#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include "ftcp.h"

#define IFNAME "eth0"           /* Network interface to use. */

void error(char *msg)
{
  fprintf(stderr, "ftcp: ERROR");
  if (msg != NULL)
    fprintf(stderr, " %s", msg);
  if (errno != 0)
    fprintf(stderr, " [%s]", strerror(errno));
  fprintf(stderr, ".\n");

  exit(1);
}

int main(int argc, char *argv[])
{
  ftcp_t fp;

  fp.ifname = IFNAME;

  /* Check freeze TCP status for network interface IFNAME */
  if (ftcp(FTCP_FREEZE_CHECK, &fp) == -1 || fp.val == -ENODEV)
    error("FTCP_FREEZE_CHECK failed");

  printf("Freeze TCP is %s for interface " IFNAME ".\n",
         (fp.val == 1) ? "enabled" : "disabled");

  /* Enable freeze TCP for network interface IFNAME */
  printf("Enabling Freeze TCP for interface " IFNAME ".\n");
  if (ftcp(FTCP_FREEZE_ON, &fp) == -1 || fp.val == -ENODEV)
    error("FTCP_FREEZE_ON failed");

  /* Wait a short while so packet(s) with zero window advertisement
   *  get sent.
   */
  usleep(500000);

  /* Drop all packets going through IFNAME */
  printf("Disabling network interface " IFNAME ".\n");
  if (ftcp(FTCP_IF_DISABLE, &fp) == -1 || fp.val == -ENODEV)
    error("FTCP_IF_DISABLE failed");

  /* Wait a while */
  sleep(5);

  /* Disable freeze TCP for network interface IFNAME */
  printf("Disabling Freeze TCP for interface " IFNAME ".\n");
  if (ftcp(FTCP_FREEZE_OFF, &fp) == -1 || fp.val == -ENODEV)
    error("FTCP_FREEZE_OFF failed");

  /* Allow packets back through IFNAME */
  printf("Enabling network interface " IFNAME ".\n");
  if (ftcp(FTCP_IF_ENABLE, &fp) == -1 || fp.val == -ENODEV)
    error("FTCP_IF_ENABLE failed");

  /* Send duplicate ACKs */
  printf("Sending 3 duplicate ACKs on all established TCP connections.\n");
  if (ftcp(FTCP_DUP_ACKS3, &fp) == -1 || fp.val == -ENODEV)
    error("FTCP_DUP_ACKS3 failed");

  exit(0);
}