Function webSocketEcho

packages/cli/test/dev/utils.ts:158–243

(
  port: number,
  path: string,
  message: string
)

}

export function webSocketEcho(
  port: number,
  path: string,
  message: string
): Promise<string> {
  return new Promise((resolve, reject) => {
    const socket = net.connect(port, '127.0.0.1');
    const key = randomBytes(16).toString('base64');
    let buffer: Uint8Array<ArrayBufferLike> = new Uint8Array(0);
    let handshakeComplete = false;
    let settled = false;

    const timeout = setTimeout(() => {
      fail(new Error('Timed out waiting for WebSocket response'));
    }, 10_000);

    const settle = (fn: () => void) => {
      if (settled) return;
      settled = true;
      clearTimeout(timeout);
      fn();
    };

    const fail = (error: Error) => {
      settle(() => {
        socket.destroy();
        reject(error);
      });
    };

    socket.once('error', fail);
    socket.on('data', chunk => {
      buffer = appendBytes(buffer, toBytes(chunk));

      if (!handshakeComplete) {
        const headerEnd = indexOfBytes(buffer, headerSeparator);
        if (headerEnd === -1) return;

        const headers = Buffer.from(buffer.subarray(0, headerEnd)).toString(
          'utf8'
        );
        if (!headers.startsWith('HTTP/1.1 101 Switching Protocols')) {
          fail(new Error(`Unexpected WebSocket handshake:\n${headers}`));
          return;
        }

        const accept = createHash('sha1')
          .update(`${key}258EAFA5-E914-47DA-95CA-C5AB0DC85B11`)
          .digest('base64');
        if (
          !headers
            .toLowerCase()
            .includes(`sec-websocket-accept: ${accept.toLowerCase()}`)
        ) {
          fail(new Error(`Unexpected Sec-WebSocket-Accept:\n${headers}`));
          return;
        }