<?php namespace Phpcmf\Library;


/**
 * http://www.xunruicms.com
 * 本文件是框架系统文件，二次开发时不可以修改本文件，可以通过继承类方法来重写此文件
 **/


/**
 * 安全过滤
 */
class Security {

	/**
	 * List of sanitize filename strings
	 *
	 * @var	array
	 */
	public $filename_bad_chars = [
		'../', '<!--', '-->', '<', '>',
		"'", '"', '&', '$', '#',
		'{', '}', '[', ']', '=',
		';', '?', '%20', '%22',
		'%3c',		// <
		'%253c',	// <
		'%3e',		// >
		'%0e',		// >
		'%28',		// (
		'%29',		// )
		'%2528',	// (
		'%26',		// &
		'%24',		// $
		'%3f',		// ?
		'%3b',		// ;
		'%3d'		// =
    ];

	/**
	 * Character set
	 *
	 * Will be overridden by the constructor.
	 *
	 * @var	string
	 */
	public $charset = 'UTF-8';

	/**
	 * XSS Hash
	 *
	 * Random Hash for protecting URLs.
	 *
	 * @var	string
	 */
	protected $_xss_hash;

	/**
	 * List of never allowed strings
	 *
	 * @var	array
	 */
	protected $_never_allowed_str =	[
		'document.cookie' => '[xss_clean]',
		'(document).cookie' => '[xss_clean]',
		'document.write'  => '[xss_clean]',
		'(document).write'  => '[xss_clean]',
		'.parentNode'     => '[xss_clean]',
		'.innerHTML'      => '[xss_clean]',
		'-moz-binding'    => '[xss_clean]',
		'<!--'            => '&lt;!--',
		'-->'             => '--&gt;',
		'<![CDATA['       => '&lt;![CDATA[',
		'<comment>'	  => '&lt;comment&gt;',
		'<%'              => '&lt;&#37;'
    ];

	// 替换前的处理
	protected $_never_call_str = [
        '&quot;javascript:'    => '&quot;javascript_xunruicms:',
    ];

	/**
	 * List of never allowed regex replacements
	 *
	 * @var	array
	 */
	protected $_never_allowed_regex = [
		'javascript\s*:',
		'(\(?document\)?|\(?window\)?(\.document)?)\.(location|on\w*)',
		'expression\s*(\(|&\#40;)', // CSS and IE
		'vbscript\s*:', // IE, surprise!
		'wscript\s*:', // IE
		'jscript\s*:', // IE
		'vbs\s*:', // IE
		'Redirect\s+30\d',
		"([\"'])+data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?"
    ];



	// --------------------------------------------------------------------

	/**
	 * XSS Clean
	 *
	 * Sanitizes data so that Cross Site Scripting Hacks can be
	 * prevented.  This method does a fair amount of work but
	 * it is extremely thorough, designed to prevent even the
	 * most obscure XSS attempts.  Nothing is ever 100% foolproof,
	 * of course, but I haven't been able to get anything passed
	 * the filter.
	 *
	 * Note: Should only be used to deal with data upon submission.
	 *	 It's not something that should be used for general
	 *	 runtime processing.
	 *
	 * @link	http://channel.bitflux.ch/wiki/XSS_Prevention
	 * 		Based in part on some code and ideas from Bitflux.
	 *
	 * @link	http://ha.ckers.org/xss.html
	 * 		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.
	 *
	 * @param	string|string[]	$str		Input data
	 * @param 	bool		$is_image	Whether the input is an image
	 * @return	string
	 */
	public function xss_clean($str, $is_image = FALSE)
	{
		if (is_numeric($str)) {
			return $str;
		} elseif (!$str) {
	        return '';
        }

		// Is the string an array?
		if (is_array($str))
		{
			foreach ($str as $key => &$value)
			{
				$str[$key] = $this->xss_clean($value);
			}

			return $str;
		}

        if (json_encode( $str) === false) {
            return '[xss_clean]'; // 判断含有乱码直接过滤为空
        }

