1 /**

     2  * $Id: server.c,v 1.1.1.1 2008-04-28 17:32:53 mbroeker Exp $

     3  * $Source: /development/c/demos/ddos/server.c,v $

     4  *

     5  */

     6 

     7 #include <stdio.h>

     8 #include <stdlib.h>

     9 #include <string.h>

    10 #include <unistd.h>

    11 #include <sys/socket.h>

    12 #include <netinet/in.h>

    13 #include <arpa/inet.h>

    14 #include <sys/types.h>

    15 #include <signal.h>

    16 

    17 int set_limit (int);

    18 

    19 int main (int argc, char **argv)

    20 {

    21     char message[81];

    22     int server_socket;

    23     int client_socket;

    24     struct sockaddr_in sa;

    25     struct sockaddr_in ca;

    26     socklen_t size;

    27     int len;

    28     int status;

    29     pid_t pid;

    30     pid_t parent_pid;

    31 

    32     server_socket = socket (AF_INET, SOCK_STREAM, IPPROTO_TCP);

    33     if (server_socket == -1) {

    34         perror ("socket");

    35         return EXIT_FAILURE;

    36     }

    37 

    38     sa.sin_family = AF_INET;

    39     sa.sin_port = htons (4000);

    40     sa.sin_addr.s_addr = INADDR_ANY;

    41 

    42     size = sizeof (sa);

    43 

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

    45     if (status != 0) {

    46         perror ("BIND");

    47         return EXIT_FAILURE;

    48     }

    49 

    50     status = listen (server_socket, 10);

    51     if (status != 0) {

    52         perror ("LISTEN");

    53         return EXIT_FAILURE;

    54     }

    55 

    56     int links = 0;

    57 

    58     parent_pid = getpid ();

    59 

    60     /*

    61      * Child quits immediately, father mustn't wait

    62      */

    63     signal (SIGCHLD, SIG_IGN);

    64 

    65     if (set_limit (500) != 0) {

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

    67         return EXIT_FAILURE;

    68     }

    69 

    70     for (;;) {

    71         size = sizeof (ca);

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

    73 

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

    75 

    76         pid = fork ();

    77         switch (pid) {

    78         case 0:                /* Child */

    79             close (server_socket);

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

    81                 break;

    82             message[len] = 0;

    83 

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

    85             sleep (10);

    86 

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

    88             shutdown (client_socket, SHUT_RDWR);

    89             close (client_socket);

    90             return 1;

    91         case -1:

    92             perror ("Fork Error");

    93             close (client_socket);

    94             /*

    95              * server is still alive and will continue

    96              * * when resources are available

    97              */

    98             break;

    99         default:               /* PID > 0 */

   100             close (client_socket);

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

   102         }

   103     }

   104     close (server_socket);

   105     return 0;

   106 }