/*
    Program to measure packet loss between two hosts
    Copyright (C) 2008  Kasper Dupont

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>

#ifndef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/if.h>
#include <linux/if_tun.h>

#include <sys/time.h>
#include <time.h>
#include <errno.h>
#include <dirent.h>
#include <unistd.h>

#include <netdb.h>
#include <pwd.h>
#include <grp.h>

#define SAMPLES 16
#define DELAY 15

static inline void errstop(const char *s)
{
  perror(s);
  exit(1);
}

int main(int argc, char ** argv) {
  struct sockaddr_in sa;
  socklen_t sal;
  struct hostent *host;
  uint16_t local_port=0, remote_port=0;
  int sock_fd;

  int index=0;
  int counters[SAMPLES];
  int lastprinted=SAMPLES-1;
  int nexttolastprinted=-1;
  int total_counter=0;

  if (argc == 4) {
    local_port=atoi(argv[1]);
    remote_port=atoi(argv[3]);
  }

  if ((local_port == 0) || (remote_port == 0)) {
    fprintf(stderr,"Usage: %s <port> <peer> <port>\n",argv[0]);
    return 1;
  }

  host=gethostbyname(argv[2]);
  if (!host) {
    perror(argv[2]);
    return 1;
  }

  sock_fd=socket(PF_INET,SOCK_DGRAM,0);
  if (sock_fd == -1) errstop("scoket");

  sa.sin_family = AF_INET;
  sa.sin_port = htons(local_port);
  sa.sin_addr.s_addr=0;

  if (bind(sock_fd,(struct sockaddr*)&sa,sizeof(sa))) errstop("bind");

  sa.sin_family = AF_INET;
  sa.sin_port = htons(remote_port);
  sa.sin_addr.s_addr=*(unsigned long int *)(host->h_addr);
  sal=sizeof(sa);

  fcntl(sock_fd,F_SETFL,O_NONBLOCK);

  while(1) {
    int foobuf,counter,i;
    ++index;
    counters[index%SAMPLES]=0;

    sendto(sock_fd,"",1,0,&sa,sal);
    sleep(DELAY);
    while (recvfrom(sock_fd,&foobuf,2,0,&sa,&sal) == 1) {
      ++total_counter;
      ++counters[index%SAMPLES];
    }

    counter=0;
    for (i=0;i<SAMPLES;++i)
      counter+=counters[i];

    if ((index > SAMPLES) && (counter != lastprinted)) {
      if ((counter > lastprinted + 1) ||
	  (lastprinted > counter + 1) ||
	  (lastprinted == 0))
      {
	lastprinted=counter;
	nexttolastprinted=-1;
      } else if (counter !=nexttolastprinted) {
	nexttolastprinted=lastprinted;
	lastprinted=counter;
      }
      if (counter == lastprinted) {
	char *s,*c;
	time_t t=time(NULL);
	s=ctime(&t);
	c=strchr(s,'\n');
	if (c) *c=0;
	printf("%s  -  Received total: %d - last %d minutes: %d\n",
	       s,total_counter,(SAMPLES*DELAY)/60,counter);
	fflush(stdout);
	lastprinted=counter;
      }
    }
  }
}