YuCheng Hu
1ec191d88b
+YUCHENG HU+ git-svn-id: https://svn.code.sf.net/p/hawebs/svn@423 a2543c7e-f6e9-4f8a-8bff-1ffc34733512
82 lines
2.3 KiB
PHP
82 lines
2.3 KiB
PHP
<?php
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/**
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* Piwik - Open source web analytics
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*
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* @link http://piwik.org
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* @license http://www.gnu.org/licenses/gpl-3.0.html Gpl v3 or later
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* @version $Id: Nonce.php 1986 2010-03-24 14:32:50Z vipsoft $
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*
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* @category Piwik
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* @package Piwik
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*/
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/**
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* Nonce class.
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*
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* A cryptographic nonce -- "number used only once" -- is often recommended as part of a robust defense against cross-site request forgery (CSRF/XSRF).
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* Desrable characteristics: limited lifetime, uniqueness, unpredictability (pseudo-randomness).
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*
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* We use a session-dependent nonce with a configurable expiration that combines and hashes:
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* - a private salt because it's non-public
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* - time() because it's unique
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* - a mix of PRNGs (pseudo-random number generators) to increase entropy and make it less predictable
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*
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* @package Piwik
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*/
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class Piwik_Nonce
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{
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/**
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* Generate nonce
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*
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* @param string $id Unique id to avoid namespace conflicts, e.g., ModuleName.ActionName
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* @param int $ttl Optional time-to-live in seconds; default is 5 minutes
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* @return string Nonce
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*/
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static public function getNonce($id, $ttl = 300)
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{
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// save session-dependent nonce
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$ns = new Zend_Session_Namespace($id);
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$nonce = $ns->nonce;
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// re-use an unexpired nonce (a small deviation from the "used only once" principle, so long as we do not reset the expiration)
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// to handle browser pre-fetch or double fetch caused by some browser add-ons/extensions
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if(empty($nonce))
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{
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// generate a new nonce
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$nonce = md5(Piwik_Common::getSalt() . time() . Piwik_Common::generateUniqId());
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$ns->nonce = $nonce;
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$ns->setExpirationSeconds($ttl, 'nonce');
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}
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return $nonce;
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}
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/**
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* Verify nonce and check referrer (if present, i.e., it may be suppressed by the browser or a proxy/network).
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*
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* @param string $id Unique id
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* @param string $cnonce Nonce sent to client
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* @return bool true if valid; false otherwise
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*/
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static public function verifyNonce($id, $cnonce)
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{
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$ns = new Zend_Session_Namespace($id);
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$nonce = $ns->nonce;
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// validate token
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if(empty($cnonce) || $cnonce !== $nonce)
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{
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return false;
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}
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// validate referer
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$referer = Piwik_Url::getReferer();
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if(!empty($referer) && (Piwik_Url::getLocalReferer() === false))
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{
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return false;
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}
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return true;
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}
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}
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