基于Discuz security.inc.php代码的深入分析

[Discuz!] (C)2001-2009 Comsenz Inc.
This is NOT a freeware,use is subject to license terms$Id: security.inc.PHP 16688 2008-11-14 06:41:07Z cnteacher $
*/

//如果没有设定 IN_DISCUZ ，则访问出错

if(!defined('IN_DISCUZ')) {
exit('Access Denied');
}

// 使用位移 $attackevasive 来设定 论坛防御级别 ，如果是 1 或者是 4 的话， 1=cookie 刷新限制 ， 4=二次请求

// 读取上次时间到当前存放cookies数组，并将现在时间放置cookies
// 将$_DCOOKIE['lastrequest'] 不断加密 存放last访问时间到 lastrequest_cookies
if($attackevasive & 1 || $attackevasive & 4) {
$_DCOOKIE['lastrequest'] = authcode($_DCOOKIE['lastrequest'],'DECODE');
dsetcookie('lastrequest',authcode($timestamp,'ENCODE'),$timestamp + 816400,1,true);
}

//如果确认被攻击，则展示提示语 1

if($attackevasive & 1) {
if($timestamp - $_DCOOKIE['lastrequest'] < 1) {
securitymessage('attachsave_1_subject','attachsave_1_message');
}
}

//如检查到 HTTP_X_FORWARDED_FOR 有以下 参数 ，将提示 使用代理

if(($attackevasive & 2) && ($_SERVER['HTTP_X_FORWARDED_FOR'] ||
$_SERVER['HTTP_VIA'] || $_SERVER['HTTP_PROXY_CONNECTION'] ||
$_SERVER['HTTP_USER_AGENT_VIA'] || $_SERVER['HTTP_CACHE_INFO'] ||
$_SERVER['HTTP_PROXY_CONNECTION'])) {
securitymessage('attachsave_2_subject','attachsave_2_message',FALSE);
}

//如果在限定的时间内访问多次，将判断为二次请求

if($attackevasive & 4) {
if(empty($_DCOOKIE['lastrequest']) || $timestamp - $_DCOOKIE['lastrequest'] > 300) {
securitymessage('attachsave_4_subject','attachsave_4_message');
}
}

//如果需要回答问题，则判断为8

if($attackevasive & 8) {
list($questionkey,$questionanswer,$questiontime) = explode('|',authcode($_DCOOKIE['secqcode'],'DECODE'));
include_once DISCUZ_ROOT.'./forumdata/cache/cache_secqaa.PHP';
if(!$questionanswer || !$questiontime || $_DCACHE['secqaa'][$questionkey]['answer'] != $questionanswer) {if(empty($_POST['secqsubmit']) || (!empty($_POST['secqsubmit']) && $_DCACHE['secqaa'][$questionkey]['answer'] != md5($_POST['answer']))) {
$questionkey = array_rand($_DCACHE['secqaa']);
dsetcookie('secqcode',authcode($questionkey.'||'.$timestamp,true);
securitymessage($_DCACHE['secqaa'][$questionkey]['question'],'',FALSE,TRUE);
} else {
dsetcookie('secqcode',authcode($questionkey.'|'.$_DCACHE['secqaa'][$questionkey]['answer'].'|'.$timestamp,true);
}
}}/**
* 输出被攻击提示语言，如果是ajax，展示一個错误層， 如果是請求， 則展示错误頁面
* @param $subject
* @param $message
* @param $reload
* @param $form
* @return unknown_type
*/
function securitymessage($subject,$message,$reload = TRUE,$form = FALSE) {$scuritylang = array(
'attachsave_1_subject' => '频繁刷新限制',
'attachsave_1_message' => '您访问本站速度过快或者刷新间隔时间小于两秒！请等待页面自动跳转 ...',
'attachsave_2_subject' => '代理服务器访问限制',
'attachsave_2_message' => '本站现在限制使用代理服务器访问，请去除您的代理设置，直接访问本站。',
'attachsave_4_subject' => '页面重载开启',
'attachsave_4_message' => '欢迎光临本站，页面正在重新载入，请稍候 ...'
);$subject = $scuritylang[$subject] ? $scuritylang[$subject] : $subject;
$message = $scuritylang[$message] ? $scuritylang[$message] : $message;
if($_GET['inajax']) {
ajaxshowheader();
echo '';
ajaxshowfooter();
} else {
echo '';
echo '';
echo '';
echo '';
echo 'if($reload) {
echo '';
}
if($form) {
echo '';
}
echo '';
echo '';
}
exit();
}
function ajaxshowheader() {
global $charset,$inajax;
ob_end_clean();
@header("Expires: -1");
@header("Cache-Control: no-store,private,post-check=0,pre-check=0,max-age=0",FALSE);
@header("Pragma: no-cache");
header("Content-type: application/xml");
echo "/n}function ajaxshowfooter() {
echo ']]>';
}?>