Sending Udp multicast on Windows

win_udp.cpp

extern "C" {
#include <winsock2.h>
}
// https://en.wikipedia.org/wiki/Multicast_address
int main()
{
    auto wsaData = WSAData {};
    WSAStartup(MAKEWORD(2, 0), &wsaData);

    auto sock = socket(AF_INET, SOCK_DGRAM, 0);
    auto addr = sockaddr_in {
        .sin_family = AF_INET,
        .sin_port = htons(12345)
    };
    addr.sin_addr.S_un.S_addr = inet_addr("224.0.75.80");
    auto yes = 1;
    setsockopt(sock, SOL_SOCKET, SO_BROADCAST,
        (char*)&yes, sizeof(yes));

    auto message = "HELLO";

    sendto(sock, message, strlen(message), 0,
        (struct sockaddr*)&addr, sizeof(addr));

    closesocket(sock);
    WSACleanup();
    return 0;
}