int mb_reply( int socket, int msg_id, int msg_len, u_char *msg )
msg_id is the request number sent with the incoming message.
mb_reply sends msg_len bytes of msg in response to a MB_TWOWAY message.
socket is a connector returned by a previous call to
Replying to a MB_ONEWAY or a MB_MULTIWAY message is a protocol error which is silently ignored by the bus. Replying to a MB_TWOWAY message after the bus has already responded with a MB_TIMEOUT message is also silently ignored.
mb_reply returns 0 if msg could be written to socket or -1 if an error occurred.