HTML filter that is HTML5 compliant

Question

Is there a simple approach to add a HTML5 ruleset for HTMLPurifier?

HP can be configured to recognize new tags with:

// setup configurable HP instance
$config = HTMLPurifier_Config::createDefault();
$config->set('HTML.DefinitionID', 'html5 draft');
$config->set('HTML.DefinitionRev', 1);
$config->set('Cache.DefinitionImpl', null); // no caching
$def = $config->getHTMLDefinition(true);

// add a new tag
$form = $def->addElement(
  'article',   // name
  'Block',     // content set
  'Flow',      // allowed children
  'Common',    // attribute collection
  array(       // attributes
  )
);

// add a new attribute
$def->addAttribute('a', 'contextmenu', "ID");

However this is clearly a bit of work. Since there are a lot of new HTML5 tags and attributes that had to be registered. And new global attributes should be combinable even with existing HTML 4 tags. (It's difficult to judge from the docs how to augment core rules). So, is there a more useful config format/array structure to feed new and updated tag+attribute+context configuration (inline/block/empty/flow/..) into HTMLPurifier?

# mostly confused about how to extend existing tags:
$def->addAttribute('input', 'type', "...|...|...");

# or how to allow data-* attributes (if I actually wanted that):
$def->addAttribute("data-*", ...

And of course not all new HTML5 tags are fit for unrestricted allowance. HTMLPurifier is all about content filtering. Defining value constraints is where it's at. -- <canvas> for example might not be that big of a deal when it appears in user content. Because it's useless at best without Javascript (which HP already filters out). But other tags and attributes might be undesirable; so a flexible configuration structure is imperative for enabling/disabling tags and their associated attributes.

(Guess I should update some research...). But there's still no practical compendium/specification (no, XML DTDs aren't) that suits a HP configuration.

• http://simon.html5.org/html-elements
• http://www.w3.org/TR/html5-diff/#new-elements
• http://www.w3.org/TR/html5-diff/#new-attributes

(Uh, and HTML5 is no longer a draft.)

Answer 1

There's this configuration for HTMLpurify to allow newer HTML5 tags.

Source: https://github.com/kennberg/php-htmlpurfier-html5

.

<?php
/**
 * Load HTMLPurifier with HTML5, TinyMCE, YouTube, Video support.
 *
 * Copyright 2014 Alex Kennberg (https://github.com/kennberg/php-htmlpurifier-html5)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

require_once(LIB_DIR . 'third-party/htmlpurifier/HTMLPurifier.safe-includes.php');


function load_htmlpurifier($allowed) {
  $config = HTMLPurifier_Config::createDefault();
  $config->set('HTML.Doctype', 'HTML 4.01 Transitional');
  $config->set('CSS.AllowTricky', true);
  $config->set('Cache.SerializerPath', '/tmp');

  // Allow iframes from:
  // o YouTube.com
  // o Vimeo.com
  $config->set('HTML.SafeIframe', true);
  $config->set('URI.SafeIframeRegexp', '%^(http:|https:)?//(www.youtube(?:-nocookie)?.com/embed/|player.vimeo.com/video/)%');

  $config->set('HTML.Allowed', implode(',', $allowed));

  // Set some HTML5 properties
  $config->set('HTML.DefinitionID', 'html5-definitions'); // unqiue id
  $config->set('HTML.DefinitionRev', 1);

  if ($def = $config->maybeGetRawHTMLDefinition()) {
    // http://developers.whatwg.org/sections.html
    $def->addElement('section', 'Block', 'Flow', 'Common');
    $def->addElement('nav',     'Block', 'Flow', 'Common');
    $def->addElement('article', 'Block', 'Flow', 'Common');
    $def->addElement('aside',   'Block', 'Flow', 'Common');
    $def->addElement('header',  'Block', 'Flow', 'Common');
    $def->addElement('footer',  'Block', 'Flow', 'Common');

    // Content model actually excludes several tags, not modelled here
    $def->addElement('address', 'Block', 'Flow', 'Common');
    $def->addElement('hgroup', 'Block', 'Required: h1 | h2 | h3 | h4 | h5 | h6', 'Common');

    // http://developers.whatwg.org/grouping-content.html
    $def->addElement('figure', 'Block', 'Optional: (figcaption, Flow) | (Flow, figcaption) | Flow', 'Common');
    $def->addElement('figcaption', 'Inline', 'Flow', 'Common');

    // http://developers.whatwg.org/the-video-element.html#the-video-element
    $def->addElement('video', 'Block', 'Optional: (source, Flow) | (Flow, source) | Flow', 'Common', array(
      'src' => 'URI',
      'type' => 'Text',
      'width' => 'Length',
      'height' => 'Length',
      'poster' => 'URI',
      'preload' => 'Enum#auto,metadata,none',
      'controls' => 'Bool',
    ));
    $def->addElement('source', 'Block', 'Flow', 'Common', array(
      'src' => 'URI',
      'type' => 'Text',
    ));

    // http://developers.whatwg.org/text-level-semantics.html
    $def->addElement('s',    'Inline', 'Inline', 'Common');
    $def->addElement('var',  'Inline', 'Inline', 'Common');
    $def->addElement('sub',  'Inline', 'Inline', 'Common');
    $def->addElement('sup',  'Inline', 'Inline', 'Common');
    $def->addElement('mark', 'Inline', 'Inline', 'Common');
    $def->addElement('wbr',  'Inline', 'Empty', 'Core');

    // http://developers.whatwg.org/edits.html
    $def->addElement('ins', 'Block', 'Flow', 'Common', array('cite' => 'URI', 'datetime' => 'CDATA'));
    $def->addElement('del', 'Block', 'Flow', 'Common', array('cite' => 'URI', 'datetime' => 'CDATA'));

    // TinyMCE
    $def->addAttribute('img', 'data-mce-src', 'Text');
    $def->addAttribute('img', 'data-mce-json', 'Text');

    // Others
    $def->addAttribute('iframe', 'allowfullscreen', 'Bool');
    $def->addAttribute('table', 'height', 'Text');
    $def->addAttribute('td', 'border', 'Text');
    $def->addAttribute('th', 'border', 'Text');
    $def->addAttribute('tr', 'width', 'Text');
    $def->addAttribute('tr', 'height', 'Text');
    $def->addAttribute('tr', 'border', 'Text');
  }

  return new HTMLPurifier($config);
}

Answer 2

The php tidy extension can be configured to recognize html5 tags. http://tidy.sourceforge.net/docs/quickref.html#new-blocklevel-tags

Answer 3

im using a fix for wordpress but maybe this can help you too (at least for the array part)

http://nicolasgallagher.com/using-html5-elements-in-wordpress-post-content/

http://hybridgarden.com/blog/misc/adding-html5-capability-to-wordpress/

also:

http://code.google.com/p/html5lib/ A Python and PHP implementations of a HTML parser based on the WHATWG HTML5 specification for maximum compatibility with major desktop web browsers.