<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

/**
 * SafeHTML Parser
 *
 * PHP versions 4 and 5
 *
 * @category   HTML
 * @package    SafeHTML
 * @author     Roman Ivanov <thingol@mail.ru>
 * @copyright  2004-2005 Roman Ivanov
 * @license    http://www.debian.org/misc/bsd.license  BSD License (3 Clause)
 * @version    1.3.7
 * @link       http://pixel-apes.com/safehtml/
 */


/**
 * This package requires HTMLSax3 package
 */
require_once(XML_HTMLSAX3 . 'HTMLSax3.php');

 
/**
 *
 * SafeHTML Parser
 *
 * This parser strips down all potentially dangerous content within HTML:
 * <ul>
 * <li>opening tag without its closing tag</li>
 * <li>closing tag without its opening tag</li>
 * <li>any of these tags: "base", "basefont", "head", "html", "body", "applet", 
 * "object", "iframe", "frame", "frameset", "script", "layer", "ilayer", "embed", 
 * "bgsound", "link", "meta", "style", "title", "blink", "xml" etc.</li>
 * <li>any of these attributes: on*, data*, dynsrc</li>
 * <li>javascript:/vbscript:/about: etc. protocols</li>
 * <li>expression/behavior etc. in styles</li>
 * <li>any other active content</li>
 * </ul>
 * It also tries to convert code to XHTML valid, but htmltidy is far better 
 * solution for this task.
 *
 * <b>Example:</b>
 * <pre>
 * $parser =& new SafeHTML();
 * $result = $parser->parse($doc);
 * </pre>
 *
 * @category   HTML
 * @package    SafeHTML
 * @author     Roman Ivanov <thingol@mail.ru>
 * @copyright  1997-2005 Roman Ivanov
 * @license    http://www.debian.org/misc/bsd.license  BSD License (3 Clause)
 * @version    Release: @package_version@
 * @link       http://pear.php.net/package/SafeHTML
 */
class SafeHTML 
{
/**
 * Storage for resulting HTML output
 *
 * @var string
 * @access private
 */
var $_xhtml = '';

/**
 * Array of counters for each tag
 *
 * @var array
 * @access private
 */
var $_counter = array();

/**
 * Stack of unclosed tags
 *
 * @var array
 * @access private
 */
var $_stack = array();

/**
 * Array of counters for tags that must be deleted with all content
 *
 * @var array
 * @access private
 */
var $_dcCounter = array();

/**
 * Stack of unclosed tags that must be deleted with all content
 *
 * @var array
 * @access private
 */
var $_dcStack = array();

/**
 * Stores level of list (ol/ul) nesting
 *
 * @var int
 * @access private
 */
var $_listScope = 0; 

/**
 * Stack of unclosed list tags 
 *
 * @var array
 * @access private
 */
var $_liStack = array();

/**
 * Array of prepared regular expressions for protocols (schemas) matching
 *
 * @var array
 * @access private
 */
var $_protoRegexps = array();

/**
 * Array of prepared regular expressions for CSS matching
 *
 * @var array
 * @access private
 */
var $_cssRegexps = array();

/**
 * 允许的标签
 * @var array
 * @access public
 */
var $allowTags = array();

/**
 * 禁止的标签
 * @var array
 * @access public
 */
var $disallowTags = array();

/**
 * List of single tags ("<tag />")
 *
 * @var array
 * @access public
 */
var $singleTags = array('area', 'br', 'img', 'input', 'hr', 'wbr', );

/**
 * List of dangerous tags (such tags will be deleted)
 *
 * @var array
 * @access public
 */
var $deleteTags = array(
	'applet', 'base',   'basefont', 'bgsound', 'blink',  'body', 
	'embed',  'frame',  'frameset', 'head',    'html',   'ilayer', 
	'iframe', 'layer',  'link',     'meta',    'object', 'style', 
	'title',  'script', 
	);

/**
 * List of dangerous tags (such tags will be deleted, and all content 
 * inside this tags will be also removed)
 *
 * @var array
 * @access public
 */
var $deleteTagsContent = array('script', 'style', 'title', 'xml', );

/**
 * Type of protocols filtering ('white' or 'black')
 *
 * @var string
 * @access public
 */
var $protocolFiltering = 'white';

