Open Source Software

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 4.09 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/.



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