/moodle/lib/htmlpurifier/HTMLPurifier/HTMLModuleManager.php

<?php

require_once 'HTMLPurifier/HTMLModule.php';
require_once 'HTMLPurifier/ElementDef.php';
require_once 'HTMLPurifier/Doctype.php';
require_once 'HTMLPurifier/DoctypeRegistry.php';

require_once 'HTMLPurifier/ContentSets.php';
require_once 'HTMLPurifier/AttrTypes.php';
require_once 'HTMLPurifier/AttrCollections.php';

require_once 'HTMLPurifier/AttrDef.php';
require_once 'HTMLPurifier/AttrDef/Enum.php';

// W3C modules
require_once 'HTMLPurifier/HTMLModule/CommonAttributes.php';
require_once 'HTMLPurifier/HTMLModule/Text.php';
require_once 'HTMLPurifier/HTMLModule/Hypertext.php';
require_once 'HTMLPurifier/HTMLModule/List.php';
require_once 'HTMLPurifier/HTMLModule/Presentation.php';
require_once 'HTMLPurifier/HTMLModule/Edit.php';
require_once 'HTMLPurifier/HTMLModule/Bdo.php';
require_once 'HTMLPurifier/HTMLModule/Tables.php';
require_once 'HTMLPurifier/HTMLModule/Image.php';
require_once 'HTMLPurifier/HTMLModule/StyleAttribute.php';
require_once 'HTMLPurifier/HTMLModule/Legacy.php';
require_once 'HTMLPurifier/HTMLModule/Target.php';
require_once 'HTMLPurifier/HTMLModule/Scripting.php';
require_once 'HTMLPurifier/HTMLModule/XMLCommonAttributes.php';
require_once 'HTMLPurifier/HTMLModule/NonXMLCommonAttributes.php';
require_once 'HTMLPurifier/HTMLModule/Ruby.php';
require_once 'HTMLPurifier/HTMLModule/Object.php';

// tidy modules
require_once 'HTMLPurifier/HTMLModule/Tidy.php';
require_once 'HTMLPurifier/HTMLModule/Tidy/XHTMLAndHTML4.php';
require_once 'HTMLPurifier/HTMLModule/Tidy/XHTML.php';
require_once 'HTMLPurifier/HTMLModule/Tidy/Proprietary.php';

HTMLPurifier_ConfigSchema::define(
    'HTML', 'Doctype', '', 'string',
    'Doctype to use during filtering. '.
    'Technically speaking this is not actually a doctype (as it does '.
    'not identify a corresponding DTD), but we are using this name '.
    'for sake of simplicity. When non-blank, this will override any older directives '.
    'like %HTML.XHTML or %HTML.Strict.'
);
HTMLPurifier_ConfigSchema::defineAllowedValues('HTML', 'Doctype', array(
    '', 'HTML 4.01 Transitional', 'HTML 4.01 Strict',
    'XHTML 1.0 Transitional', 'XHTML 1.0 Strict',
    'XHTML 1.1'
));

HTMLPurifier_ConfigSchema::define(
    'HTML', 'CustomDoctype', null, 'string/null',
'
A custom doctype for power-users who defined there own document
type. This directive only applies when %HTML.Doctype is blank.
This directive has been available since 2.0.1.
'
);

HTMLPurifier_ConfigSchema::define(
    'HTML', 'Trusted', false, 'bool',
    'Indicates whether or not the user input is trusted or not. If the '.
    'input is trusted, a more expansive set of allowed tags and attributes '.
    'will be used. This directive has been available since 2.0.0.'
);

HTMLPurifier_ConfigSchema::define(
    'HTML', 'AllowedModules', null, 'lookup/null', '
<p>
    A doctype comes with a set of usual modules to use. Without having
    to mucking about with the doctypes, you can quickly activate or
    disable these modules by specifying which modules you wish to allow
    with this directive. This is most useful for unit testing specific
    modules, although end users may find it useful for their own ends.
</p>
<p>
    If you specify a module that does not exist, the manager will silently
    fail to use it, so be careful! User-defined modules are not affected
    by this directive. Modules defined in %HTML.CoreModules are not
    affected by this directive. This directive has been available since 2.0.0.
</p>
');

