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       getpeername - get name of connected peer socket


       Standard C library (libc, -lc)


       #include <sys/socket.h>

       int getpeername(int sockfd, struct sockaddr *restrict addr,
                       socklen_t *restrict addrlen);


       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.


       On  success, zero is returned.  On error, -1 is returned, and errno is set to indicate the


       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

       EINVAL addrlen is invalid (e.g., is negative).

              Insufficient resources were available in the system to perform the operation.

              The socket is not connected.

              The file descriptor sockfd does not refer to a socket.


       POSIX.1-2001, POSIX.1-2008, SVr4, 4.4BSD (getpeername() first appeared in 4.2BSD).


       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).


       accept(2), bind(2), getsockname(2), ip(7), socket(7), unix(7)