rdr_rcv_msg
rcv_status = rdr_rcv_msg(sp->fd, &reply_hdr, &reply_data,
rcv_status = rdr_rcv_msg(sp->fd, &op_hdr, &op_data,
int rdr_rcv_msg(int fd, rdr_msg_hdr_t *hdr, cfga_params_t *param, int timeout);