HTMLPurifier_ConfigSchema::define(
    'HTML', 'CoreModules', array(
        'Structure' => true,
        'Text' => true,
        'Hypertext' => true,
        'List' => true,
        'NonXMLCommonAttributes' => true,
        'XMLCommonAttributes' => true,
        'CommonAttributes' => true
     ), 'lookup', '
<p>
    Certain modularized doctypes (XHTML, namely), have certain modules
    that must be included for the doctype to be an conforming document
    type: put those modules here. By default, XHTML\'s core modules
    are used. You can set this to a blank array to disable core module
    protection, but this is not recommended. This directive has been
    available since 2.0.0.
</p>
');

class HTMLPurifier_HTMLModuleManager
{
    
    /**
     * Instance of HTMLPurifier_DoctypeRegistry
     * @public
     */
    var $doctypes;
    
    /**
     * Instance of current doctype
     * @public
     */
    var $doctype;
    
    /**
     * Instance of HTMLPurifier_AttrTypes
     * @public
     */
    var $attrTypes;
    
    /**
     * Active instances of modules for the specified doctype are
     * indexed, by name, in this array.
     */
    var $modules = array();
    
    /**
     * Array of recognized HTMLPurifier_Module instances, indexed by 
     * module's class name. This array is usually lazy loaded, but a
     * user can overload a module by pre-emptively registering it.
     */
    var $registeredModules = array();
    
    /**
     * List of extra modules that were added by the user using addModule().
     * These get unconditionally merged into the current doctype, whatever
     * it may be.
     */
    var $userModules = array();
    
    /**
     * Associative array of element name to list of modules that have
     * definitions for the element; this array is dynamically filled.
     */
    var $elementLookup = array();
    
    /** List of prefixes we should use for registering small names */
    var $prefixes = array('HTMLPurifier_HTMLModule_');
    
    var $contentSets;     /**< Instance of HTMLPurifier_ContentSets */
    var $attrCollections; /**< Instance of HTMLPurifier_AttrCollections */
    
    /** If set to true, unsafe elements and attributes will be allowed */
    var $trusted = false;
    
    function HTMLPurifier_HTMLModuleManager() {
        
        // editable internal objects
        $this->attrTypes = new HTMLPurifier_AttrTypes();
        $this->doctypes  = new HTMLPurifier_DoctypeRegistry();
        
        // setup default HTML doctypes
        
        // module reuse
        $common = array(
            'CommonAttributes', 'Text', 'Hypertext', 'List',
            'Presentation', 'Edit', 'Bdo', 'Tables', 'Image',
            'StyleAttribute', 'Scripting', 'Object'
        );
        $transitional = array('Legacy', 'Target');
        $xml = array('XMLCommonAttributes');
        $non_xml = array('NonXMLCommonAttributes');
        
        $this->doctypes->register(
            'HTML 4.01 Transitional', false,
            array_merge($common, $transitional, $non_xml),
            array('Tidy_Transitional', 'Tidy_Proprietary'),
            array(),
            '-//W3C//DTD HTML 4.01 Transitional//EN',
            'http://www.w3.org/TR/html4/loose.dtd'
        );
        
        $this->doctypes->register(
            'HTML 4.01 Strict', false,
            array_merge($common, $non_xml),
            array('Tidy_Strict', 'Tidy_Proprietary'),
            array(),
            '-//W3C//DTD HTML 4.01//EN',
            'http://www.w3.org/TR/html4/strict.dtd'
        );
        
        $this->doctypes->register(
            'XHTML 1.0 Transitional', true,
            array_merge($common, $transitional, $xml, $non_xml),
            array('Tidy_Transitional', 'Tidy_XHTML', 'Tidy_Proprietary'),
            array(),
            '-//W3C//DTD XHTML 1.0 Transitional//EN',
            'http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd'
        );
        
