UDP listening and monitoring

I already created a UDP socket (UDP was connected), and now I wanted the server to listen, and if any client is trying to connect, then the UDP receiver will receive and send the socket to a new stream to perform recvfrom and the receive operation.

So how will I do this? How does the client tell the server that it wants to connect? Can I use FD_CONNECTand FD_ACCEPTabove UDP?

Thank.