From ac2e413ec03c68b39819292a3ecf28dadd61d470 Mon Sep 17 00:00:00 2001
From: David Eisner <david.eisner@oriel.oxon.org>
Date: Fri, 1 Nov 2013 09:27:31 +0000
Subject: [PATCH] Advertise MPD with Avahi

A rudimentary implementation to resolve #39, ignoring dbus errors (just restart), name collisions (choose a fresh name), etc.
---
 mopidy/frontends/mpd/__init__.py |  2 ++
 mopidy/frontends/mpd/actor.py    | 26 ++++++++++++++++++++
 mopidy/frontends/mpd/ext.conf    |  2 ++
 mopidy/frontends/mpd/zeroconf.py | 42 ++++++++++++++++++++++++++++++++
 4 files changed, 72 insertions(+)
 create mode 100644 mopidy/frontends/mpd/zeroconf.py

diff --git a/mopidy/frontends/mpd/__init__.py b/mopidy/frontends/mpd/__init__.py
index 276be450..28f9c951 100644
--- a/mopidy/frontends/mpd/__init__.py
+++ b/mopidy/frontends/mpd/__init__.py
@@ -23,6 +23,8 @@ class Extension(ext.Extension):
         schema['password'] = config.Secret(optional=True)
         schema['max_connections'] = config.Integer(minimum=1)
         schema['connection_timeout'] = config.Integer(minimum=1)
+        schema['zeroconf_enabled'] = config.Boolean()
+        schema['zeroconf_name'] = config.String()
         return schema
 
     def validate_environment(self):
diff --git a/mopidy/frontends/mpd/actor.py b/mopidy/frontends/mpd/actor.py
index 4d983b73..b48b2b65 100644
--- a/mopidy/frontends/mpd/actor.py
+++ b/mopidy/frontends/mpd/actor.py
@@ -17,6 +17,9 @@ class MpdFrontend(pykka.ThreadingActor, CoreListener):
         super(MpdFrontend, self).__init__()
         hostname = network.format_hostname(config['mpd']['hostname'])
         port = config['mpd']['port']
+        self.config = config
+        self.hostname = hostname
+        self.port = port
 
         try:
             network.Server(
@@ -36,8 +39,31 @@ class MpdFrontend(pykka.ThreadingActor, CoreListener):
 
         logger.info('MPD server running at [%s]:%s', hostname, port)
 
+    def on_start(self):
+        try:
+            if self.config['mpd']['zeroconf_enabled']:
+                name = self.config['mpd']['zeroconf_name']
+                import re
+                lo = re.search('(?<![.\d])(127|0)[.]', self.hostname)
+                hostname = "" if lo else self.hostname
+
+                from zeroconf import Zeroconf
+                self.service = Zeroconf(
+                    stype="_mpd._tcp",
+                    name=name, port=self.port, host=hostname)
+                self.service.publish()
+
+                logger.info('Registered with Avahi as %s', name)
+        except Exception as e:
+            logger.warning('Avahi registration failed (%s)', e)
+
     def on_stop(self):
         process.stop_actors_by_class(session.MpdSession)
+        try:
+            if self.service:
+                self.service.unpublish()
+        except Exception as e:
+            logger.warning('Avahi unregistration failed (%s)', e)
 
     def send_idle(self, subsystem):
         listeners = pykka.ActorRegistry.get_by_class(session.MpdSession)
diff --git a/mopidy/frontends/mpd/ext.conf b/mopidy/frontends/mpd/ext.conf
index bf77100c..667aff24 100644
--- a/mopidy/frontends/mpd/ext.conf
+++ b/mopidy/frontends/mpd/ext.conf
@@ -5,3 +5,5 @@ port = 6600
 password =
 max_connections = 20
 connection_timeout = 60
+zeroconf_enabled = true
+zeroconf_name = Mopidy
diff --git a/mopidy/frontends/mpd/zeroconf.py b/mopidy/frontends/mpd/zeroconf.py
new file mode 100644
index 00000000..db92877a
--- /dev/null
+++ b/mopidy/frontends/mpd/zeroconf.py
@@ -0,0 +1,42 @@
+import dbus
+
+__all__ = ["Zeroconf"]
+
+
+class Zeroconf:
+    """A simple class to publish a network service with zeroconf using
+    avahi.
+
+    """
+
+    def __init__(self, name, port, stype="_http._tcp",
+                 domain="", host="", text=""):
+        self.name = name
+        self.stype = stype
+        self.domain = domain
+        self.host = host
+        self.port = port
+        self.text = text
+
+    def publish(self):
+        bus = dbus.SystemBus()
+        server = dbus.Interface(
+            bus.get_object(
+                "org.freedesktop.Avahi",
+                "/"),
+            "org.freedesktop.Avahi.Server")
+
+        g = dbus.Interface(
+            bus.get_object("org.freedesktop.Avahi",
+                           server.EntryGroupNew()),
+            "org.freedesktop.Avahi.EntryGroup")
+
+        g.AddService(-1, -1, dbus.UInt32(0),
+                     self.name, self.stype, self.domain, self.host,
+                     dbus.UInt16(self.port), self.text)
+
+        g.Commit()
+        self.group = g
+
+    def unpublish(self):
+        self.group.Reset()