Class WSServer

packages/utils/wsServer.ts:52–184

};

export class WSServer {
  private _wsServer: WebSocketServer | undefined;
  server: http.Server | undefined;
  private _delegate: WSServerDelegate;
  // Allowed Host headers for HTTP requests. null disables the check (server bound to a public address).
  private _allowedHosts: Set<string> | null = null;

  constructor(delegate: WSServerDelegate) {
    this._delegate = delegate;
  }

  async listen(port: number = 0, hostname: string | undefined, path: string): Promise<string> {
    debugLogger.log('server', `Server started at ${new Date()}`);

    // Default to loopback so the WebSocket RPC is not exposed to the network unless
    // the caller explicitly opts in by passing a host (e.g. '0.0.0.0').
    hostname ??= 'localhost';

    const server = createHttpServer((request, response) => this._onRequest(request, response));
    server.on('error', error => debugLogger.log('server', String(error)));
    this.server = server;

    const wsEndpoint = await new Promise<string>((resolve, reject) => {
      server.listen(port, hostname, () => {
        const address = server.address();
        if (!address) {
          reject(new Error('Could not bind server socket'));
          return;
        }
        if (typeof address === 'string') {
          resolve(`${address}${path}`);
          return;
        }
        // Advertise the bound IP literal in the wsEndpoint so the client connects to
        // the same address family the server bound to. Otherwise the client and
        // server resolvers can disagree on what 'localhost' means (see #40605).
        this._allowedHosts = computeAllowedHosts(hostname, address.address);
        resolve(`ws://${urlHostFromAddress(address)}:${address.port}${path}`);
      }).on('error', reject);
    });

    debugLogger.log('server', 'Listening at ' + wsEndpoint);

    this._wsServer = new wsServer({
      noServer: true,
      perMessageDeflate,
    });

    this._wsServer.on('headers', headers => this._delegate.onHeaders(headers));

    server.on('upgrade', (request, socket, head) => {
      const pathname = new URL('http://localhost' + request.url!).pathname;
      if (pathname !== path) {
        socket.write(`HTTP/${request.httpVersion} 400 Bad Request\r\n\r\n`);
        socket.destroy();
        return;
      }
      if (this._allowedHosts && !this._isAllowedOrigin(request.headers.origin)) {