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 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.

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 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.

CONFORMING TO
       POSIX.1-2001,  POSIX.1-2008, SVr4, 4.4BSD (getpeername() first appeared
       in 4.2BSD).

NOTES
       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  con-
       nect(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).

SEE ALSO
       accept(2), bind(2), getsockname(2), ip(7), socket(7), unix(7)

COLOPHON
       This page is part of release 4.16 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
       https://www.kernel.org/doc/man-pages/.



Linux                             2017-09-15                    GETPEERNAME(2)