Allow IQ timeouts to be asynchronous, by passing a timeout_callback parameter to send(). An example modification of disco is included. If this approach is approved, I'll go through and update the other plugins.

sleekxmpp/plugins/xep_0030/disco.py

@@ -324,6 +324,8 @@ class XEP_0030(BasePlugin):
             callback -- Optional callback to execute when a reply is
                         received instead of blocking and waiting for
                         the reply.
+            timeout_callback -- Optional callback to execute when no result 
+                        has been received in timeout seconds.
         """
         if local is None:
             if jid is not None and not isinstance(jid, JID):
@@ -364,7 +366,8 @@ class XEP_0030(BasePlugin):
         iq['disco_info']['node'] = node if node else ''
         return iq.send(timeout=kwargs.get('timeout', None),
                        block=kwargs.get('block', True),
-                       callback=kwargs.get('callback', None))
+                       callback=kwargs.get('callback', None),
+                       timeout_callback=kwargs.get('timeout_callback', None))
 
     def set_info(self, jid=None, node=None, info=None):
         """
@@ -405,6 +408,8 @@ class XEP_0030(BasePlugin):
             iterator -- If True, return a result set iterator using
                         the XEP-0059 plugin, if the plugin is loaded.
                         Otherwise the parameter is ignored.
+            timeout_callback -- Optional callback to execute when no result 
+                        has been received in timeout seconds.
         """
         if local or local is None and jid is None:
             items = self.api['get_items'](jid, node,
@@ -423,7 +428,8 @@ class XEP_0030(BasePlugin):
         else:
             return iq.send(timeout=kwargs.get('timeout', None),
                            block=kwargs.get('block', True),
-                           callback=kwargs.get('callback', None))
+                           callback=kwargs.get('callback', None),
+                           timeout_callback=kwargs.get('timeout_callback', None))
 
     def set_items(self, jid=None, node=None, **kwargs):
         """

sleekxmpp/stanza/iq.py

@@ -154,7 +154,7 @@ class Iq(RootStanza):
         StanzaBase.reply(self, clear)
         return self
 
-    def send(self, block=True, timeout=None, callback=None, now=False):
+    def send(self, block=True, timeout=None, callback=None, now=False, timeout_callback=None):
         """
         Send an <iq> stanza over the XML stream.
 
@@ -181,11 +181,28 @@ class Iq(RootStanza):
             now      -- Indicates if the send queue should be skipped and send
                         the stanza immediately. Used during stream
                         initialization. Defaults to False.
+            timeout_callback -- Optional reference to a stream handler function.
+                        Will be executed when the timeout expires before a 
+                        response has been received with the originally-sent IQ 
+                        stanza.  Only called if there is a callback parameter
+                        (and therefore are in async mode).
         """
         if timeout is None:
             timeout = self.stream.response_timeout
         if callback is not None and self['type'] in ('get', 'set'):
             handler_name = 'IqCallback_%s' % self['id']
+            if timeout_callback:
+                self.callback = callback
+                self.timeout_callback = timeout_callback
+                self.stream.schedule('IqTimeout_%s' % self['id'], 
+                                     timeout, 
+                                     self._fire_timeout, 
+                                     repeat=False)            
+                handler = Callback(handler_name,
+                                   MatcherId(self['id']),
+                                   self._handle_result,
+                                   once=True)
+            else:
                 handler = Callback(handler_name,
                                    MatcherId(self['id']),
                                    callback,
@@ -206,6 +223,16 @@ class Iq(RootStanza):
         else:
             return StanzaBase.send(self, now=now)
 
+    def _handle_result(self, iq):
+        # we got the IQ, so don't fire the timeout
+        self.stream.scheduler.remove('IqTimeout_%s' % self['id'])
+        self.callback(iq)
+
+    def _fire_timeout(self):
+        # don't fire the handler for the IQ, if it finally does come in
+        self.stream.remove_handler('IqCallback_%s' % self['id'])
+        self.timeout_callback(self)
+
     def _set_stanza_values(self, values):
         """
         Set multiple stanza interface values using a dictionary.

tests/test_stream_handlers.py

@@ -153,6 +153,35 @@ class TestHandlers(SleekTest):
         self.failUnless(events == ['foo'],
                 "Iq callback was not executed: %s" % events)
 
+    def testIqTimeoutCallback(self):
+        """Test that iq.send(tcallback=handle_foo, timeout_callback=handle_timeout) works."""
+        events = []
+
+        def handle_foo(iq):
+            events.append('foo')
+
+        def handle_timeout(iq):
+            events.append('timeout')
+
+        iq = self.Iq()
+        iq['type'] = 'get'
+        iq['id'] = 'test-foo'
+        iq['to'] = 'user@localhost'
+        iq['query'] = 'foo'
+        iq.send(callback=handle_foo, timeout_callback=handle_timeout, timeout=0.05)
+
+        self.send("""
+          <iq type="get" id="test-foo" to="user@localhost">
+            <query xmlns="foo" />
+          </iq>
+        """)
+
+        # Give event queue time to process
+        time.sleep(0.1)
+
+        self.failUnless(events == ['timeout'],
+                "Iq timeout was not executed: %s" % events)
+
     def testMultipleHandlersForStanza(self):
         """
         Test that multiple handlers for a single stanza work