[Pkg-utopia-maintainers] Bug#433945: avahi-daemon: .local in unicast detection not perfect

[Lennart Poettering]

Package: avahi-daemon
Version: 0.6.19-2
Severity: normal


The .local-in-unicast-dns detection is not perfect. Apparently some IP
routers do not properly respond to SOA queries if asked for non-existing
domains. One example being the WLAN router of the ETAP hotel here at
GUADEC in Birmingham. This router has a catchall DNS set up and
sometimes responds with an A RR if asked for a SOA RR. This has the
unfortunate effect that the query doesn't fail and the check script
wrongly assumes that there is a unicast DNS domain called ".local" while
there actually is not. The "host" command seems not to check whether the
data in a DNS response packet actually matches the data in the DNS query
packet.

To work around this the check script should check if the output of
"host" actually includes real SOA data.

OTOH there are a couple of unicast DNS set ups around where RR
definitions reside  in a subhierarchy of .local, i.e. foo.bar.local
instead of just foo.local. If "bar.local" itself does not exist in the
DNS zone files this case is not detect as ".local in unicast DNS" cases,
while it actually should. I would suggest checking the "domain" and
"search" lines from resolv.conf for domains ending with ".local". If so,
treat this as a ".local in unicast DNS" case. Presumably if people have
set up unicast .local domains they also specify them in the DNS search
domains. A check like this would also have the big advantage that a
couple of superfluous DNS queries (which might timeout, ...) can be
skipped in many cases.

Lennart

-- System Information:
Debian Release: lenny/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable')
Architecture: i386 (i686)

Kernel: Linux 2.6.21-2-686 (SMP w/2 CPU cores)
Locale: LANG=de_DE at euro, LC_CTYPE=de_DE at euro (charmap=ISO-8859-15)
Shell: /bin/sh linked to /bin/bash

Versions of packages avahi-daemon depends on:
ii  adduser                       3.103      Add and remove users and groups
ii  dbus                          1.1.1-3    simple interprocess messaging syst
ii  libavahi-common3              0.6.19-2   Avahi common library
ii  libavahi-core5                0.6.19-2   Avahi's embeddable mDNS/DNS-SD lib
ii  libc6                         2.6-2      GNU C Library: Shared libraries
ii  libcap1                       1:1.10-14  support for getting/setting POSIX.
ii  libdaemon0                    0.10-1     lightweight C library for daemons
ii  libdbus-1-3                   1.1.1-3    simple interprocess messaging syst
ii  libexpat1                     1.95.8-3.4 XML parsing C library - runtime li
ii  lsb-base                      3.1-23.1   Linux Standard Base 3.1 init scrip

Versions of packages avahi-daemon recommends:
ii  libnss-mdns                   0.10-3     NSS module for Multicast DNS name 

-- no debconf information