fix: NetworkServer/Client don't use Connect/DisconnectMessage anymore. fixes a bug where external connects could try sending that message causing undefined behaviour (#2577)

Assets/Mirror/Runtime/LocalConnections.cs

@@ -87,6 +87,12 @@ internal class ULocalConnectionToServer : NetworkConnectionToServer
 
         public override string address => "localhost";
 
+        // see caller for comments on why we need this
+        bool connectedEventPending;
+        bool disconnectedEventPending;
+        internal void QueueConnectedEvent() => connectedEventPending = true;
+        internal void QueueDisconnectedEvent() => disconnectedEventPending = true;
+
         internal override void Send(ArraySegment<byte> segment, int channelId = Channels.DefaultReliable)
         {
             if (segment.Count == 0)
@@ -101,6 +107,13 @@ internal override void Send(ArraySegment<byte> segment, int channelId = Channels
 
         internal void Update()
         {
+            // should we still process a connected event?
+            if (connectedEventPending)
+            {
+                connectedEventPending = false;
+                NetworkClient.OnConnectedEvent?.Invoke(this);
+            }
+
             // process internal messages so they are applied at the correct time
             while (buffer.HasPackets())
             {
@@ -112,6 +125,13 @@ internal void Update()
             }
 
             buffer.ResetBuffer();
+
+            // should we still process a disconnected event?
+            if (disconnectedEventPending)
+            {
+                disconnectedEventPending = false;
+                NetworkClient.OnDisconnectedEvent?.Invoke(this);
+            }
         }
 
         /// <summary>

Assets/Mirror/Runtime/Messages.cs

@@ -30,10 +30,6 @@ public struct NotReadyMessage : NetworkMessage { }
 
     public struct AddPlayerMessage : NetworkMessage { }
 
-    public struct DisconnectMessage : NetworkMessage { }
-
-    public struct ConnectMessage : NetworkMessage { }
-
     public struct SceneMessage : NetworkMessage
     {
         public string sceneName;

Assets/Mirror/Runtime/NetworkClient.cs

@@ -56,6 +56,13 @@ public static class NetworkClient
         /// </summary>
         public static bool isLocalClient => connection is ULocalConnectionToServer;
 
+        // OnConnected / OnDisconnected used to be NetworkMessages that were
+        // invoked. this introduced a bug where external clients could send
+        // Connected/Disconnected messages over the network causing undefined
+        // behaviour.
+        internal static Action<NetworkConnection> OnConnectedEvent;
+        internal static Action<NetworkConnection> OnDisconnectedEvent;
+
         /// <summary>
         /// Connect client to a NetworkServer instance.
         /// </summary>
@@ -124,8 +131,18 @@ public static void ConnectHost()
         /// </summary>
         public static void ConnectLocalServer()
         {
+            // call server OnConnected with server's connection to client
             NetworkServer.OnConnected(NetworkServer.localConnection);
-            NetworkServer.localConnection.Send(new ConnectMessage());
+
+            // call client OnConnected with client's connection to server
+            // => previously we used to send a ConnectMessage to
+            //    NetworkServer.localConnection. this would queue the message
+            //    until NetworkClient.Update processes it.
+            // => invoking the client's OnConnected event directly here makes
+            //    tests fail. so let's do it exactly the same order as before by
+            //    queueing the event for next Update!
+            //OnConnectedEvent?.Invoke(connection);
+            ((ULocalConnectionToServer)connection).QueueConnectedEvent();
         }
 
         /// <summary>
@@ -164,7 +181,7 @@ static void OnDisconnected()
 
             ClientScene.HandleClientDisconnect(connection);
 
