NAME
getsockname —
get socket name
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/socket.h>
int
getsockname(
int
s,
struct sockaddr *
restrict name,
socklen_t *
restrict namelen);
DESCRIPTION
getsockname() returns the locally bound address information
for a specified socket.
Common uses of this function are as follows:
- When bind(2)
is called with a port number of 0 (indicating the kernel should pick an
ephemeral port) getsockname() is used to retrieve the
kernel-assigned port number.
- When a process calls
bind(2) on a wildcard IP
address, getsockname() is used to retrieve the local IP
address for the connection.
- When a function wishes to know the address family of a
socket, getsockname() can be used.
getsockname() takes three parameters:
s, Contains the file descriptor for the socket to be
looked up.
name points to a
sockaddr
structure which will hold the resulting address information. Normal use
requires one to use a structure specific to the protocol family in use, such
as
sockaddr_in
(IPv4) or
sockaddr_in6
(IPv6), cast to a (struct sockaddr *).
For greater portability (such as newer protocol families) the new structure
sockaddr_storage exists.
sockaddr_storage
is large
enough to hold any of the other sockaddr_* variants. On return, it should be
cast to the correct sockaddr type, according to the current protocol family.
namelen indicates the amount of space pointed to by
name, in bytes. Upon return,
namelen is set to the actual size of the returned
address information.
If the address of the destination socket for a given socket connection is
needed, the
getpeername(2)
function should be used instead.
If
name does not point to enough space to hold the entire
socket address, the result will be truncated to
namelen
bytes.
RETURN VALUES
On success,
getsockname() returns a 0, and
namelen is set to the actual size of the socket address
returned in
name. Otherwise,
errno
is set, and a value of -1 is returned.
ERRORS
The call succeeds unless:
-
-
- [
EBADF
]
- The argument s is not a valid
descriptor.
-
-
- [
EFAULT
]
- The name parameter points to memory
not in a valid part of the process address space.
-
-
- [
EINVAL
]
- The socket has been shut down.
-
-
- [
ENOBUFS
]
- Insufficient resources were available in the system to
perform the operation.
-
-
- [
ENOTCONN
]
- The socket is not connected.
-
-
- [
ENOTSOCK
]
- The argument s is a file, not a
socket.
SEE ALSO
bind(2),
socket(2)
HISTORY
The
getsockname() function call appeared in
4.2BSD.