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BIND(2) | Linux Programmer's Manual | BIND(2) |
NAME¶
bind - bind a name to a socketSYNOPSIS¶
#include <sys/types.h> /* See NOTES */ #include <sys/socket.h>int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
DESCRIPTION¶
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)).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.
RETURN VALUE¶
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.ERRORS¶
- EACCES
- The address is protected, and the user is not the superuser.
- EADDRINUSE
- The given address is already in use.
- EBADF
- sockfd is not a valid descriptor.
- EINVAL
- The socket is already bound to an address.
- ENOTSOCK
- sockfd is a descriptor for a file, not a socket.
- EACCES
- Search permission is denied on a component of the path prefix. (See also path_resolution(7).)
- EADDRNOTAVAIL
- A nonexistent interface was requested or the requested address was not local.
- EFAULT
- addr points outside the user's accessible address space.
- EINVAL
- The addrlen is wrong, or the socket was not in the AF_UNIX family.
- ELOOP
- Too many symbolic links were encountered in resolving addr.
- ENAMETOOLONG
- addr is too long.
- ENOENT
- The file does not exist.
- ENOMEM
- Insufficient kernel memory was available.
- ENOTDIR
- A component of the path prefix is not a directory.
- EROFS
- The socket inode would reside on a read-only file system.
CONFORMING TO¶
SVr4, 4.4BSD, POSIX.1-2001 (bind() first appeared in 4.2BSD).NOTES¶
POSIX.1-2001 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.BUGS¶
The transparent proxy options are not described.EXAMPLE¶
An example of the use of bind() with Internet domain sockets can be found in getaddrinfo(3).#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) */ }
SEE ALSO¶
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)COLOPHON¶
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2007-12-28 | Linux |