[libvirt] Turning off libvirtd mdns by default

[Stef Walter]

In the GNOME UI we'd like to make use of Avahi discovery and name 
resolution "out of the box". A typical use case is for discovery of 
printers that are advertised using MDNS. This should work even on 
potentially 'hostile' networks such as a wireless access point in a 
print shop or airport. It should work without user configuration.

https://fedoraproject.org/wiki/Desktop/Whiteboards/AvahiDefault

In order to turn on Avahi by default, and make it work by default, we'd 
like to make it possible to use Avahi without advertising any 
information to the network by default. Advertising information to the 
network (even the host name) without the user's configuration or consent 
is a privacy issue.

libvirtd advertises itself via MDNS on the network by default. I 
understand that MDNS discovery of libvirtd is really handy in many cases.

However since one has to configure network access in libvirtd anyway  -- 
none of the access methods work "out of the box" to my understanding -- 
I'd like to suggest turning off libvirtd's MDNS publishing by default. 
As part of setting up libvirtd for network access, the user would turn 
on mdns_adv.

I hope that makes sense. Let me know if I've gotten something wrong.

Would you accept a patch to do this? Or would you suggest that we try 
and do this downstream in the Fedora/RHEL packages instead?

Cheers,

Stef