Use ejabberd_cluster:send() in SM/C2S

src/ejabberd_c2s.erl

@@ -146,10 +146,9 @@ send_error(#{lserver := LServer} = State, Pkt, Err) ->
 	{Pkt1, State1} -> xmpp_stream_in:send_error(State1, Pkt1, Err)
     end.
 
--spec route(pid(), term()) -> ok.
+-spec route(pid(), term()) -> boolean().
 route(Pid, Term) ->
-    Pid ! Term,
-    ok.
+    ejabberd_cluster:send(Pid, Term).
 
 -spec set_timeout(state(), timeout()) -> state().
 set_timeout(State, Timeout) ->

src/ejabberd_cluster.erl

@@ -113,21 +113,28 @@ get_node_by_id(ID) ->
     Mod = get_mod(),
     Mod:get_node_by_id(ID).
 
+%% Note that false positive returns are possible, while false negatives are not.
+%% In other words: positive return value (i.e. 'true') doesn't guarantee
+%% successful delivery, while negative return value ('false') means
+%% the delivery has definitely failed.
 -spec send(dst(), term()) -> boolean().
-send(Dst, Msg) ->
-    IsLocal = case Dst of
-		  {_, Node} -> Node == node();
-		  Pid when is_pid(Pid) -> node(Pid) == node();
-		  Name when is_atom(Name) -> true;
-		  _ -> false
-	      end,
-    if IsLocal ->
-	    erlang:send(Dst, Msg),
+send({Name, Node}, Msg) when Node == node() ->
+    send(Name, Msg);
+send(undefined, _Msg) ->
+    false;
+send(Name, Msg) when is_atom(Name) ->
+    send(whereis(Name), Msg);
+send(Pid, Msg) when is_pid(Pid) andalso node(Pid) == node() ->
+    case erlang:is_process_alive(Pid) of
+	true ->
+	    erlang:send(Pid, Msg),
 	    true;
-       true ->
-	    Mod = get_mod(),
-	    Mod:send(Dst, Msg)
-    end.
+	false ->
+	    false
+    end;
+send(Dst, Msg) ->
+    Mod = get_mod(),
+    Mod:send(Dst, Msg).
 
 -spec wait_for_sync(timeout()) -> ok | {error, any()}.
 wait_for_sync(Timeout) ->