/**
 * List of "dangerous" protocols (used for blacklist-filtering)
 *
 * @var array
 * @access public
 */
var $blackProtocols = array(
	'about',   'chrome',     'data',       'disk',     'hcp',     
	'help',    'javascript', 'livescript', 'lynxcgi',  'lynxexec', 
	'ms-help', 'ms-its',     'mhtml',      'mocha',    'opera',   
	'res',     'resource',   'shell',      'vbscript', 'view-source', 
	'vnd.ms.radio',          'wysiwyg', 
	);

/**
 * List of "safe" protocols (used for whitelist-filtering)
 *
 * @var array
 * @access public
 */
var $whiteProtocols = array(
	'ed2k',   'file', 'ftp',  'gopher', 'http',  'https', 
	'irc',    'mailto', 'news', 'nntp', 'telnet', 'webcal', 
	'xmpp',   'callto',
	);

/**
 * List of attributes that can contain protocols
 *
 * @var array
 * @access public
 */
var $protocolAttributes = array(
	'action', 'background', 'codebase', 'dynsrc', 'href', 'lowsrc', 'src', 
	);

/**
 * List of dangerous CSS keywords
 *
 * Whole style="" attribute will be removed, if parser will find one of 
 * these keywords
 *
 * @var array
 * @access public
 */
var $cssKeywords = array(
	'absolute', 'behavior',       'behaviour',   'content', 'expression', 
	'fixed',    'include-source', 'moz-binding',
	);

/**
 * List of tags that can have no "closing tag"
 *
 * @var array
 * @access public
 * @deprecated XHTML does not allow such tags
 */
var $noClose = array();

/**
 * List of block-level tags that terminates paragraph
 *
 * Paragraph will be closed when this tags opened
 *
 * @var array
 * @access public
 */
var $closeParagraph = array(
	'address', 'blockquote', 'center', 'dd',      'dir',       'div', 
	'dl',      'dt',         'h1',     'h2',      'h3',        'h4', 
	'h5',      'h6',         'hr',     'isindex', 'listing',   'marquee', 
	'menu',    'multicol',   'ol',     'p',       'plaintext', 'pre', 
	'table',   'ul',         'xmp', 
	);

/**
 * List of table tags, all table tags outside a table will be removed
 *
 * @var array
 * @access public
 */
var $tableTags = array(
	'caption', 'col', 'colgroup', 'tbody', 'td', 'tfoot', 'th', 
	'thead',   'tr', 
	);

/**
 * List of list tags
 *
 * @var array
 * @access public
 */
var $listTags = array('dir', 'menu', 'ol', 'ul', 'dl', );

/**
 * List of dangerous attributes
 *
 * @var array
 * @access public
 */
var $attributes = array('dynsrc', 'id', 'name', );

/**
 * List of allowed "namespaced" attributes
 *
 * @var array
 * @access public
 */
var $attributesNS = array('xml:lang', );

/**
 * Constructs class
 *
 * @access public
 */
function SafeHTML() 
{
	//making regular expressions based on Proto & CSS arrays
	foreach ($this->blackProtocols as $proto) {
		$preg = "/[\s\x01-\x1F]*";
		for ($i=0; $i<strlen($proto); $i++) {
			$preg .= $proto{$i} . "[\s\x01-\x1F]*";
		}
		$preg .= ":/i";
		$this->_protoRegexps[] = $preg;
	}

	foreach ($this->cssKeywords as $css) {
		$this->_cssRegexps[] = '/' . $css . '/i';
	}
	return true;
}

/**
 * Handles the writing of attributes - called from $this->_openHandler()
 *
 * @param array $attrs array of attributes $name => $value
 * @return boolean
 * @access private
 */
function _writeAttrs ($attrs) 
{
	if (is_array($attrs)) {
		foreach ($attrs as $name => $value) {

			$name = strtolower($name);

			if (strpos($name, 'on') === 0) {
				continue;
			}
			if (strpos($name, 'data') === 0) {
				continue;
			}
			if (in_array($name, $this->attributes)) {
				continue;
			}
			if (!preg_match("/^[a-z0-9]+$/i", $name)) {
				if (!in_array($name, $this->attributesNS))
				{
					continue;
				}
			}

			if (($value === TRUE) || (is_null($value))) {
				$value = $name;
			}

			if ($name == 'style') {

				// removes insignificant backslahes
				$value = str_replace("\\", '', $value);

