RE: flush buffer using socket recv() with non-blocking flag

The BIG question is, How do you know you received all of the response?
Is there a special control character? If you write 100 bytes and
receive more than 100 bytes, you can compare the first 100 bytes to what
you written and flush that out of your receive buffer. If you received
all the response, you are done, if not, loop back and read again. Being
that you are dealing with a modem, the response will trickle in, unless
the Cisco device is buffering and sending complete packets in one burst.
I have dealt with reading modems via IP before and I had to loop and
perform several reads on the socket to get the entire string. It was
framed packet <STX>Data<ETX><LRC>. Had to read on byte past ETX.