CI框架源码阅读---------Security.php
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
* CodeIgniter
*
* An open source application development framework for PHP 5.1.6 or newer
*
* @package CodeIgniter
* @author ExpressionEngine Dev Team
* @copyright Copyright (c) 2008 - 2011, EllisLab, Inc.
* @license http://codeigniter.com/user_guide/license.html
* @link http://codeigniter.com
* @since Version 1.0
* @filesource
*/
// ------------------------------------
/**
* Security Class
* 本类包含一些方法，能帮助您创建安全的应用程序，对输入的数据进行安全方面的处理。
* CI官方手册本类的地址：http://codeigniter.org.cn/user_guide/libraries/security.html
* @package CodeIgniter
* @subpackage Libraries
* @category Security
* @author ExpressionEngine Dev Team
* @link http://codeigniter.com/user_guide/libraries/security.html
*/
class CI_Security {
/**
* Random Hash for protecting URLs
* 为保护URL（跨站脚本攻击）的随机hash值
* @var string
* @access protected
*/
protected $_xss_hash = '';
/**
* Random Hash for Cross Site Request Forgery Protection Cookie
* 防止跨站请求伪造cookie的随机hash
* @var string
* @access protected
*/
protected $_csrf_hash = '';
/**
* Expiration time for Cross Site Request Forgery Protection Cookie
* Defaults to two hours (in seconds)
* 跨站请求保护Cookie的过期时间，默认是2小时（单位秒）
* @var int
* @access protected
*/
protected $_csrf_expire = 7200;
/**
* Token name for Cross Site Request Forgery 伪造 Protection Cookie
* 跨站请求伪造保护的Cookie令牌名
* @var string
* @access protected
*/
protected $_csrf_token_name = 'ci_csrf_token';
/**
* Cookie name for Cross Site Request Forgery Protection Cookie
* 跨站请求伪造保护的Cookie的Cookie名
* @var string
* @access protected
*/
protected $_csrf_cookie_name = 'ci_csrf_token';
/**
* List of never allowed strings
* 决不允许的字符串的列表
* @var array
* @access protected
*/
protected $_never_allowed_str = array(
'document.cookie' => '[removed]',
'document.write' => '[removed]',
'.parentNode' => '[removed]',
'.innerHTML' => '[removed]',
'window.location' => '[removed]',
'-moz-binding' => '[removed]',
'<!--' => '<!--',
'-->' => '-->',
' '' => '<comment>'
);
/* never allowed, regex replacement */
/**
* List of never allowed regex replacement
* 不允许的正则替换字符串列表
* @var array
* @access protected
*/
protected $_never_allowed_regex = array(
'javascript\s*:',
'expression\s*(\(|&\#40;)', // CSS and IE
'vbscript\s*:', // IE, surprise!
'Redirect\s+302',
"([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?"
);
/**
* Constructor
*
* @return void
*/
public function __construct()
{
// Is CSRF protection enabled?
// csrf 是否开启
if (config_item('csrf_protection') === TRUE)
{
// CSRF config 读取CSRF 配置并赋值给本类下的对应的属性
foreach (array('csrf_expire', 'csrf_token_name', 'csrf_cookie_name') as $key)
{
if (FALSE !== ($val = config_item($key)))
{
$this->{'_'.$key} = $val;
}
}
// Append application specific cookie prefix
// 添加应用指定的cookie前缀
if (config_item('cookie_prefix'))
{
$this->_csrf_cookie_name = config_item('cookie_prefix').$this->_csrf_cookie_name;
}
// Set the CSRF hash
// 设置CSRF hash
$this->_csrf_set_hash();
}
log_message('debug', "Security Class Initialized");
}
// --------------------------------
/**
* Verify Cross Site Request Forgery Protection
* 验证跨站请求伪造保护
* @return object
*/
public function csrf_verify()
{
// If it's not a POST request we will set the CSRF cookie
// 如果不是post请求我们要设置 CSRF cookie
if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST')
{
return $this->csrf_set_cookie();
}
// Do the tokens exist in both the _POST and _COOKIE arrays?
