getpeername

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 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 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 5.08 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)