-            connection?.InvokeHandler(new DisconnectMessage(), -1);
+            if (connection != null) OnDisconnectedEvent?.Invoke(connection);
         }
 
         internal static void OnDataReceived(ArraySegment<byte> data, int channelId)
@@ -187,7 +204,7 @@ static void OnConnected()
                 // thus we should set the connected state before calling the handler
                 connectState = ConnectState.Connected;
                 NetworkTime.UpdateClient();
-                connection.InvokeHandler(new ConnectMessage(), -1);
+                OnConnectedEvent?.Invoke(connection);
             }
             else logger.LogError("Skipped Connect message handling because connection is null.");
         }
@@ -206,7 +223,15 @@ public static void Disconnect()
             {
                 if (isConnected)
                 {
-                    NetworkServer.localConnection.Send(new DisconnectMessage());
+                    // call client OnDisconnected with connection to server
+                    // => previously we used to send a DisconnectMessage to
+                    //    NetworkServer.localConnection. this would queue the
+                    //    message until NetworkClient.Update processes it.
+                    // => invoking the client's OnDisconnected event directly
+                    //    here makes tests fail. so let's do it exactly the same
+                    //    order as before by queueing the event for next Update!
+                    //OnDisconnectedEvent?.Invoke(connection);
+                    ((ULocalConnectionToServer)connection).QueueDisconnectedEvent();
                 }
                 NetworkServer.RemoveLocalConnection();
             }

Assets/Mirror/Runtime/NetworkManager.cs

@@ -776,8 +776,8 @@ bool InitializeSingleton()
 
         void RegisterServerMessages()
         {
-            NetworkServer.RegisterHandler<ConnectMessage>(OnServerConnectInternal, false);
+            NetworkServer.OnConnectedEvent = OnServerConnectInternal;
-            NetworkServer.RegisterHandler<DisconnectMessage>(OnServerDisconnectInternal, false);
+            NetworkServer.OnDisconnectedEvent = OnServerDisconnectInternal;
             NetworkServer.RegisterHandler<AddPlayerMessage>(OnServerAddPlayerInternal);
             NetworkServer.RegisterHandler<ErrorMessage>(OnServerErrorInternal, false);
 
@@ -787,8 +787,8 @@ void RegisterServerMessages()
 
         void RegisterClientMessages()
         {
-            NetworkClient.RegisterHandler<ConnectMessage>(OnClientConnectInternal, false);
+            NetworkClient.OnConnectedEvent = OnClientConnectInternal;
-            NetworkClient.RegisterHandler<DisconnectMessage>(OnClientDisconnectInternal, false);
+            NetworkClient.OnDisconnectedEvent = OnClientDisconnectInternal;
             NetworkClient.RegisterHandler<NotReadyMessage>(OnClientNotReadyMessageInternal);
             NetworkClient.RegisterHandler<ErrorMessage>(OnClientErrorInternal, false);
             NetworkClient.RegisterHandler<SceneMessage>(OnClientSceneInternal, false);
@@ -1168,7 +1168,7 @@ public Transform GetStartPosition()
 
         #region Server Internal Message Handlers
 
-        void OnServerConnectInternal(NetworkConnection conn, ConnectMessage connectMsg)
+        void OnServerConnectInternal(NetworkConnection conn)
         {
             logger.Log("NetworkManager.OnServerConnectInternal");
 
@@ -1202,7 +1202,7 @@ void OnServerAuthenticated(NetworkConnection conn)
             OnServerConnect(conn);
         }
 
-        void OnServerDisconnectInternal(NetworkConnection conn, DisconnectMessage msg)
+        void OnServerDisconnectInternal(NetworkConnection conn)
         {
             logger.Log("NetworkManager.OnServerDisconnectInternal");
             OnServerDisconnect(conn);
@@ -1249,7 +1249,7 @@ void OnServerErrorInternal(NetworkConnection conn, ErrorMessage msg)
 
         #region Client Internal Message Handlers
 
-        void OnClientConnectInternal(NetworkConnection conn, ConnectMessage message)
+        void OnClientConnectInternal(NetworkConnection conn)
         {
             logger.Log("NetworkManager.OnClientConnectInternal");
 
@@ -1287,7 +1287,7 @@ void OnClientAuthenticated(NetworkConnection conn)
             }
         }
 
-        void OnClientDisconnectInternal(NetworkConnection conn, DisconnectMessage msg)
+        void OnClientDisconnectInternal(NetworkConnection conn)
         {
             logger.Log("NetworkManager.OnClientDisconnectInternal");
             OnClientDisconnect(conn);

