[avahi] Possible bug in CNAME resolution

[Trent Lloyd]

Hi Kyle,

> On 21 Sep 2015, at 11:50 PM, Kyle Edwards <kedwards at bullex.com> wrote:
> 
> Hi all,
> 
> I have recently discovered what I believe may be a bug in avahi-daemon.
> It seems to have something to do with CNAME resolution. I have a bunch
> of devices on a network named xxxx.local, with an additional CNAME
> record named xxxx.net pointing to xxxx.local. Every once in a while,
> when a device gets removed from the network, avahi-daemon crashes on
> another device, with this error message:
> 
>> on: running [xxxx.local]: browse.c:298: lookup_multicast_callback:
> Assertion `avahi_key_equal(b->key, l->key)' failed.
>> Aborted
> 
> I added some more debug statements and got this:
> 
>> browse.c: b->key: yyyy.net	IN	AAAA
>> browse.c: l->key: yyyy.local	IN	AAAA
>> on: running [xxxx.local]: browse.c:306: lookup_multicast_callback:
> Assertion `avahi_key_equal(b->key, l->key)' failed.
> Aborted
> 
> So, it looks like the AvahiSRBLookup key and the AvahiSRecordBrowser key
> are different for some reason. I am running Avahi 0.6.31. Would somebody
> be able to help me? Thanks in advance.

Thanks for the report.  This definitely looks like a bug we should fix.

Can you confirm for me a few things;
 - Can you send your avahi-daemon.conf (privately is fine if you prefer)
 - Can you confirm where the xxxx.net CNAME exists, is this in "normal" DNS? And thus you lookup “host.domain.com” which CNAMEs to “host.local”? It’s not entirely clear so if you can fully describe how to replicate your setup that would be ideal.
 - Can you confirm your nsswitch.conf configuration for hosts, e.g.
   # grep hosts /etc/nsswitch.conf

Regards,
Trent