// 如果请求令牌不存在，调用csrf_show_error 报错
if ( ! isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name]))
{
$this->csrf_show_error();
}
// Do the tokens match?
// 如果令牌不对，报错。
if ($_POST[$this->_csrf_token_name] != $_COOKIE[$this->_csrf_cookie_name])
{
$this->csrf_show_error();
}
// We kill this since we're done and we don't want to
// polute the _POST array
// 销毁领牌子，因为我们不想污染_POST 数组
unset($_POST[$this->_csrf_token_name]);
// Nothing should last forever
// 销毁cookie名 并重新设置hash和cookie
unset($_COOKIE[$this->_csrf_cookie_name]);
$this->_csrf_set_hash();
$this->csrf_set_cookie();
log_message('debug', 'CSRF token verified');
return $this;
}
// --------------------------------
/**
* Set Cross Site Request Forgery Protection Cookie
* 设置伪造cookie保护跨站请求
* @return object
*/
public function csrf_set_cookie()
{
$expire = time() + $this->_csrf_expire;
$secure_cookie = (config_item('cookie_secure') === TRUE) ? 1 : 0;
// 当存在https时设置cookie
if ($secure_cookie && (empty($_SERVER['HTTPS']) OR strtolower($_SERVER['HTTPS']) === 'off'))
{
return FALSE;
}
// 设置cookie
setcookie($this->_csrf_cookie_name, $this->_csrf_hash, $expire, config_item('cookie_path'), config_item('cookie_domain'), $secure_cookie);
log_message('debug', "CRSF cookie Set");
return $this;
}
// --------------------------------
/**
* Show CSRF Error
* 显示CSRF错误
* @return void
*/
public function csrf_show_error()
{
show_error('The action you have requested is not allowed.');
}
// --------------------------------
/**
* Get CSRF Hash
* 获取CSRF hash
* Getter Method
*
* @return string self::_csrf_hash
*/
public function get_csrf_hash()
{
return $this->_csrf_hash;
}
// --------------------------------
/**
* Get CSRF Token Name
* 获取CSRF 令排名
* Getter Method
*
* @return string self::csrf_token_name
*/
public function get_csrf_token_name()
{
return $this->_csrf_token_name;
}
// --------------------------------
/**
* XSS Clean
*
* Sanitizes 清理 data so that Cross Site Scripting Hacks can be
* prevented.阻止 This function does a fair amount of work but
* it is extremely thorough, designed to prevent even the
* most obscure XSS attempts 企图. Nothing is ever 100% foolproof,
* of course, but I haven't been able to get anything passed
* the filter.
* 对数据进行过滤，从而可以防止跨站脚本攻击。这个函数做了一些工作，但是它是非常彻底的，
* 甚至可以防止大多数模糊的XSS企图。当然，没有什么是100%安全的，
* 但是我们在这个过滤器中已经做了所欲我们所能做想到的了。
*
* Note: This function should only be used to deal with data
* upon submission. It's not something that should
* be used for general runtime processing.
* 注意：这个函数只能用来处理已经提交的数据。
* 在通常的运行过程中，不应该使用该函数。
*
* This function was based in part on some code and ideas I
* got from Bitflux: http://channel.bitflux.ch/wiki/XSS_Prevention
*
* To help develop this script I used this great list of
* vulnerabilities along with a few other hacks I've
* harvested from examining vulnerabilities in other programs:
* http://ha.ckers.org/xss.html
*
* @param mixed string or array
* @param bool
* @return string
*/
public function xss_clean($str, $is_image = FALSE)
{
/*
* Is the string an array?
