EntityStateMessageUnreliable with custom handling

Assets/Mirror/Core/Messages.cs

@@ -94,6 +94,7 @@ public struct ObjectHideMessage : NetworkMessage
         public uint netId;
     }
 
+    // state update for Traditional reliable sync
     public struct EntityStateMessage : NetworkMessage
     {
         public uint netId;
@@ -102,6 +103,15 @@ public struct EntityStateMessage : NetworkMessage
         public ArraySegment<byte> payload;
     }
 
+    // state update for FastPaced unreliable sync
+    public struct EntityStateMessageUnreliable : NetworkMessage
+    {
+        public uint netId;
+        // the serialized component data
+        // -> ArraySegment to avoid unnecessary allocations
+        public ArraySegment<byte> payload;
+    }
+
     // whoever wants to measure rtt, sends this to the other end.
     public struct NetworkPingMessage : NetworkMessage
     {

Assets/Mirror/Core/NetworkClient.cs

@@ -505,6 +505,7 @@ internal static void RegisterMessageHandlers(bool hostMode)
                 RegisterHandler<ObjectSpawnFinishedMessage>(_ => { });
                 // host mode doesn't need state updates
                 RegisterHandler<EntityStateMessage>(_ => { });
+                RegisterHandler<EntityStateMessageUnreliable>(_ => { });
             }
             else
             {
@@ -516,6 +517,7 @@ internal static void RegisterMessageHandlers(bool hostMode)
                 RegisterHandler<ObjectSpawnStartedMessage>(OnObjectSpawnStarted);
                 RegisterHandler<ObjectSpawnFinishedMessage>(OnObjectSpawnFinished);
                 RegisterHandler<EntityStateMessage>(OnEntityStateMessage);
+                RegisterHandler<EntityStateMessageUnreliable>(OnEntityStateMessageUnreliable);
             }
 
             // These handlers are the same for host and remote clients
@@ -1393,6 +1395,18 @@ static void OnEntityStateMessage(EntityStateMessage message)
             else Debug.LogWarning($"Did not find target for sync message for {message.netId}. Were all prefabs added to the NetworkManager's spawnable list?\nNote: this can be completely normal because UDP messages may arrive out of order, so this message might have arrived after a Destroy message.");
         }
 
+        static void OnEntityStateMessageUnreliable(EntityStateMessageUnreliable message)
+        {
+            // Debug.Log($"NetworkClient.OnUpdateVarsMessage {msg.netId}");
+            if (spawned.TryGetValue(message.netId, out NetworkIdentity identity) && identity != null)
+            {
+                // iniital is always 'true' because unreliable state sync alwasy serializes full
+                using (NetworkReaderPooled reader = NetworkReaderPool.Get(message.payload))
+                    identity.DeserializeClient(reader, true);
+            }
+            else Debug.LogWarning($"Did not find target for sync message for {message.netId}. Were all prefabs added to the NetworkManager's spawnable list?\nNote: this can be completely normal because UDP messages may arrive out of order, so this message might have arrived after a Destroy message.");
+        }
+
         static void OnRPCMessage(RpcMessage message)
         {
             // Debug.Log($"NetworkClient.OnRPCMessage hash:{message.functionHash} netId:{message.netId}");
@@ -1567,7 +1581,7 @@ static void Broadcast()
                         if (writer.Position > 0)
                         {
                             // send state update message
-                            EntityStateMessage message = new EntityStateMessage
+                            EntityStateMessageUnreliable message = new EntityStateMessageUnreliable
                             {
                                 netId = identity.netId,
                                 payload = writer.ToArraySegment()

Assets/Mirror/Core/NetworkIdentity.cs

@@ -1090,8 +1090,9 @@ internal void SerializeClient(SyncMethod method, NetworkWriter writer)
         }
 
         // deserialize components from the client on the server.
-        // there's no 'initialState'. server always knows the initial state.
+        // for reliable state sync, server always knows the initial state.
-        internal bool DeserializeServer(NetworkReader reader)
+        // for unreliable, we always sync full state so we still need the parameter.
+        internal bool DeserializeServer(NetworkReader reader, bool initialState)
         {
             // ensure NetworkBehaviours are valid before usage
             ValidateComponents();
@@ -1115,7 +1116,7 @@ internal bool DeserializeServer(NetworkReader reader)
                         // deserialize this component
                         // server always knows the initial state (initial=false)
                         // disconnect if failed, to prevent exploits etc.
-                        if (!comp.Deserialize(reader, false)) return false;
+                        if (!comp.Deserialize(reader, initialState)) return false;
 
                         // server received state from the owner client.
                         // set dirty so it's broadcast to other clients too.