		/*
		 * URL Decode
		 *
		 * Just in case stuff like this is submitted:
		 *
		 * <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
		 */
		if (stripos($str, '%') !== false)
		{
			do
			{
				$oldstr = $str;
				$str = rawurldecode($str);
				$str = preg_replace_callback('#%(?:\s*[0-9a-f]){2,}#i', [$this, '_urldecodespaces'], $str);
			}
			while ($oldstr !== $str);
			unset($oldstr);
		}

		/*
		 * Convert character entities to ASCII
		 *
		 * 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.
		 */

		// 不进行二次编码的xss过滤
		//$str = preg_replace_callback("/[^a-z0-9>]+[a-z0-9]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
		//$str = preg_replace_callback('/<\w+.*/si', array($this, '_decode_entity'), $str);

		// Remove Invisible Characters Again!
		$str = remove_invisible_characters($str);

		/*
		 * Convert all tabs to spaces
		 *
		 * This prevents strings like this: ja	vascript
		 * NOTE: we deal with spaces between characters later.
		 * NOTE: preg_replace was found to be amazingly slow here on
		 * large blocks of data, so we use str_replace.
		 */
		$str = str_replace("\t", ' ', $str);

		// Capture converted string for later comparison
		$converted_string = $str;

		// Remove Strings that are never allowed
		//$str = $this->_do_never_allowed($str);

		/*
		 * Makes PHP tags safe
		 *
		 * Note: XML tags are inadvertently replaced too:
		 *
		 * <?xml
		 *
		 * But it doesn't seem to pose a problem.
		 */
		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', '&lt;?\\1', $str);
		}
		else
		{
			$str = str_replace(['<?', '?'.'>'], ['&lt;?', '?&gt;'], $str);
		}

		/*
		 * Compact any exploded words
		 *
		 * This corrects words like:  j a v a s c r i p t
		 * These words are compacted back to their correct state.
		 */
		$words = [
            'javascript', 'expression', 'vbscript', 'jscript', 'wscript',
            'vbs', 'script', 'base64', 'applet', 'alert', 'document',
            'write', 'cookie', 'window', 'confirm', 'prompt', 'eval'
        ];

		foreach ($words as $word)
		{
			$word = implode('\s*', str_split($word)).'\s*';

			// We only want to do this when it is followed by a non-word character
			// That way valid stuff like "dealer to" does not become "dealerto"
			$str = preg_replace_callback('#('.substr($word, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);
		}

		/*
		 * Remove disallowed Javascript in links or img tags
		 * We used to do some version comparisons and use of stripos(),
		 * but it is dog slow compared to these simplified non-capturing
		 * preg_match(), especially if the pattern exists in the string
		 *
		 * Note: It was reported that not only space characters, but all in
		 * the following pattern can be parsed as separators between a tag name
		 * and its attributes: [\d\s"\'`;,\/\=\(\x00\x0B\x09\x0C]
		 * ... however, remove_invisible_characters() above already strips the
		 * hex-encoded ones, so we'll skip them below.
		 */
		do
		{
			$original = $str;

			if (preg_match('/<a/i', $str))
			{
				$str = preg_replace_callback('#<a(?:rea)?[^a-z0-9>]+([^>]*?)(?:>|$)#si', array($this, '_js_link_removal'), $str);
			}

			if (preg_match('/<img/i', $str))
			{
				$str = preg_replace_callback('#<img[^a-z0-9]+([^>]*?)(?:\s?/?>|$)#si', array($this, '_js_img_removal'), $str);
			}

			if (preg_match('/script|xss/i', $str))
			{
				$str = preg_replace('#</*(?:script|xss).*?>#si', '[xss_clean]', $str);
			}
		}
		while ($original !== $str);
		unset($original);

