Server now correctly handles client disconnection

Author: Gallasko

examples/SimpleClientServer/application.cpp

@@ -118,24 +118,24 @@ void initGame(int argc, char** argv)
     // Todo delete this somewhere (should be when the system is deleted)
     auto *backend = new SdlNetworkBackend(netCfg);
 
-    mainWindow->ecs.createSystem<NetworkSystem>(backend, netCfg);
+    mainWindow->ecs->createSystem<NetworkSystem>(backend, netCfg);
 
     if (not isServer)
     {
-        mainWindow->ecs.createSystem<TestSystem>();
+        mainWindow->ecs->createSystem<TestSystem>();
     }
 
     // SDL_Quit();
 
     printf("Engine initialized ...\n");
 
-    mainWindow->ecs.dumbTaskflow();
+    mainWindow->ecs->dumbTaskflow();
 
     mainWindow->render();
 
     mainWindow->resize(820, 640);
 
-    mainWindow->ecs.start();
+    mainWindow->ecs->start();
 
     printf("Engine initialized\n");
 }

src/Engine/Networking/backend_sdl.cpp

@@ -132,6 +132,15 @@ namespace pg
         return _isConnectedToServer;
     }
 
+    void SdlNetworkBackend::closeTcp(SocketHandle sock)
+    {
+        if (sock)
+        {
+            SDLNet_TCP_DelSocket(sockSet, static_cast<TCPsocket>(sock));
+            SDLNet_TCP_Close(static_cast<TCPsocket>(sock));
+        }
+    }
+
     bool SdlNetworkBackend::sendTcp(SocketHandle sock, const NetPayload& data)
     {
         if (not sock)
@@ -222,9 +231,6 @@ namespace pg
             }
             else
             {
-                SDLNet_TCP_DelSocket(sockSet, _tcpSock);
-                SDLNet_TCP_Close(_tcpSock);
-                _tcpSock = nullptr;
                 _isConnectedToServer = false;
                 LOG_ERROR(DOM, "TCP receive failed, disconnected from server !");
             }
@@ -289,10 +295,6 @@ namespace pg
             }
             else
             {
-                SDLNet_TCP_DelSocket(socketSet, tcpSock);
-                SDLNet_TCP_Close(tcpSock);
-
-                tcpSock = nullptr;
                 socketClosed = true;
                 LOG_ERROR(DOM, "TCP receive failed, disconnected from server !");
             }
@@ -316,10 +318,6 @@ namespace pg
             }
             else
             {
-                SDLNet_TCP_DelSocket(sockSet, _tcpSock);
-                SDLNet_TCP_Close(_tcpSock);
-
-                _tcpSock = nullptr;
                 _isConnectedToServer = false;
                 socketClosed = true;
 

src/Engine/Networking/backend_sdl.h

@@ -21,6 +21,8 @@ namespace pg
         // Client‐side: connect to server using cfg.peerAddress/cfg.tcpPort
         bool connectToServer() override;
 
+        virtual void closeTcp(SocketHandle sock) override;
+
         // Send raw data
         bool sendUdp(const IpEndpoint& dest, const NetPayload& data) override;
         bool sendTcp(SocketHandle sock, const NetPayload& data) override;

src/Engine/Networking/ibackend.h

@@ -23,6 +23,8 @@ namespace pg
         bool _isConnectedToServer = false;
         inline bool isConnectedToServer() const { return _isConnectedToServer; }
 
+        virtual void closeTcp(SocketHandle sock) = 0;
+
         // Send raw packet (header+payload)
         virtual bool sendUdp(const IpEndpoint& dest, const NetPayload& data) = 0;
         virtual bool sendTcp(SocketHandle sock, const NetPayload& data) = 0;

src/Engine/Networking/network_system.cpp

@@ -204,7 +204,7 @@ namespace pg
         // 2) Process incoming packets
         // Process Tcp data
 
-        auto now = getCurrentTime();
+        std::set<uint32_t> disconnectedClients;
 
         for (auto& client : clients)
         {
@@ -217,6 +217,7 @@ namespace pg
             {
                 if (sendTCPMessage(ci.clientId, ci.token, NetMsgType::Ping, {0}, ci.tcpSock))
                 {
+                    auto now = getCurrentTime();
                     LOG_INFO("NetSys", "Sent ping to client: " << ci.clientId << " at time: " << now);
                     ci.lastPingSentMs = 0;
                 }
@@ -241,6 +242,14 @@ namespace pg
                     handleServerMessage(msg.header, msg.payload);
                 }
             }
+
+            if (tcpClosed)
+            {
+                LOG_WARNING("NetSys", "TCP connection closed by client: " << ci.clientId);
+
+                disconnectedClients.insert(ci.clientId);
+                break;
+            }
         }
 
         // Process Udp data
@@ -259,6 +268,11 @@ namespace pg
             }
             // LOG_INFO("NetSys", "Received UDP request from ip: " << ipPortKey(ip));
         }
+
+        for (auto id : disconnectedClients)
+        {
+            disconnectClient(id);
+        }
     }
 
     void NetworkSystem::runClientFrame(float dt)
@@ -363,4 +377,21 @@ namespace pg
         handleMessage(header, payload);
     }
 
+    void NetworkSystem::disconnectClient(uint32_t id)
+    {
+        auto it = idToTcp.find(id);
+
+        if (it != idToTcp.end())
+        {
+            auto tcpSock = it->second;
+
+            clients.erase(tcpSock);
+            idToTcp.erase(it);
+
+            backend->closeTcp(tcpSock);
+
+            LOG_INFO("NetSys", "Client " << id << " disconnected and cleaned up");
+        }
+    }
+
 } // namespace pg

src/Engine/Networking/network_system.h

@@ -139,7 +139,7 @@ namespace pg
         size_t nextPacketNumber = 0;
 
         // Reassembly‐buffer timestamping:
-        std::map<uint32_t, uint64_t> fragmentTimers; // packetNumber → first‐seen timestamp
+        std::map<uint32_t, uint64_t> fragmentTimers; // packetNumber -> first‐seen timestamp
         NetPacketBuffer reassembly;
 
         // Server state
@@ -178,6 +178,8 @@ namespace pg
         void handleMessage(const PacketHeader& header, const NetPayload& payload);
         void handleServerMessage(const PacketHeader& header, const NetPayload& payload);
         void handleClientMessage(const PacketHeader& header, const NetPayload& payload);
+
+        void disconnectClient(uint32_t id);
     };
 
 }