<?php

// Generate a visitor id for this hit. If there is a visitor id in the cookie, use that, otherwise use the guid if we have one, otherwise use a random number.
function getVisitorId($guid, $account, $userAgent, $cookie)
{
				// If there is a value in the cookie, don't change it.
				if (!empty($cookie)) return $cookie;
				return "0x" . substr(md5((!empty($guid)) ? $guid . $account : $userAgent . uniqid(rand(0, 0x7fffffff), true)), 0, 16);
}


// Writes the bytes of a 1x1 transparent gif into the response.
function writeGifData()
{
header("Content-Type: image/gif");
header("Cache-Control: private, no-cache, no-cache=Set-Cookie, proxy-revalidate");
header("Pragma: no-cache");
header("Expires: Wed, 17 Sep 1975 21:32:10 GMT");
echo pack('H*','4749463839610100010080ff00ffffff0000002c00000000010001000002024401003b');
}


// Make a tracking request to Google Analytics from this server.
// Copies the headers from the original request to the new one.
// If request containg utmdebug parameter, exceptions encountered
// communicating with Google Analytics are thown.
function sendRequestToGoogleAnalytics($utmUrl)
{
				$options = array(
								"http" => array(
												"method" => "GET",
												"user_agent" => $_SERVER["HTTP_USER_AGENT"],
												"header" => ("Accepts-Language: " . $_SERVER["HTTP_ACCEPT_LANGUAGE"]))
								);
				if (!empty($_GET["utmdebug"]))$data = file_get_contents($utmUrl, false, stream_context_create($options));
				else $data = @file_get_contents($utmUrl, false, stream_context_create($options));
}


// Track a page view, updates all the cookies and campaign tracker, makes a server side request to Google Analytics and writes the transparent gif byte data to the response.
function trackPageView()
{
				$domainName = $_SERVER["SERVER_NAME"];
				if (empty($domainName)) $domainName = "";
				
				// Get the referrer from the utmr parameter, this is the referrer to the page that contains the tracking pixel, not the referrer for tracking pixel.
				$documentReferer = $_GET["utmr"];
				if (empty($documentReferer) && $documentReferer !== "0") $documentReferer = "-";
				else $documentReferer = urldecode($documentReferer);
				
				$documentPath = $_GET["utmp"];
				if (empty($documentPath))$documentPath = "";
				else $documentPath = urldecode($documentPath);

				$visitorId = getVisitorId($_SERVER["HTTP_X_DCMGUID"], $_GET["utmac"], "{$_SERVER['HTTP_USER_AGENT']}", $_COOKIE['__utmmobile']);
				
				// Always try and add the cookie to the response.
				setrawcookie(
								'__utmmobile',
								$visitorId,
								time() + 63072000,
								'/');

				$utmGifLocation = "http://www.google-analytics.com/__utm.gif";
				// Construct the gif hit url.
				$utmUrl = $utmGifLocation . "?" .
				"utmwv=" . '4.4sh' .
				"&utmn=" . rand(0, 0x7fffffff) .
				"&utmhn=" . urlencode($domainName) .
				"&utmr=" . urlencode($documentReferer) .
				"&utmp=" . urlencode($documentPath) .
				"&utmac=" . $_GET["utmac"] .
				"&utmcc=__utma%3D999.999.999.999.999.1%3B" .
				"&utmvid=" . $visitorId .
				"&utmip=" . (preg_match("/^([^.]+\.[^.]+\.[^.]+\.).*/", $_SERVER["REMOTE_ADDR"], $matches)) ? $matches[1] . "0":'';

				sendRequestToGoogleAnalytics($utmUrl);
				// If the debug parameter is on, add a header to the response that contains
				// the url that was used to contact Google Analytics.
				if (!empty($_GET["utmdebug"])) header("X-GA-MOBILE-URL:" . $utmUrl);
				// Finally write the gif data to the response.
				writeGifData();
}

?><?php
trackPageView();

?>