mirror of
https://github.com/ezyang/htmlpurifier.git
synced 2024-11-14 09:18:41 +00:00
383 lines
13 KiB
PHP
383 lines
13 KiB
PHP
<?php
|
|
|
|
/**
|
|
* Forgivingly lexes HTML (SGML-style) markup into tokens.
|
|
*
|
|
* A lexer parses a string of SGML-style markup and converts them into
|
|
* corresponding tokens. It doesn't check for well-formedness, although its
|
|
* internal mechanism may make this automatic (such as the case of
|
|
* HTMLPurifier_Lexer_DOMLex). There are several implementations to choose
|
|
* from.
|
|
*
|
|
* A lexer is HTML-oriented: it might work with XML, but it's not
|
|
* recommended, as we adhere to a subset of the specification for optimization
|
|
* reasons. This might change in the future. Also, most tokenizers are not
|
|
* expected to handle DTDs or PIs.
|
|
*
|
|
* This class should not be directly instantiated, but you may use create() to
|
|
* retrieve a default copy of the lexer. Being a supertype, this class
|
|
* does not actually define any implementation, but offers commonly used
|
|
* convenience functions for subclasses.
|
|
*
|
|
* @note The unit tests will instantiate this class for testing purposes, as
|
|
* many of the utility functions require a class to be instantiated.
|
|
* This means that, even though this class is not runnable, it will
|
|
* not be declared abstract.
|
|
*
|
|
* @par
|
|
*
|
|
* @note
|
|
* We use tokens rather than create a DOM representation because DOM would:
|
|
*
|
|
* @par
|
|
* -# Require more processing and memory to create,
|
|
* -# Is not streamable, and
|
|
* -# Has the entire document structure (html and body not needed).
|
|
*
|
|
* @par
|
|
* However, DOM is helpful in that it makes it easy to move around nodes
|
|
* without a lot of lookaheads to see when a tag is closed. This is a
|
|
* limitation of the token system and some workarounds would be nice.
|
|
*/
|
|
class HTMLPurifier_Lexer
|
|
{
|
|
|
|
/**
|
|
* Whether or not this lexer implements line-number/column-number tracking.
|
|
* If it does, set to true.
|
|
*/
|
|
public $tracksLineNumbers = false;
|
|
|
|
// -- STATIC ----------------------------------------------------------
|
|
|
|
/**
|
|
* Retrieves or sets the default Lexer as a Prototype Factory.
|
|
*
|
|
* By default HTMLPurifier_Lexer_DOMLex will be returned. There are
|
|
* a few exceptions involving special features that only DirectLex
|
|
* implements.
|
|
*
|
|
* @note The behavior of this class has changed, rather than accepting
|
|
* a prototype object, it now accepts a configuration object.
|
|
* To specify your own prototype, set %Core.LexerImpl to it.
|
|
* This change in behavior de-singletonizes the lexer object.
|
|
*
|
|
* @param HTMLPurifier_Config $config
|
|
* @return HTMLPurifier_Lexer
|
|
* @throws HTMLPurifier_Exception
|
|
*/
|
|
public static function create($config)
|
|
{
|
|
if (!($config instanceof HTMLPurifier_Config)) {
|
|
$lexer = $config;
|
|
trigger_error(
|
|
"Passing a prototype to
|
|
HTMLPurifier_Lexer::create() is deprecated, please instead
|
|
use %Core.LexerImpl",
|
|
E_USER_WARNING
|
|
);
|
|
} else {
|
|
$lexer = $config->get('Core.LexerImpl');
|
|
}
|
|
|
|
$needs_tracking =
|
|
$config->get('Core.MaintainLineNumbers') ||
|
|
$config->get('Core.CollectErrors');
|
|
|
|
$inst = null;
|
|
if (is_object($lexer)) {
|
|
$inst = $lexer;
|
|
} else {
|
|
if (is_null($lexer)) {
|
|
do {
|
|
// auto-detection algorithm
|
|
if ($needs_tracking) {
|
|
$lexer = 'DirectLex';
|
|
break;
|
|
}
|
|
|
|
if (class_exists('DOMDocument', false) &&
|
|
method_exists('DOMDocument', 'loadHTML') &&
|
|
!extension_loaded('domxml')
|
|
) {
|
|
// check for DOM support, because while it's part of the
|
|
// core, it can be disabled compile time. Also, the PECL
|
|
// domxml extension overrides the default DOM, and is evil
|
|
// and nasty and we shan't bother to support it
|
|
$lexer = 'DOMLex';
|
|
} else {
|
|
$lexer = 'DirectLex';
|
|
}
|
|
} while (0);
|
|
} // do..while so we can break
|
|
|
|
// instantiate recognized string names
|
|
switch ($lexer) {
|
|
case 'DOMLex':
|
|
$inst = new HTMLPurifier_Lexer_DOMLex();
|
|
break;
|
|
case 'DirectLex':
|
|
$inst = new HTMLPurifier_Lexer_DirectLex();
|
|
break;
|
|
case 'PH5P':
|
|
$inst = new HTMLPurifier_Lexer_PH5P();
|
|
break;
|
|
default:
|
|
throw new HTMLPurifier_Exception(
|
|
"Cannot instantiate unrecognized Lexer type " .
