input.php

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		// Is there a tag? If so it will certainly start with a '<'
		$tagOpen_start	= strpos($source, '<');

		while ($tagOpen_start !== false)
		{
			// Get some information about the tag we are processing
			$preTag			.= substr($postTag, 0, $tagOpen_start);
			$postTag		= substr($postTag, $tagOpen_start);
			$fromTagOpen	= substr($postTag, 1);
			$tagOpen_end	= strpos($fromTagOpen, '>');

			// Let's catch any non-terminated tags and skip over them
			if ($tagOpen_end === false) {
				$postTag		= substr($postTag, $tagOpen_start +1);
				$tagOpen_start	= strpos($postTag, '<');
				continue;
			}

			// Do we have a nested tag?
			$tagOpen_nested = strpos($fromTagOpen, '<');
			$tagOpen_nested_end	= strpos(substr($postTag, $tagOpen_end), '>');
			if (($tagOpen_nested !== false) && ($tagOpen_nested < $tagOpen_end)) {
				$preTag			.= substr($postTag, 0, ($tagOpen_nested +1));
				$postTag		= substr($postTag, ($tagOpen_nested +1));
				$tagOpen_start	= strpos($postTag, '<');
				continue;
			}

			// Lets get some information about our tag and setup attribute pairs
			$tagOpen_nested	= (strpos($fromTagOpen, '<') + $tagOpen_start +1);
			$currentTag		= substr($fromTagOpen, 0, $tagOpen_end);
			$tagLength		= strlen($currentTag);
			$tagLeft		= $currentTag;
			$attrSet		= array ();
			$currentSpace	= strpos($tagLeft, ' ');

			// Are we an open tag or a close tag?
			if (substr($currentTag, 0, 1) == '/') {
				// Close Tag
				$isCloseTag		= true;
				list ($tagName)	= explode(' ', $currentTag);
				$tagName		= substr($tagName, 1);
			} else {
				// Open Tag
				$isCloseTag		= false;
				list ($tagName)	= explode(' ', $currentTag);
			}

			/*
			 * Exclude all "non-regular" tagnames
			 * OR no tagname
			 * OR remove if xssauto is on and tag is blacklisted
			 */
			if ((!preg_match("/^[a-z][a-z0-9]*$/i", $tagName)) || (!$tagName) || ((in_array(strtolower($tagName), $this->tagBlacklist)) && ($this->xssAuto))) {
				$postTag		= substr($postTag, ($tagLength +2));
				$tagOpen_start	= strpos($postTag, '<');
				// Strip tag
				continue;
			}

			/*
			 * Time to grab any attributes from the tag... need this section in
			 * case attributes have spaces in the values.
			 */
			while ($currentSpace !== false)
			{
				$fromSpace		= substr($tagLeft, ($currentSpace +1));
				$nextSpace		= strpos($fromSpace, ' ');
				$openQuotes		= strpos($fromSpace, '"');
				$closeQuotes	= strpos(substr($fromSpace, ($openQuotes +1)), '"') + $openQuotes +1;

				// Do we have an attribute to process? [check for equal sign]
				if (strpos($fromSpace, '=') !== false) {
					/*
					 * If the attribute value is wrapped in quotes we need to
					 * grab the substring from the closing quote, otherwise grab
					 * till the next space
					 */
					if (($openQuotes !== false) && (strpos(substr($fromSpace, ($openQuotes +1)), '"') !== false)) {
						$attr = substr($fromSpace, 0, ($closeQuotes +1));
					} else {
						$attr = substr($fromSpace, 0, $nextSpace);
					}
				} else {
					/*
					 * No more equal signs so add any extra text in the tag into
					 * the attribute array [eg. checked]
					 */
					if ($fromSpace != '/') {
						$attr = substr($fromSpace, 0, $nextSpace);
					}
				}

				// Last Attribute Pair
				if (!$attr && $fromSpace != '/') {
					$attr = $fromSpace;
				}

				// Add attribute pair to the attribute array
				$attrSet[] = $attr;

				// Move search point and continue iteration
				$tagLeft		= substr($fromSpace, strlen($attr));
				$currentSpace	= strpos($tagLeft, ' ');
			}

			// Is our tag in the user input array?
			$tagFound = in_array(strtolower($tagName), $this->tagsArray);

			// If the tag is allowed lets append it to the output string
			if ((!$tagFound && $this->tagsMethod) || ($tagFound && !$this->tagsMethod)) {

