Bug 10851 – no fallback to nameserver 0.0.0.0 if /etc/resolv.conf is missing

Bug 10851 - no fallback to nameserver 0.0.0.0 if /etc/resolv.conf is missing


Summary:	no fallback to nameserver 0.0.0.0 if /etc/resolv.conf is missing

Status:	RESOLVED FIXED

Product:	glibc
Classification:	Unclassified
Component:	libc
Version:	unspecified

Importance:	P2 normal
Target Milestone:	---
Assigned To:	Ulrich Drepper

URL:
Keywords:

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2009-10-26 17:38 UTC by Aurelien Jarno
Modified:	2010-09-14 17:04 UTC (History)
CC List:	1 user (show)

See Also:
Host:	x86_64-unknown-linux-gnu
Target:	x86_64-unknown-linux-gnu
Build:	x86_64-unknown-linux-gnu
Last reconfirmed:

Attachments
Patch to fix the problem (433 bytes, patch) 2009-10-26 17:38 UTC, Aurelien Jarno	Details \| Diff
New patch (1.12 KB, patch) 2009-11-08 18:41 UTC, Aurelien Jarno	Details \| Diff
alternative patch (860 bytes, patch) 2009-11-20 08:28 UTC, Petr Baudis	Details \| Diff
Show Obsolete (1) View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.

Description Aurelien Jarno 2009-10-26 17:38:25 UTC

Starting with glibc 2.10, there is no fallback to nameserver 0.0.0.0 anymore if
/etc/resolv.conf is missing. This is due to this change:

2008-12-02  Ulrich Drepper  <drepper@redhat.com>

        * resolv/res_init.c (__res_vinit): Initialize nscount to zero.

This value should be set back to 1 so that the following code is actually useful:
#ifdef USELOOPBACK
        statp->nsaddr.sin_addr = inet_makeaddr(IN_LOOPBACKNET, 1);
#else
        statp->nsaddr.sin_addr.s_addr = INADDR_ANY;
#endif
        statp->nsaddr.sin_family = AF_INET;
        statp->nsaddr.sin_port = htons(NAMESERVER_PORT);

Comment 1 Aurelien Jarno 2009-10-26 17:38:48 UTC

Created attachment 4322 [details]
Patch to fix the problem

Comment 2 Aurelien Jarno 2009-11-08 18:41:44 UTC

Created attachment 4369 [details]
New patch

The previous patch does not work in case /etc/resolv.conf exists, but does not
contain a nameserver entry. This new patch also takes that into account.

Comment 3 Petr Baudis 2009-11-09 16:38:06 UTC

See also http://sourceware.org/ml/libc-alpha/2009-02/msg00028.html :(

Comment 4 Petr Baudis 2009-11-20 08:28:19 UTC

Created attachment 4402 [details]
alternative patch

Oops, I haven't noticed you already implemented a fix; anyway, here's what I've
done independently, somewhat simpler patch. YMMV.

Comment 5 Ulrich Drepper 2010-08-25 14:48:07 UTC

I checked in a different patch.

Comment 6 Aurelien Jarno 2010-09-02 17:55:04 UTC

(In reply to comment #5)
> I checked in a different patch.

... but broken what. You forget to set statp->nscount to 1, so it doesn't work.

Comment 7 Petr Baudis 2010-09-14 17:04:19 UTC

Fixed in Git now for good, hopefully.