Re: IPv4 and IPv6 addresses in resolv.conf

[Rich Felker <dalias@aerifal.cx>]

On Fri, Nov 29, 2013 at 12:44:10PM -0500, Rich Felker wrote:
> On Fri, Nov 29, 2013 at 06:09:26PM +0800, orc wrote:
> > Hi list,
> > It is possible in future to have both ipv4 and ipv6 addresses in resolv.conf?
> > Currently dns resolver reads first address and if it is ipv6 address
> > then it goes on and second address (127.0.0.1 as example) also
> > interpreted as ipv6 one, result is attempt to send data to
> > 127::7f00:1.
> 
> If this is happening, it's a bug. The intent is that both v4 and v6
> are supported. I'll see if I can reproduce it and if it's not too hard
> to fix I'll try to get a fix in before the release.

Can you clarify if you're using latest git or 0.9.14? I can't
reproduce this in current git, but it looks like the misinterpretation
was due to __ipparse bugs which nsz fixed. The behavior I'm seeing,
which is what was intended (I was slightly wrong in my above
expression of intent) is that only nameservers in the same address
family as the first nameserver get used, and nameservers in the other
get ignored. This is suboptimal but at least not horribly broken.

What I think would be the correct behavior is noting whether any v6
addresses are seen, and if so, converting the v4 addresses to
v4-mapped v6 addresses and using IPv6 for all communication. Does this
sound reasonable?

Rich