<?php

# List the allowed domain names below, between quote
#   characters, with all but the last followed by a comma.
#
# This is to restrict opportunities for cross site
#   scripting. Pages can only be retrieved from the
#   domains listed here.
#
# In order to retrieve pages from both example.com and
#   www.example.com, both domains must be listed.

$AllowedDomains = Array(
"www.cs.vu.nl",
"www.few.vu.nl"
);


# Notes:

# Check for a URL in the query string, as a value in a
#   GET variable, or as a value in a POST variable. The
#   first to match is used. If none match, exit.

if( isset($_SERVER['QUERY_STRING']) and preg_match('/^http:\/\//i',$_SERVER['QUERY_STRING']) )
{ $url = $_SERVER['QUERY_STRING']; }
elseif( isset($_GET['url']) and preg_match('/^http:\/\//i',$_GET['url']) )
{ $url = $_GET['url']; }
elseif( isset($_POST['url']) and preg_match('/^http:\/\//i',$_POST['url']) )
{ $url = $_POST['url']; }
else
{ exit; }


# Verify the domain in the URL is allowed. If unable to
#   verify, exit.

$checkdomain = preg_replace('/^http:\/\//i','',$url);
$checkdomain = preg_replace('/\/.*$/','',$checkdomain);
$checkdomain = strtolower($checkdomain);
$domainokay = false;
foreach($AllowedDomains as $domain)
{
	if( $checkdomain == strtolower($domain) )
	{
		$domainokay = true;
		break;
	}
}
if(! $domainokay)
{ exit; }


# An URL may be used as a filename with function readfile()
#   when URL-aware fopen wrappers are enabled. See
#   http://us2.php.net/manual/en/ref.filesystem.php#ini.allow-url-fopen

readfile($url);
exit;
# When URL-aware fopen wrappers are not enabled, the
#   following can be used.


# Retrieve the page and echo it to the browser.

# Break URL into host and URI parts.
if(strpos($url,'/') == 0)
{
	$host = $_SERVER['SERVER_NAME'];
	$uri = $url;
}
else
{
	$url = preg_replace('/^.+?:\/\//','',$url);
	$pos = strpos($url,'/');
	$host = substr($url,0,$pos);
	$uri = substr($url,$pos);
}
# Open socket and store remote web page in $content
$content = '';
$fp = @fsockopen("$host",80,$errno,$errstr,30);
if(!$fp)
{
	echo("Error: $errstr ($errno)");
	exit;
}
else
{

	fwrite($fp,"GET $uri HTTP/1.0\r\n");
	fwrite($fp,"Host: $host\r\n");
	if( isset($_SERVER['HTTP_USER_AGENT']) )
	{ fwrite($fp,'User-Agent: '.$_SERVER['HTTP_USER_AGENT']."\r\n"); }
	fwrite($fp,"Connection: Close\r\n");
	fwrite($fp,"\r\n");
	while (! feof($fp) )
	{ $content .= fgets($fp,1024); }
	fclose($fp);
}
# Remove header lines from content and echo the rest to
#   the browser.
if( strpos($content,"\r") > 0 )
{ echo( preg_replace('/^.+?[\r\n]{4,}/s','',$content) ); }
else
{ echo( preg_replace('/^.+?\n{2,}/s','',$content) ); }
?>