        $this->doctypes->register(
            'XHTML 1.0 Strict', true,
            array_merge($common, $xml, $non_xml),
            array('Tidy_Strict', 'Tidy_XHTML', 'Tidy_Strict', 'Tidy_Proprietary'),
            array(),
            '-//W3C//DTD XHTML 1.0 Strict//EN',
            'http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd'
        );
        
        $this->doctypes->register(
            'XHTML 1.1', true,
            array_merge($common, $xml, array('Ruby')),
            array('Tidy_Strict', 'Tidy_XHTML', 'Tidy_Proprietary', 'Tidy_Strict'), // Tidy_XHTML1_1
            array(),
            '-//W3C//DTD XHTML 1.1//EN',
            'http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd'
        );
        
    }
    
    /**
     * Registers a module to the recognized module list, useful for
     * overloading pre-existing modules.
     * @param $module Mixed: string module name, with or without
     *                HTMLPurifier_HTMLModule prefix, or instance of
     *                subclass of HTMLPurifier_HTMLModule.
     * @note This function will not call autoload, you must instantiate
     *       (and thus invoke) autoload outside the method.
     * @note If a string is passed as a module name, different variants
     *       will be tested in this order:
     *          - Check for HTMLPurifier_HTMLModule_$name
     *          - Check all prefixes with $name in order they were added
     *          - Check for literal object name
     *          - Throw fatal error
     *       If your object name collides with an internal class, specify
     *       your module manually. All modules must have been included
     *       externally: registerModule will not perform inclusions for you!
     * @warning If your module has the same name as an already loaded
     *          module, your module will overload the old one WITHOUT
     *          warning.
     */
    function registerModule($module) {
        if (is_string($module)) {
            // attempt to load the module
            $original_module = $module;
            $ok = false;
            foreach ($this->prefixes as $prefix) {
                $module = $prefix . $original_module;
                if ($this->_classExists($module)) {
                    $ok = true;
                    break;
                }
            }
            if (!$ok) {
                $module = $original_module;
                if (!$this->_classExists($module)) {
                    trigger_error($original_module . ' module does not exist',
                        E_USER_ERROR);
                    return;
                }
            }
            $module = new $module();
        }
        if (empty($module->name)) {
            trigger_error('Module instance of ' . get_class($module) . ' must have name');
            return;
        }
        $this->registeredModules[$module->name] = $module;
    }
    
    /**
     * Safely tests for class existence without invoking __autoload in PHP5
     * or greater.
     * @param $name String class name to test
     * @note If any other class needs it, we'll need to stash in a 
     *       conjectured "compatibility" class
     * @private
     */
    function _classExists($name) {
        static $is_php_4 = null;
        if ($is_php_4 === null) {
            $is_php_4 = version_compare(PHP_VERSION, '5', '<');
        }
        if ($is_php_4) {
            return class_exists($name);
        } else {
            return class_exists($name, false);
        }
    }
    
    /**
     * Adds a module to the current doctype by first registering it,
     * and then tacking it on to the active doctype
     */
    function addModule($module) {
        $this->registerModule($module);
        if (is_object($module)) $module = $module->name;
        $this->userModules[] = $module;
    }
    
    /**
     * Adds a class prefix that registerModule() will use to resolve a
     * string name to a concrete class
     */
    function addPrefix($prefix) {
        $this->prefixes[] = $prefix;
    }
    
    /**
     * Performs processing on modules, after being called you may
     * use getElement() and getElements()
     * @param $config Instance of HTMLPurifier_Config
     */
    function setup($config) {
        
        $this->trusted = $config->get('HTML', 'Trusted');
        
        // generate
        $this->doctype = $this->doctypes->make($config);
        $modules = $this->doctype->modules;
        
        // take out the default modules that aren't allowed
        $lookup = $config->get('HTML', 'AllowedModules');
        $special_cases = $config->get('HTML', 'CoreModules');
        
        if (is_array($lookup)) {
            foreach ($modules as $k => $m) {
                if (isset($special_cases[$m])) continue;
                if (!isset($lookup[$m])) unset($modules[$k]);
            }
        }
        
