<?php
/*
* tracking.php:
* Interface to our web tracking stuff.
*
* Copyright (c) 2005 UK Citizens Online Democracy. All rights reserved.
* Email: chris@mysociety.org; WWW: http://www.mysociety.org/
*
* $Id: tracking.php,v 1.13 2006/08/15 13:05:00 chris Exp $
*
*/
require_once('urls.php');
/* track_code [EXTRA]
* Return some HTML which will cause the page visit to be
* recorded (by a browser suffering from the relevant privacy problem this
* exploits). If specified, EXTRA should be a simple string which will be
* recorded with the visit. */
function track_code($extra = null) {
if (!defined('OPTION_TRACKING') || !OPTION_TRACKING)
return '';
$salt = sprintf('%08x', rand());
$url = url_invoked();
$sign = null;
$img = null;
if (is_null($extra)) {
return '';
} else {
$sign = sha1(OPTION_TRACKING_SECRET . "\0$salt\0$url\0$extra");
$img = url_new(OPTION_TRACKING_URL, false,
"salt", $salt,
"url", $url,
"extra", $extra,
"sign", $sign
);
}
return '<!-- This "web bug" image is used to collect data which we use to improve our services. More on this at https://secure.mysociety.org/track/ --><img alt="" src="' . htmlspecialchars($img) . '" width="1" height="1">';
}
/* track_event [EXTRA]
* Like track_code, above, but actually output the HTML immediately. */
function track_event($extra = null) {
print track_code($extra);
}
?>
