disconnect instead of crashing, if server sends invalid packet

ClassicalSharp/Network/Enums.cs

@@ -50,6 +50,8 @@ public static class Opcode {
 		public const byte CpeSetEntityProperty = 42;
 		public const byte CpeTwoWayPing = 43;
 		public const byte CpeSetInventoryOrder = 44;
+
+		public const byte Count = 45;
 	}
 }
 

ClassicalSharp/Network/NetworkProcessor.cs

@@ -160,12 +160,20 @@ public sealed class NetworkProcessor : IServerConnection {
 					continue;
 				}
 
-				if (opcode > maxHandledPacket) {
-					throw new InvalidOperationException("Invalid opcode: " + opcode);
+				if (opcode >= handlers.Length) {
+					game.Disconnect("Disconnected!", "Server sent invalid packet " + opcode + "!"); return;
 				}
-
 				if ((reader.size - reader.index) < packetSizes[opcode]) break;
-				ReadPacket(opcode);
+
+				reader.Skip(1); // remove opcode
+				lastOpcode = opcode;			
+				lastPacket = DateTime.UtcNow;
+
+				Action handler = handlers[opcode];
+				if (handler == null) {
+					game.Disconnect("Disconnected!", "Server sent invalid packet " + opcode + "!"); return;
+				}
+				handler();
 			}
 
 			reader.RemoveProcessed();
@@ -186,7 +194,6 @@ public sealed class NetworkProcessor : IServerConnection {
 		public void Set(byte opcode, Action handler, int packetSize) {
 			handlers[opcode] = handler;
 			packetSizes[opcode] = (ushort)packetSize;
-			maxHandledPacket = Math.Max(opcode, maxHandledPacket);
 		}
 
 		public void SendPacket() {
@@ -203,17 +210,6 @@ public sealed class NetworkProcessor : IServerConnection {
 			}
 		}
 
-		void ReadPacket(byte opcode) {
-			reader.Skip(1); // remove opcode
-			lastOpcode = opcode;
-			Action handler = handlers[opcode];
-			lastPacket = DateTime.UtcNow;
-
-			if (handler == null) {
-				throw new InvalidOperationException("Unsupported opcode: " + opcode);
-			}
-			handler();
-		}
 
 		public override void Reset(Game game) {
 			UsingExtPlayerList = false;
@@ -244,9 +240,8 @@ public sealed class NetworkProcessor : IServerConnection {
 			writer.ExtendedPositions = false; writer.ExtendedBlocks = false;
 		}
 
-		internal Action[] handlers = new Action[256];
-		internal ushort[] packetSizes = new ushort[256];
-		int maxHandledPacket = 0;
+		internal Action[] handlers = new Action[Opcode.Count];
+		internal ushort[] packetSizes = new ushort[Opcode.Count];
 
 		void BlockChanged(object sender, BlockChangedEventArgs e) {
 			Vector3I p = e.Coords;

src/Client/ServerConnection.c

@@ -248,7 +248,6 @@ struct Stream net_writeStream;
 UInt8 net_readBuffer[4096 * 5];
 UInt8 net_writeBuffer[131];
 
-Int32 net_maxHandledPacket;
 bool net_writeFailed;
 Int32 net_ticks;
 DateTime net_lastPacket;
@@ -276,7 +275,7 @@ static void MPConnection_FinishConnect(void) {
 	Event_RaiseReal(&WorldEvents_Loading, 0.0f);
 
 	String streamName = String_FromConst("network socket");
-	Stream_ReadonlyMemory(&net_readStream, net_readBuffer, sizeof(net_readBuffer), &streamName);
+	Stream_ReadonlyMemory(&net_readStream,   net_readBuffer,  sizeof(net_readBuffer),  &streamName);
 	Stream_WriteonlyMemory(&net_writeStream, net_writeBuffer, sizeof(net_writeBuffer), &streamName);
 
 	net_readStream.Meta.Mem.Left   = 0; /* initally no memory to read */
@@ -435,15 +434,23 @@ static void MPConnection_Tick(struct ScheduledTask* task) {
 			continue;
 		}
 
-		if (opcode > net_maxHandledPacket) { ErrorHandler_Fail("Invalid opcode"); }
+		if (opcode >= OPCODE_COUNT) {
+			String title = String_FromConst("Disconnected");
+			String msg   = String_FromConst("Server sent invalid packet!");
+			Game_Disconnect(&title, &msg); return; 
+		}
 		if (net_readStream.Meta.Mem.Left < Net_PacketSizes[opcode]) break;
 
 		Stream_Skip(&net_readStream, 1); /* remove opcode */
 		net_lastOpcode = opcode;
-		Net_Handler handler = Net_Handlers[opcode];
 		DateTime_CurrentUTC(&net_lastPacket);
 
-		if (!handler) { ErrorHandler_Fail("Unsupported opcode"); }
+		Net_Handler handler = Net_Handlers[opcode];
+		if (!handler) { 
+			String title = String_FromConst("Disconnected");
+			String msg = String_FromConst("Server sent invalid packet!");
+			Game_Disconnect(&title, &msg); return;
+		}
 		handler(&net_readStream);
 	}
 
@@ -470,7 +477,6 @@ static void MPConnection_Tick(struct ScheduledTask* task) {
 void Net_Set(UInt8 opcode, Net_Handler handler, UInt16 packetSize) {
 	Net_Handlers[opcode] = handler;
 	Net_PacketSizes[opcode] = packetSize;
-	net_maxHandledPacket = max(opcode, net_maxHandledPacket);
 }
 
 void Net_SendPacket(void) {
@@ -485,7 +491,7 @@ void Net_SendPacket(void) {
 		}
 	}
 
-	net_writeStream.Meta.Mem.Cur   = net_writeStream.Meta.Mem.Base;
+	net_writeStream.Meta.Mem.Cur  = net_writeStream.Meta.Mem.Base;
 	net_writeStream.Meta.Mem.Left = net_writeStream.Meta.Mem.Length;
 }
 
@@ -524,7 +530,6 @@ static void MPConnection_Reset(void) {
 	}
 
 	net_writeFailed = false;
-	net_maxHandledPacket = 0;
 	Handlers_Reset();
 	ServerConnection_Free();
 }

src/Client/ServerConnection.h

@@ -53,6 +53,8 @@ enum OPCODE_ {
 	OPCODE_CPE_SET_ENTITY_PROPERTY,
 	OPCODE_CPE_TWO_WAY_PING,
 	OPCODE_CPE_SET_INVENTORY_ORDER,
+
+	OPCODE_COUNT,
 };
 
 struct PickedPos;
@@ -90,7 +92,6 @@ void ServerConnection_InitMultiplayer(void);
 void ServerConnection_MakeComponent(struct IGameComponent* comp);
 
 typedef void (*Net_Handler)(struct Stream* stream);
-#define OPCODE_COUNT 45
 UInt16 Net_PacketSizes[OPCODE_COUNT];
 Net_Handler Net_Handlers[OPCODE_COUNT];
 void Net_Set(UInt8 opcode, Net_Handler handler, UInt16 size);