bind — bind a name to a socket
#include <sys/types.h> /* See NOTES */ #include <sys/socket.h>
int
bind( |
int sockfd, |
| const struct sockaddr *addr, | |
socklen_t addrlen); |
When a socket is created with socket(2), it exists in a
name space (address family) but has no address assigned to
it. bind() assigns the address
specified by addr to
the socket referred to by the file descriptor sockfd. addrlen specifies the size, in
bytes, of the address structure pointed to by addr. Traditionally, this
operation is called “assigning a name to a
socket”.
It is normally necessary to assign a local address using
bind() before a SOCK_STREAM socket may receive connections
(see accept(2)).
The rules used in name binding vary between address
families. Consult the manual entries in Section 7 for
detailed information. For AF_INET see ip(7), for AF_INET6 see ipv6(7), for AF_UNIX see unix(7), for AF_APPLETALK see ddp(7), for AF_PACKET see packet(7), for AF_X25 see x25(7) and for AF_NETLINK see netlink(7).
The actual structure passed for the addr argument will depend on
the address family. The sockaddr structure is defined as
something like:
struct sockaddr { sa_family_t sa_family;char sa_data[14];};
The only purpose of this structure is to cast the
structure pointer passed in addr in order to avoid compiler
warnings. See EXAMPLE below.
On success, zero is returned. On error, −1 is
returned, and errno is set
appropriately.
The address is protected, and the user is not the superuser.
The given address is already in use.
(Internet domain sockets) The port number was
specified as zero in the socket address structure, but,
upon attempting to bind to an ephemeral port, it was
determined that all port numbers in the ephemeral port
range are currently in use. See the discussion of
/proc/sys/net/ipv4/ip_local_port_range
ip(7).
sockfd is
not a valid file descriptor.
The socket is already bound to an address.
addrlen is
wrong, or addr
is not a valid address for this socket's domain.
The file descriptor sockfd does not refer to
a socket.
The following errors are specific to UNIX domain
(AF_UNIX) sockets:
Search permission is denied on a component of the path prefix. (See also path_resolution(7).)
A nonexistent interface was requested or the requested address was not local.
addr points
outside the user's accessible address space.
Too many symbolic links were encountered in
resolving addr.
addr is too
long.
A component in the directory prefix of the socket pathname does not exist.
Insufficient kernel memory was available.
A component of the path prefix is not a directory.
The socket inode would reside on a read-only filesystem.
POSIX.1 does not require the inclusion of <sys/types.h> and this header file is not required on
Linux. However, some historical (BSD) implementations
required this header file, and portable applications are
probably wise to include it.
The third argument of bind()
is in reality an int (and this is
what 4.x BSD and libc4 and libc5 have). Some POSIX confusion
resulted in the present socklen_t,
also used by glibc. See also accept(2).
An example of the use of bind() with Internet domain sockets can be
found in getaddrinfo(3).
The following example shows how to bind a stream socket in
the UNIX (AF_UNIX) domain, and
accept connections:
#include <sys/socket.h>
#include <sys/un.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define MY_SOCK_PATH "/somepath"
#define LISTEN_BACKLOG 50
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
int
main(int argc, char *argv[])
{
int sfd, cfd;
struct sockaddr_un my_addr, peer_addr;
socklen_t peer_addr_size;
sfd = socket(AF_UNIX, SOCK_STREAM, 0);
if (sfd == −1)
handle_error("socket");
memset(&my_addr, 0, sizeof(struct sockaddr_un));
/* Clear structure */
my_addr.sun_family = AF_UNIX;
strncpy(my_addr.sun_path, MY_SOCK_PATH,
sizeof(my_addr.sun_path) − 1);
if (bind(sfd, (struct sockaddr *) &my_addr,
sizeof(struct sockaddr_un)) == −1)
handle_error("bind");
if (listen(sfd, LISTEN_BACKLOG) == −1)
handle_error("listen");
/* Now we can accept incoming connections one
at a time using accept(2) */
peer_addr_size = sizeof(struct sockaddr_un);
cfd = accept(sfd, (struct sockaddr *) &peer_addr,
&peer_addr_size);
if (cfd == −1)
handle_error("accept");
/* Code to deal with incoming connection(s)... */
/* When no longer required, the socket pathname, MY_SOCK_PATH
should be deleted using unlink(2) or remove(3) */
}
accept(2), connect(2), getsockname(2), listen(2), socket(2), getaddrinfo(3), getifaddrs(3), ip(7), ipv6(7), path_resolution(7), socket(7), unix(7)
This page is part of release 4.07 of the Linux man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
|
Copyright 1993 Rickard E. Faith (faithcs.unc.edu) Portions extracted from /usr/include/sys/socket.h, which does not have any authorship information in it. It is probably available under the GPL. %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. %%%LICENSE_END Other portions are from the 6.9 (Berkeley) 3/10/91 man page: Copyright (c) 1983 The Regents of the University of California. All rights reserved. %%%LICENSE_START(BSD_4_CLAUSE_UCB) Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by the University of California, Berkeley and its contributors. 4. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. %%%LICENSE_END Modified Mon Oct 21 23:05:29 EDT 1996 by Eric S. Raymond <esrthyrsus.com> Modified 1998 by Andi Kleen $Id: bind.2,v 1.3 1999/04/23 19:56:07 freitag Exp $ Modified 2004-06-23 by Michael Kerrisk <mtk.manpagesgmail.com> |