Assets/Mirror/Runtime/NetworkServer.cs

@@ -91,6 +91,13 @@ public static class NetworkServer
         /// </summary>
         public static float disconnectInactiveTimeout = 60f;
 
+        // OnConnected / OnDisconnected used to be NetworkMessages that were
+        // invoked. this introduced a bug where external clients could send
+        // Connected/Disconnected messages over the network causing undefined
+        // behaviour.
+        internal static Action<NetworkConnection> OnConnectedEvent;
+        internal static Action<NetworkConnection> OnDisconnectedEvent;
+
         /// <summary>
         /// This shuts down the server and disconnects all clients.
         /// </summary>
@@ -567,7 +574,7 @@ internal static void OnConnected(NetworkConnectionToClient conn)
 
             // add connection and invoke connected event
             AddConnection(conn);
-            conn.InvokeHandler(new ConnectMessage(), -1);
+            OnConnectedEvent?.Invoke(conn);
         }
 
         internal static void OnDisconnected(int connectionId)
@@ -586,7 +593,7 @@ internal static void OnDisconnected(int connectionId)
 
         static void OnDisconnected(NetworkConnection conn)
         {
-            conn.InvokeHandler(new DisconnectMessage(), -1);
+            OnDisconnectedEvent?.Invoke(conn);
             if (logger.LogEnabled()) logger.Log("Server lost client:" + conn);
         }
 

Assets/Mirror/Tests/Editor/BuiltInMessages.cs

@@ -30,30 +30,6 @@ public void CommandMessage()
                     Is.EqualTo(message.payload.Array[message.payload.Offset + i]));
         }
 
-        [Test]
-        public void ConnectMessage()
-        {
-            // try setting value with constructor
-            ConnectMessage message = new ConnectMessage();
-            byte[] arr = MessagePackerTest.PackToByteArray(message);
-            Assert.DoesNotThrow(() =>
-            {
-                MessagePackerTest.UnpackFromByteArray<ConnectMessage>(arr);
-            });
-        }
-
-        [Test]
-        public void DisconnectMessage()
-        {
-            // try setting value with constructor
-            DisconnectMessage message = new DisconnectMessage();
-            byte[] arr = MessagePackerTest.PackToByteArray(message);
-            Assert.DoesNotThrow(() =>
-            {
-                MessagePackerTest.UnpackFromByteArray<DisconnectMessage>(arr);
-            });
-        }
-
         [Test]
         public void ErrorMessage()
         {

Assets/Mirror/Tests/Editor/MessagePackerTest.cs

@@ -54,13 +54,13 @@ public void TestPacking()
         [Test]
         public void UnpackWrongMessage()
         {
-            ConnectMessage message = new ConnectMessage();
+            SpawnMessage message = new SpawnMessage();
 
             byte[] data = PackToByteArray(message);
 
             Assert.Throws<FormatException>(() =>
             {
-                DisconnectMessage unpacked = UnpackFromByteArray<DisconnectMessage>(data);
+                UpdateVarsMessage unpacked = UnpackFromByteArray<UpdateVarsMessage>(data);
             });
         }
 

Assets/Mirror/Tests/Editor/NetworkBehaviourTests.cs

@@ -300,8 +300,6 @@ public void SendCommandInternal()
             // we need to start a server and connect a client in order to be
             // able to send commands
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<SpawnMessage>((conn, msg) => { }, false);
             NetworkServer.Listen(1);
@@ -413,8 +411,6 @@ public void SendRPCInternal()
             // we need to start a server and connect a client in order to be
             // able to send commands
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<SpawnMessage>((conn, msg) => { }, false);
             NetworkServer.Listen(1);
@@ -499,8 +495,6 @@ public void SendTargetRPCInternal()
             // we need to start a server and connect a client in order to be
             // able to send commands
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<SpawnMessage>((conn, msg) => { }, false);
             NetworkServer.Listen(1);

Assets/Mirror/Tests/Editor/NetworkClientTests.cs

@@ -17,13 +17,8 @@ public void SetUp()
             Transport.activeTransport = transportGO.AddComponent<MemoryTransport>();
 
