This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee  document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                   GETPEERNAME(3POSIX)

       The getpeername() function shall retrieve the peer address of the specified socket, store this address in
       the  sockaddr  structure  pointed to by the address argument, and store the length of this address in the
       object pointed to by the address_len argument.

       The address_len argument points to a socklen_t object which on input specifies the length of the supplied
       sockaddr structure, and on output specifies the length of the stored address.  If the  actual  length  of
       the  address  is  greater than the length of the supplied sockaddr structure, the stored address shall be
       truncated.

       If the protocol permits connections by unbound clients, and the peer is not bound, then the value  stored
       in the object pointed to by address is unspecified.

       The getpeername() function shall fail if:

       EBADF  The socket argument is not a valid file descriptor.

       EINVAL The socket has been shut down.

       ENOTCONN
              The socket is not connected or otherwise has not had the peer pre-specified.

       ENOTSOCK
              The socket argument does not refer to a socket.

       EOPNOTSUPP
              The operation is not supported for the socket protocol.

       The getpeername() function may fail if:

       ENOBUFS
              Insufficient resources were available in the system to complete the call.

       Thefollowingsectionsareinformative.

       None.

       None.

       getpeername — get the name of the peer socket

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       None.

       Upon  successful  completion,  0  shall  be  returned.  Otherwise,  -1 shall be returned and errno set to
       indicate the error.

accept(), bind(), getsockname(), socket()

       The Base Definitions volume of POSIX.1‐2017, <sys_socket.h>

       #include <sys/socket.h>

       int getpeername(int socket, struct sockaddr *restrict address,
           socklen_t *restrict address_len);