* 需要过滤的字符串是数组吗？
*
*/
if (is_array($str))
{
while (list($key) = each($str))
{
$str[$key] = $this->xss_clean($str[$key]);
}
return $str;
}
/*
* Remove Invisible Characters
* 移除不可见字符
*/
$str = remove_invisible_characters($str);
// Validate Entities in URLs
// 验证在URL中的字符实体
$str = $this->_validate_entities($str);
/*
* URL Decode
* URL解码
* Just in case stuff like this is submitted:
* 防止下面这样的东西提交
* <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a>
*
* Note: Use rawurldecode() so it does not remove plus signs
* rawurldecode() 不会把加号（'+'）解码为空格，而 urldecode() 可以。
*
*/
$str = rawurldecode($str);
/*
* Convert character entities to ASCII
* 把实体字符转换成ASCII码
* 这使得我们下面的测试是可靠的，我们仅仅转换实体内的标签，因为这些是会造成安全问题的实体
* This permits our tests below to work reliably.
* We only convert entities that are within tags since
* these are the ones that will pose security problems.
*
*/
$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
$str = preg_replace_callback("/|_do_never_allowed($str);
/*
* Makes PHP tags safe
* 使PHP标签安全
* Note: XML tags are inadvertently replaced too:
* 注意： XML标签也会被无意的替换
* <?xml *
* But it doesn't seem to pose a problem.
* 但是它似乎不会构成问题
*/
if ($is_image === TRUE)
{
// Images have a tendency to have the PHP short opening and
// closing tags every so often so we skip those and only
// do the long opening tags.
$str = preg_replace('/<\?(php)/i', "<?\\1", $str);
}
else
{
$str = str_replace(array('<?', '?'.'>'), array('', '?>'), $str);
}
/*
* Compact any exploded words
* 压缩所有分解了的单词
* This corrects words like: j a v a s c r i p t
* These words are compacted back to their correct state.
*/
$words = array(
'javascript', 'expression', 'vbscript', 'script', 'base64',
'applet', 'alert', 'document', 'write', 'cookie', 'window'
);
foreach ($words as $word)
{
$temp = '';
for ($i = 0, $wordlen = strlen($word); $i ]*?)(>|$)#si", array($this, '_js_link_removal'), $str);
}
if (preg_match("/<img preg_replace_callback alt=" CI框架源码阅览-Security.php " >]*?)(\s?/?>|$)#si", array($this, '_js_img_removal'), $str);
}
if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str))
{
$str = preg_replace("##si", '[removed]', $str);
}
}
while($original != $str);
unset($original);
// Remove evil attributes such as style, onclick and xmlns
// 移除有害的属性，比如style ， onclick ， xmlns
$str = $this->_remove_evil_attributes($str, $is_image);
/*
* Sanitize naughty HTML elements
* 清理不适当的HTML元素
* If a tag containing any of the words in the list
* below is found, the tag gets converted to entities.
* 如果一个标签包含任何一个下面列表中的单词，这个标签转换为一个字符实体
* So this: <blink>
* Becomes: <blink>
*/
$naughty = 'alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss';
$str = preg_replace_callback('#_do_never_allowed($str);
/*
* Images are Handled in a Special Way
* - Essentially, we want to know that after all of the character
* conversion is done whether any unwanted, likely XSS, code was found.
* If not, we return TRUE, as the image is clean.
* However, if the string post-conversion does not matched the
* string post-removal of XSS, then it fails, as there was unwanted XSS
* code found and removed/changed during processing.
*/
if ($is_image === TRUE)
{
return ($str == $converted_string) ? TRUE: FALSE;
}
log_message('debug', "XSS Filtering completed");
return $str;
}
// --------------------------------
/**
* Random Hash for protecting URLs
* 随即生成一个_xss_hssh
* @return string
*/
public function xss_hash()
{
if ($this->_xss_hash == '')
{
mt_srand();
$this->_xss_hash = md5(time() + mt_rand(0, 1999999999));
}
return $this->_xss_hash;
}
// --------------------------------
/**
* HTML Entities Decode
* HTML 实体解码
* This function is a replacement for html_entity_decode()
* 这个函数用来替换 html_entity_decode()函数
* The reason we are not using html_entity_decode() by itself is because
* while it is not technically技术上 correct to leave out the semicolon
* at the end of an entity most browsers will still interpret the entity
* correctly. html_entity_decode() does not convert entities without
* semicolons, so we are left with our own little solution here. Bummer.
