Bug#428434: libc6: Resolver prefers IPv4 to IPv6 in some cases

[Friedemann Stoyan <fstoyan@swapon.de>]

Package: libc6
Version: 2.3.6.ds1-13
Severity: normal

Hi,

In some cases the resolver prefers IPv4 to IPv6. This happens when:

- the A-RR is a RFC 1918 Address
- there is a more specific route for this address

Example:

$ ip route list table all 192.168.17.1
local 192.168.17.1 dev lo  table 255  proto kernel  scope host  src 192.168.17.1

$ host -t any test1.libc6test.swapon.de
test1.libc6test.swapon.de has IPv6 address 2001:6f8:12ec::1
test1.libc6test.swapon.de has address 10.10.10.10

$ host -t any test2.libc6test.swapon.de
test2.libc6test.swapon.de has IPv6 address 2001:6f8:12ec::1
test2.libc6test.swapon.de has address 192.168.17.1

$ host -t any test3.libc6test.swapon.de
test3.libc6test.swapon.de has IPv6 address 2001:6f8:12ec::1
test3.libc6test.swapon.de has address 81.169.139.143

$ telnet test1.libc6test.swapon.de
Trying 2001:6f8:12ec::1...
Trying 10.10.10.10...

$ telnet test2.libc6test.swapon.de
Trying 192.168.17.1...
Trying 2001:6f8:12ec::1...

$ telnet test3.libc6test.swapon.de
Trying 2001:6f8:12ec::1...
Trying 81.169.139.143...

The releases "2.3.2.ds1-22sarge6" (Sarge) and "2.5-9+b1" (Lenny) are not
affected.

-- System Information:
Debian Release: 4.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-4-686
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)

Versions of packages libc6 depends on:
ii  tzdata                        2007b-1    Time Zone and Daylight Saving Time

libc6 recommends no packages.