glibc/manual/examples/isockad.c

/* Internet Socket Example using sockaddr_in.
   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 <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

void
init_sockaddr (struct sockaddr_in *name,
	       const char *hostname,
	       uint16_t port)
{
  struct hostent *hostinfo;

  name->sin_family = AF_INET;
  name->sin_port = htons (port);
  hostinfo = gethostbyname (hostname);
  if (hostinfo == NULL)
    {
      fprintf (stderr, "Unknown host %s.\n", hostname);
      exit (EXIT_FAILURE);
    }
  name->sin_addr = *(struct in_addr *) hostinfo->h_addr;
}