* 当编码字符后没有写；时，大部分浏览器都能够正确的解释代码，但是，html_entity_decode将不会解释它
* html_entity_decode()不会转换没有分号的实体，所以使用自己的解决方案
* @param string
* @param string
* @return string
*/
public function entity_decode($str, $charset='UTF-8')
{
if (stristr($str, '&') === FALSE)
{
return $str;
}
$str = html_entity_decode($str, ENT_COMPAT, $charset);
$str = preg_replace('~(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);
return preg_replace('~([0-9]{2,4})~e', 'chr(\\1)', $str);
}
// --------------------------------
/**
* Filename Security
* 文件名安全
* @param string
* @param bool
* @return string
*/
public function sanitize_filename($str, $relative_path = FALSE)
{
$bad = array(
"../",
"<!--",
"-->",
"",
"'",
'"',
'&',
'$',
'#',
'{',
'}',
'[',
']',
'=',
';',
'?',
"%20",
"%22",
"%3c", //
"%0e", // >
"%28", // (
"%29", // )
"%2528", // (
"%26", // &
"%24", // $
"%3f", // ?
"%3b", // ;
"%3d" // =
);
if ( ! $relative_path)
{
$bad[] = './';
$bad[] = '/';
}
$str = remove_invisible_characters($str, FALSE);
return stripslashes(str_replace($bad, '', $str));
}
// ----------------------------
/**
* Compact Exploded Words
* 压缩搜索到得单词
* Callback function for xss_clean() to remove whitespace from
* things like j a v a s c r i p t
* 回调函数，用于xss_clean()，从类似于 j a v a s c r i p t中移除空格
*
*
* @param type
* @return type
*/
protected function _compact_exploded_words($matches)
{
return preg_replace('/\s+/s', '', $matches[1]).$matches[2];
}
// --------------------------------
/*
* Remove Evil HTML Attributes (like evenhandlers and style)
* 移除有害的html属性，（像事件处理和样式）
* It removes the evil attribute and either:
* - Everything up until a space
* For example, everything between the pipes:
* <a class="link">
* - Everything inside the quotes
* For example, everything between the pipes:
* </a><a alert class="link">
*
* @param string $str The string to check
* @param boolean $is_image TRUE if this is an image
* @return string The string with the evil attributes removed
*/
protected function _remove_evil_attributes($str, $is_image)
{
// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns
// 所有的havascript事件处理器
$evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction');
if ($is_image === TRUE)
{
/*
* Adobe Photoshop puts XML metadata into JFIF images,
* including namespacing, so we have to allow this for images.
* Adobe Photoshop在JFIF图片中放入了XML元数据
* 包含命名空间，所以我们必须对图片允许这些
*/
unset($evil_attributes[array_search('xmlns', $evil_attributes)]);
}
do {
$count = 0;
$attribs = array();
// find occurrences of illegal attribute strings without quotes
// 找出没有加引号的的不合法的属性
preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*([^\s>]*)/is', $str, $matches, PREG_SET_ORDER);
foreach ($matches as $attr)
{
$attribs[] = preg_quote($attr[0], '/');
}
// find occurrences of illegal 非法 attribute strings with quotes (042 and 047 are octal quotes)
// 找出没有引号的不合法属性（042，4,0是八进制引号）
preg_match_all("/(".implode('|', $evil_attributes).")\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is", $str, $matches, PREG_SET_ORDER);
foreach ($matches as $attr)
{
$attribs[] = preg_quote($attr[0], '/');
}
// replace illegal attribute strings that are inside an html tag
// 替换html标签中的非法属性
if (count($attribs) > 0)
{
$str = preg_replace("/\-])(.*?)(".implode('|', $attribs).")(.*?)([\s>', '', '_filter_attributes(str_replace(array(''), '', $match[1]))
),
$match[0]
);
}
// --------------------------------
/**
* JS Image Removal
* js图片清理
* Callback function for xss_clean() to sanitize image tags
* This limits the PCRE backtracks, making it more performance friendly