		/*
		 * Sanitize naughty HTML elements
		 *
		 * If a tag containing any of the words in the list
		 * below is found, the tag gets converted to entities.
		 *
		 * So this: <blink>
		 * Becomes: &lt;blink&gt;
		 */
		$pattern = '#'
			.'<((?<slash>/*\s*)((?<tagName>[a-z0-9]+)(?=[^a-z0-9]|$)|.+)' // tag start and name, followed by a non-tag character
			.'[^\s\042\047a-z0-9>/=]*' // a valid attribute character immediately after the tag would count as a separator
			// optional attributes
			.'(?<attributes>(?:[\s\042\047/=]*' // non-attribute characters, excluding > (tag close) for obvious reasons
			.'[^\s\042\047>/=]+' // attribute characters
			// optional attribute-value
				.'(?:\s*=' // attribute-value separator
					.'(?:[^\s\042\047=><`]+|\s*\042[^\042]*\042|\s*\047[^\047]*\047|\s*(?U:[^\s\042\047=><`]*))' // single, double or non-quoted value
				.')?' // end optional attribute-value group
			.')*)' // end optional attributes group
			.'[^>]*)(?<closeTag>\>)?#isS';

		// Note: It would be nice to optimize this for speed, BUT
		//       only matching the naughty elements here results in
		//       false positives and in turn - vulnerabilities!
		do
		{
			$old_str = $str;
			$str = preg_replace_callback($pattern, array($this, '_sanitize_naughty_html'), $str);
		}
		while ($old_str !== $str);
		unset($old_str);

		/*
		 * Sanitize naughty scripting elements
		 *
		 * 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.
		 *
		 * For example:	eval('some code')
		 * Becomes:	eval&#40;'some code'&#41;
		 */
		$str = preg_replace(
			'#(alert|prompt|confirm|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si',
			'\\1\\2&#40;\\3&#41;',
			$str
		);

		// Same thing, but for "tag functions" (e.g. eval`some code`)
		// See https://github.com/bcit-ci/CodeIgniter/issues/5420
		$str = preg_replace(
			'#(alert|prompt|confirm|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)`(.*?)`#si',
			'\\1\\2&#96;\\3&#96;',
			$str
		);

		//最终清理
        //
        ////这增加了一点额外的预防措施
        //
        ////有东西通过了上面的过滤器
		$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);
		}


        // now the only remaining whitespace attacks are \t, \n, and \r
        $ra = ['onabort', 'onactivate', 'onafterprint', 'onafterupdate', 'onbeforeactivate', 'onbeforecopy', 'onbeforecut', 'onbeforedeactivate', 'onbeforeeditfocus', 'onbeforepaste', 'onbeforeprint', 'onbeforeunload', 'onbeforeupdate', 'onblur', 'onbounce', 'oncellchange', 'onchange', 'onclick', 'oncontextmenu', 'oncontrolselect', 'oncopy', 'oncut', 'ondataavailable', 'ondatasetchanged', 'ondatasetcomplete', 'ondblclick', 'ondeactivate', 'ondrag', 'ondragend', 'ondragenter', 'ondragleave', 'ondragover', 'ondragstart', 'ondrop', 'onerror', 'onerrorupdate', 'onfilterchange', 'onfinish', 'onfocus', 'onfocusin', 'onfocusout', 'onhelp', 'onkeydown', 'onkeypress', 'onkeyup', 'onlayoutcomplete', 'onload', 'onlosecapture', 'onmousedown', 'onmouseenter', 'onmouseleave', 'onmousemove', 'onmouseout', 'onmouseover', 'onmouseup', 'onmousewheel', 'onmove', 'onmoveend', 'onmovestart', 'onpaste', 'onpropertychange', 'onreadystatechange', 'onreset', 'onresize', 'onresizeend', 'onresizestart', 'onrowenter', 'onrowexit', 'onrowsdelete', 'onrowsinserted', 'onscroll', 'onselect', 'onselectionchange', 'onselectstart', 'onstart', 'onstop', 'onsubmit', 'onunload'];
        foreach ($ra as $t) {
            $str = str_replace(' '.$t.'="', ' '.$t.'=', $str);
        }

		return $str;
	}

	// --------------------------------------------------------------------

	/**
	 * XSS Hash
	 *
	 * Generates the XSS hash if needed and returns it.
	 *
	 * @see		CI_Security::$_xss_hash
	 * @return	string	XSS hash
	 */
	public function xss_hash()
	{
		if ($this->_xss_hash === NULL)
		{
			$rand = $this->get_random_bytes(16);
			$this->_xss_hash = ($rand === FALSE)
				? md5(uniqid(mt_rand(), TRUE))
				: bin2hex($rand);
		}

