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 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 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

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