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AF_UNIX versus AF_INET
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bind(2) System Calls Manual bind(2) NAME
bind() - bind an address to a socket SYNOPSIS
AF_CCITT only AF_INET, AF_INET6 and AF_VME_LINK only AF_UNIX only UNIX 03 only (X/Open Sockets) Obsolescent UNIX 95 only (X/Open Sockets) DESCRIPTION
The system call assigns an address to an unbound socket. When a socket is created with it exists in an address space (address family) but has no address assigned. causes the socket whose descriptor is s to become bound to the address specified in the socket address structure pointed to by addr. addrlen must specify the size of the address structure. Since the size of the socket address structure varies between socket address fami- lies, the correct socket address structure should be used with each address family (for example, for AF_INET and AF_VME_LINK, for AF_INET6, and for AF_UNIX). Typically, the function is used to pass this value in the call (for example, The rules used in address binding vary between communication domains. For example, when binding an AF_UNIX socket to a path name (such as an open file having that name is created in the file system. When the bound socket is closed, that file still exists unless it is removed or unlinked. When binding an AF_INET socket or an AF_INET6 socket, sin_port can be a port number or it can be zero. If sin_port is zero, the system assigns an unused port number automatically. AF_VME_LINK Only The system call is used only by servers and not clients. X/Open Sockets Compilation Environment See xopen_networking(7). RETURN VALUE
returns the following values: Successful completion. Failure. is set to indicate the error. ERRORS
If fails, is set to one of the following values. The requested address is protected, and the current user has inadequate permission to access it. (This error can be returned by AF_INET or AF_INET6 only.) The specified address is already in use. The specified address is invalid or not available from the local machine, or for AF_CCITT sockets which use "wild card" addressing, the specified address space overlays the address space of an existing bind. The specified address is not a valid address for the address family of this socket. s is not a valid file descriptor. No addr parameter was specified. addr is not a valid pointer. The socket is already bound to an address, the socket has been shut down, addrlen is a bad value, or an attempt was made to an AF_UNIX socket to an NFS-mounted (remote) name. AF_CCITT: The protocol-ID length is negative or greater than 8, the X.121 address string contains an illegal character, or the X.121 address string is greater than 15 digits long. AF_VME_LINK: An explicit bind can be made only to a well-known port. The x25ifname field name specifies an interface that was shut down, or never initialized, or whose Level 2 protocol indi- cates that the link is not working: Wires might be broken, the interface hoods on the modem are broken, the modem failed, the phone connection failed (this error can be returned by AF_CCITT only), noise interfered with the line for a long period of time. The X.25 Level 2 protocol is down. The X.25 link is not working: Wires might be broken, or connections are loose on the interface hoods at the modem, the modem failed, or noise interfered with the line for an extremely long period of time. No buffer space is available. The cannot complete. No memory is available. The cannot complete. The x25ifname field name specifies a nonexistent interface. (This error can be returned by AF_CCITT only.) s is a valid file descriptor, but it is not a socket. The socket referenced by s does not support address binding. The connection is already bound. (AF_VME_LINK.) OBSOLESCENCE
Currently, the and types are the same size. This is compatible with the UNIX 95 and UNIX 03 profiles. However, in a future release, might be a different size, but that should not adversely affect application behavior in this case. Applications may use now. But applications that need to be portable to the UNIX 95 profile should follow the X/Open specification (see xopen_networking(7)). WARNINGS
Linking binary objects compiled to specification and binary objects compiled to specification to the same executable may result in unex- pected behavior, including application abnormal termination and unexpected socket errors. See xopen_networking(7) for details and remedy. FUTURE DIRECTION
Currently, the default behavior is the however, it might be changed to in a future release. At that time, any behavior that is incompati- ble with might be obsoleted. Applications that conform to the X/Open specification now will avoid migration problems (see xopen_network- ing(7)). AUTHOR
was developed by HP and the University of California, Berkeley. SEE ALSO
connect(2), getsockname(2), listen(2), socket(2), privileges(5), thread_safety(5), inet(7F), IPv6(7P), sctp(7), TCP(7P), UDP(7P), UNIX(7P), xopen_networking(7). STANDARDS CONFORMANCE
bind(2)
