Question

I just created a little reliable file transfer using udp but it only handles one client. So I thought about using fork() to get the server to handle multiple clients. But, i don’t really know how to proceed. For now, I know I don’t need to change the client side and the server is the one that will do the dirty work. Any thought/ideas on how to tackle that problem is greatly appreciated.
Ps. here is how I started:

 void sigchldAction(int sig) {
 while (waitpid(-1, 0, WNOHANG) > 0) {
     ;
 }int main(int argc, char *argv[]) {

 return;
} //This is my function that waits for all the processes 

Here is my server:

int main(int argc, char *argv[]) {
    struct sockaddr_in serv_addr;
    int port_number, socket_fd;
    port_number = atoi(argv[1]);

    signal(SIGCHLD, sigchldAction);

    if ((socket_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)  exit(EXIT_FAILURE);
    if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR,
 (const void *)&optval, sizeof(int)) < 0) exit(EXIT_FAILURE);

    bzero((void *)&serv_addr, sizeof(struct sockaddr_in));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(port_number);
    if (bind(socket_fd, (struct sockaddr *)&serv_addr,
         sizeof(struct sockaddr_in)) < 0) exit(EXIT_FAILURE);

    pid_t child_pid;
    while (1) {
    child_pid = fork();

    switch (child_pid) {
        case -1:
            perror("Fork() Failed. \n");
            exit(EXIT_FAILURE);
            break;
        case 0:
            process_request(socket_fd);
            exit(EXIT_SUCCESS);
            break;
        case 1:
            close(socket_fd);
            break;

    } 

}
    close(socket_fd);
exit(EXIT_SUCCESS);
}

Then my process_request function takes care of any incoming data.

Answer 1

If you’re using UDP you don’t have a connection; it’s a connectionless protocol.

If you’re going to fork, you’d need to do what ftpd does and tell the remote client to send the forked child packets on a different port than the original one (and of course have the child receive on that port).