#!/usr/bin/perl
use strict;
use warnings;

# This script use IP option called "record route" for emulate traceroute.
# Unfortunately max size of ip options is only 40 bytes and we can see
# just 9 hops, other hops will be ignored ;(

use Net::RawIP;
use Getopt::Long qw(GetOptions);

my %opt;
GetOptions(\%opt, 'interface=s', 'source=s', 'dest=s');
die "Usage $0 --interface <interface> --dest <dest host> --source <your host>"
    unless($opt{dest} && $opt{interface} && $opt{source});

my $rawip = Net::RawIP->new({icmp =>{}});

$rawip->set({
            ip => {
                saddr => $opt{source},
                daddr => $opt{dest},
            },
	        icmp => {
                type => 8,
                id => $$,
            }
        });  

my $data = "\5".("\0" x 37);

$rawip->optset(ip => {
                type => [(7)],
                data => [($data)],
                });

my $filt = "ip proto \\icmp and dst host $opt{source}";
my $size = 1500;
my $tout = 30;
my $pcap = $rawip->pcapinit($opt{interface}, $filt, $size, $tout);
my $i    = 0;

my @a;
if (fork) {
    loop $pcap,1, \&dmp, \@a; 
}
else {
    sleep 1;
    $rawip->set({icmp => {sequence => $i,data => timem()}});
    $rawip->send(1,1);
}

sub dmp {
    $rawip->bset(substr($_[2],14));

    my $opt = ($rawip->optget(ip => {type => [(7)] } ))[2];
    $opt = substr($opt, 2);
    my @route = unpack("N9", $opt);
    my $j = 0;
    for my $site (@route) {
        last unless $site;
        printf(" -> ") if $j;
		printf("\n") if $j == 4;
        printf("%u.%u.%u.%u", unpack("C4", pack("N", $site)));
        $j++;
    }
    printf("\n");
}