Bug#479144: libc6-i386: in some 32bit apps, resolving fails when lib32nss-mdns is not installed

[A Mennucc <debdev@mennucci.sns.it>]

Package: libc6-i386
Version: 2.7-10
Severity: important

hi

This bug was found when trying to use the upstream binary of firefox 3.0
inside a amd64 Debian (or Ubuntu). In some situations, firefox cannot
resolve hostnames (and is then completely unusable).

Here is the bug, as described by Sylvain Pasche in
https://bugzilla.mozilla.org/show_bug.cgi?id=414197
vvvvvvvv
I've been seeing this on Ubuntu Hardy 8.04 64bit too. Any trunk or branch 32bit
build fails to resolve hostnames. After some debugging I could isolate that the
getaddrinfo() libc call is always failing to resolve anything.

I turns out I was missing the lib32nss-mdns package. The /etc/nsswitch.conf
default configuration contains:

hosts:          files mdns4_minimal [NOTFOUND=return] dns mdns4

So without the lib32nss-mdns package, the libc can't load the mdns4_minimal
module and aborts the resolution.
^^^^^^^^

Actually, according to the document  'info libc "Actions in the NSS configuration"'
if the module mdns4_minimal is not available, then the behaviour should be:
  `unavail'
     The service is permanently unavailable.  This can either mean the
     needed file is not available, or, for DNS, the server is not
     available or does not allow queries.  The default action is
     `continue'.
but unfortunately (as reported long ago in bug 365048), the above does not work.

I see two ways to solve this bug.
1) libc6-i386 should depend on  lib32nss-mdns
2) the affected line in /etc/nsswitch.conf be changed to
 hosts:          files dns mdns4
3) fix bug 365048 

Any of the two above changes fix the problem.

a.

-- System Information:
Debian Release: lenny/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.25-1-amd64 (SMP w/2 CPU cores)
Locale: LANG=it_IT.UTF-8, LC_CTYPE=it_IT.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages libc6-i386 depends on:
ii  libc6                         2.7-10     GNU C Library: Shared libraries

libc6-i386 recommends no packages.

-- no debconf information