|
|
htmlspecialchars($lexer)
|
|
);
|
|
}
|
|
}
|
|
|
|
if (!$inst) {
|
|
throw new HTMLPurifier_Exception('No lexer was instantiated');
|
|
}
|
|
|
|
// once PHP DOM implements native line numbers, or we
|
|
// hack out something using XSLT, remove this stipulation
|
|
if ($needs_tracking && !$inst->tracksLineNumbers) {
|
|
throw new HTMLPurifier_Exception(
|
|
'Cannot use lexer that does not support line numbers with ' .
|
|
'Core.MaintainLineNumbers or Core.CollectErrors (use DirectLex instead)'
|
|
);
|
|
}
|
|
|
|
return $inst;
|
|
|
|
}
|
|
|
|
// -- CONVENIENCE MEMBERS ---------------------------------------------
|
|
|
|
public function __construct()
|
|
{
|
|
$this->_entity_parser = new HTMLPurifier_EntityParser();
|
|
}
|
|
|
|
/**
|
|
* Most common entity to raw value conversion table for special entities.
|
|
* @type array
|
|
*/
|
|
protected $_special_entity2str =
|
|
array(
|
|
'"' => '"',
|
|
'&' => '&',
|
|
'<' => '<',
|
|
'>' => '>',
|
|
''' => "'",
|
|
''' => "'",
|
|
''' => "'"
|
|
);
|
|
|
|
public function parseText($string, $config) {
|
|
return $this->parseData($string, false, $config);
|
|
}
|
|
|
|
public function parseAttr($string, $config) {
|
|
return $this->parseData($string, true, $config);
|
|
}
|
|
|
|
/**
|
|
* Parses special entities into the proper characters.
|
|
*
|
|
* This string will translate escaped versions of the special characters
|
|
* into the correct ones.
|
|
*
|
|
* @param string $string String character data to be parsed.
|
|
* @return string Parsed character data.
|
|
*/
|
|
public function parseData($string, $is_attr, $config)
|
|
{
|
|
// following functions require at least one character
|
|
if ($string === '') {
|
|
return '';
|
|
}
|
|
|
|
// subtracts amps that cannot possibly be escaped
|
|
$num_amp = substr_count($string, '&') - substr_count($string, '& ') -
|
|
($string[strlen($string) - 1] === '&' ? 1 : 0);
|
|
|
|
if (!$num_amp) {
|
|
return $string;
|
|
} // abort if no entities
|
|
$num_esc_amp = substr_count($string, '&');
|
|
$string = strtr($string, $this->_special_entity2str);
|
|
|
|
// code duplication for sake of optimization, see above
|
|
$num_amp_2 = substr_count($string, '&') - substr_count($string, '& ') -
|
|
($string[strlen($string) - 1] === '&' ? 1 : 0);
|
|
|
|
if ($num_amp_2 <= $num_esc_amp) {
|
|
return $string;
|
|
}
|
|
|
|
// hmm... now we have some uncommon entities. Use the callback.
|
|
if ($config->get('Core.LegacyEntityDecoder')) {
|
|
$string = $this->_entity_parser->substituteSpecialEntities($string);
|
|
} else {
|
|
if ($is_attr) {
|
|
$string = $this->_entity_parser->substituteAttrEntities($string);
|
|
} else {
|
|
$string = $this->_entity_parser->substituteTextEntities($string);
|
|
}
|
|
}
|
|
return $string;
|
|
}
|
|
|
|
/**
|
|
* Lexes an HTML string into tokens.
|
|
* @param $string String HTML.
|
|
* @param HTMLPurifier_Config $config
|
|
* @param HTMLPurifier_Context $context
|
|
* @return HTMLPurifier_Token[] array representation of HTML.
|
|
*/
|
|
public function tokenizeHTML($string, $config, $context)
|
|
{
|
|
trigger_error('Call to abstract class', E_USER_ERROR);
|
|
}
|
|
|
|
/**
|
|
* Translates CDATA sections into regular sections (through escaping).
|
|
* @param string $string HTML string to process.
|
|
* @return string HTML with CDATA sections escaped.
|
|
*/
|
|
protected static function escapeCDATA($string)
|
|
{
|
|
return preg_replace_callback(
|
|
'/<!\[CDATA\[(.+?)\]\]>/s',
|
|
array('HTMLPurifier_Lexer', 'CDATACallback'),
|
|
$string
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Special CDATA case that is especially convoluted for <script>
|
|
* @param string $string HTML string to process.
|
|
* @return string HTML with CDATA sections escaped.
