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61 .\" Modified Mon Oct 21 23:05:29 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
62 .\" Modified 1998 by Andi Kleen
63 .\" $Id: bind.2,v 1.3 1999/04/23 19:56:07 freitag Exp $
64 .\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
66 .TH BIND 2 2007-12-28 "Linux" "Linux Programmer's Manual"
68 bind \- bind a name to a socket
71 .BR "#include <sys/types.h>" " /* See NOTES */"
72 .B #include <sys/socket.h>
74 .BI "int bind(int " sockfd ", const struct sockaddr *" addr ,
75 .BI " socklen_t " addrlen );
78 When a socket is created with
80 it exists in a name space (address family) but has no address assigned to it.
82 assigns the address specified by
84 to the socket referred to by the file descriptor
87 specifies the size, in bytes, of the address structure pointed to by
89 Traditionally, this operation is called \(lqassigning a name to a socket\(rq.
91 It is normally necessary to assign a local address using
95 socket may receive connections (see
98 The rules used in name binding vary between address families.
99 Consult the manual entries in Section 7 for detailed information.
129 The actual structure passed for the
131 argument will depend on the address family.
134 structure is defined as something like:
139 sa_family_t sa_family;
145 The only purpose of this structure is to cast the structure
148 in order to avoid compiler warnings.
151 On success, zero is returned.
152 On error, \-1 is returned, and
154 is set appropriately.
158 .\" e.g., privileged port in AF_INET domain
159 The address is protected, and the user is not the superuser.
162 The given address is already in use.
166 is not a valid descriptor.
169 The socket is already bound to an address.
170 .\" This may change in the future: see
171 .\" .I linux/unix/sock.c for details.
175 is a descriptor for a file, not a socket.
177 The following errors are specific to UNIX domain
182 Search permission is denied on a component of the path prefix.
184 .BR path_resolution (7).)
187 A nonexistent interface was requested or the requested
188 address was not local.
192 points outside the user's accessible address space.
197 is wrong, or the socket was not in the
202 Too many symbolic links were encountered in resolving
210 The file does not exist.
213 Insufficient kernel memory was available.
216 A component of the path prefix is not a directory.
219 The socket inode would reside on a read-only file system.
221 SVr4, 4.4BSD, POSIX.1-2001
223 first appeared in 4.2BSD).
224 .\" SVr4 documents an additional
226 .\" general error condition, and
231 .\" UNIX-domain error conditions.
233 POSIX.1-2001 does not require the inclusion of
235 and this header file is not required on Linux.
236 However, some historical (BSD) implementations required this header
237 file, and portable applications are probably wise to include it.
239 The third argument of
243 (and this is what 4.x BSD and libc4 and libc5 have).
244 Some POSIX confusion resulted in the present
250 The transparent proxy options are not described.
251 .\" FIXME What *are* transparent proxy options?
253 An example of the use of
255 with Internet domain sockets can be found in
258 The following example shows how to bind a stream socket in the UNIX
260 domain, and accept connections:
261 .\" listen.7 refers to this example.
262 .\" accept.7 refers to this example.
263 .\" unix.7 refers to this example.
266 #include <sys/socket.h>
272 #define MY_SOCK_PATH "/somepath"
273 #define LISTEN_BACKLOG 50
275 #define handle_error(msg) \\
276 do { perror(msg); exit(EXIT_FAILURE); } while (0)
279 main(int argc, char *argv[])
282 struct sockaddr_un my_addr, peer_addr;
283 socklen_t peer_addr_size;
285 sfd = socket(AF_UNIX, SOCK_STREAM, 0);
287 handle_error("socket");
289 memset(&my_addr, 0, sizeof(struct sockaddr_un));
290 /* Clear structure */
291 my_addr.sun_family = AF_UNIX;
292 strncpy(my_addr.sun_path, MY_SOCK_PATH,
293 sizeof(my_addr.sun_path) \- 1);
295 if (bind(sfd, (struct sockaddr *) &my_addr,
296 sizeof(struct sockaddr_un)) == \-1)
297 handle_error("bind");
299 if (listen(sfd, LISTEN_BACKLOG) == \-1)
300 handle_error("listen");
302 /* Now we can accept incoming connections one
303 at a time using accept(2) */
305 peer_addr_size = sizeof(struct sockaddr_un);
306 cfd = accept(sfd, (struct sockaddr *) &peer_addr,
309 handle_error("accept");
311 /* Code to deal with incoming connection(s)... */
313 /* When no longer required, the socket pathname, MY_SOCK_PATH
314 should be deleted using unlink(2) or remove(3) */
327 .BR path_resolution (7),