getsockopt()

PROTOTYPE

#include <sockets.h>

int getsockopt(int socket, int level, int optname, void *optval, int *optlen);

DESCRIPTION

getsockopt() reads various options that control socket or protocol behavior. socket is a handle returned by socket(). level indicates the software layer controlled by the option. optname specifies the selected option. optval and optlen point to a parameter value and a parameter size, respectively, that are output by getsockopt(). The supported options are listed here.

If successful, getsockopt() returns 0. Otherwise, it sets errno and returns -1.

ERROR CODES

EFAULT	optval is NULL or optlen is not correct for the specified option.
EINVAL	optval has an invalid value.
ENETDOWN	TargetTCP has not been initialized.
ENOPROTOOPT	The combination of level and optname is unsupported.
ENOTSOCK	socket is not a valid socket handle.
EOPNOTSUPP	Operation not supported, socket type is not correct for specified option.

EXAMPLE

  int timeo;
  socklen_t olen = sizeof(timeo);

  /*-------------------------------------------------------------------*/
  /* Read and display the send timeout in milliseconds.                */
  /*-------------------------------------------------------------------*/
  rc = getsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, &timeo, &olen);
  if (rc < 0) exit(errno);
  printf("Send timeout = %u ms\n", timeo);