#!/usr/bin/env perl
use strict;
use Getopt::Std;
use Net::Ping;
use POSIX;
use Socket;
use Switch;
use Time::HiRes qw/time/;

# force print before buffer is full
$| = 1;

# imcp requires root access
die("pinger must be run as root\n") if($> != 0);

my $alive = 1;
my(%switches, $time, $name, $startTime, $finishTime);

# handle command line options
my $status = getopts('drnth', \%switches);
help() if(!$status || $switches{'h'});
for (keys %switches) {
  switch($_) {
    case 'd'    { $alive = 0; }
    case 'r'    { $alive = 1; }
    case 'n'    { $name = 1; }
    case 't'    { $time = 1; }
    else        {}
  }
}


die("Usage: pinger START_IP [END_IP]\n")if(scalar(@ARGV) < 1 || scalar(@ARGV) > 2);

$startTime = time if($time);
my $p = Net::Ping->new('icmp');
my @ips;

# must be IP addresses
if($ARGV[0] !~ /((?:\d{1,3}\.){3}\d{1,3})/ || (defined($ARGV[1]) && $ARGV[1] !~ /((?:\d{1,3}\.){3}\d{1,3})/)) {
  die("Both arguments must be IP addresses if two are specified.\n");
}

my @ip1 = split(/\./, $ARGV[0]);
# Set the second IP address to the first if no second argument
my @ip2 = (scalar(@ARGV) == 2) ? split(/\./, $ARGV[1]) : @ip1;

# and only the final octet should differ
if($ip1[0] != $ip2[0] || $ip1[1] != $ip2[1] || $ip1[2] != $ip2[2]) {
  die("The first three octets of the IP addresses must match.\n")
}

# reverse IPs if 1 is larger than 2
if($ip1[3] > $ip2[3]) {
  my $temp = $ip2[3];
  $ip2[3] = $ip1[3];
  $ip1[3] = $temp;
}

my $baseIp = $ip1[0] . '.' . $ip1[1] . '.' . $ip1[2];
my $start = $ip1[3];
my $end = $ip2[3];
my $count = $ip2[3] - $ip1[3] + 1;

for(my $i = $start, my $k = 1; $i <= $end; $i++, $k++) {
  progressBar($k, $count);

  my $ip = $baseIp . '.' . $i;

  my $reachable = $p->ping($ip, 1);
  if($reachable == $alive) {
    if($name && $reachable) {
      my $hostaddr = gethostbyaddr(inet_aton($ip), AF_INET);
      $ip = $hostaddr if($hostaddr ne "");
    }

    push(@ips, $ip);
  }
}
$p->close();
$finishTime = time if($time);

print "\n\n";
($alive) ? print "Reachable:\n" : print "Dead:\n";
print join(", ", @ips);
print "\n\n";

if($time) {
  my $completed = $finishTime - $startTime;
  printf("Completed in %.2f seconds.\n", $completed);
}

# details from http://stackoverflow.com/questions/1782107/how-do-i-retrieve-the-terminal-width-in-perl
sub findTerminalWidth {
  my($winsize, $row, $col, $xpixel, $ypixel);
  my $available = 1;
  require 'sys/ioctl.ph';
  $available = 0 unless defined &TIOCGWINSZ;
  open(TTY, "+</dev/tty") or $available = 0;
  $available = 0 unless (ioctl(TTY, &TIOCGWINSZ, $winsize = ''));
  if($available == 1) {
    ($row, $col, $xpixel, $ypixel) = unpack('S4', $winsize);
  } else {
    return -1;
  }
  close(TTY);
  
  return $col;
}

sub progressBar {
  my($current, $total) = @_;
  my $width = findTerminalWidth();

  my $barWidth = $width - 11;
  my $percent = ($current / $total) * 100;
  my $barPercent = int($percent / 100 * $barWidth);
  printf(" [%3d\%",$percent);
  if($width > 0) {
    print "] [";
    for(my $i = 1; $i < $barWidth; $i++) {
      ($i <= $barPercent) ? print '=' : print ' ';
    }
  }
  print "]\r";
}

sub help {
  print "usage:\t pinger [-d] start [finish]\n\n";
  print "\t-d\t\tList dead addresses\n";
  print "\t-n\t\tReturn list as hostnames when possible\n";
  print "\t-r\t\tList reachable addresses (default)\n";
  print "\t-t\t\tTime ping execution\n";
  exit(1);
}