// Copyright (C) Jann Horn (2013)
// You can redistribute this code under the terms of the GPLv2 or GPLv3.
// THIS PROGRAM IS FOR EDUCATIONAL PURPOSES ONLY!
// I AM NOT RESPONSIBLE FOR WHAT YOU DO WITH THIS PROGRAM OR THE IMPACT THIS
// PROGRAM MIGHT HAVE ON YOUR SYSTEMS! YOU HAVE BEEN WARNED!

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

char *target;

void run(void) {
  int pipefds[2];
  if (pipe(pipefds)) perror("can't create pipe"), exit(1);
  int parent_fd = pipefds[0];
  int child_fd = pipefds[1];

  pid_t pid = fork();
  if (pid < 0) perror("can't fork"), exit(1);

  if (pid == 0) {
    int nullfd = open("/dev/null", O_RDWR);
    dup2(nullfd, 0);
    dup2(nullfd, 2);
    close(nullfd);
    close(parent_fd);
    dup2(child_fd, 1);
    close(child_fd);
    execlp("hping3", "hping3", "-c", "20", "-p", "80", "-i", "u100000", "--syn", target, NULL);
    perror("can't exec"), exit(1);
  }
  close(child_fd);

  char indata[4096];
  int indata_written = 0;
  int rres;
  while ((rres=read(parent_fd, indata+indata_written, 4095-indata_written)) > 0) {
    indata_written += rres;
    if (indata_written >= 4095) fputs("too much information", stderr), exit(1);
  }
  if (rres < 0) perror("failure reading from child"), exit(1);
  indata[indata_written] = '\0';
  close(parent_fd);

  char *s = indata;
  int last_id = -1;
  int sum = 0;
  while ((s=strstr(s, " id=")) != NULL) {
    s += 4;
    int id = atoi(s);
    if (last_id != -1) {
      int diff = id - last_id;
      if (diff < 0) diff += (256*256);
      sum += diff;
    }
    last_id = id;
  }

  printf("%i %i\n", (int)time(NULL), sum);
}

int main(int argc, char **argv) {
  if (argc != 2) fputs("bad invocation\n", stderr), exit(1);
  target = argv[1];

  setbuf(stdout, NULL);

  while (1) {
    run();
    sleep(300);
  }
}