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HTMLPurifier.php 8.62 KiB
<?php
/*! @mainpage
*
* HTML Purifier is an HTML filter that will take an arbitrary snippet of
* HTML and rigorously test, validate and filter it into a version that
* is safe for output onto webpages. It achieves this by:
*
* -# Lexing (parsing into tokens) the document,
* -# Executing various strategies on the tokens:
* -# Removing all elements not in the whitelist,
* -# Making the tokens well-formed,
* -# Fixing the nesting of the nodes, and
* -# Validating attributes of the nodes; and
* -# Generating HTML from the purified tokens.
*
* However, most users will only need to interface with the HTMLPurifier
* and HTMLPurifier_Config.
*/
/*
HTML Purifier 4.0.0 - Standards Compliant HTML Filtering
Copyright (C) 2006-2008 Edward Z. Yang
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* Facade that coordinates HTML Purifier's subsystems in order to purify HTML.
*
* @note There are several points in which configuration can be specified
* for HTML Purifier. The precedence of these (from lowest to
* highest) is as follows:
* -# Instance: new HTMLPurifier($config)
* -# Invocation: purify($html, $config)
* These configurations are entirely independent of each other and
* are *not* merged (this behavior may change in the future).
*
* @todo We need an easier way to inject strategies using the configuration
* object.
*/
class HTMLPurifier
{
/** Version of HTML Purifier */
public $version = '4.0.0';
/** Constant with version of HTML Purifier */
const VERSION = '4.0.0';
/** Global configuration object */
public $config;
/** Array of extra HTMLPurifier_Filter objects to run on HTML, for backwards compatibility */
private $filters = array();
/** Single instance of HTML Purifier */
private static $instance;
protected $strategy, $generator;
/**
* Resultant HTMLPurifier_Context of last run purification. Is an array
* of contexts if the last called method was purifyArray().
*/
public $context;
/**
* Initializes the purifier.
* @param $config Optional HTMLPurifier_Config object for all instances of
* the purifier, if omitted, a default configuration is
* supplied (which can be overridden on a per-use basis).
* The parameter can also be any type that
* HTMLPurifier_Config::create() supports.
*/
public function __construct($config = null) {
$this->config = HTMLPurifier_Config::create($config);
$this->strategy = new HTMLPurifier_Strategy_Core();
}
/**
* Adds a filter to process the output. First come first serve
* @param $filter HTMLPurifier_Filter object
*/
public function addFilter($filter) {
trigger_error('HTMLPurifier->addFilter() is deprecated, use configuration directives in the Filter namespace or Filter.Custom', E_USER_WARNING);
$this->filters[] = $filter;
}
/**
* Filters an HTML snippet/document to be XSS-free and standards-compliant.
*
* @param $html String of HTML to purify
* @param $config HTMLPurifier_Config object for this operation, if omitted,
* defaults to the config object specified during this
* object's construction. The parameter can also be any type
* that HTMLPurifier_Config::create() supports.
* @return Purified HTML
*/
public function purify($html, $config = null) {
// :TODO: make the config merge in, instead of replace
$config = $config ? HTMLPurifier_Config::create($config) : $this->config;
// implementation is partially environment dependant, partially
// configuration dependant
$lexer = HTMLPurifier_Lexer::create($config);
$context = new HTMLPurifier_Context();
// setup HTML generator
$this->generator = new HTMLPurifier_Generator($config, $context);
$context->register('Generator', $this->generator);
// set up global context variables
if ($config->get('Core.CollectErrors')) {
// may get moved out if other facilities use it
$language_factory = HTMLPurifier_LanguageFactory::instance();
$language = $language_factory->create($config, $context);
$context->register('Locale', $language);
$error_collector = new HTMLPurifier_ErrorCollector($context);
$context->register('ErrorCollector', $error_collector);
}
// setup id_accumulator context, necessary due to the fact that
// AttrValidator can be called from many places
$id_accumulator = HTMLPurifier_IDAccumulator::build($config, $context);
$context->register('IDAccumulator', $id_accumulator);
$html = HTMLPurifier_Encoder::convertToUTF8($html, $config, $context);
// setup filters
$filter_flags = $config->getBatch('Filter');
$custom_filters = $filter_flags['Custom'];
unset($filter_flags['Custom']);
$filters = array();
foreach ($filter_flags as $filter => $flag) {
if (!$flag) continue;
if (strpos($filter, '.') !== false) continue;
$class = "HTMLPurifier_Filter_$filter";
$filters[] = new $class;
}
foreach ($custom_filters as $filter) {
// maybe "HTMLPurifier_Filter_$filter", but be consistent with AutoFormat
$filters[] = $filter;
}
$filters = array_merge($filters, $this->filters);
// maybe prepare(), but later
for ($i = 0, $filter_size = count($filters); $i < $filter_size; $i++) {
$html = $filters[$i]->preFilter($html, $config, $context);
}
// purified HTML
$html =
$this->generator->generateFromTokens(
// list of tokens
$this->strategy->execute(
// list of un-purified tokens
$lexer->tokenizeHTML(
// un-purified HTML
$html, $config, $context
),
$config, $context
)
);
for ($i = $filter_size - 1; $i >= 0; $i--) {
$html = $filters[$i]->postFilter($html, $config, $context);
}
$html = HTMLPurifier_Encoder::convertFromUTF8($html, $config, $context);
$this->context =& $context;
return $html;
}
/**
* Filters an array of HTML snippets
* @param $config Optional HTMLPurifier_Config object for this operation.
* See HTMLPurifier::purify() for more details.
* @return Array of purified HTML
*/
public function purifyArray($array_of_html, $config = null) {
$context_array = array();
foreach ($array_of_html as $key => $html) {
$array_of_html[$key] = $this->purify($html, $config);
$context_array[$key] = $this->context;
}
$this->context = $context_array;
return $array_of_html;
}
/**
* Singleton for enforcing just one HTML Purifier in your system * @param $prototype Optional prototype HTMLPurifier instance to
* overload singleton with, or HTMLPurifier_Config
* instance to configure the generated version with.
*/
public static function instance($prototype = null) {
if (!self::$instance || $prototype) {
if ($prototype instanceof HTMLPurifier) {
self::$instance = $prototype;
} elseif ($prototype) {
self::$instance = new HTMLPurifier($prototype);
} else {
self::$instance = new HTMLPurifier();
}
}
return self::$instance;
}
/**
* @note Backwards compatibility, see instance()
*/
public static function getInstance($prototype = null) {
return HTMLPurifier::instance($prototype);
}
}
// vim: et sw=4 sts=4