		return $this->_xss_hash;
	}

	// --------------------------------------------------------------------

	/**
	 * Get random bytes
	 *
	 * @param	int	$length	Output length
	 * @return	string
	 */
	public function get_random_bytes($length)
	{
		if (empty($length) OR ! ctype_digit((string) $length))
		{
			return FALSE;
		}

		if (function_exists('random_bytes'))
		{
			try
			{
				// The cast is required to avoid TypeError
				return random_bytes((int) $length);
			}
			catch (Exception $e)
			{
				// If random_bytes() can't do the job, we can't either ...
				// There's no point in using fallbacks.
				log_message('error', $e->getMessage());
				return FALSE;
			}
		}

		// Unfortunately, none of the following PRNGs is guaranteed to exist ...
		if (defined('MCRYPT_DEV_URANDOM') && ($output = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)) !== FALSE)
		{
			return $output;
		}


		if (is_readable('/dev/urandom') && ($fp = fopen('/dev/urandom', 'rb')) !== FALSE)
		{
			// Try not to waste entropy ...
			is_php('5.4') && stream_set_chunk_size($fp, $length);
			$output = fread($fp, $length);
			fclose($fp);
			if ($output !== FALSE)
			{
				return $output;
			}
		}

		if (function_exists('openssl_random_pseudo_bytes'))
		{
			return openssl_random_pseudo_bytes($length);
		}

		return FALSE;
	}

	// --------------------------------------------------------------------

	/**
	 * HTML Entities Decode
	 *
	 * A replacement for html_entity_decode()
	 *
	 * The reason we are not using html_entity_decode() by itself is because
	 * while it is not technically 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.
	 *
	 * @link	http://php.net/html-entity-decode
	 *
	 * @param	string	$str		Input
	 * @param	string	$charset	Character set
	 * @return	string
	 */
	public function entity_decode($str, $charset = NULL)
	{
		if (strpos($str, '&') === FALSE)
		{
			return $str;
		}

		static $_entities;

		isset($charset) OR $charset = $this->charset;
		$flag = is_php('5.4')
			? ENT_COMPAT | ENT_HTML5
			: ENT_COMPAT;

		if ( ! isset($_entities))
		{
			$_entities = array_map('strtolower', get_html_translation_table(HTML_ENTITIES, $flag, $charset));

			// If we're not on PHP 5.4+, add the possibly dangerous HTML 5
			// entities to the array manually
			if ($flag === ENT_COMPAT)
			{
				$_entities[':'] = '&colon;';
				$_entities['('] = '&lpar;';
				$_entities[')'] = '&rpar;';
				$_entities["\n"] = '&NewLine;';
				$_entities["\t"] = '&Tab;';
			}
		}

		do
		{
			$str_compare = $str;

			// Decode standard entities, avoiding false positives
			if (preg_match_all('/&[a-z]{2,}(?![a-z;])/i', $str, $matches))
			{
				$replace = [];
				$matches = array_unique(array_map('strtolower', $matches[0]));
				foreach ($matches as &$match)
				{
					if (($char = array_search($match.';', $_entities, TRUE)) !== FALSE)
					{
						$replace[$match] = $char;
					}
				}

				$str = str_replace(array_keys($replace), array_values($replace), $str);
			}

			// Decode numeric & UTF16 two byte entities
			$str = html_entity_decode(
				preg_replace('/(&#(?:x0*[0-9a-f]{2,5}(?![0-9a-f;])|(?:0*\d{2,4}(?![0-9;]))))/iS', '$1;', $str),
				$flag,
				$charset
			);

			if ($flag === ENT_COMPAT)
			{
				$str = str_replace(array_values($_entities), array_keys($_entities), $str);
			}
		}
		while ($str_compare !== $str);
		return $str;
	}

