How to UDP Broadcast with C in Linux?

Question

How to UDP Broadcast with C in Linux?

Answer 1

Unwind has it right, except you should use 'sendto'

Here is an example, that assumes you already have a socket. It was taken from clamav

static void
broadcast(const char *mess)
{
    struct sockaddr_in s;

    if(broadcastSock < 0)
        return;

    memset(&s, '\0', sizeof(struct sockaddr_in));
    s.sin_family = AF_INET;
    s.sin_port = (in_port_t)htons(tcpSocket ? tcpSocket : 3310);
    s.sin_addr.s_addr = htonl(INADDR_BROADCAST);

    cli_dbgmsg("broadcast %s to %d\n", mess, broadcastSock);
    if(sendto(broadcastSock, mess, strlen(mess), 0, (struct sockaddr *)&s, sizeof(struct sockaddr_in)) < 0)
        perror("sendto");
}