code: func (h *cryptoSetup) ReadHandshakeMessage() ([]byte, error) {
  	msg, ok := <-h.messageChan
  	if !ok {
  		return nil, errors.New("error while handling the handshake message")
  	}
  	return msg, nil
  }
docs: // ReadHandshakeMessage is called by TLS.
  // It blocks until a new handshake message is available.