[avahi] Link local IPV6 addresses

[Alexander Larsson]

I recently ran into an issue with link local ipv6 addresses and avahi.
The machine i ran on was ipv6-enabled, but on a non-ipv6 network. This
meant that the ipv6 address used on the eth0 iface was a randomly picked
"link-local" address. Avahi would then announce both an ipv4 and an ipv6
service, and if you query for both it would return the ipv6 one by
default.

However, the link local ipv6 address is quite a pain in the ass to use.
For instance, any use of it with the socket api requires you to also
specify the iface to use, meaning you have to special case things, and
you can't store the address in an ip address only field.

It would be nice if Avahi could default to return the ipv4 address if
there is both an ipv6/ipv4 versions and the ipv6 address is link-local.

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 Alexander Larsson                                            Red Hat, Inc 
                   alexl at redhat.com    alla at lysator.liu.se 
He's a lounge-singing arachnophobic cyborg with a winning smile and a way with 
the ladies. She's a high-kicking renegade mercenary with someone else's 
memories. They fight crime!