Bug 45858

When two network interfaces are in the same network segment, and a remote server is available, avahi reports this:


~@karen.dragonfear α:
avahi-browse -a | grep pulse
+  wlan0 IPv4 pulse@paola.dragonfear                        PulseAudio Sound Server local
+  wlan0 IPv4 pulse@paola.dragonfear: Internal Audio        PulseAudio Sound Sink local
+   p5p1 IPv4 pulse@paola.dragonfear: Internal Audio        PulseAudio Sound Sink local
+   p5p1 IPv4 pulse@paola.dragonfear                        PulseAudio Sound Server local

And the sink appears in the local server as a remote sink.

When one network interface is disconnected, this happens in avahi:

-   p5p1 IPv4 pulse@paola.dragonfear                        PulseAudio Sound Server local
-   p5p1 IPv4 pulse@paola.dragonfear: Internal Audio        PulseAudio Sound Sink local

The sink DISAPPEARS from pulseaudio volume control.  However both sink and server CONTINUE to be available in wlan0:

+  wlan0 IPv4 pulse@paola.dragonfear                        PulseAudio Sound Server local
+  wlan0 IPv4 pulse@paola.dragonfear: Internal Audio        PulseAudio Sound Sink local

Note that, at this point, connecting p5p1 again makes the sink reappear in pulseaudio volume control.

This points to a bug in module-zeroconf-discover, where it does the simpleton thing of adding a sink by name when it sees the sink appear, and removes it when it sees the sink disappear.

What it should do instead, is keep a reference count to the sink, and increment the count when it appears on a network interface in avahi, decrement the count when it disappears on a network interface, and only display it as an available sink when the reference count is >0.  Alternatively, PA zeroconf-discover could consult avahi to see if a sink with the same name continues to be available in another network interface.

Thanks in advance for the fix!  :-)