				// removes CSS comments
				while (1)
				{
				 $_value = preg_replace("!/\*.*?\*/!s", '', $value);
				 if ($_value == $value) break;
				 $value = $_value;
				}

				// replace all & to &amp;
				$value = str_replace('&amp;', '&', $value);
				$value = str_replace('&', '&amp;', $value);

				foreach ($this->_cssRegexps as $css) {
				   if (preg_match($css, $value)) { 
					   continue 2;
				   }
				}
				foreach ($this->_protoRegexps as $proto) {
					if (preg_match($proto, $value)) {
					   continue 2;
					}
				}
			}

			$tempval = preg_replace('/&#(\d+);?/me', "chr('\\1')", $value); //"'
			$tempval = preg_replace('/&#x([0-9a-f]+);?/mei', "chr(hexdec('\\1'))", $tempval);

			if ((in_array($name, $this->protocolAttributes)) && 
				(strpos($tempval, ':') !== false)) 
			{
				if ($this->protocolFiltering == 'black') {
					foreach ($this->_protoRegexps as $proto) {
						if (preg_match($proto, $tempval)) continue 2;
					}
				} else {
					$_tempval = explode(':', $tempval);
					$proto = $_tempval[0];
					if (!in_array($proto, $this->whiteProtocols)) {
						continue;
					}
				}
			}

			$value = str_replace("\"", "&quot;", $value);
			$this->_xhtml .= ' ' . $name . '="' . $value . '"';
		}
	}
	return true;
}

/**
 * Opening tag handler - called from HTMLSax
 *
 * @param object $parser HTML Parser
 * @param string $name   tag name
 * @param array  $attrs  tag attributes
 * @return boolean
 * @access private
 */
function _openHandler(&$parser, $name, $attrs) 
{
	$name = strtolower($name);
	
	if(in_array($name, $this->disallowTags)){
		//如果标签被禁止
		return true;
	}
	
	if(!in_array($name, $this->allowTags)){
		//不在允许的标签范围内,允许的标签具有最高优先级,如果匹配将忽略禁止的标签
	
	
	if (in_array($name, $this->deleteTagsContent)) {
		array_push($this->_dcStack, $name);
		$this->_dcCounter[$name] = isset($this->_dcCounter[$name]) ? $this->_dcCounter[$name]+1 : 1;
	}
	if (count($this->_dcStack) != 0) {
		return true;
	}

	if (in_array($name, $this->deleteTags)) {
		return true;
	}
	
	
	}
	
	if (!preg_match("/^[a-z0-9]+$/i", $name)) {
		if (preg_match("!(?:\@|://)!i", $name)) {
			$this->_xhtml .= '&lt;' . $name . '&gt;';
		}
		return true;
	}

	if (in_array($name, $this->singleTags)) {
		$this->_xhtml .= '<' . $name;
		$this->_writeAttrs($attrs);
		$this->_xhtml .= ' />';
		return true;
	}

	// TABLES: cannot open table elements when we are not inside table
	if ((isset($this->_counter['table'])) && ($this->_counter['table'] <= 0) 
		&& (in_array($name, $this->tableTags))) 
	{
		return true;
	}

	// PARAGRAPHS: close paragraph when closeParagraph tags opening
	if ((in_array($name, $this->closeParagraph)) && (in_array('p', $this->_stack))) {
		$this->_closeHandler($parser, 'p');
	}

	// LISTS: we should close <li> if <li> of the same level opening
	if ($name == 'li' && count($this->_liStack) && 
		$this->_listScope == $this->_liStack[count($this->_liStack)-1]) 
	{
		$this->_closeHandler($parser, 'li');
	}

	// LISTS: we want to know on what nesting level of lists we are
	if (in_array($name, $this->listTags)) {
		$this->_listScope++;
	}
	if ($name == 'li') {
		array_push($this->_liStack, $this->_listScope);
	}
		
	$this->_xhtml .= '<' . $name;
	$this->_writeAttrs($attrs);
	$this->_xhtml .= '>';
	array_push($this->_stack,$name);
	$this->_counter[$name] = isset($this->_counter[$name]) ? $this->_counter[$name]+1 : 1;
	return true;
}

/**
 * Closing tag handler - called from HTMLSax
 *
 * @param object $parsers HTML parser
 * @param string $name    tag name
 * @return boolean
 * @access private
 */
function _closeHandler(&$parser, $name) 
{

