Byte Stream Example - The GNU C Library

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#### 16.9.6 Byte Stream Socket Example

Here is an example client program that makes a connection for a byte stream socket in the Internet namespace. It doesn't do anything particularly interesting once it has connected to the server; it just sends a text string to the server and exits.

This program uses `init_sockaddr` to set up the socket address; see Inet Example.

         #include <stdio.h>
         #include <errno.h>
         #include <stdlib.h>
         #include <unistd.h>
         #include <sys/types.h>
         #include <sys/socket.h>
         #include <netinet/in.h>
         #include <netdb.h>

         #define PORT            5555
         #define MESSAGE         "Yow!!! Are we having fun yet?!?"
         #define SERVERHOST      "mescaline.gnu.org"

         void
         write_to_server (int filedes)
         {
           int nbytes;

           nbytes = write (filedes, MESSAGE, strlen (MESSAGE) + 1);
           if (nbytes < 0)
             {
               perror ("write");
               exit (EXIT_FAILURE);
             }
         }

         int
         main (void)
         {
           extern void init_sockaddr (struct sockaddr_in *name,
                                      const char *hostname,
                                      uint16_t port);
           int sock;
           struct sockaddr_in servername;

           /* Create the socket. */
           sock = socket (PF_INET, SOCK_STREAM, 0);
           if (sock < 0)
             {
               perror ("socket (client)");
               exit (EXIT_FAILURE);
             }

           /* Connect to the server. */
           init_sockaddr (&servername, SERVERHOST, PORT);
           if (0 > connect (sock,
                            (struct sockaddr *) &servername,
                            sizeof (servername)))
             {
               perror ("connect (client)");
               exit (EXIT_FAILURE);
             }

           /* Send data to the server. */
           write_to_server (sock);
           close (sock);
           exit (EXIT_SUCCESS);
         }