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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

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     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)