Expand support for XEP-0184.

New stanza interfaces:

    Adding a message receipt request:

        msg['request_receipt'] = True

    Adding a message receipt:

        msg['receipt'] = '123-24234'

    Retrieving the acked message ID:

        ack_id = msg['receipt']
        print(ack_id)
        '123-24234'

New configuration options:

    auto_ack:
        If True, auto reply to messages that request receipts.

        Defaults to True

    auto_request:
        If True, auto add receipt requests to appropriate outgoing
        messages.

        Defaults to False

sleekxmpp/plugins/xep_0184/receipt.py

@@ -0,0 +1,120 @@
+"""
+    SleekXMPP: The Sleek XMPP Library
+    Copyright (C) 2012 Erik Reuterborg Larsson, Nathanael C. Fritz
+    This file is part of SleekXMPP.
+
+    See the file LICENSE for copying permission.
+"""
+
+import logging
+
+from sleekxmpp.stanza import Message
+from sleekxmpp.xmlstream import register_stanza_plugin
+from sleekxmpp.xmlstream.handler import Callback
+from sleekxmpp.xmlstream.matcher import StanzaPath
+from sleekxmpp.plugins import BasePlugin
+from sleekxmpp.plugins.xep_0184 import stanza, Request, Received
+
+
+class XEP_0184(BasePlugin):
+
+    """
+    XEP-0184: Message Delivery Receipts
+    """
+
+    name = 'xep_0184'
+    description = 'XEP-0184: Message Delivery Receipts'
+    dependencies = set(['xep_0030'])
+    stanza = stanza
+
+    ack_types = ('normal', 'chat', 'headline')
+
+    def plugin_init(self):
+        self.auto_ack = self.config.get('auto_ack', True)
+        self.auto_request = self.config.get('auto_request', False)
+
+        register_stanza_plugin(Message, Request)
+        register_stanza_plugin(Message, Received)
+
+        self.xmpp.add_filter('out', self._filter_add_receipt_request)
+
+        self.xmpp.register_handler(
+                Callback('Message Receipt',
+                    StanzaPath('message/receipt'),
+                    self._handle_receipt_received))
+
+        self.xmpp.register_handler(
+                Callback('Message Receipt Request',
+                    StanzaPath('message/request_receipt'),
+                    self._handle_receipt_request))
+
+        self.xmpp['xep_0030'].add_feature('urn:xmpp:receipts')
+
+    def ack(self, msg):
+        """
+        Acknowledge a message by sending a receipt.
+
+        Arguments:
+            msg -- The message to acknowledge.
+        """
+        ack = self.xmpp.Message()
+        ack['to'] = msg['from']
+        ack['from'] = msg['to']
+        ack['receipt'] = msg['id']
+        ack['id'] = self.xmpp.new_id()
+        ack.send()
+
+    def _handle_receipt_received(self, msg):
+        self.xmpp.event('receipt_received', msg)
+
+    def _handle_receipt_request(self, msg):
+        """
+        Auto-ack message receipt requests if ``self.auto_ack`` is ``True``.
+
+        Arguments:
+            msg -- The incoming message requesting a receipt.
+        """
+        if self.auto_ack:
+            if msg['type'] in self.ack_types:
+                if not msg['receipt']:
+                    self.ack(msg)
+
+    def _filter_add_receipt_request(self, stanza):
+        """
+        Auto add receipt requests to outgoing messages, if:
+
+            - ``self.auto_request`` is set to ``True``
+            - The message is not for groupchat
+            - The message does not contain a receipt acknowledgment
+            - The recipient is a bare JID or, if a full JID, one
+              that has the ``urn:xmpp:receipts`` feature enabled
+
+        The disco cache is checked if a full JID is specified in
+        the outgoing message, which may mean a round-trip disco#info
+        delay for the first message sent to the JID if entity caps
+        are not used.
+        """
+
+        if not self.auto_request:
+            return stanza
+
+        if not isinstance(stanza, Message):
+            return stanza
+                
+        if stanza['request_receipt']:
+            return stanza
+
+        if not stanza['type'] in self.ack_types:
+            return stanza
+                    
+        if stanza['receipt']:
+            return stanza
+
+        if stanza['to'].resource:
+            if not self.xmpp['xep_0030'].supports(stanza['to'],
+                    feature='urn:xmpp:receipts',
+                    cached=True):
+                return stanza
+
+        stanza['request_receipt'] = True
+        return stanza