GETPEERNAME(2) |
Linux Programmer's Manual |
GETPEERNAME(2) |
NAME
getpeername - get name of connected peer socket
SYNOPSIS
#include <sys/socket.h>
int getpeername(int
sockfd
, struct sockaddr *
addr
, socklen_t *
addrlen
);
DESCRIPTION
getpeername() returns the address of the peer connected to the socket
sockfd, in the buffer pointed to by
addr. The
addrlen argument should be initialized to indicate the amount of space pointed to by
addr. On return it contains the actual size of the name returned (in bytes). The name is truncated if the buffer provided is too small.
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.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
ERRORS
-
EBADF
-
The argument
sockfd is not a valid descriptor.
-
EFAULT
-
The
addr argument points to memory not in a valid part of the process address space.
-
EINVAL
-
addrlen is invalid (e.g., is negative).
-
ENOBUFS
-
Insufficient resources were available in the system to perform the operation.
-
ENOTCONN
-
The socket is not connected.
-
ENOTSOCK
-
The argument
sockfd is a file, not a socket.
CONFORMING TO
SVr4, 4.4BSD (the
getpeername() function call first appeared in 4.2BSD), POSIX.1-2001.
NOTES
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
recvfrom(2).
SEE ALSO
accept(2),
bind(2),
getsockname(2),
ip(7),
socket(7),
unix(7)
COLOPHON
This page is part of release 3.53 of the Linux
man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.