/**

 * Copyright (C) 2008 Markus Broeker

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <sys/types.h>

#include <signal.h>

int set_proc_limit (int);

int main (int argc, char **argv)

{

    char message[81];

    int server_socket;

    int client_socket;

    struct sockaddr_in sa;

    struct sockaddr_in ca;

    socklen_t size;

    int len;

    int status;

    pid_t pid;

    pid_t parent_pid;

    server_socket = socket (AF_INET, SOCK_STREAM, IPPROTO_TCP);

    if (server_socket == -1) {

        perror ("socket");

        return EXIT_FAILURE;

    }

    sa.sin_family = AF_INET;

    sa.sin_port = htons (4000);

    sa.sin_addr.s_addr = INADDR_ANY;

    size = sizeof (sa);

    status = bind (server_socket, (struct sockaddr *)&sa, size);

    if (status != 0) {

        perror ("BIND");

        return EXIT_FAILURE;

    }

    status = listen (server_socket, 10);

    if (status != 0) {

        perror ("LISTEN");

        return EXIT_FAILURE;

    }

    int links = 0;

    parent_pid = getpid ();

    /*

     * Child quits immediately, father mustn't wait

     */

    signal (SIGCHLD, SIG_IGN);

    if (set_proc_limit (200) != 0) {

        printf ("Cannot limit the process limit\n");

        return EXIT_FAILURE;

    }

    for (;;) {

        size = sizeof (ca);

        client_socket = accept (server_socket, (struct sockaddr *)&sa, (socklen_t *) & size);

        printf ("PARENT PID = %d\n", parent_pid);

        pid = fork ();

        switch (pid) {

        case 0:                /* Child */

            close (server_socket);

            if ((len = read (client_socket, message, 80)) == -1)

                break;

            message[len] = 0;

            len = write (client_socket, "Please wait...\r\n", 17);

            sleep (10);

            printf ("DELETING LINK [%04d] %04d\n", getpid (), links--);

            shutdown (client_socket, SHUT_RDWR);

            close (client_socket);

            return 1;

        case -1:

            perror ("Fork Error");

            close (client_socket);

            /*

             * server is still alive and will continue

             * * when resources are available

             */

            break;

        default:               /* PID > 0 */

            close (client_socket);

            printf ("Starting LINK [%04d] %04d\n", pid, links++);

        }

    }

    return close (server_socket);

}