BIND

bind ? bind a name to a socket

#include <sys/types.h>
#include <sys/socket.h>

int bind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen);

bind gives the socket sockfd the local address my_addr. my_addr is addrlen bytes long. Traditionally, this is called “assigning a name to a socket.” When a socket is created with socket(2), it exists in a name space (address family) but has no name assigned.

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_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).

On success, zero is returned. On error, ?1 is returned, and errno is set appropriately.

EBADF

sockfd is not a valid descriptor.

EINVAL

The socket is already bound to an address. This may change in the future: see linux/unix/sock.c for details.

EACCES

The address is protected, and the user is not the super-user.

ENOTSOCK

Argument is a descriptor for a file, not a socket.

The following errors are specific to UNIX domain (AF_UNIX) sockets:

EINVAL

The addrlen is wrong, or the socket was not in the AF_UNIX family.

EROFS

The socket inode would reside on a read-only file system.

EFAULT

my_addr points outside the user’s accessible address space.

ENAMETOOLONG

my_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.

EACCES

Search permission is denied on a component of the path prefix.

ELOOP

Too many symbolic links were encountered in resolving my_addr.

The transparent proxy options are not described.

SVr4, 4.4BSD (the bind function first appeared in BSD 4.2). SVr4 documents additional EADDRNOTAVAIL, EADDRINUSE, and ENOSR general error conditions, and additional EIO, EISDIR and EROFS Unix-domain error conditions.

The third argument of bind is in reality an int (and this is what BSD 4.* and libc4 and libc5 have). Some POSIX confusion resulted in the present socklen_t. The draft standard has not been adopted yet, but glibc2 already follows it and also has socklen_t. See also accept(2).

accept(2), connect(2), listen(2), socket(2), getsockname(2), ip(7), socket(7)