#!/usr/bin/perl -w
#
# Copyright (c) 2002 Nathan Lutchansky
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

use strict;
use CGI;

#
# IPv6 web bug
#
# This little script is designed to run on a dual-stack (IPv4 and IPv6)
# web server.  It will redirect users to one of two different pages
# depending on the protocol used to request the page.  Users connecting
# with IPv4 are redirected to the page passed in the "v4dest" field, and
# users connecting with IPv6 are redirected to the page passed in the
# "v6dest" field.  Optionally, the string "__IP__" (sans quotes) may be
# included in the v6dest field and will be replaced by the user's IPv6
# address upon redirection.
#
# For more information, see <http://www.litech.org/webbug/>.
#
# If you copy this script to your own site, you may want to change
# the two variables below.  They appear when the script is run without
# input.
#

my $version = "IPv6 web bug v0.2";
my $descr = "http://www.litech.org/webbug/";

####

my $q = new CGI;
my $ip = $ENV{"REMOTE_ADDR"};
if($q->param() && $q->param('v4dest') && $q->param('v6dest'))
{
	if( $ip =~ /\./ )
	{
		print $q->redirect('http://'.$q->param('v4dest'));
	} else
	{
		my $dest = $q->param('v6dest');
		$dest =~ s/__IP__/$ip/e;
		print $q->redirect('http://'.$dest);
	}
} else
{
	print $q->header, $q->start_html($version),
		$q->p("Client IP: $ip"),
		$q->p("See",$q->a({-href=>$descr},$descr),
				"for more information about this script."),
		$q->end_html;
}