getpeername(2)getpeername(2)NAMEgetpeername - Gets the name of the peer socket
SYNOPSIS
#include <sys/socket.h>
int getpeername(
int socket,
struct sockaddr *address,
socklen_t *address_len );
[XNS4.0] The definition of the getpeername() function in XNS4.0 uses a
size_t data type instead of a socklen_t data type as specified in
XNS5.0 (the previous definition).
[Tru64 UNIX] The following definition of the getpeername() function
does not conform to current standards and is supported only for back‐
ward compatibility (see standards(5)). int getpeername(
int socket,
struct sockaddr *address,
int *address_len );
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
getpeername(): XNS4.0, XNS5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the descriptor number of a connected socket. Points to a
sockaddr structure, the format of which is determined by the domain and
by the behavior requested for the socket. The sockaddr structure is an
overlay for a sockaddr_in, sockaddr_un, sockaddr_in6, or sockaddr_stor‐
age structure, depending on which of the supported address families is
active.
[Tru64 UNIX] If the compile-time option _SOCKADDR_LEN is
defined before the sys/socket.h header file is included, the
sockaddr structure takes 4.4BSD behavior, with a field for spec‐
ifying the length of the socket address. Otherwise, the default
4.3BSD sockaddr structure is used, with the length of the socket
address assumed to be 14 bytes or less.
If _SOCKADDR_LEN is defined, the 4.3BSD sockaddr structure is
defined with the name osockaddr. Specifies the length of the
sockaddr structure pointed to by the address parameter.
DESCRIPTION
The getpeername() function retrieves the name of the peer socket con‐
nected to the specified socket.
If the actual length of the address is greater than the length of the
sockaddr structure, the address is truncated.
If the protocol permits connections by unbound clients and the peer is
unbound, the value pointed to by address is unspecified.
A process created by another process can inherit open sockets, but may
need to identify the addresses of the sockets it has inherited. The
getpeername() function allows a process to retrieve the address of the
peer socket at the remote end of the socket connection.
NOTES
The getpeername() function operates only on connected sockets.
A process can use the getsockname() function to retrieve the local
address of a socket.
[Tru64 UNIX] When compiled in the X/Open UNIX environment or the
POSIX.1g socket environment, calls to the getpeername() function are
internally renamed by prepending _E to the function name. When you are
debugging a module that includes the getpeername() function and for
which _XOPEN_SOURCE_EXTENDED or _POSIX_PII_SOCKET has been defined, use
_Egetpeername to refer to the getpeername() call. See standards(5) for
further information.
RETURN VALUES
Upon successful completion, a value of 0 (zero) is returned and the
address parameter holds the address of the peer socket. If the getpeer‐
name() function fails, a value of -1 is returned and errno is set to
indicate the error.
ERRORS
If the getpeername() function fails, errno may be set to one of the
following values: The socket parameter is not valid. The address or
address_len parameter is not in a readable OR writable part of the user
address space. The socket has been shut down. Insufficient resources
were available in the system to complete the call. The available
STREAMS resources were insufficient for the operation to complete. The
socket is not connected. The socket parameter refers to a file, not a
socket. The operation is not supported for the socket protocol.
SEE ALSO
Functions: accept(2), bind(2), getsockname(2), socket(2).
Standards: standards(5).
Network Programmer's Guide
getpeername(2)
