Ben Morrow <b...@morrow.me.uk> wrote in <20130109154435.ga81...@anubis.morrow.me.uk>:
be> So getipnodebyname is behaving correctly here: the host has both IPv4 be> and IPv6 addresses, and Sendmail is requesting both native and v4-mapped be> addresses be returned in all cases. The v4-mapped addresses are then be> sorted to the top of the list. be> be> On FreeBSD, where net.inet6.ip6.v6only is on by default, I believe this be> is incorrect, and Sendmail should be passing 0 for the flags argument, be> unless it's going to check or clear the IPV6_V6ONLY socket option. There be> is no point binding a socket to a v4-mapped address if the kernel isn't be> going to deliver IPv4 connections to it. Sendmail should also be binding be> to all the addresses returned, if it isn't already, rather than just the be> first: this would make the problem go away, since both v4-mapped and be> native IPv6 sockets would be bound, and the v4-mapped ones would simply be> never get any connections. I reread the RFC 2553 and realize your explanation is correct. gshapiro's explanation was a behavior in the case of (AF_INET6, AI_DEFAULT), not (AF_INET6, AI_DEFAULT|AI_ALL). I think sendmail should work regardless of net.inet6.ip6.v6only. Is just dropping AI_ALL enough for that? When AAAA RR is found, no v4-mapped address will return in that case. Is this correct? be> Fixing this by setting ipv6_prefer is not necessarily a good idea; this be> will cause IPv6 addresses to be preferred across the whole system, and be> unless your IPv6 connectivity is at least as good as your IPv4, that be> probably isn't what you want. Yes, I agree that ipv6_prefer is not a correct way to solve this specific issue. be> > Just curious, but is there any specific reason not to return an error be> > when Family=inet6 and no AAAA RR? be> be> In this case, Sendmail explicitly requested that v4-mapped addresses be be> returned in all cases... -- Hiroki
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