glibc/manual/examples/filecli.c

/* Example of Reading Datagrams
   Copyright (C) 1991-2018 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, if not, see <http://www.gnu.org/licenses/>.
*/

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/un.h>

#define SERVER	"/tmp/serversocket"
#define CLIENT	"/tmp/mysocket"
#define MAXMSG	512
#define MESSAGE	"Yow!!! Are we having fun yet?!?"

int
main (void)
{
  extern int make_named_socket (const char *name);
  int sock;
  char message[MAXMSG];
  struct sockaddr_un name;
  size_t size;
  int nbytes;

  /* Make the socket. */
  sock = make_named_socket (CLIENT);

  /* Initialize the server socket address. */
  name.sun_family = AF_LOCAL;
  strcpy (name.sun_path, SERVER);
  size = strlen (name.sun_path) + sizeof (name.sun_family);

  /* Send the datagram. */
  nbytes = sendto (sock, MESSAGE, strlen (MESSAGE) + 1, 0,
		   (struct sockaddr *) & name, size);
  if (nbytes < 0)
    {
      perror ("sendto (client)");
      exit (EXIT_FAILURE);
    }

  /* Wait for a reply. */
  nbytes = recvfrom (sock, message, MAXMSG, 0, NULL, 0);
  if (nbytes < 0)
    {
      perror ("recfrom (client)");
      exit (EXIT_FAILURE);
    }

  /* Print a diagnostic message. */
  fprintf (stderr, "Client: got message: %s\n", message);

  /* Clean up. */
  remove (CLIENT);
  close (sock);
}