Bug#435646: libc6: resolver considers IPv6 enabled when any IPv6 address is configured

[Aurelien Jarno <aurelien@aurel32.net>]

Andrew McMillan a écrit :
> Package: libc6
> Version: 2.6-5
> Severity: important
> Tags: patch
> 
> 
> Hi,
> 
> Tolleff fog Heen has written a patch for the resolver, so that it does
> not start performing (or waiting for) AAAA lookups unless a globally
> scoped IPv6 address is present on some interface.
> 
> Since Debian enables IPv6 by default, most users will have a system with
> an IPv6 address on the loopback interface (as well as a link-local
> address on each other interface) which will cause the current code to
> commence lookups for AAAA records, only falling back to requesting A
> records when these fail or timeout.
> 
> The patch here:
> 
> http://err.no/patches/glibc-only-lookup-ipv6-if-it-makes-sense.diff
> 
> seems to take a reasonable approach, since it will not be possible to
> connect to IPv6 addresses without a globally scoped address (plus
> routing :-) in any case.
> 
> This is an important issue because some users are so inconvenienced as
> to be behind broken DNS infrastructure which ignores AAAA requests,
> resulting in frequent timeouts with much confusion and frustration.
> 

I have already been given the link to this patch. It sounds reasonable,
but first I would like to know if it is in use on more than one machine,
for both IPv4 and IPv4 + IPv6 setups?

I don't really want to apply a patch that can cause regressions.

Cheers,
Aurelien

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