#!/usr/bin/perl -w

use strict;

# first (and only) argument should be a port number to look for
my $testPort = $ARGV[0] || die "Usage: tor-exitpoint <port number>\n";

# fetch tor server list from server, cache locally to be nice...
my $cache = ".tor-policies";
my $cacheExpiration = 60*60;
if((! -f $cache) || (stat($cache))[9] + $cacheExpiration < time())
{
    print "Fetching aggregate tor policy file.\n";
    system "wget -q http://tor.noreply.org:9030/ -O - > $cache";
}

# parse rules for each server..
my $routerName;
my $routerIP;
my $findPort = 0;
open(TOR,$cache) || die "can't open cache file: $!";
while(<TOR>)
{
    chomp;
    if(m#^router\s+(.*)\s+(\d+\.\d+\.\d+\.\d+)#)
    {
	# found router list
	$routerName = $1;
	$routerIP = $2;
	$findPort = 1;
    } elsif($findPort && m#^(reject|accept)\s+\*:(\d+|\*)-?(\d+)?# )
    {
	my $type = $1;
	my $startport = $2;
	my $endport = $3 || $2;

	if($startport eq "*" || ( $startport <= $testPort
		&& $endport >= $testPort ))
	{
	    print "$routerName ($routerIP) " . $type . "s $testPort ($_)\n";
	    $findPort = 0;
	}
    }
}
close(TOR);