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e48a2af4f5
The proximate cause for doing this is to fix a bug that causes replies to PTR queries with more than one answer to have the second and subsequent answers ignored. The fix turned into a small re-write which removed a very old hack. When caching reponses which include CNAME records, the cache system stores the CNAME with a link to the record representing the target of the CNAME. This isn't possible for PTR records representing IP addresses since the name stored is the target of the PTR, record and its name is inferred from the address in the cache record. Such cache records have the F_REVERSE flag set. To get around this, long ago, the code which stores such records elided the CNAME entirely, so 4.3.2.1.in-addr.arpa CNAME 18/3.2.1.in-addr.arpa 18/3.2.1.in-addr.arpa PTR myhost.example.com would be stored as 4.3.2.1.in-addr.arpa PTR myhost.example.com and returned from the cache to subsequent requestor in that form. Since that hack was committed, dnsmasq has learned to cache arbitrary RRs. So now we can store the PTR records for all the no-trivial cases. The means the CNAME chains ending in PTR records don't get mangled, and we can store PTR records whose name in not w.x.y.x.in-addr.arpa or the IPv6 equivalent.