#!/usr/bin/perl -w
# redirect.pl - redirects a browser to the URL contained in QUERY_STRING
# by Jonathan Eisenzopf. v1.0 19990818
# Copyright (c) 1999 Jupitermedia Corp. All Rights Reserved.
# See http://www.webreference.com/perl for more information
#
# 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 2 of the License, or
# (at your option) any later version.              

use strict;
use CGI;
use CGI::Carp;
use URI;

# CONSTANTS
my $restricted = 1;
my %ok_hosts = ('www.webreference.com' => 1,
		'www.internet.com' => 1,
		'www.webdeveloper.com' => 1,
		'www.wdvl.com' => 1,
	    'eisen.textant.com' => 1
		);

# MAIN
my $q = new CGI;

# print error if QUERY_STRING is empty
&error("Must specify URL") unless defined $q->keywords;

# print error if there is no HTTP referer
&error("Cannot run script directly") unless defined $q->referer;

# get referer URL
my $referer = new URI($q->referer);

# print error if $restricted is on and referer is not in @ok_hosts
&error("Host ".$referer->host." is not allow to redirect")
    if $restricted && !exists($ok_hosts{$referer->host});

# redirect
print $q->redirect($q->keywords);

# SUBROUTINES
sub error {
    my $message = shift;
    print $q->header;
    print "<H1>$message</H1>";
    die "$message";
}