Improve logging of external authentication failures

src/ejabberd_auth_external.erl

@@ -64,27 +64,27 @@ check_password(User, AuthzId, Server, Password) ->
 set_password(User, Server, Password) ->
     case extauth:set_password(User, Server, Password) of
 	Res when is_boolean(Res) -> ok;
-	{error, Reason} -> failure(Reason)
+	{error, Reason} -> failure(User, Server, ?FUNCTION_NAME, Reason)
     end.
 
 try_register(User, Server, Password) ->
     case extauth:try_register(User, Server, Password) of
 	true -> ok;
 	false -> {error, not_allowed};
-	{error, Reason} -> failure(Reason)
+	{error, Reason} -> failure(User, Server, ?FUNCTION_NAME, Reason)
     end.
 
 user_exists(User, Server) ->
     case extauth:user_exists(User, Server) of
 	Res when is_boolean(Res) -> Res;
-	{error, Reason} -> failure(Reason)
+	{error, Reason} -> failure(User, Server, ?FUNCTION_NAME, Reason)
     end.
 
 remove_user(User, Server) ->
     case extauth:remove_user(User, Server) of
 	false -> {error, not_allowed};
 	true -> ok;
-	{error, Reason} -> failure(Reason)
+	{error, Reason} -> failure(User, Server, ?FUNCTION_NAME, Reason)
     end.
 
 check_password_extauth(User, _AuthzId, Server, Password) ->
@@ -92,16 +92,17 @@ check_password_extauth(User, _AuthzId, Server, Password) ->
 	    case extauth:check_password(User, Server, Password) of
 		Res when is_boolean(Res) -> Res;
 		{error, Reason} ->
-		    failure(Reason),
+		    failure(User, Server, ?FUNCTION_NAME, Reason),
 		    false
 	    end;
        true ->
 	    false
     end.
 
--spec failure(any()) -> {error, db_failure}.
-failure(Reason) ->
-    ?ERROR_MSG("External authentication program failure: ~p", [Reason]),
+-spec failure(binary(), binary(), atom(), any()) -> {error, db_failure}.
+failure(User, Server, Fun, Reason) ->
+    ?ERROR_MSG("External authentication program failed when calling "
+	       "'~s' for ~s@~s: ~p", [Fun, User, Server, Reason]),
     {error, db_failure}.
 
 opt_type(extauth_cache) ->