	$name = strtolower($name);

	if (isset($this->_dcCounter[$name]) && ($this->_dcCounter[$name] > 0) && 
		(in_array($name, $this->deleteTagsContent))) 
	{
		while ($name != ($tag = array_pop($this->_dcStack))) {
		$this->_dcCounter[$tag]--;
		}

		$this->_dcCounter[$name]--;
	}

	if (count($this->_dcStack) != 0) {
		return true;
	}

	if ((isset($this->_counter[$name])) && ($this->_counter[$name] > 0)) {
		while ($name != ($tag = array_pop($this->_stack))) {
		   $this->_closeTag($tag);
		}

		$this->_closeTag($name);
	}
	return true;
}

/**
 * Closes tag 
 *
 * @param string $tag tag name
 * @return boolean
 * @access private
 */
function _closeTag($tag) 
{
	if (!in_array($tag, $this->noClose)) {
		$this->_xhtml .= '</' . $tag . '>';
	}

	$this->_counter[$tag]--;

	if (in_array($tag, $this->listTags)) {
		$this->_listScope--;
	}

	if ($tag == 'li') {
		array_pop($this->_liStack);
	}
	return true;
}

/**
 * Character data handler - called from HTMLSax
 *
 * @param object $parser HTML parser
 * @param string $data   textual data
 * @return boolean
 * @access private
 */
function _dataHandler(&$parser, $data) 
{
	if (count($this->_dcStack) == 0) {
		$this->_xhtml .= $data;
	}
	return true;
}

/**
 * Escape handler - called from HTMLSax
 *
 * @param object $parser HTML parser
 * @param string $data   comments or other type of data
 * @return boolean
 * @access private
 */
function _escapeHandler(&$parser, $data) 
{
	return true;
}

/**
 * Returns the XHTML document
 *
 * @return string Processed (X)HTML document
 * @access public
 */
function getXHTML () 
{
	while ($tag = array_pop($this->_stack)) {
		$this->_closeTag($tag);
	}

	return $this->_xhtml;
}

/**
 * Clears current document data
 *
 * @return boolean
 * @access public
 */
function clear() 
{
	$this->_xhtml = '';
	return true;
}

/**
 * Main parsing fuction
 *
 * @param string $doc HTML document for processing
 * @return string Processed (X)HTML document
 * @access public
 */
function parse($doc) 
{

	// Save all '<' symbols
	$doc = preg_replace("/<(?=[^a-zA-Z\/\!\?\%])/", '&lt;', $doc);

	// Web documents shouldn't contains \x00 symbol
	$doc = str_replace("\x00", '', $doc);

	// Opera6 bug workaround
	$doc = str_replace("\xC0\xBC", '&lt;', $doc);

	// UTF-7 encoding ASCII decode
	$doc = $this->repackUTF7($doc);

	// Instantiate the parser
	$parser=& new XML_HTMLSax3();

	// Set up the parser
	$parser->set_object($this);

	$parser->set_element_handler('_openHandler','_closeHandler');
	$parser->set_data_handler('_dataHandler');
	$parser->set_escape_handler('_escapeHandler');

	$parser->parse($doc);
	
	return $this->getXHTML();

}


/**
 * UTF-7 decoding fuction
 *
 * @param string $str HTML document for recode ASCII part of UTF-7 back to ASCII
 * @return string Decoded document
 * @access private
 */
function repackUTF7($str)
{
	return preg_replace_callback('!\+([0-9a-zA-Z/]+)\-!', array($this, 'repackUTF7Callback'), $str);
}

/**
 * Additional UTF-7 decoding fuction
 *
 * @param string $str String for recode ASCII part of UTF-7 back to ASCII
 * @return string Recoded string
 * @access private
 */
function repackUTF7Callback($str)
{
   $str = base64_decode($str[1]);
   $str = preg_replace_callback('/^((?:\x00.)*)((?:[^\x00].)+)/', array($this, 'repackUTF7Back'), $str);
   return preg_replace('/\x00(.)/', '$1', $str);
}

/**
 * Additional UTF-7 encoding fuction
 *
 * @param string $str String for recode ASCII part of UTF-7 back to ASCII
 * @return string Recoded string
 * @access private
 */
function repackUTF7Back($str)
{
   return $str[1].'+'.rtrim(base64_encode($str[2]), '=').'-';
}

}

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * c-hanging-comment-ender-p: nil
 * End:
 */

?>
