Automatically reconnect to NetworkManager

When NetworkManager restarts, they will have different unique object
names on the system bus. Trying to the old objects will fail, so when
that happens we can simply reconnect.

To activate automatic reconnection, call
NetworkManager.NetworkManager.auto_reconnect after setting up your
mainloop.

NetworkManager.py

@@ -10,6 +10,7 @@
 import socket
 import struct
 import sys
+import weakref
 
 PY3 = sys.version_info >= (3,0)
 if PY3:
@@ -26,17 +27,21 @@ def debug(msg, data):
 except:
     debug = lambda *args: None
 
+auto_reconnect = True
+registry = []
+
 class NMDbusInterface(object):
     bus = dbus.SystemBus()
     dbus_service = 'org.freedesktop.NetworkManager'
     object_path = None
 
     def __init__(self, object_path=None):
+        global registry
         if isinstance(object_path, NMDbusInterface):
             object_path = object_path.object_path
         self.object_path = self.object_path or object_path
-        self.proxy = self.bus.get_object(self.dbus_service, self.object_path)
-        self.interface = dbus.Interface(self.proxy, self.interface_name)
+        self.signals = []
+        self.connect()
 
         properties = []
         try:
@@ -50,6 +55,25 @@ def __init__(self, object_path=None):
             if not hasattr(self.__class__, p):
                 setattr(self.__class__, p, self._make_property(p))
 
+        registry.append(weakref.proxy(self))
+
+    def connect(self):
+        self.proxy = self.bus.get_object(self.dbus_service, self.object_path)
+        self.interface = dbus.Interface(self.proxy, self.interface_name)
+        signals = self.signals[:]
+        self.signals = []
+        for signal, handler, args, kwargs in signals:
+            self.connect_to_signal(signal, handler, *args, **kwargs)
+
+    def reconnect(self, name, old, new):
+        if str(new) == "" or str(name) != 'org.freedesktop.NetworkManager':
+            return
+        for obj in registry:
+            try:
+                obj.connect()
+            except ReferenceError:
+                pass
+
     def _make_property(self, name):
         def get_func(self):
             data = self.proxy.Get(self.interface_name, name, dbus_interface='org.freedesktop.DBus.Properties')
@@ -121,6 +145,7 @@ def proxy_call(*args, **kwargs):
         return proxy_call
 
     def connect_to_signal(self, signal, handler, *args, **kwargs):
+        self.signals.append((signal, handler, args, kwargs))
         def helper(*args, **kwargs):
             args = [self.unwrap(x) for x in args]
             handler(*args, **kwargs)
@@ -138,6 +163,11 @@ class NetworkManager(NMDbusInterface):
     interface_name = 'org.freedesktop.NetworkManager'
     object_path = '/org/freedesktop/NetworkManager'
 
+    def auto_reconnect(self):
+        global auto_reconnect
+        auto_reconnect = True
+        self.bus.add_signal_receiver(self.reconnect, 'NameOwnerChanged', 'org.freedesktop.DBus')
+
     def preprocess(self, name, args, kwargs):
         if name in ('AddConnection', 'Update', 'UpdateUnsaved', 'AddAndActivateConnection'):
             settings = copy.deepcopy(args[0])

docs/index.rst

@@ -82,6 +82,11 @@ This class represents the :data:`org.freedesktop.NetworkManager` interface.
 Note that :data:`NetworkManager.NetworkManager` actually is the singleton
 instance of this class.
 
+.. method:: auto_reconnect
+
+Call this method to automatically update D-Bus paths and reconnect signals when
+NetworkManager restarts.
+
 .. class:: Settings
 
 This class represents the :data:`org.freedesktop.NetworkManager.Settings`

examples/listener.py

@@ -5,6 +5,7 @@
 import dbus.mainloop.glib; dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
 from gi.repository import GObject
 import NetworkManager
+NetworkManager.NetworkManager.auto_reconnect()
 
 d_args = ('sender', 'destination', 'interface', 'member', 'path')
 d_args = dict([(x + '_keyword', 'd_' + x) for x in d_args])