Bug#563552: libc: resolver doesn't fallback to secondary dns-server when first one is ipv6 and unreachable

[Aurelien Jarno <aurelien@aurel32.net>]

Luca Bruno a écrit :
> Aurelien Jarno scrisse:
> 
>> It is not something I am able to reproduce here, so it may be due to
>> your configuration setup.
> 
> I don't remember having touched anything in particular, but I can't
> exclude it totally. This is a fairly recent lenny-install upgraded to sid.
> 
>> Do you have ipv6 available on the machine?
> 
> Yep, tunneled via sixxs:
> lucab@thetis:~$ /sbin/ifconfig 
> eth1      Link encap:Ethernet  HWaddr 00:13:ce:c1:a3:77  
>           inet addr:192.168.1.3  Bcast:192.168.1.255  Mask:255.255.255.0
>           inet6 addr: fe80::213:ceff:fec1:a377/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:1536812 errors:118 dropped:118 overruns:0 frame:0
>           TX packets:1561524 errors:0 dropped:1 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000 
>           RX bytes:1363535775 (1.2 GiB)  TX bytes:170704340 (162.7 MiB)
>           Interrupt:11 Base address:0x8000 Memory:b000b000-b000bfff 
> 
> lo        Link encap:Local Loopback  
>           inet addr:127.0.0.1  Mask:255.0.0.0
>           inet6 addr: ::1/128 Scope:Host
>           UP LOOPBACK RUNNING  MTU:16436  Metric:1
>           RX packets:206 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:206 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0 
>           RX bytes:12664 (12.3 KiB)  TX bytes:12664 (12.3 KiB)
> 
> sixxs     Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
>           inet6 addr: 2001:1418:100:22d::2/64 Scope:Global
>           inet6 addr: fe80::1418:100:22d:2/64 Scope:Link
>           UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1280  Metric:1
>           RX packets:104152 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:90623 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:500 
>           RX bytes:91635397 (87.3 MiB)  TX bytes:8090471 (7.7 MiB)
> 
> 
>> Have you changed /etc/gai.conf or have other lines
>> in /etc/resolv.conf?
> 
> No; first line here is an example of a non-existing nameserver, to simulate 
> unreachability.
> 
> lucab@thetis:~$ cat /etc/resolv.conf 
> nameserver 2001:1418:10:2::12
> nameserver 8.8.8.8
> 
> lucab@thetis:~$ grep -v '^#' /etc/gai.conf 
> 
> lucab@thetis:~$
> 
>> How do you test that? Using "getent ahosts"?
> 
> With above described setup, it is directly observable 
> as every apps stop resolving names, but even getent shows that:
> 
> lucab@thetis:~$ getent ahosts www.debian.org || echo bad
> bad
> 

This is not observable here, with the same configuration as yours. Have
you tried an other nameserver than 8.8.8.8, or 8.8.8.8 alone?

What's the output of 'strace getent ahosts www.debian.org'?

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net