New hook: muc_filter_presence

Add a hook that allows for modifying or dropping presence stanzas sent
to MUC rooms.

src/mod_muc_room.erl

@@ -1035,14 +1035,25 @@ get_participant_data(From, StateData) ->
     end.
 
 process_presence(From, Nick,
-		 #xmlel{name = <<"presence">>, attrs = Attrs} = Packet,
+		 #xmlel{name = <<"presence">>, attrs = Attrs0} = Packet0,
 		 StateData) ->
-    Type = xml:get_attr_s(<<"type">>, Attrs),
+    Type0 = xml:get_attr_s(<<"type">>, Attrs0),
+    IsOnline = is_user_online(From, StateData),
+    if Type0 == <<"">>;
+       IsOnline and ((Type0 == <<"unavailable">>) or (Type0 == <<"error">>)) ->
+	   case ejabberd_hooks:run_fold(muc_filter_presence,
+					StateData#state.server_host,
+					Packet0,
+					[StateData,
+					 StateData#state.jid,
+					 From, Nick]) of
+	     drop ->
+		 {next_state, normal_state, StateData};
+	     #xmlel{attrs = Attrs} = Packet ->
+		 Type = xml:get_attr_s(<<"xml:lang">>, Attrs),
 		 Lang = xml:get_attr_s(<<"xml:lang">>, Attrs),
 		 StateData1 = case Type of
 				<<"unavailable">> ->
-		       case is_user_online(From, StateData) of
-			 true ->
 				    NewPacket = case
 						  {(StateData#state.config)#config.allow_visitor_status,
 						   is_visitor(From, StateData)}
@@ -1065,21 +1076,16 @@ process_presence(From, Nick,
 						   xml:get_tag_cdata(Status_el)
 					     end,
 				    remove_online_user(From, NewState, Reason);
-			 _ -> StateData
-		       end;
 				<<"error">> ->
-		       case is_user_online(From, StateData) of
-			 true ->
 				    ErrorText =
 					<<"This participant is kicked from the "
 					  "room because he sent an error presence">>,
 				    expulse_participant(Packet, From, StateData,
 							translate:translate(Lang,
 									    ErrorText));
-			 _ -> StateData
-		       end;
 				<<"">> ->
-		       case is_user_online(From, StateData) of
+				    if not IsOnline ->
+					   add_new_user(From, Nick, Packet, StateData);
 				       true ->
 					   case is_nick_change(From, Nick, StateData) of
 					     true ->
@@ -1140,12 +1146,14 @@ process_presence(From, Nick,
 									      StateData),
 						 send_new_presence(From, NewState),
 						 NewState
-			     end;
-			 _ -> add_new_user(From, Nick, Packet, StateData)
-		       end;
-		   _ -> StateData
+					   end
+				    end
 			      end,
-    close_room_if_temporary_and_empty(StateData1).
+		 close_room_if_temporary_and_empty(StateData1)
+	   end;
+       true ->
+	   {next_state, normal_state, StateData}
+    end.
 
 close_room_if_temporary_and_empty(StateData1) ->
     case not (StateData1#state.config)#config.persistent