Implement support for Telnet TTYPE (Terminal Type) option

README.md

@@ -79,11 +79,11 @@ Example .env file:
 TELNET_HOST=127.0.0.1       # Required | the IP of your MUD
 TELNET_PORT=23              # Required | the PORT of your MUD
 SOCKET_ROOT=/socket.io      # Required | the named socket for
-HOST=0.0.0.0                # Optional, defaults to '0.0.0.0' | the IP the backend will listen for
-PORT=5000                   # Optional, defaults to 5000 | the PORT the backend will listen for
-TELNET_TLS=false            # Optional, defaults to 'false' | set this to true if you want a secure connection
-SOCKET_TIMEOUT=900000       # Optional, defaults to 900000 (15 min) | timeout for any lost frontend<->backend connection
-CHARSET=utf8                # Optional, defaults to 'utf8'
+NAME=webmud3                # Optional | defaults to 'webmud3'        | the name of the client
+HOST=0.0.0.0                # Optional | defaults to '0.0.0.0'        | the IP the backend will listen for
+PORT=5000                   # Optional | defaults to 5000             | the PORT the backend will listen for
+TELNET_TLS=false            # Optional | defaults to 'false'          | set this to true if you want a secure connection
+SOCKET_TIMEOUT=900000       # Optional | defaults to 900000 (15 min)  | timeout for any lost frontend <-> backend connection
 ```
 
 > [!TIP]

backend/src/core/environment/environment.ts

@@ -21,6 +21,7 @@ export class Environment implements IEnvironment {
   public readonly socketRoot: string;
   public readonly socketTimeout: number;
   public readonly environment: 'production' | 'development';
+  public readonly name: string;
 
   /**
    * Private constructor to enforce singleton pattern.
@@ -64,6 +65,8 @@ export class Environment implements IEnvironment {
 
     this.projectRoot = resolveModulePath('../../../main.js');
 
+    this.name = String(getEnvironmentVariable('NAME', false, 'webmud3b'));
+
     logger.info('[Environment] initialized', this);
   }
 

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

@@ -1,6 +1,7 @@
 export type EnvironmentKeys =
   | 'HOST' // Optional | defaults to '0.0.0.0' | the IP the backend will listen for
   | 'PORT' // Optional | defaults to 5000 | the PORT the backend will listen for
+  | 'NAME' // Required | the name of your client. Will be send to the MUD. Defaults to 'webmud3b'
   | '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

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

@@ -2,11 +2,9 @@ export interface IEnvironment {
   readonly telnetHost: string;
   readonly telnetPort: number;
   readonly telnetTLS: boolean;
-
+  readonly name: string;
   readonly projectRoot: string;
   readonly socketRoot: string;
-
   readonly socketTimeout: number;
-
   readonly environment: 'production' | 'development';
 }

backend/src/core/middleware/use-sockets.ts

@@ -13,5 +13,6 @@ export const useSockets = (
     telnetPort: environment.telnetPort,
     useTelnetTls: environment.telnetTLS,
     socketRoot: environment.socketRoot,
+    clientName: environment.name,
   });
 };

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

@@ -27,6 +27,7 @@ export class SocketManager extends Server<
       telnetPort: number;
       useTelnetTls: boolean;
       socketRoot: string;
+      clientName: string;
     },
   ) {
     super(server, {
@@ -144,6 +145,7 @@ export class SocketManager extends Server<
           this.managerOptions.telnetHost,
           this.managerOptions.telnetPort,
           this.managerOptions.useTelnetTls,
+          this.managerOptions.clientName,
         );
 
         telnetClient.on('data', (data: string | Buffer) => {

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

@@ -13,6 +13,7 @@ import { handleEchoOption } from './utils/handle-echo-option.js';
 import { handleLinemodeOption } from './utils/handle-linemode-option.js';
 import { handleNawsOption } from './utils/handle-naws-option.js';
 import { handleSGAOption } from './utils/handle-sga-option.js';
+import { handleTTypeOption } from './utils/handle-ttype-option.js';
 import { TelnetSocketWrapper } from './utils/telnet-socket-wrapper.js';
 
 type TelnetClientEvents = {
@@ -54,7 +55,12 @@ export class TelnetClient extends EventEmitter<TelnetClientEvents> {
    * @param {number} telnetPort - The port number of the Telnet server.
