getpeername - get name of connected peer socket
#include <sys/socket.h>
int getpeername(int sockfd, struct sockaddr
*addr, socklen_t *addrlen);
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.
On success, zero is returned. On error, -1 is returned, and
errno is set
appropriately.
- EBADF
- The argument sockfd is not a valid file 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 file descriptor sockfd does not refer to a socket.
POSIX.1-2001, POSIX.1-2008, SVr4, 4.4BSD (
getpeername() first appeared in
4.2BSD).
For background on the
socklen_t type, see
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).
accept(2),
bind(2),
getsockname(2),
ip(7),
socket(7),
unix(7)