				// Reconstruct tag with allowed attributes
				if (!$isCloseTag) {
					// Open or Single tag
					$attrSet = $this->_cleanAttributes($attrSet);
					$preTag .= '<'.$tagName;
					for ($i = 0; $i < count($attrSet); $i ++)
					{
						$preTag .= ' '.$attrSet[$i];
					}

					// Reformat single tags to XHTML
					if (strpos($fromTagOpen, '</'.$tagName)) {
						$preTag .= '>';
					} else {
						$preTag .= ' />';
					}
				} else {
					// Closing Tag
					$preTag .= '</'.$tagName.'>';
				}
			}

			// Find next tag's start and continue iteration
			$postTag		= substr($postTag, ($tagLength +2));
			$tagOpen_start	= strpos($postTag, '<');
		}

		// Append any code after the end of tags and return
		if ($postTag != '<') {
			$preTag .= $postTag;
		}
		return $preTag;
	}

	/**
	 * Internal method to strip a tag of certain attributes
	 *
	 * @access	protected
	 * @param	array	$attrSet	Array of attribute pairs to filter
	 * @return	array	Filtered array of attribute pairs
	 * @since	1.5
	 */
	function _cleanAttributes($attrSet)
	{
		// Initialize variables
		$newSet = array();

		// Iterate through attribute pairs
		for ($i = 0; $i < count($attrSet); $i ++)
		{
			// Skip blank spaces
			if (!$attrSet[$i]) {
				continue;
			}

			// Split into name/value pairs
			$attrSubSet = explode('=', trim($attrSet[$i]), 2);
			list ($attrSubSet[0]) = explode(' ', $attrSubSet[0]);

			/*
			 * Remove all "non-regular" attribute names
			 * AND blacklisted attributes
			 */
			if ((!preg_match('/[a-z]*$/i', $attrSubSet[0])) || (($this->xssAuto) && ((in_array(strtolower($attrSubSet[0]), $this->attrBlacklist)) || (substr($attrSubSet[0], 0, 2) == 'on')))) {
				continue;
			}

			// XSS attribute value filtering
			if ($attrSubSet[1]) {
				// strips unicode, hex, etc
				$attrSubSet[1] = str_replace('&#', '', $attrSubSet[1]);
				// strip normal newline within attr value
				$attrSubSet[1] = preg_replace('/\s+/', '', $attrSubSet[1]);
				// strip double quotes
				$attrSubSet[1] = str_replace('"', '', $attrSubSet[1]);
				// convert single quotes from either side to doubles (Single quotes shouldn't be used to pad attr value)
				if ((substr($attrSubSet[1], 0, 1) == "'") && (substr($attrSubSet[1], (strlen($attrSubSet[1]) - 1), 1) == "'")) {
					$attrSubSet[1] = substr($attrSubSet[1], 1, (strlen($attrSubSet[1]) - 2));
				}
				// strip slashes
				$attrSubSet[1] = stripslashes($attrSubSet[1]);
			}

			// Autostrip script tags
			if (JFilterInput::checkAttribute($attrSubSet)) {
				continue;
			}

			// Is our attribute in the user input array?
			$attrFound = in_array(strtolower($attrSubSet[0]), $this->attrArray);

			// If the tag is allowed lets keep it
			if ((!$attrFound && $this->attrMethod) || ($attrFound && !$this->attrMethod)) {

				// Does the attribute have a value?
				if ($attrSubSet[1]) {
					$newSet[] = $attrSubSet[0].'="'.$attrSubSet[1].'"';
				} elseif ($attrSubSet[1] == "0") {
					/*
					 * Special Case
					 * Is the value 0?
					 */
					$newSet[] = $attrSubSet[0].'="0"';
				} else {
					$newSet[] = $attrSubSet[0].'="'.$attrSubSet[0].'"';
				}
			}
		}
		return $newSet;
	}

	/**
	 * Try to convert to plaintext
	 *
	 * @access	protected
	 * @param	string	$source
	 * @return	string	Plaintext string
	 * @since	1.5
	 */
	function _decode($source)
	{
		// entity decode
		$trans_tbl = get_html_translation_table(HTML_ENTITIES);
		foreach($trans_tbl as $k => $v) {
			$ttr[$v] = utf8_encode($k);
		}
		$source = strtr($source, $ttr);
		// convert decimal
		$source = preg_replace('/&#(\d+);/me', "chr(\\1)", $source); // decimal notation
		// convert hex
		$source = preg_replace('/&#x([a-f0-9]+);/mei', "chr(0x\\1)", $source); // hex notation
		return $source;
	}
}