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; int i; UNUSED(zone); if (state->putnamedrr == NULL) { return (ISC_R_NOTIMPLEMENTED); } for (i = 0; i < MAX_RECORDS; i++) { isc_result_t result; if (strlen(state->current[i].name) == 0U) { continue; } result = state->putnamedrr(allnodes, state->current[i].name, state->current[i].type, state->current[i].ttl, state->current[i].data); if (result != ISC_R_SUCCESS) { return (result); } } return (ISC_R_SUCCESS); } /* * Start a transaction */ isc_result_t dlz_newversion(const char *zone, void *dbdata, void **versionp) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; if (state->transaction_started) { loginfo("dlz_example: transaction already started for zone %s", zone); return (ISC_R_FAILURE); } state->transaction_started = true; *versionp = (void *)&state->transaction_started; return (ISC_R_SUCCESS); } /* * End a transaction */ void dlz_closeversion(const char *zone, bool commit, void *dbdata, void **versionp) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; if (!state->transaction_started) { loginfo("dlz_example: transaction not started for zone %s", zone); *versionp = NULL; return; } state->transaction_started = false; *versionp = NULL; if (commit) { int i; loginfo("dlz_example: committing transaction on zone %s", zone); for (i = 0; i < MAX_RECORDS; i++) { if (strlen(state->deletes[i].name) > 0U) { (void)del_name(state, &state->current[0], state->deletes[i].name, state->deletes[i].type, state->deletes[i].ttl, state->deletes[i].data); } } for (i = 0; i < MAX_RECORDS; i++) { if (strlen(state->adds[i].name) > 0U) { (void)add_name(state, &state->current[0], state->adds[i].name, state->adds[i].type, state->adds[i].ttl, state->adds[i].data); } } } else { loginfo("dlz_example: cancelling transaction on zone %s", zone); } memset(state->adds, 0, sizeof(state->adds)); memset(state->deletes, 0, sizeof(state->deletes)); } /* * Configure a writeable zone */ isc_result_t dlz_configure(dns_view_t *view, dns_dlzdb_t *dlzdb, void *dbdata) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; isc_result_t result; loginfo("dlz_example: starting configure"); if (state->writeable_zone == NULL) { loginfo("dlz_example: no writeable_zone method available"); return (ISC_R_FAILURE); } result = state->writeable_zone(view, dlzdb, state->zone_name); if (result != ISC_R_SUCCESS) { loginfo("dlz_example: failed to configure zone %s", state->zone_name); return (result); } loginfo("dlz_example: configured writeable zone %s", state->zone_name); return (ISC_R_SUCCESS); } /* * Authorize a zone update */ bool dlz_ssumatch(const char *signer, const char *name, const char *tcpaddr, const char *type, const char *key, uint32_t keydatalen, unsigned char *keydata, void *dbdata) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; UNUSED(tcpaddr); UNUSED(type); UNUSED(key); UNUSED(keydatalen); UNUSED(keydata); if (strncmp(name, "deny.", 5) == 0) { loginfo("dlz_example: denying update of name=%s by %s", name, signer); return (false); } loginfo("dlz_example: allowing update of name=%s by %s", name, signer); return (true); } static isc_result_t modrdataset(struct dlz_example_data *state, const char *name, const char *rdatastr, struct record *list) { char *full_name, *dclass, *type, *data, *ttlstr, *buf; char absolute[1024]; isc_result_t result; char *saveptr = NULL; buf = strdup(rdatastr); if (buf == NULL) { return (ISC_R_FAILURE); } /* * The format is: * FULLNAME\tTTL\tDCLASS\tTYPE\tDATA * * The DATA field is space separated, and is in the data format * for the type used by dig */ full_name = strtok_r(buf, "\t", &saveptr); if (full_name == NULL) { goto error; } ttlstr = strtok_r(NULL, "\t", &saveptr); if (ttlstr == NULL) { goto error; } dclass = strtok_r(NULL, "\t", &saveptr); if (dclass == NULL) { goto error; } type = strtok_r(NULL, "\t", &saveptr); if (type == NULL) { goto error; } data = strtok_r(NULL, "\t", &saveptr); if (data == NULL) { goto error; } if (name[strlen(name) - 1] != '.') { snprintf(absolute, sizeof(absolute), "%s.", name); name = absolute; } result = add_name(state, list, name, type, strtoul(ttlstr, NULL, 10), data); free(buf); return (result); error: free(buf); return (ISC_R_FAILURE); } isc_result_t dlz_addrdataset(const char *name, const char *rdatastr, void *dbdata, void *version) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; if (version != (void *)&state->transaction_started) { return (ISC_R_FAILURE); } loginfo("dlz_example: adding rdataset %s '%s'", name, rdatastr); return (modrdataset(state, name, rdatastr, &state->adds[0])); } isc_result_t dlz_subrdataset(const char *name, const char *rdatastr, void *dbdata, void *version) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; if (version != (void *)&state->transaction_started) { return (ISC_R_FAILURE); } loginfo("dlz_example: subtracting rdataset %s '%s'", name, rdatastr); return (modrdataset(state, name, rdatastr, &state->deletes[0])); } isc_result_t dlz_delrdataset(const char *name, const char *type, void *dbdata, void *version) { struct dlz_example_data *state = (struct dlz_example_data *)dbdata; if (version != (void *)&state->transaction_started) { return (ISC_R_FAILURE); } loginfo("dlz_example: deleting rdataset %s of type %s", name, type); return (ISC_R_SUCCESS); }