getpeername(2)



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  in-
       formation  (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)

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