udp socket with c++ and windows API

Question

I'm writting an UDP server for a game. Do you know if is possible to have multisocket in UDP on one port ? or I must use dynamic port (one socket = one port) ?

thanks

Answer 1

It make no large sense to create multiple socket on one UDP port. UDP is not point 2 point protocol like TCP so using one "server" socket bind to specific port you can handle hundreds of clients.

Answer 2

See Using SO_REUSEADDR... :

Using SO_REUSEADDR

The SO_REUSEADDR socket option allows a socket to forcibly bind to a port in use by another socket . The second socket calls setsockopt with the optname parameter set to SO_REUSEADDR and the optval parameter set to a boolean value of TRUE before calling bind on the same port as the original socket. Once the second socket has successfully bound, the behavior for all sockets bound to that port is indeterminate. For example, if all of the sockets on the same port provide TCP service, any incoming TCP connection requests over the port cannot be guaranteed to be handled by the correct socket — the behavior is non-deterministic. A malicious program can use SO_REUSEADDR to forcibly bind sockets already in use for standard network protocol services in order to deny access to those service. No special privileges are required to use this option.

Bonus reading: What exactly does SO_REUSEADDR do? .

Answer 3

Sure you can have multiple UDP sockets on one port if SO_REUSEADDR is specified via setsockopt. However, I doubt that what you really need is using one UDP socket to communicate with multiple clients, which is also feasible. UDP is not connection-oriented, UDP APIs like sendto and recvfrom could distinguish different peers on one socket.