manual/examples/filesrv.c

   1 /* Datagram Socket Example
   2    Copyright (C) 1991-2017 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU General Public License
   6    as published by the Free Software Foundation; either version 2
   7    of the License, or (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, if not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 #include <stdio.h>
  19 #include <errno.h>
  20 #include <stdlib.h>
  21 #include <sys/socket.h>
  22 #include <sys/un.h>
  23
  24 #define SERVER  "/tmp/serversocket"
  25 #define MAXMSG  512
  26
  27 int
  28 main (void)
  29 {
  30   int sock;
  31   char message[MAXMSG];
  32   struct sockaddr_un name;
  33   size_t size;
  34   int nbytes;
  35
  36   /* Remove the filename first, it's ok if the call fails */
  37   unlink (SERVER);
  38
  39   /* Make the socket, then loop endlessly. */
  40   sock = make_named_socket (SERVER);
  41   while (1)
  42     {
  43       /* Wait for a datagram. */
  44       size = sizeof (name);
  45       nbytes = recvfrom (sock, message, MAXMSG, 0,
  46                          (struct sockaddr *) & name, &size);
  47       if (nbytes < 0)
  48         {
  49           perror ("recfrom (server)");
  50           exit (EXIT_FAILURE);
  51         }
  52
  53       /* Give a diagnostic message. */
  54       fprintf (stderr, "Server: got message: %s\n", message);
  55
  56       /* Bounce the message back to the sender. */
  57       nbytes = sendto (sock, message, nbytes, 0,
  58                        (struct sockaddr *) & name, size);
  59       if (nbytes < 0)
  60         {
  61           perror ("sendto (server)");
  62           exit (EXIT_FAILURE);
  63         }
  64     }
  65 }