名稱

bind - 綁定一個名字到一個套接字

內容簡介

#include 
#include 
int bind(int sockfd, const struct sockaddr *my_addr ", socklen_t " addrlen );

描述

bind() gives the socket sockfd the local address my_addr. my_addr is addrlen bytes long. Traditionally, this is called \(lqassigning a name to a socket.\(rq 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_STREAMsocket 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 seeipv6(7), for AF_UNIX see unix(7), for AF_APPLETALK see ddp(7), for AF_PACKET seepacket(7), for AF_X25 see x25(7) and for AF_NETLINK see netlink(7).

The actual structure passed for the my_addr argument will depend on the address family. The sockaddr structure is defined as something like:

#include 
#include 
#include 
#include 

#define MY_SOCK_PATH "/somepath"

int
main(int argc, char *argv[])
{
    int sfd;
    struct sockaddr_un addr;
   
    sfd = socket(AF_UNIX, SOCK_STREAM, 0);        
    if (sfd == -1) {
        perror("socket");
        exit(EXIT_FAILURE);
    }
    memset(&addr, 0, sizeof(struct sockaddr_un)); 
                        /* Clear structure */
    addr.sun_family = AF_UNIX;                    
    strncpy(addr.sun_path, MY_SOCK_PATH,
            sizeof(addr.sun_path) - 1);
    if (bind(sfd, (struct sockaddr *) &addr,
            sizeof(struct sockaddr_un)) == -1) {
        perror("bind");
        exit(EXIT_FAILURE);
    }
    ...
}

The only purpose of this structure is to cast the structure pointer passed in my_addr in order to avoid compiler warnings. The following example shows how this is done when binding a socket in the Unix (AF_UNIX) domain:

struct sockaddr {
    sa_family_t sa_family;
    char        sa_data[14];
}

返回值

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

錯誤

Error Code	描述
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.
The following errors are specific to UNIX domain (AF_UNIX) sockets:
EACCES	Search permission is denied on a component of the path prefix. (See also path_resolution(2).)
EADDRNOTAVAIL	A non-existent interface was requested or the requested address was not local.
EFAULT	my_addr points outside the user’s accessible address space.
EINVAL	The addrlen is wrong, or the socket was not in the AF_UNIXfamily.
ELOOP	Too many symbolic links were encountered in resolving my_addr.
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.
EROFS	The socket inode would reside on a read-only file system.

BUGS

透明代理的選擇冇有被描述。

遵循於

SVr4, 4.4BSD (the bind() function first appeared in 4.2BSD).

注意

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).

另請參閱

• accept (2)

• connect (2)

• getsockname (2)

• listen (2)

• path_resolution (2)

• socket (2)