message: Fix return value of recv_pocket
diff: @@ -1539,7 +1539,7 @@ ssize_t Socket::recv_packet(double timeout)
  //error package
  if (buf_len < 0)
  {
  - return 0;
  + return -1;
  }
  else if (buf_len == 0)
  {
  @@ -1555,7 +1555,7 @@ ssize_t Socket::recv_packet(double timeout)
  else if (buf_len > protocol.package_max_length)
  {
  set_err(SW_ERROR_PACKAGE_LENGTH_TOO_LARGE, "remote packet is too big");
  - return 0;
  + return -1;
  }
  if ((size_t) buf_len == read_buffer->length)
  