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 buf‐
       fer 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  getpeer‐
       name()  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 get‐
       peername() 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 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



Linux                                       2013-02-12                             GETPEERNAME(2)