File Source for safehtml.php

<?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 SVN: $Id: safehtml.php 23054 2007-10-25 15:04:24Z landseer $
* @link http://pixel-apes.com/safehtml/
*/
/**
* This package requires HTMLSax3 package
*/
Loader::requireOnce(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();
/**
* 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', ); // commented out as bugfix for #5188
// TODO: make this configurable
/**
* 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 &
$value = str_replace('&', '&', $value);
$value = str_replace('&', '&', $value);
foreach ($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("\"", """, $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, $this->deleteTagsContent)) {
array_push($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 .= '<' . $name . '>';
}
return true;
}
if (in_array($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\/\!\?\%])/", '<', $doc);
// Web documents shouldn't contains \x00 symbol
$doc = str_replace("\x00", '', $doc);
// Opera6 bug workaround
$doc = str_replace("\xC0\xBC", '<', $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:
*/

Source for file safehtml.php