getpeername — get name of connected peer socket
|struct sockaddr *addr,|
getpeername() returns the
address of the peer connected to the socket
sockfd, in the buffer pointed
should be initialized to indicate the amount of space pointed
addr. On return
it contains the actual size of the name returned (in bytes).
The name is truncated if the buffer provided is too
The returned address is truncated if the buffer provided
is too small; in this case,
addrlen will return a value
greater than was supplied to the call.
On success, zero is returned. On error, −1 is
errno is set
sockfd is not a valid
argument points to memory not in a valid part of the
process address space.
invalid (e.g., is negative).
Insufficient resources were available in the system to perform the operation.
The socket is not connected.
The file descriptor
sockfd does not refer to
The third argument of
getpeername() 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).
For stream sockets, once a connect(2) has been
performed, either socket can call
getpeername() to obtain the address of the
peer socket. On the other hand, datagram sockets are
connectionless. Calling connect(2) on a datagram
socket merely sets the peer address for outgoing datagrams
sent with write(2) or recv(2). The caller of
connect(2) can use
getpeername() to obtain the
peer address that it earlier set for the socket. However, the
peer socket is unaware of this information, and calling
getpeername() on the peer
socket will return no useful information (unless a connect(2) call was also
executed on the peer). Note also that the receiver of a
datagram can obtain the address of the sender when using
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(#)getpeername.2 6.5 (Berkeley) 3/10/91
Modified Sat Jul 24 16:37:50 1993 by Rik Faith <faithcs.unc.edu>
Modified Thu Jul 30 14:37:50 1993 by Martin Schulze <joeydebian.org>
Modified Sun Mar 28 21:26:46 1999 by Andries Brouwer <aebcwi.nl>
Modified 17 Jul 2002, Michael Kerrisk <mtk.manpagesgmail.com>
Added 'socket' to NAME, so that "man -k socket" will show this page.