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
* PHP 5.2+ on image tag heavy strings
*
* @param array
* @return string
*/
protected function _js_img_removal($match)
{
return str_replace(
$match[1],
preg_replace(
'#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script>_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
),
$match[0]
);
}
// --------------------------------
/**
* Attribute Conversion
* 属性转换
* Used as a callback for XSS Clean
*
* @param array
* @return string
*/
protected function _convert_attribute($match)
{
return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);
}
// --------------------------------
/**
* Filter Attributes
* 过滤属性
* Filters tag attributes for consistency and safety
* 为一致性和安全性过滤标签属性
* @param string
* @return string
*/
protected function _filter_attributes($str)
{
$out = '';
if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches))
{
foreach ($matches[0] as $match)
{
$out .= preg_replace("#/\*.*?\*/#s", '', $match);
}
}
return $out;
}
// --------------------------------
/**
* HTML Entity Decode Callback
* html实体解码
* Used as a callback for XSS Clean
*
* @param array
* @return string
*/
protected function _decode_entity($match)
{
return $this->entity_decode($match[0], strtoupper(config_item('charset')));
}
// --------------------------------
/**
* Validate URL entities
* 验证URL字符实体
* Called by xss_clean()
*
* @param string
* @return string
*/
protected function _validate_entities($str)
{
/*
* Protect GET variables in URLs
* 保护url中的GET变量
*/
// 901119URL5918AMP18930PROTECT8198
$str = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-]+)|i', $this->xss_hash()."\\1=\\2", $str);
/*
* Validate standard character entities
* 验证标准字符实体
*
* Add a semicolon if missing. We do this to enable
* the conversion of entities to ASCII later.
* 如果没有的话，添加一个分号。这样做是为了以后允许字符实体到ASCII的转换
*
*/
$str = preg_replace('#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i', "\\1;\\2", $str);
/*
* Validate UTF16 two byte encoding (x00)
* 验证UTF16两个字节的编码（x00）
* Just as above, adds a semicolon if missing.
* 像上面一样如果不存在添加一个分号。
*/
$str = preg_replace('#(&\#x?)([0-9A-F]+);?#i',"\\1\\2;",$str);
/*
* Un-Protect GET variables in URLs
* URL中不保护的GET变量
*/
$str = str_replace($this->xss_hash(), '&', $str);
return $str;
}
// ----------------------------------
/**
* Do Never Allowed
* 移除不允许的字符
* A utility function for xss_clean()
*
* @param string
* @return string
*/
protected function _do_never_allowed($str)
{
$str = str_replace(array_keys($this->_never_allowed_str), $this->_never_allowed_str, $str);
foreach ($this->_never_allowed_regex as $regex)
{
$str = preg_replace('#'.$regex.'#is', '[removed]', $str);
}
return $str;
}
// --------------------------------
/**
* Set Cross Site Request Forgery Protection Cookie
* 设置跨站请求保护Cookie
* @return string
*/
protected function _csrf_set_hash()
{
if ($this->_csrf_hash == '')
{
// If the cookie exists we will use it's value.
// We don't necessarily want to regenerate it with
// each page load since a page could contain embedded
// sub-pages causing this feature to fail
// 如果Cookie存在，我们将使用原先的值
// 我们不是必须要在每各加载的页面都要更新它，因为当一个页面可能要包含嵌入的子页面时，
// 嵌入的子页面会造成这个特性的失败
if (isset($_COOKIE[$this->_csrf_cookie_name]) &&
preg_match('#^[0-9a-f]{32}$#iS', $_COOKIE[$this->_csrf_cookie_name]) === 1)
{
return $this->_csrf_hash = $_COOKIE[$this->_csrf_cookie_name];
}
return $this->_csrf_hash = md5(uniqid(rand(), TRUE));
}
return $this->_csrf_hash;
}
}
/* End of file Security.php */
/* Location: ./system/libraries/Security.php */
</script></a></blink></blink></comment>