	// --------------------------------------------------------------------

	/**
	 * Sanitize Filename
	 *
	 * @param	string	$str		Input file name
	 * @param 	bool	$relative_path	Whether to preserve paths
	 * @return	string
	 */
	public function sanitize_filename($str, $relative_path = FALSE)
	{
		$bad = $this->filename_bad_chars;

		if ( ! $relative_path)
		{
			$bad[] = './';
			$bad[] = '/';
		}

		$str = remove_invisible_characters($str, FALSE);

		do
		{
			$old = $str;
			$str = str_replace($bad, '', $str);
		}
		while ($old !== $str);

		return stripslashes($str);
	}

	// ----------------------------------------------------------------

	/**
	 * Strip Image Tags
	 *
	 * @param	string	$str
	 * @return	string
	 */
	public function strip_image_tags($str)
	{
		return preg_replace(
			array(
				'#<img[\s/]+.*?src\s*=\s*(["\'])([^\\1]+?)\\1.*?\>#i',
				'#<img[\s/]+.*?src\s*=\s*?(([^\s"\'=<>`]+)).*?\>#i'
			),
			'\\2',
			$str
		);
	}

	// ----------------------------------------------------------------

	/**
	 * URL-decode taking spaces into account
	 *
	 * @see		https://github.com/bcit-ci/CodeIgniter/issues/4877
	 * @param	array	$matches
	 * @return	string
	 */
	protected function _urldecodespaces($matches)
	{
		$input    = $matches[0];
		$nospaces = preg_replace('#\s+#', '[xss_clean_space]', $input);
		return ($nospaces === $input)
			? $input
			: rawurldecode($nospaces);
	}

	// ----------------------------------------------------------------

	/**
	 * Compact Exploded Words
	 *
	 * Callback method for xss_clean() to remove whitespace from
	 * things like 'j a v a s c r i p t'.
	 *
	 * @used-by	CI_Security::xss_clean()
	 * @param	array	$matches
	 * @return	string
	 */
	protected function _compact_exploded_words($matches)
	{
		return preg_replace('/\s+/s', '', $matches[1]).$matches[2];
	}

	// --------------------------------------------------------------------

	/**
	 * Sanitize Naughty HTML
	 *
	 * Callback method for xss_clean() to remove naughty HTML elements.
	 *
	 * @used-by	CI_Security::xss_clean()
	 * @param	array	$matches
	 * @return	string
	 */
	protected function _sanitize_naughty_html($matches)
	{

		static $naughty_tags    = array(
			'alert', 'area', 'prompt', 'confirm', 'applet', 'audio', 'basefont', 'base', 'behavior', 'bgsound',
			'blink', 'body',  'expression', 'form', 'frameset', 'frame', 'head', 'html', 'ilayer',
			 'input', 'button', 'select', 'isindex', 'layer', 'link', 'meta', 'keygen', 'object',
			'plaintext', 'script', 'textarea', 'title', 'math',  'svg', 'xml', 'xss',
            //'iframe', 'video', 'embed', 'style'  //排除过滤
		);

		static $evil_attributes = array(
			'on\w+', 'xmlns', 'formaction', 'form', 'xlink:href', 'FSCommand', 'seekSegmentTime'
            //  ,'style' 排除过滤
		);

		// First, escape unclosed tags
		if (empty($matches['closeTag']))
		{
			return '&lt;'.$matches[1];
		}
		// Is the element that we caught naughty? If so, escape it
		elseif (in_array(strtolower($matches['tagName']), $naughty_tags, TRUE))
		{
			return '&lt;'.$matches[1].'&gt;';
		}
		// For other tags, see if their attributes are "evil" and strip those
		elseif (isset($matches['attributes']))
		{
			// We'll store the already fitlered attributes here
			$attributes = array();

			// Attribute-catching pattern
			$attributes_pattern = '#'
				.'(?<name>[^\s\042\047>/=]+)' // attribute characters
				// optional attribute-value
				.'(?:\s*=(?<value>[^\s\042\047=><`]+|\s*\042[^\042]*\042|\s*\047[^\047]*\047|\s*(?U:[^\s\042\047=><`]*)))' // attribute-value separator
				.'#i';

			// Blacklist pattern for evil attribute names
			$is_evil_pattern = '#^('.implode('|', $evil_attributes).')$#i';