        // merge in custom modules
        $modules = array_merge($modules, $this->userModules);
        
        foreach ($modules as $module) {
            $this->processModule($module);
            $this->modules[$module]->setup($config);
        }
        
        foreach ($this->doctype->tidyModules as $module) {
            $this->processModule($module);
            $this->modules[$module]->setup($config);
        }
        
        // setup lookup table based on all valid modules
        foreach ($this->modules as $module) {
            foreach ($module->info as $name => $def) {
                if (!isset($this->elementLookup[$name])) {
                    $this->elementLookup[$name] = array();
                }
                $this->elementLookup[$name][] = $module->name;
            }
        }
        
        // note the different choice
        $this->contentSets = new HTMLPurifier_ContentSets(
            // content set assembly deals with all possible modules,
            // not just ones deemed to be "safe"
            $this->modules
        );
        $this->attrCollections = new HTMLPurifier_AttrCollections(
            $this->attrTypes,
            // there is no way to directly disable a global attribute,
            // but using AllowedAttributes or simply not including
            // the module in your custom doctype should be sufficient
            $this->modules
        );
    }
    
    /**
     * Takes a module and adds it to the active module collection,
     * registering it if necessary.
     */
    function processModule($module) {
        if (!isset($this->registeredModules[$module]) || is_object($module)) {
            $this->registerModule($module);
        }
        $this->modules[$module] = $this->registeredModules[$module];
    }
    
    /**
     * Retrieves merged element definitions.
     * @return Array of HTMLPurifier_ElementDef
     */
    function getElements() {
        
        $elements = array();
        foreach ($this->modules as $module) {
            foreach ($module->info as $name => $v) {
                if (isset($elements[$name])) continue;
                // if element is not safe, don't use it
                if (!$this->trusted && ($v->safe === false)) continue;
                $elements[$name] = $this->getElement($name);
            }
        }
        
        // remove dud elements, this happens when an element that
        // appeared to be safe actually wasn't
        foreach ($elements as $n => $v) {
            if ($v === false) unset($elements[$n]);
        }
        
        return $elements;
        
    }
    
    /**
     * Retrieves a single merged element definition
     * @param $name Name of element
     * @param $trusted Boolean trusted overriding parameter: set to true
     *                 if you want the full version of an element
     * @return Merged HTMLPurifier_ElementDef
     */
    function getElement($name, $trusted = null) {
        
        $def = false;
        if ($trusted === null) $trusted = $this->trusted;
        
        $modules = $this->modules;
        
        if (!isset($this->elementLookup[$name])) {
            return false;
        }
        
        foreach($this->elementLookup[$name] as $module_name) {
            
            $module = $modules[$module_name];
            
            // copy is used because, ideally speaking, the original
            // definition should not be modified. Usually, this will
            // make no difference, but for consistency's sake
            $new_def = $module->info[$name]->copy();
            
            // refuse to create/merge in a definition that is deemed unsafe
            if (!$trusted && ($new_def->safe === false)) {
                $def = false;
                continue;
            }
            
            if (!$def && $new_def->standalone) {
                // element with unknown safety is not to be trusted.
                // however, a merge-in definition with undefined safety
                // is fine
                if (!$trusted && !$new_def->safe) continue;
                $def = $new_def;
            } elseif ($def) {
                $def->mergeIn($new_def);
            } else {
                // could "save it for another day":
                // non-standalone definitions that don't have a standalone
                // to merge into could be deferred to the end
                continue;
            }
            
            // attribute value expansions
            $this->attrCollections->performInclusions($def->attr);
            $this->attrCollections->expandIdentifiers($def->attr, $this->attrTypes);
            
            // descendants_are_inline, for ChildDef_Chameleon
            if (is_string($def->content_model) &&
                strpos($def->content_model, 'Inline') !== false) {
                if ($name != 'del' && $name != 'ins') {
                    // this is for you, ins/del
                    $def->descendants_are_inline = true;
                }
            }
            
            $this->contentSets->generateChildDef($def, $module);
        }
            
        // add information on required attributes
        foreach ($def->attr as $attr_name => $attr_def) {
            if ($attr_def->required) {
                $def->required_attr[] = $attr_name;
            }
        }
        
        return $def;
        
    }
    
}