Add socket and telnet keepalive configurations

README.md

@@ -82,6 +82,9 @@ NAME=webmud3                                # Optional | defaults to 'webmud3'
 TELNET_HOST=127.0.0.1                       # Required | the IP of your MUD
 TELNET_PORT=23                              # Required | the PORT of your MUD
 TELNET_TLS=false                            # Optional | defaults to 'false'          | set this to true if you want a secure connection
+TELNET_KEEPALIVE_DELAY=30000                # Optional | defaults to 30000 (30s)       | TCP keepalive interval for telnet connections
+SOCKET_PING_INTERVAL=25000                  # Optional | defaults to 25000 (25s)       | Socket.IO ping interval
+SOCKET_PING_TIMEOUT=20000                   # Optional | defaults to 20000 (20s)       | Socket.IO ping timeout
 SOCKET_TIMEOUT=900000                       # Optional | defaults to 900000 (15 min)  | timeout for any lost frontend <-> backend connection
 SOCKET_ROOT=/socket.io                      # Required | URL for the socket connection. e.g. 'https://mud.example.com/socket.io'
 ENVIRONMENT='development'                   # Optional | accepts values 'development' or 'production' | defaults to 'production' | Enables Debug REST Endpoint /api/info and allows for permissive CORS if set to 'development'

backend/src/core/environment/environment.ts

@@ -19,7 +19,10 @@ export class Environment implements IEnvironment {
   public readonly telnetTLS: boolean;
   public readonly projectRoot: string;
   public readonly socketRoot: string;
+  public readonly socketPingInterval: number;
+  public readonly socketPingTimeout: number;
   public readonly socketTimeout: number;
+  public readonly telnetKeepAliveDelay: number;
   public readonly environment: 'production' | 'development';
   public readonly name: string;
   public readonly corsAllowList: string[];
@@ -49,10 +52,22 @@ export class Environment implements IEnvironment {
 
     this.socketRoot = String(getEnvironmentVariable('SOCKET_ROOT'));
 
+    this.socketPingInterval = Number(
+      getEnvironmentVariable('SOCKET_PING_INTERVAL', false, '25000'),
+    );
+
+    this.socketPingTimeout = Number(
+      getEnvironmentVariable('SOCKET_PING_TIMEOUT', false, '20000'),
+    );
+
     this.socketTimeout = Number(
       getEnvironmentVariable('SOCKET_TIMEOUT', false, '900000'),
     );
 
+    this.telnetKeepAliveDelay = Number(
+      getEnvironmentVariable('TELNET_KEEPALIVE_DELAY', false, '30000'),
+    );
+
     const environment = String(
       getEnvironmentVariable('ENVIRONMENT', false, 'production'),
     ).toLocaleLowerCase();

backend/src/core/environment/types/environment-keys.ts

@@ -5,6 +5,9 @@ export type EnvironmentKeys =
   | 'TELNET_HOST' // Required | the IP of your MUD
   | 'TELNET_PORT' // Required | the PORT of your MUD
   | 'TELNET_TLS' // Optional | defaults to 'false' | set this to true if you want a secure connection
+  | 'TELNET_KEEPALIVE_DELAY' // in milliseconds | default: 30000 (30s) | TCP keepalive interval for telnet connections
+  | 'SOCKET_PING_INTERVAL' // in milliseconds | default: 25000 (25s) | Socket.IO ping interval
+  | 'SOCKET_PING_TIMEOUT' // in milliseconds | default: 20000 (20s) | Socket.IO ping timeout
   | 'SOCKET_TIMEOUT' // in milliseconds | default: 900000 (15 min) | determines how long messages are buffed for the disconnected frontend and when the telnet connection is closed
   | 'SOCKET_ROOT' // Required | URL for the socket connection. e.g. 'https://mud.example.com/socket.io'
   | 'ENVIRONMENT' // Optional | accepts values 'development' or 'production' | defaults to 'production' | Enables Debug REST Endpoint /api/info and allows for permissive CORS if set to 'development'

backend/src/core/environment/types/environment.ts

@@ -5,7 +5,10 @@ export interface IEnvironment {
   readonly name: string;
   readonly projectRoot: string;
   readonly socketRoot: string;
+  readonly socketPingInterval: number;
+  readonly socketPingTimeout: number;
   readonly socketTimeout: number;
+  readonly telnetKeepAliveDelay: number;
   readonly environment: 'production' | 'development';
   readonly corsAllowList: string[];
 }

