doc/examples/udp.c

   1 /* This example code is placed in the public domain. */
   2
   3 #ifdef HAVE_CONFIG_H
   4 #include <config.h>
   5 #endif
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <sys/types.h>
  11 #include <sys/socket.h>
  12 #include <arpa/inet.h>
  13 #include <netinet/in.h>
  14 #include <unistd.h>
  15
  16 #define SA struct sockaddr
  17
  18 /* tcp.c */
  19 int udp_connect (void);
  20 void udp_close (int sd);
  21
  22 /* Connects to the peer and returns a socket
  23  * descriptor.
  24  */
  25 extern int
  26 udp_connect (void)
  27 {
  28   const char *PORT = "5557";
  29   const char *SERVER = "127.0.0.1";
  30   int err, sd;
  31   struct sockaddr_in sa;
  32
  33   /* connects to server
  34    */
  35   sd = socket (AF_INET, SOCK_DGRAM, 0);
  36
  37   memset (&sa, '\0', sizeof (sa));
  38   sa.sin_family = AF_INET;
  39   sa.sin_port = htons (atoi (PORT));
  40   inet_pton (AF_INET, SERVER, &sa.sin_addr);
  41
  42   err = connect (sd, (SA *) & sa, sizeof (sa));
  43   if (err < 0)
  44     {
  45       fprintf (stderr, "Connect error\n");
  46       exit (1);
  47     }
  48
  49   return sd;
  50 }
  51
  52 /* closes the given socket descriptor.
  53  */
  54 extern void
  55 udp_close (int sd)
  56 {
  57   close (sd);
  58 }