Send notifications on MUC configuration changes

Notify clients when the room configuration changes, as mandated by
XEP-0045, #10.2.1.

Closes #623.

src/mod_muc_room.erl

@@ -3732,6 +3732,7 @@ set_xoption([_ | _Opts], _Config) ->
     {error, ?ERR_BAD_REQUEST}.
 
 change_config(Config, StateData) ->
+    send_config_change_info(Config, StateData),
     NSD = StateData#state{config = Config},
     case {(StateData#state.config)#config.persistent,
 	  Config#config.persistent}
@@ -3752,6 +3753,39 @@ change_config(Config, StateData) ->
       _ -> {result, [], NSD}
     end.
 
+send_config_change_info(Config, #state{config = Config}) -> ok;
+send_config_change_info(New, #state{config = Old} = StateData) ->
+    Codes = case {Old#config.logging, New#config.logging} of
+	      {false, true} -> [<<"170">>];
+	      {true, false} -> [<<"171">>];
+	      _ -> []
+	    end
+	      ++
+	      case {Old#config.anonymous, New#config.anonymous} of
+		{true, false} -> [<<"172">>];
+		{false, true} -> [<<"173">>];
+		_ -> []
+	      end
+		++
+		case Old#config{anonymous = New#config.anonymous,
+				logging = New#config.logging} of
+		  New -> [];
+		  _ -> [<<"104">>]
+		end,
+    StatusEls = [#xmlel{name = <<"status">>,
+			attrs = [{<<"code">>, Code}],
+			children = []} || Code <- Codes],
+    Message = #xmlel{name = <<"message">>,
+		     attrs = [{<<"type">>, <<"groupchat">>},
+			      {<<"id">>, randoms:get_string()}],
+		     children = [#xmlel{name = <<"x">>,
+					attrs = [{<<"xmlns">>, ?NS_MUC_USER}],
+					children = StatusEls}]},
+    send_multiple(StateData#state.jid,
+		  StateData#state.server_host,
+		  StateData#state.users,
+		  Message).
+
 remove_nonmembers(StateData) ->
     lists:foldl(fun ({_LJID, #user{jid = JID}}, SD) ->
 			Affiliation = get_affiliation(JID, SD),

test/ejabberd_SUITE.erl

@@ -1122,10 +1122,11 @@ muc_master(Config) ->
                   end
           end, RoomCfg#xdata.fields),
     NewRoomCfg = #xdata{type = submit, fields = NewFields},
-    %% BUG: We should not receive any sub_els!
+    ID = send(Config, #iq{type = set, to = Room,
-    #iq{type = result, sub_els = [_|_]} =
-        send_recv(Config, #iq{type = set, to = Room,
 			  sub_els = [#muc_owner{config = NewRoomCfg}]}),
+    ?recv2(#iq{type = result, id = ID},
+	   #message{from = Room, type = groupchat,
+		    sub_els = [#muc_user{status_codes = [104]}]}),
     %% Set subject
     send(Config, #message{to = Room, type = groupchat,
                           body = [#text{data = Subject}]}),