			// Each iteration filters a single attribute
			do
			{
				// Strip any non-alpha characters that may precede an attribute.
				// Browsers often parse these incorrectly and that has been a
				// of numerous XSS issues we've had.
				$matches['attributes'] = preg_replace('#^[^a-z]+#i', '', $matches['attributes']);

				if ( ! preg_match($attributes_pattern, $matches['attributes'], $attribute, PREG_OFFSET_CAPTURE))
				{
					// No (valid) attribute found? Discard everything else inside the tag
					break;
				}

				if (
					// Is it indeed an "evil" attribute?
					preg_match($is_evil_pattern, $attribute['name'][0])
					// Or does it have an equals sign, but no value and not quoted? Strip that too!
					OR (trim($attribute['value'][0]) === '')
				)
				{
                    if (CI_DEBUG) {
                        $attributes[] = 'xss_clean_'.$attribute[0][0];
                    } else {
                        $attributes[] = 'xss=clean';
                    }
				}
				else
				{
					$attributes[] = $attribute[0][0];
				}

				$matches['attributes'] = substr($matches['attributes'], $attribute[0][1] + strlen($attribute[0][0]));
			}
			while ($matches['attributes'] !== '');

			$attributes = empty($attributes)
				? ''
				: ' '.implode(' ', $attributes);
			return '<'.$matches['slash'].$matches['tagName'].$attributes.'>';
		}

		return $matches[0];
	}

	// --------------------------------------------------------------------

	/**
	 * JS Link Removal
	 *
	 * Callback method 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.
	 *
	 * @used-by	CI_Security::xss_clean()
	 * @param	array	$match
	 * @return	string
	 */
	protected function _js_link_removal($match)
	{
		return str_replace(
			$match[1],
			preg_replace(
				'#href=.*?(?:(?:alert|prompt|confirm)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|<script|<xss|d\s*a\s*t\s*a\s*:)#si',
				'',
				$this->_filter_attributes($match[1])
			),
			$match[0]
		);
	}

	// --------------------------------------------------------------------

	/**
	 * JS Image Removal
	 *
	 * Callback method 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.
	 *
	 * @used-by	CI_Security::xss_clean()
	 * @param	array	$match
	 * @return	string
	 */
	protected function _js_img_removal($match)
	{
		return str_replace(
			$match[1],
			preg_replace(
				'#src=.*?(?:(?:alert|prompt|confirm|eval)(?:\(|&\#40;|`|&\#96;)|javascript:|livescript:|mocha:|charset=|window\.|\(?document\)?\.|\.cookie|<script|<xss|base64\s*,)#si',
				'',
				$this->_filter_attributes($match[1])
			),
			$match[0]
		);
	}

	// --------------------------------------------------------------------

	/**
	 * Attribute Conversion
	 *
	 * @used-by	CI_Security::xss_clean()
	 * @param	array	$match
	 * @return	string
	 */
	protected function _convert_attribute($match)
	{
		return str_replace(['>', '<', '\\'], ['&gt;', '&lt;', '\\\\'], $match[0]);
	}

	// --------------------------------------------------------------------

	/**
	 * Filter Attributes
	 *
	 * Filters tag attributes for consistency and safety.
	 *
	 * @used-by	CI_Security::_js_img_removal()
	 * @used-by	CI_Security::_js_link_removal()
	 * @param	string	$str
	 * @return	string
	 */
	protected function _filter_attributes($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
	 *
	 * @used-by	CI_Security::xss_clean()
	 * @param	array	$match
	 * @return	string
	 */
	protected function _decode_entity($match)
	{
		// Protect GET variables in URLs
		// 901119URL5918AMP18930PROTECT8198
		$match = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-/]+)|i', $this->xss_hash().'\\1=\\2', $match[0]);

		// Decode, then un-protect URL GET vars
		return str_replace(
			$this->xss_hash(),
			'&',
			$this->entity_decode($match, $this->charset)
		);
	}

	// --------------------------------------------------------------------

	/**
	 * Do Never Allowed
	 *
	 * @used-by	CI_Security::xss_clean()
	 * @param 	string
	 * @return 	string
	 */
	protected function _do_never_allowed($str)
	{

        $str = str_replace(array_keys($this->_never_call_str), $this->_never_call_str, $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', '_\\0', $str);
		}

		$str = str_replace($this->_never_call_str, array_keys($this->_never_call_str), $str);

		return $str;
	}


}