Assets/Mirror/Core/NetworkServer.cs

@@ -296,6 +296,7 @@ internal static void RegisterMessageHandlers()
             RegisterHandler<NetworkPingMessage>(NetworkTime.OnServerPing, false);
             RegisterHandler<NetworkPongMessage>(NetworkTime.OnServerPong, false);
             RegisterHandler<EntityStateMessage>(OnEntityStateMessage, true);
+            RegisterHandler<EntityStateMessageUnreliable>(OnEntityStateMessageUnreliable, true);
             RegisterHandler<TimeSnapshotMessage>(OnTimeSnapshotMessage, true);
         }
 
@@ -384,7 +385,8 @@ static void OnEntityStateMessage(NetworkConnectionToClient connection, EntitySta
                     {
                         // DeserializeServer checks permissions internally.
                         // failure to deserialize disconnects to prevent exploits.
-                        if (!identity.DeserializeServer(reader))
+                        // for reliable sync, server always knows initial state so updates are initialState=false.
+                        if (!identity.DeserializeServer(reader, false))
                         {
                             if (exceptionsDisconnect)
                             {
@@ -407,6 +409,46 @@ static void OnEntityStateMessage(NetworkConnectionToClient connection, EntitySta
             // else Debug.LogWarning($"Did not find target for sync message for {message.netId} . Note: this can be completely normal because UDP messages may arrive out of order, so this message might have arrived after a Destroy message.");
         }
 
+        // for client's owned ClientToServer components.
+        static void OnEntityStateMessageUnreliable(NetworkConnectionToClient connection, EntityStateMessageUnreliable message)
+        {
+            // need to validate permissions carefully.
+            // an attacker may attempt to modify a not-owned or not-ClientToServer component.
+
+            // valid netId?
+            if (spawned.TryGetValue(message.netId, out NetworkIdentity identity) && identity != null)
+            {
+                // owned by the connection?
+                if (identity.connectionToClient == connection)
+                {
+                    using (NetworkReaderPooled reader = NetworkReaderPool.Get(message.payload))
+                    {
+                        // DeserializeServer checks permissions internally.
+                        // failure to deserialize disconnects to prevent exploits.
+                        // for unreliable sync, we always send full state (initialState=true).
+                        if (!identity.DeserializeServer(reader, true))
+                        {
+                            if (exceptionsDisconnect)
+                            {
+                                Debug.LogError($"Server failed to deserialize client unreliable state for {identity.name} with netId={identity.netId}, Disconnecting.");
+                                connection.Disconnect();
+                            }
+                            else
+                                Debug.LogWarning($"Server failed to deserialize client unreliable state for {identity.name} with netId={identity.netId}.");
+                        }
+                    }
+                }
+                // An attacker may attempt to modify another connection's entity
+                // This could also be a race condition of message in flight when
+                // RemoveClientAuthority is called, so not malicious.
+                // Don't disconnect, just log the warning.
+                else
+                    Debug.LogWarning($"EntityStateMessage from {connection} for {identity.name} without authority.");
+            }
+            // no warning. don't spam server logs.
+            // else Debug.LogWarning($"Did not find target for sync message for {message.netId} . Note: this can be completely normal because UDP messages may arrive out of order, so this message might have arrived after a Destroy message.");
+        }
+
         // client sends TimeSnapshotMessage every sendInterval.
         // batching already includes the remoteTimestamp.
         // we simply insert it on-message here.
@@ -1916,7 +1958,7 @@ static void BroadcastToConnection(NetworkConnectionToClient connection)
                     serialization = SerializeForConnection(identity, connection, SyncMethod.FastPaced);
                     if (serialization != null)
                     {
-                        EntityStateMessage message = new EntityStateMessage
+                        EntityStateMessageUnreliable message = new EntityStateMessageUnreliable
                         {
                             netId = identity.netId,
                             payload = serialization.ToArraySegment()

Assets/Mirror/Examples/Tanks/Prefabs/Tank.prefab

@@ -67,7 +67,7 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: d993bac37a92145448c1ea027b3e9ddc, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  syncMethod: 0
+  syncMethod: 1
   syncDirection: 1
   syncMode: 0
   syncInterval: 0
@@ -99,7 +99,7 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: d993bac37a92145448c1ea027b3e9ddc, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  syncMethod: 0
+  syncMethod: 1
   syncDirection: 1
   syncMode: 0
   syncInterval: 0
@@ -131,7 +131,7 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: 7deadf756194d461e9140e42d651693b, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  syncMethod: 0
+  syncMethod: 1
   syncDirection: 0
   syncMode: 0
   syncInterval: 0.1