1/* Byte Stream Socket Example
2 Copyright (C) 1991-2022 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or
5 modify it under the terms of the GNU General Public License
6 as published by the Free Software Foundation; either version 2
7 of the License, or (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, see <https://www.gnu.org/licenses/>.
16*/
17
18#include <stdio.h>
19#include <errno.h>
20#include <stdlib.h>
21#include <unistd.h>
22#include <sys/types.h>
23#include <sys/socket.h>
24#include <netinet/in.h>
25#include <netdb.h>
26
27#define PORT 5555
28#define MESSAGE "Yow!!! Are we having fun yet?!?"
29#define SERVERHOST "www.gnu.org"
30
31void
32write_to_server (int filedes)
33{
34 int nbytes;
35
36 nbytes = write (filedes, MESSAGE, strlen (MESSAGE) + 1);
37 if (nbytes < 0)
38 {
39 perror ("write");
40 exit (EXIT_FAILURE);
41 }
42}
43
44
45int
46main (void)
47{
48 extern void init_sockaddr (struct sockaddr_in *name,
49 const char *hostname,
50 uint16_t port);
51 int sock;
52 struct sockaddr_in servername;
53
54 /* Create the socket. */
55 sock = socket (PF_INET, SOCK_STREAM, protocol: 0);
56 if (sock < 0)
57 {
58 perror ("socket (client)");
59 exit (EXIT_FAILURE);
60 }
61
62 /* Connect to the server. */
63 init_sockaddr (name: &servername, SERVERHOST, PORT);
64 if (0 > connect (fd: sock,
65 addr: (struct sockaddr *) &servername,
66 len: sizeof (servername)))
67 {
68 perror ("connect (client)");
69 exit (EXIT_FAILURE);
70 }
71
72 /* Send data to the server. */
73 write_to_server (filedes: sock);
74 close (fd: sock);
75 exit (EXIT_SUCCESS);
76}
77

source code of glibc/manual/examples/inetcli.c