|
|
*/
|
|
protected static function escapeCommentedCDATA($string)
|
|
{
|
|
return preg_replace_callback(
|
|
'#<!--//--><!\[CDATA\[//><!--(.+?)//--><!\]\]>#s',
|
|
array('HTMLPurifier_Lexer', 'CDATACallback'),
|
|
$string
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Special Internet Explorer conditional comments should be removed.
|
|
* @param string $string HTML string to process.
|
|
* @return string HTML with conditional comments removed.
|
|
*/
|
|
protected static function removeIEConditional($string)
|
|
{
|
|
return preg_replace(
|
|
'#<!--\[if [^>]+\]>.*?<!\[endif\]-->#si', // probably should generalize for all strings
|
|
'',
|
|
$string
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Callback function for escapeCDATA() that does the work.
|
|
*
|
|
* @warning Though this is public in order to let the callback happen,
|
|
* calling it directly is not recommended.
|
|
* @param array $matches PCRE matches array, with index 0 the entire match
|
|
* and 1 the inside of the CDATA section.
|
|
* @return string Escaped internals of the CDATA section.
|
|
*/
|
|
protected static function CDATACallback($matches)
|
|
{
|
|
// not exactly sure why the character set is needed, but whatever
|
|
return htmlspecialchars($matches[1], ENT_COMPAT, 'UTF-8');
|
|
}
|
|
|
|
/**
|
|
* Takes a piece of HTML and normalizes it by converting entities, fixing
|
|
* encoding, extracting bits, and other good stuff.
|
|
* @param string $html HTML.
|
|
* @param HTMLPurifier_Config $config
|
|
* @param HTMLPurifier_Context $context
|
|
* @return string
|
|
* @todo Consider making protected
|
|
*/
|
|
public function normalize($html, $config, $context)
|
|
{
|
|
// normalize newlines to \n
|
|
if ($config->get('Core.NormalizeNewlines')) {
|
|
$html = str_replace("\r\n", "\n", $html);
|
|
$html = str_replace("\r", "\n", $html);
|
|
}
|
|
|
|
if ($config->get('HTML.Trusted')) {
|
|
// escape convoluted CDATA
|
|
$html = $this->escapeCommentedCDATA($html);
|
|
}
|
|
|
|
// escape CDATA
|
|
$html = $this->escapeCDATA($html);
|
|
|
|
$html = $this->removeIEConditional($html);
|
|
|
|
// extract body from document if applicable
|
|
if ($config->get('Core.ConvertDocumentToFragment')) {
|
|
$e = false;
|
|
if ($config->get('Core.CollectErrors')) {
|
|
$e =& $context->get('ErrorCollector');
|
|
}
|
|
$new_html = $this->extractBody($html);
|
|
if ($e && $new_html != $html) {
|
|
$e->send(E_WARNING, 'Lexer: Extracted body');
|
|
}
|
|
$html = $new_html;
|
|
}
|
|
|
|
// expand entities that aren't the big five
|
|
if ($config->get('Core.LegacyEntityDecoder')) {
|
|
$html = $this->_entity_parser->substituteNonSpecialEntities($html);
|
|
}
|
|
|
|
// clean into wellformed UTF-8 string for an SGML context: this has
|
|
// to be done after entity expansion because the entities sometimes
|
|
// represent non-SGML characters (horror, horror!)
|
|
$html = HTMLPurifier_Encoder::cleanUTF8($html);
|
|
|
|
// if processing instructions are to removed, remove them now
|
|
if ($config->get('Core.RemoveProcessingInstructions')) {
|
|
$html = preg_replace('#<\?.+?\?>#s', '', $html);
|
|
}
|
|
|
|
$hidden_elements = $config->get('Core.HiddenElements');
|
|
if ($config->get('Core.AggressivelyRemoveScript') &&
|
|
!($config->get('HTML.Trusted') || !$config->get('Core.RemoveScriptContents')
|
|
|| empty($hidden_elements["script"]))) {
|
|
$html = preg_replace('#<script[^>]*>.*?</script>#i', '', $html);
|
|
}
|
|
|
|
return $html;
|
|
}
|
|
|
|
/**
|
|
* Takes a string of HTML (fragment or document) and returns the content
|
|
* @todo Consider making protected
|
|
*/
|
|
public function extractBody($html)
|
|
{
|
|
$matches = array();
|
|
$result = preg_match('|(.*?)<body[^>]*>(.*)</body>|is', $html, $matches);
|
|
if ($result) {
|
|
// Make sure it's not in a comment
|
|
$comment_start = strrpos($matches[1], '<!--');
|
|
$comment_end = strrpos($matches[1], '-->');
|
|
if ($comment_start === false ||
|
|
($comment_end !== false && $comment_end > $comment_start)) {
|
|
return $matches[2];
|
|
}
|
|
}
|
|
return $html;
|
|
}
|
|
}
|
|
|
|
// vim: et sw=4 sts=4
|