    * @param {boolean} useTls - Indicates whether to use TLS encryption for the connection.
    */
-  constructor(telnetHost: string, telnetPort: number, useTls: boolean) {
+  constructor(
+    telnetHost: string,
+    telnetPort: number,
+    useTls: boolean,
+    clientName: string,
+  ) {
     super();
 
     const telnetConnection = createTelnetConnection(
@@ -74,6 +80,10 @@ export class TelnetClient extends EventEmitter<TelnetClientEvents> {
       [TelnetOptions.TELOPT_NAWS, handleNawsOption(this.telnetSocket)],
       [TelnetOptions.TELOPT_SGA, handleSGAOption(this.telnetSocket)],
       [TelnetOptions.TELOPT_LINEMODE, handleLinemodeOption(this.telnetSocket)],
+      [
+        TelnetOptions.TELOPT_TTYPE,
+        handleTTypeOption(this.telnetSocket, clientName),
+      ],
     ]);
 
     this.telnetSocket.on('connect', () => this.handleConnect());

backend/src/features/telnet/utils/handle-ttype-option.ts

@@ -0,0 +1,66 @@
+import { TelnetSocket } from 'telnet-stream';
+
+import { TelnetOptions } from '../models/telnet-options.js';
+import { TelnetControlSequences } from '../types/telnet-control-sequences.js';
+import { TelnetOptionHandler } from '../types/telnet-option-handler.js';
+import { TelnetOptionResult } from '../types/telnet-option-result.js';
+import { TelnetSubnegotiationResult } from '../types/telnet-subnegotiation-result.js';
+
+enum TelnetTTypeSubnogiation {
+  TTYPE_SEND = 1,
+}
+
+const handleTTypeDo = (socket: TelnetSocket) => (): TelnetOptionResult => {
+  socket.writeWill(TelnetOptions.TELOPT_TTYPE);
+
+  return { controlSequence: TelnetControlSequences.WILL };
+};
+
+const handleTTypeDont = (socket: TelnetSocket) => (): TelnetOptionResult => {
+  socket.writeWont(TelnetOptions.TELOPT_TTYPE);
+
+  return { controlSequence: TelnetControlSequences.WONT };
+};
+
+const handleTTypeWill = (socket: TelnetSocket) => (): TelnetOptionResult => {
+  socket.writeDont(TelnetOptions.TELOPT_TTYPE);
+
+  // This makes no sense since WE are giving the type of the terminal
+  return { controlSequence: TelnetControlSequences.DONT };
+};
+
+const handleTTypeWont = (socket: TelnetSocket) => (): TelnetOptionResult => {
+  socket.writeDont(TelnetOptions.TELOPT_TTYPE);
+
+  return { controlSequence: TelnetControlSequences.DONT };
+};
+
+const handleTTypeSub =
+  (socket: TelnetSocket, clientName: string) =>
+  (serverChunk: Buffer): TelnetSubnegotiationResult => {
+    if (new Uint8Array(serverChunk)[0] === TelnetTTypeSubnogiation.TTYPE_SEND) {
+      const buffer = Buffer.from(clientName);
+
+      socket.writeSub(TelnetOptions.TELOPT_TTYPE, buffer);
+
+      return {
+        clientChunk: buffer,
+        clientOption: clientName,
+      };
+    }
+
+    return null;
+  };
+
+export const handleTTypeOption = (
+  socket: TelnetSocket,
+  clientName: string,
+): TelnetOptionHandler => {
+  return {
+    handleDo: handleTTypeDo(socket),
+    handleDont: handleTTypeDont(socket),
+    handleWill: handleTTypeWill(socket),
+    handleWont: handleTTypeWont(socket),
+    handleSub: handleTTypeSub(socket, clientName),
+  };
+};