NAME
getpeername —
get name of connected
peer
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/socket.h>
int
getpeername(
int
s,
struct sockaddr *
restrict name,
socklen_t *
restrict namelen);
DESCRIPTION
The
getpeername() function returns the name of the peer
connected to the socket
s. One common use occurs when a
process inherits an open socket, such as TCP servers forked from
inetd(8). In this scenario,
getpeername() is used to determine the connecting client's
IP address.
The function takes three parameters:
-
-
- s
- contains the file descriptor of the socket whose peer
should be looked up.
-
-
- name
- points to a
sockaddr
structure that
will hold the address information for the connected peer. 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, especially with the newer protocol families, the
new struct sockaddr_storage
should be used.
sockaddr_storage
is large enough to hold any of
the other sockaddr_* variants. On return, it can be cast to the correct
sockaddr type, based on the protocol family contained in its ss_family
field.
-
-
- namelen
- indicates the amount of space pointed to by
name, in bytes.
If address information for the local end of the socket is required, the
getsockname(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
If the call succeeds, a 0 is returned 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.
-
-
- [
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
accept(2),
bind(2),
getsockname(2),
socket(2)
STANDARDS
The function conforms to
IEEE Std 1003.1-2008
(“POSIX.1”).
HISTORY
The
getpeername() function call appeared in
4.2BSD.