* below is found, the tag gets converted to entities.
$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('#
/*
* Sanitize naughty scripting elements
* 清理不合法的脚本元素
* Similar to above, only instead of looking for
* tags it looks for PHP and JavaScript commands
* that are disallowed. Rather than removing the
* code, it simply converts the parenthesis to entities
* rendering the code un-executable.
* 上面的类似，仅仅替换查询到的类似于PHP和Javascript命令的不被允许的标签
* 胜过移除这些代码，转换这些代码为不可执行的实体更好
*
* For example: eval('some code')
* Becomes: eval('some code')
*/
$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $str);
// Final clean up
// 最后的清理
// This adds a bit of extra precaution in case
// something got through the above filters
// 额外预防，防止上面的处理产生不合法的字符
$str = $this->_do_never_allowed($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", //
"%253c", //
"%3e", // >
"%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:
* - Everything inside the quotes
* For example, everything between the pipes:
*
* @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('|', $attribs).")(.*?)([\s>
}
} while ($count);
return $str;
}
// --------------------------------------------------------------------
/**
* Sanitize Naughty HTML
* 消除有害的html
* Callback function for xss_clean() to remove naughty HTML elements
*
* @param array
* @return string
*/
protected function _sanitize_naughty_html($matches)
{
// encode opening brace
$str = '
// encode captured opening or closing brace to prevent recursive vectors
$str .= str_replace(array('>', '', '
$matches[4]);
return $str;
}
// --------------------------------------------------------------------
/**
* JS Link Removal
* js链接清理
* Callback function for xss_clean() to sanitize links
* This limits the PCRE backtracks, making it more performance friendly
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
* PHP 5.2+ on link-heavy strings
* 调用xss_clean 清理连接
* @param array
* @return string
*/
protected function _js_link_removal($match)
{
return str_replace(
$match[1],
preg_replace(
'#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script>
<div> '', </script>
$this->_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>
<div> '', </script>
$this->_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('>', '', '
}
// --------------------------------------------------------------------
/**
* 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
