Function readHelloLine

src/mcp/proxy.ts:422–471

* Read one CRLF/LF-terminated JSON line from the socket, parse it as the * daemon hello, and return it. Bounded to MAX_HELLO_LINE_BYTES so a * malicious or broken peer can't OOM us. Times out at 3s — a healthy daemon * sends hello immediately on accept.

(socket: net.Socket)

 * sends hello immediately on accept.
 */
function readHelloLine(socket: net.Socket): Promise<DaemonHello> {
  return new Promise((resolve, reject) => {
    let buffer = '';
    const cleanup = () => {
      socket.removeListener('data', onData);
      socket.removeListener('error', onError);
      socket.removeListener('close', onClose);
      clearTimeout(timer);
    };
    const onData = (chunk: string | Buffer) => {
      buffer += typeof chunk === 'string' ? chunk : chunk.toString('utf8');
      const idx = buffer.indexOf('\n');
      if (idx === -1) {
        if (buffer.length > MAX_HELLO_LINE_BYTES) {
          cleanup();
          reject(new Error('daemon hello line exceeded size limit'));
        }
        return;
      }
      const line = buffer.slice(0, idx);
      // Re-emit anything past the newline so the pipe-stage sees it.
      const tail = buffer.slice(idx + 1);
      cleanup();
      if (tail.length > 0) {
        // Push back via unshift — Node's net.Socket supports it on readable streams.
        socket.unshift(tail);
      }
      try {
        const parsed = JSON.parse(line) as DaemonHello;
        if (typeof parsed.codegraph !== 'string' || typeof parsed.pid !== 'number') {
          reject(new Error('daemon hello missing required fields'));
          return;
        }
        resolve(parsed);
      } catch (err) {
        reject(new Error(`daemon hello not JSON: ${err instanceof Error ? err.message : String(err)}`));
      }
    };
    const onError = (err: Error) => { cleanup(); reject(err); };
    const onClose = () => { cleanup(); reject(new Error('daemon closed connection before hello')); };
    const timer = setTimeout(() => {
      cleanup();
      reject(new Error('timed out waiting for daemon hello'));
    }, 3000);
    timer.unref?.();
    socket.on('data', onData);
    socket.on('error', onError);
    socket.on('close', onClose);
  });
}

/**
 * Pipe stdin → socket and socket → stdout. Resolves once either end closes