3
/*
* <-1byte(8bits) ->
* +---------------+
* | 0 | hopc |len|
* +---------------+
* | len (cont) |
* +---------------+
* | |
* +- DDP csum -+
* | |
* +---------------+
* | |
* +- Dest NET -+
* | |
* +---------------+
* | |
* +- Src NET -+
* | |
* +---------------+
* | Dest NODE |
* +---------------+
* | Src NODE |
* +---------------+
* | Dest PORT |
* +---------------+
* | Src PORT |
* +---------------+
*
* On Apples, there is also a ddp_type field, after src_port. However,
* under this unix implementation, user level processes need to be able
* to set the ddp_type. In later revisions, the ddp_type may only be
* available in a raw_appletalk interface.
*/