backend/src/core/sockets/socket-manager.ts

@@ -34,11 +34,15 @@ export class SocketManager extends Server<
       clientName: string;
     },
   ) {
+    const environment = Environment.getInstance();
+
     super(server, {
       path: managerOptions.socketRoot,
-      transports: ['websocket'],
+      transports: ['websocket', 'polling'],
+      pingInterval: environment.socketPingInterval,
+      pingTimeout: environment.socketPingTimeout,
       connectionStateRecovery: {
-        maxDisconnectionDuration: Environment.getInstance().socketTimeout,
+        maxDisconnectionDuration: environment.socketTimeout,
       },
     });
 
@@ -286,6 +290,7 @@ export class SocketManager extends Server<
           this.managerOptions.clientName,
           {
             initialViewPort,
+            keepAliveDelayMs: Environment.getInstance().telnetKeepAliveDelay,
           },
         );
 

backend/src/features/telnet/telnet-client.ts

@@ -86,7 +86,10 @@ export class TelnetClient extends EventEmitter<TelnetClientEvents> {
     telnetPort: number,
     useTls: boolean,
     clientName: string,
-    extraOptions?: { initialViewPort: { columns: number; rows: number } },
+    extraOptions?: {
+      initialViewPort: { columns: number; rows: number };
+      keepAliveDelayMs?: number;
+    },
   ) {
     super();
 
@@ -96,6 +99,20 @@ export class TelnetClient extends EventEmitter<TelnetClientEvents> {
       telnetPort,
     );
 
+    if (extraOptions?.keepAliveDelayMs !== undefined) {
+      // Enable TCP keepalive to reduce idle disconnects on intermediaries.
+      telnetConnection.setKeepAlive(true, extraOptions.keepAliveDelayMs);
+    }
+
+    telnetConnection.on('error', (error) => {
+      logger.error(
+        `[${this.socketId}] [Telnet-Client] Telnet socket error`,
+        {
+          error,
+        },
+      );
+    });
+
     if (useTls) {
       logger.info(
         `[${this.socketId}] [Telnet-Client] created https connection for telnet`,

frontend/src/app/features/sockets/sockets.service.ts

@@ -29,6 +29,8 @@ export class SocketsService {
   private readonly inputQueue: string[] = [];
   private isReconnecting = false;
   private sessionToken: string;
+  // Forces a fresh session token after reconnect failed to avoid reusing a dead backend session.
+  private forceNewSession = false;
 
   public onMudConnect = new EventEmitter<boolean>(); // Emits isNewConnection
   public onMudDisconnect = new EventEmitter();
@@ -54,7 +56,7 @@ export class SocketsService {
 
     this.manager = new Manager(socketUrl, {
       path: socketNamespace,
-      transports: ['websocket'],
+      transports: ['websocket', 'polling'],
       reconnectionAttempts: Infinity,
       reconnection: true,
     });
@@ -146,6 +148,11 @@ export class SocketsService {
     columns: number;
     rows: number;
   }): void {
+    if (this.forceNewSession) {
+      this.resetSessionToken();
+      this.forceNewSession = false;
+    }
+
     console.log(
       `[Sockets] Sockets-Service: 'connectToMud' with sessionToken: ${this.sessionToken}`,
     );
@@ -291,6 +298,7 @@ export class SocketsService {
 
   private handleReconnectFailed = () => {
     this.connectedToServer.next(false);
+    this.forceNewSession = true;
 
     console.error('[Sockets] Sockets-Service: Reconnect Failed');
   };
@@ -392,4 +400,15 @@ export class SocketsService {
       },
     );
   }
+
+  /**
+   * Resets the session token to force a clean backend session on next connect.
+   * This is used after a reconnect failure to avoid reusing a potentially dead backend session.
+   */
+  private resetSessionToken(): void {
+    const newToken = this.generateUUID();
+    this.sessionToken = newToken;
+    this.saveSessionToken(newToken);
+    this.socket.auth = { sessionToken: newToken };
+  }
 }

frontend/src/environments/environment.ts

@@ -7,7 +7,7 @@ import { Environment } from './environment.interface';
 export const environment: Environment = {
   production: false,
   // Change this to your local IP if you want to test on a mobile device in the same network
-  backendUrl: () => "http://localhost:5000",
+  backendUrl: () => 'http://localhost:5000',
 };
 
 /*