mod_irc must send presence unavailable to the departing occupant (EJAB-1417)

src/mod_irc/mod_irc_connection.erl

@@ -219,6 +219,7 @@ handle_info({route_chan, Channel, Resource,
     NewStateData =
 	case xml:get_attr_s("type", Attrs) of
 	    "unavailable" ->
+		send_stanza_unavailable(Channel, StateData),
 		S1 = ?SEND(io_lib:format("PART #~s\r\n", [Channel])),
 		S1#state{channels =
 			 dict:erase(Channel, S1#state.channels)};
@@ -656,13 +657,9 @@ terminate(_Reason, _StateName, FullStateData) ->
     bounce_messages("Server Connect Failed"),
     lists:foreach(
       fun(Chan) ->
-	      ejabberd_router:route(
-		jlib:make_jid(
-		  lists:concat([Chan, "%", StateData#state.server]),
-		  StateData#state.host, StateData#state.nick),
-		StateData#state.user,
-		{xmlelement, "presence", [{"type", "error"}],
-		 [Error]})
+	      Stanza = {xmlelement, "presence", [{"type", "error"}],
+		 [Error]},
+	      send_stanza(Chan, StateData, Stanza)
       end, dict:fetch_keys(StateData#state.channels)),
     case StateData#state.socket of
 	undefined ->
@@ -672,6 +669,30 @@ terminate(_Reason, _StateName, FullStateData) ->
     end,
     ok.
 
+send_stanza(Chan, StateData, Stanza) ->
+    ejabberd_router:route(
+      jlib:make_jid(
+	lists:concat([Chan, "%", StateData#state.server]),
+	StateData#state.host, StateData#state.nick),
+      StateData#state.user,
+      Stanza).
+
+send_stanza_unavailable(Chan, StateData) ->
+    Affiliation = "member", % this is a simplification
+    Role = "none",
+    Stanza =
+	{xmlelement, "presence", [{"type", "unavailable"}],
+	 [{xmlelement, "x", [{"xmlns", ?NS_MUC_USER}],
+	   [{xmlelement, "item",
+	     [{"affiliation", Affiliation},
+	      {"role", Role}],
+	     []},
+	    {xmlelement, "status",
+	     [{"code", "110"}],
+	     []}
+	   ]}]},
+    send_stanza(Chan, StateData, Stanza).
+
 %%%----------------------------------------------------------------------
 %%% Internal functions
 %%%----------------------------------------------------------------------