handle_dhcp() function

FunctionName : handle_dhcp Description : If an incoming DHCP message is in response to us, then trigger the state machine Parameters : arg -- arg user supplied argument (udp_pcb.recv_arg) pcb -- the udp_pcb which received data p -- the packet buffer that was received addr -- the remote IP address from which the packet was received port -- the remote port from which the packet was received Returns : none