glibc/manual/examples/isockad.c

#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;
}