             // we need a server to connect to
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
             NetworkServer.Listen(10);
-
-            // setup client handlers too
-            NetworkClient.RegisterHandler<ConnectMessage>(msg => { }, false);
         }
 
         [TearDown]

Assets/Mirror/Tests/Editor/NetworkIdentityTests.cs

@@ -844,8 +844,6 @@ public void OnStartServerInHostModeSetsIsClientTrue()
         {
             // call client connect so that internals are set up
             // (it won't actually successfully connect)
-            // -> also set up connectmessage handler to avoid unhandled msg error
-            NetworkClient.RegisterHandler<ConnectMessage>(msg => { }, false);
             NetworkClient.Connect("localhost");
 
             // manually invoke transport.OnConnected so that NetworkClient.active is set to true

Assets/Mirror/Tests/Editor/NetworkServerTest.cs

@@ -119,8 +119,6 @@ public void IsActiveTest()
         public void MaxConnectionsTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen with maxconnections=1
@@ -141,8 +139,7 @@ public void ConnectMessageHandlerTest()
         {
             // message handlers
             bool connectCalled = false;
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { connectCalled = true; }, false);
+            NetworkServer.OnConnectedEvent = conn => connectCalled = true;
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -159,8 +156,7 @@ public void DisconnectMessageHandlerTest()
         {
             // message handlers
             bool disconnectCalled = false;
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
+            NetworkServer.OnDisconnectedEvent = conn => disconnectCalled = true;
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { disconnectCalled = true; }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -180,8 +176,6 @@ public void DisconnectMessageHandlerTest()
         public void ConnectionsDictTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -216,8 +210,6 @@ public void OnConnectedOnlyAllowsNonZeroConnectionIdsTest()
             // <0 is never used
 
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -240,8 +232,6 @@ public void OnConnectedOnlyAllowsNonZeroConnectionIdsTest()
         public void ConnectDuplicateConnectionIdsTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -315,8 +305,6 @@ public void LocalClientActiveTest()
         public void AddConnectionTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -356,8 +344,6 @@ public void AddConnectionTest()
         public void RemoveConnectionTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -382,8 +368,6 @@ public void RemoveConnectionTest()
         public void DisconnectAllConnectionsTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -404,8 +388,6 @@ public void DisconnectAllConnectionsTest()
         public void DisconnectAllTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -432,8 +414,6 @@ public void DisconnectAllTest()
         public void OnDataReceivedTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // add one custom message handler
@@ -478,8 +458,6 @@ public void OnDataReceivedTest()
         public void OnDataReceivedInvalidConnectionIdTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // add one custom message handler
@@ -722,8 +700,6 @@ public void ActivateHostSceneCallsOnStartClient()
         public void SendToAllTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -758,8 +734,6 @@ public void SendToAllTest()
         public void RegisterUnregisterClearHandlerTest()
         {
             // message handlers that are needed for the test
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
 
@@ -806,7 +780,6 @@ public void RegisterUnregisterClearHandlerTest()
             // unregister second handler via ClearHandlers to test that one too. send, should fail
             NetworkServer.ClearHandlers();
             // (only add this one to avoid disconnect error)
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             writer = new NetworkWriter();
             MessagePacker.Pack(new TestMessage1(), writer);
             // log error messages are expected
@@ -821,8 +794,6 @@ public void RegisterUnregisterClearHandlerTest()
         public void SendToClientOfPlayer()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -899,8 +870,6 @@ public void GetNetworkIdentityErrorIfNotFound()
         public void ShowForConnection()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -951,8 +920,6 @@ public void ShowForConnection()
         public void HideForConnection()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen
@@ -1089,8 +1056,6 @@ public void UnSpawn()
         public void ShutdownCleanupTest()
         {
             // message handlers
-            NetworkServer.RegisterHandler<ConnectMessage>((conn, msg) => { }, false);
-            NetworkServer.RegisterHandler<DisconnectMessage>((conn, msg) => { }, false);
             NetworkServer.RegisterHandler<ErrorMessage>((conn, msg) => { }, false);
 
             // listen