Re: gethostbyaddr(3) fails when DNS PTR record has a wildcard

In article <[email protected]>,
Jeremy C. Reed <[email protected]> wrote:
>I saw this DNS entry:
>
> 10.7.18.64.in-addr.arpa. 22018  IN      PTR     *.s8a1.psmtp.com.
>
>Which resolves with dig and host and nslookup, for example:
>
> $ host 64.18.7.10
> 10.7.18.64.in-addr.arpa domain name pointer *.s8a1.psmtp.com.
>
>
>But gethostbyaddr(3) fails for that and h_errno is "3" which is:
>
>#define NO_RECOVERY     3 /* Non recoverable errors, FORMERR, REFUSED, NOTIMP */
>
>Or:
>
> NO_RECOVERY     Some unexpected server failure was encountered. This is
>                 a non-recoverable error.
> 
>And hstrerror(h_errno) has "Unknown server error".
>
>ktrace shows:
>
> 19145      1 gethost  CALL 
>recvfrom(3,0x805b000,0x10000,0,0xbfbfdd70,0xbfbfde3c)
> 19145      1 gethost  GIO   fd 3 read 71 bytes
>       "\M^[\M-Y\M^A\M^@\0\^A\0\^A\0\0\0\0\^B10\^A7\^B18\^B64\ain-addr\^Darpa\
>        \0\0\f\0\^A\M-@\f\0\f\0\^A\0\0@\M-:\0\^R\^A*\^Ds8a1\^Epsmtp\^Ccom\0"
>
>
>This is NetBSD 3.99.24.
>
>I am trying to look through /usr/src/lib/libc/net/gethnamaddr.c to see why 
>this is happening. Any clues?
>
>But has anyone else seen this type of PTR value? Is it okay? Is 
>gethostbyaddr(3) broken? (Or maybe I am using it wrong.)
>
>
>By the way, I was testing this with my pkgsrc/net/gethost tool.

The record:

10.7.18.64.in-addr.arpa domain name pointer *.s8a1.psmtp.com.

is an RFC/1034 wildcard record. gethostbyaddr() uses res_hnok()
to check for the validity of the returned hostname which only
accepts valid hostnames, not wildcarded ones like res_ownok()
accepts. I think this is by design. Anyway why are you using
the antiquated gethostbyaddr() call instead of getnameinfo()?

christos