Bug#526823: libc6 2.9-9 broke DNS resolver again
On Mon, May 4, 2009 at 6:45 AM, Aurelien Jarno <email@example.com> wrote:
> On Sun, May 03, 2009 at 08:54:07PM +0200, Luca Tettamanti wrote:
>> Package: libc6
>> Version: 2.9-9
>> Severity: normal
>> Hello, I was affected by the resolver bug that was solved in 2.9-7; as of 2.9-9
>> the resolver stopped working again. The automatic workaround that is mentioned
>> in the changelog is not working, and "single-request" in resolv.conf doesn't
>> seem to have any effect either.
>> Here's a dump of the resolver trying to get the address of google.com:
>> 14:11:00.754265 IP (tos 0x0, ttl 64, id 45448, offset 0, flags [DF], proto UDP (17), length 60)
>> 10.0.0.3.60486 > 10.0.0.138.53: [udp sum ok] 39108+ A? www.google.com. (32)
>> 14:11:00.754303 IP (tos 0x0, ttl 64, id 45449, offset 0, flags [DF], proto UDP (17), length 60)
>> 10.0.0.3.60486 > 10.0.0.138.53: [udp sum ok] 48015+ AAAA? www.google.com. (32)
>> 14:11:00.759312 IP (tos 0x0, ttl 64, id 1324, offset 0, flags [none], proto UDP (17), length 60)
>> 10.0.0.138.53 > 10.0.0.3.60486: [udp sum ok] 48015 NotImp q: AAAA? www.google.com. 0/0/0 (32)
>> 14:11:00.817710 IP (tos 0x0, ttl 64, id 1325, offset 0, flags [none], proto UDP (17), length 144)
>> 10.0.0.138.53 > 10.0.0.3.60486: 39108 q: A? www.google.com. 5/0/0 www.google.com. CNAME www.l.google.com.[|domain]
>> The DNS server (it's my ADSL router) responds NotImp to the AAAA query (it does
>> not support IPv6). The reply (CNAME) to the A query seems correct though.
> Could you please try the glibc from http://temp.aurel32.net/glibc-test/ ?
> I have backported a few more patch from upstream, but I have no way to
> know if they change something or not.
The option single-request works, the automagic workaround does not,
i.e. I always see the two requests going out in parallel.
Actually I'm not sure I understand how it's supposes to work: if the
first request fails usually the caller gives up, no?