getpeername()

PROTOTYPE

#include <sockets.h>

int getpeername(int socket, void *addr, socklen_t *addrlen);

DESCRIPTION

getpeername() outputs the remote address of the connected socket referenced by socket. If there are no errors, an address structure containing the remote address is written to *addr, either type sockaddr_in or sockaddr_in6 according to the connection type. The address and port number are written in network byte order.

On input, *addrlen is the size of the buffer pointed to addr. As output, it is the address structure size, either sizeof(struct sockaddr_in) or sizeof(struct sockaddr_in6). If the buffer size is less than the address structure size, the output is truncated to fit the buffer size.

getpeername() only succeeds on connected sockets. Since a connected socket’s remote address is either given to connect() or (optionally) output by accept(), getpeername() is not strictly necessary. However, it may be useful when one module receives a connected socket from another module.

If successful, getpeername() outputs the socket address and returns 0. Otherwise, it sets errno and returns -1.

ERROR CODES

EFAULT	addr or addrlen is NULL.
EINVAL	*addrlen is negative.
ENETDOWN	TargetTCP has not been initialized.
ENOTCONN	The socket is not connected.
ENOTSOCK	socket is not a valid socket handle.

EXAMPLE

  sockaddr_in addr;
  socklen_t addrlen;

  /*-------------------------------------------------------------------*/
  /* Exercise getpeername().                                           */
  /*-------------------------------------------------------------------*/
  addrlen = sizeof(struct sockaddr_in);
  getpeername(sock, &addr, &addrlen);
  printf("Server IP address is ");
  printIP(ntohl(addr.sin_addr));
  printf(", port is %d\n", ntohs(addr.sin_port));