OSEC

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Re: "reject_unknown_reverse_client_hostname" bouncing mail when name server is down

From: Wietse Venema (wietseporcupine.org)
Date: Thu Aug 24 2006 - 14:22:53 CDT

Jordan Russell:
> It appears that adding IPv6 support to the gethostbyaddr() code -- which
> again is already there but hiding behind an #ifdef -- would require
> fewer than 10 lines of code.
...
> #ifdef HAS_IPV6
> if (sa->sa_family == AF_INET6) {
> if ((hp = gethostbyaddr((char *) &(SOCK_ADDR_IN6_ADDR(sa)),
> sizeof(SOCK_ADDR_IN6_ADDR(sa)),
> AF_INET6)) == 0)
> return (h_errno == TRY_AGAIN ? EAI_AGAIN : EAI_NONAME);
> } else

Please cite the vendor-independent standards document that requires
that gethostbyaddr() supports IPv6, on IPv6 capable platforms.

If such a document does not exist, then the above code is non-portable,
that is, its behavior is undefined. With undefined behavior, different
systems may produce different results, if any result at all.

        Wietse