How to set up a Winsock UDP socket?

Question

I want to create a Winsock UDP socket that only sends data to a client. I want the kernel to choose an available port for me. On the other hand, I want to indicate which local I

Answer 1

Please excuse the lack of error checking:

char pkt[...];
size_t pkt_length = ...;
sockaddr_in dest;
sockaddr_in local;
WSAData data;
WSAStartup( MAKEWORD( 2, 2 ), &data );

local.sin_family = AF_INET;
local.sin_addr.s_addr = inet_addr(  );
local.sin_port = 0; // choose any

dest.sin_family = AF_INET;
dest.sin_addr.s_addr = inet_addr(  );
dest.sin_port = htons(  );

// create the socket
SOCKET s = socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
// bind to the local address
bind( s, (sockaddr *)&local, sizeof(local) );
// send the pkt
int ret = sendto( s, pkt, pkt_length, 0, (sockaddr *)&dest, sizeof(dest) );