Initial XEP-0184 support.

TODO:
 * Implement section 5.
 * Think of a way to show in GUI
    Possible way: Grey out the sent msg until we receive a <received/>,
    but only if we know the other end supports XEP-0184.
 * Maybe implement section 6?

src/common/config.py

@@ -311,6 +311,8 @@ class Config:
 			'zeroconf_jabber_id': [ opt_str, '', '', True ],
 			'zeroconf_email': [ opt_str, '', '', True ],
 			'use_env_http_proxy' : [opt_bool, False],
+			'answer_receipt' : [opt_bool, True],
+			'request_receipt' : [opt_bool, True],
 			'otr_flags': [opt_int, 58 ],
 			'publish_mood': [opt_bool, True],
 			'publish_activity': [opt_bool, True],

src/common/connection.py

@@ -1123,6 +1123,14 @@ class Connection(ConnectionHandlers):
 				namespace=common.xmpp.NS_ADDRESS)
 			addresses.addChild('address', attrs = {'type': 'ofrom',
 				'jid': forward_from})
+
+		# TODO: We should also check if the other end supports it
+		#       as XEP 0184 says checking is a SHOULD. Maybe we should
+		#       implement section 6 of the XEP as well?
+		if msgtxt and gajim.config.get_per('accounts', self.name,
+		'request_receipt'):
+			msg_iq.setTag('request', namespace='urn:xmpp:receipts')
+
 		if session:
 			# XEP-0201
 			session.last_send = time.time()
@@ -1132,7 +1140,6 @@ class Connection(ConnectionHandlers):
 			if session.enable_encryption:
 				msg_iq = session.encrypt_stanza(msg_iq)
 
-
 		self.connection.send(msg_iq)
 		if not forward_from and session and session.is_loggable():
 			no_log_for = gajim.config.get_per('accounts', self.name, 'no_log_for')\

src/common/connection_handlers.py

@@ -1694,6 +1694,16 @@ class ConnectionHandlers(ConnectionVcard, ConnectionBytestream, ConnectionDisco,
 		encrypted = False
 		xep_200_encrypted = msg.getTag('c', namespace=common.xmpp.NS_STANZA_CRYPTO)
 		
+		# Receipt requested
+		if msg.getTag('request', namespace='urn:xmpp:receipts') and \
+		gajim.config.get_per('accounts', self.name, 'answer_receipt'):
+			receipt = common.xmpp.Message(to = jid, typ = 'chat')
+			receipt.setID(msg.getID())
+			receipt.setTag('received',
+				namespace='urn:xmpp:receipts')
+			receipt.setThread(thread_id)
+			con.send(receipt)
+
 		# We don't trust libotr, that's why we only pass the message
 		# to it if necessary. otrl_proto_message_type does this check.
 		if gajim.otr_module and not xep_200_encrypted \