| <html lang="en"> |
| <head> |
| <title>Inet Example - The GNU C Library</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="The GNU C Library"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Internet-Namespace.html#Internet-Namespace" title="Internet Namespace"> |
| <link rel="prev" href="Byte-Order.html#Byte-Order" title="Byte Order"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU C library. |
| |
| This is Edition 0.12, last updated 2007-10-27, |
| of `The GNU C Library Reference Manual', for version |
| 2.8 (Sourcery G++ Lite 2011.03-41). |
| |
| Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2001, 2002, |
| 2003, 2007, 2008, 2010 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being ``Free Software Needs Free Documentation'' |
| and ``GNU Lesser General Public License'', the Front-Cover texts being |
| ``A GNU Manual'', and with the Back-Cover Texts as in (a) below. A |
| copy of the license is included in the section entitled "GNU Free |
| Documentation License". |
| |
| (a) The FSF's Back-Cover Text is: ``You have the freedom to |
| copy and modify this GNU manual. Buying copies from the FSF |
| supports it in developing GNU and promoting software freedom.''--> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Inet-Example"></a> |
| <p> |
| Previous: <a rel="previous" accesskey="p" href="Byte-Order.html#Byte-Order">Byte Order</a>, |
| Up: <a rel="up" accesskey="u" href="Internet-Namespace.html#Internet-Namespace">Internet Namespace</a> |
| <hr> |
| </div> |
| |
| <h4 class="subsection">16.6.7 Internet Socket Example</h4> |
| |
| <p>Here is an example showing how to create and name a socket in the |
| Internet namespace. The newly created socket exists on the machine that |
| the program is running on. Rather than finding and using the machine's |
| Internet address, this example specifies <code>INADDR_ANY</code> as the host |
| address; the system replaces that with the machine's actual address. |
| |
| <pre class="smallexample"> #include <stdio.h> |
| #include <stdlib.h> |
| #include <sys/socket.h> |
| #include <netinet/in.h> |
| |
| int |
| make_socket (uint16_t port) |
| { |
| int sock; |
| struct sockaddr_in name; |
| |
| /* <span class="roman">Create the socket.</span> */ |
| sock = socket (PF_INET, SOCK_STREAM, 0); |
| if (sock < 0) |
| { |
| perror ("socket"); |
| exit (EXIT_FAILURE); |
| } |
| |
| /* <span class="roman">Give the socket a name.</span> */ |
| name.sin_family = AF_INET; |
| name.sin_port = htons (port); |
| name.sin_addr.s_addr = htonl (INADDR_ANY); |
| if (bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0) |
| { |
| perror ("bind"); |
| exit (EXIT_FAILURE); |
| } |
| |
| return sock; |
| } |
| </pre> |
| <p>Here is another example, showing how you can fill in a <code>sockaddr_in</code> |
| structure, given a host name string and a port number: |
| |
| <pre class="smallexample"> #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; |
| } |
| </pre> |
| </body></html> |
| |
