. /** * Media plugin filtering * * This filter will replace any links to a media file with * a media plugin that plays that media inline * * @package filter * @subpackage mediaplugin * @copyright 2004 onwards Martin Dougiamas {@link http://moodle.com} * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later */ defined('MOODLE_INTERNAL') || die(); /** * Automatic media embedding filter class. * * It is highly recommended to configure servers to be compatible with our slasharguments, * otherwise the "?d=600x400" may not work. * * @package filter * @subpackage mediaplugin * @copyright 2004 onwards Martin Dougiamas {@link http://moodle.com} * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later */ class filter_mediaplugin extends moodle_text_filter { /** @var bool True if currently filtering trusted text */ private $trusted; /** * Setup page with filter requirements and other prepare stuff. * * @param moodle_page $page The page we are going to add requirements to. * @param context $context The context which contents are going to be filtered. */ public function setup($page, $context) { // This only requires execution once per request. static $jsinitialised = false; if ($jsinitialised) { return; } $jsinitialised = true; // Set up the media manager so that media plugins requiring JS are initialised. $mediamanager = core_media_manager::instance($page); } public function filter($text, array $options = array()) { global $CFG, $PAGE; if (!is_string($text) or empty($text)) { // non string data can not be filtered anyway return $text; } if (stripos($text, '') === false && stripos($text, '') === false && stripos($text, '') === false) { // Performance shortcut - if there are no , or tags, nothing can match. return $text; } // Check SWF permissions. $this->trusted = !empty($options['noclean']) or !empty($CFG->allowobjectembed); // Looking for tags. $matches = preg_split('/(<[^>]*>)/i', $text, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE); if (!$matches) { return $text; } // Regex to find media extensions in an tag. $embedmarkers = core_media_manager::instance()->get_embeddable_markers(); $re = '~]*href="([^"]*(?:' . $embedmarkers . ')[^"]*)"[^>]*>([^>]*)~is'; $newtext = ''; $validtag = ''; $tagname = ''; $sizeofmatches = count($matches); // We iterate through the given string to find valid tags // and build them so that the callback function can check it for // embedded content. Then we rebuild the string. foreach ($matches as $idx => $tag) { if (preg_match('||', $tag) && !empty($validtag)) { $validtag .= $tag; // Given we now have a valid tag to process it's time for // ReDoS protection. Stop processing if a word is too large. if (strlen($validtag) < 4096) { if ($tagname === 'a') { $processed = preg_replace_callback($re, array($this, 'callback'), $validtag); } else { // For audio and video tags we just process them without precheck for embeddable markers. $processed = $this->process_media_tag($validtag); } } // Rebuilding the string with our new processed text. $newtext .= !empty($processed) ? $processed : $validtag; // Wipe it so we can catch any more instances to filter. $validtag = ''; $processed = ''; } else if (preg_match('/<(a|video|audio)\s[^>]*/', $tag, $tagmatches) && $sizeofmatches > 1 && (empty($validtag) || $tagname === strtolower($tagmatches[1]))) { // Looking for a starting tag. Ignore tags embedded into each other. $validtag = $tag; $tagname = strtolower($tagmatches[1]); } else { // If we have a validtag add to that to process later, // else add straight onto our newtext string. if (!empty($validtag)) { $validtag .= $tag; } else { $newtext .= $tag; } } } // Return the same string except processed by the above. return $newtext; } /** * Replace link with embedded content, if supported. * * @param array $matches * @return string */ private function callback(array $matches) { $mediamanager = core_media_manager::instance(); global $CFG, $PAGE; // Check if we ignore it. if (preg_match('/class="[^"]*nomediaplugin/i', $matches[0])) { return $matches[0]; } // Get name. $name = trim($matches[2]); if (empty($name) or strpos($name, 'http') === 0) { $name = ''; // Use default name. } // Split provided URL into alternatives. $urls = $mediamanager->split_alternatives($matches[1], $width, $height); $options = [core_media_manager::OPTION_ORIGINAL_TEXT => $matches[0]]; return $this->embed_alternatives($urls, $name, $width, $height, $options); } /** * Renders media files (audio or video) using suitable embedded player. * * Wrapper for {@link core_media_manager::embed_alternatives()} * * @param array $urls Array of moodle_url to media files * @param string $name Optional user-readable name to display in download link * @param int $width Width in pixels (optional) * @param int $height Height in pixels (optional) * @param array $options Array of key/value pairs * @return string HTML content of embed */ protected function embed_alternatives($urls, $name, $width, $height, $options) { // Allow SWF (or not). if ($this->trusted) { $options[core_media_manager::OPTION_TRUSTED] = true; } // We could test whether embed is possible using can_embed, but to save // time, let's just embed it with the 'fallback to blank' option which // does most of the same stuff anyhow. $options[core_media_manager::OPTION_FALLBACK_TO_BLANK] = true; // NOTE: Options are not passed through from filter because the 'embed' // code does not recognise filter options (it's a different kind of // option-space) as it can be used in non-filter situations. $result = core_media_manager::instance()->embed_alternatives($urls, $name, $width, $height, $options); // If something was embedded, return it, otherwise return original. if ($result !== '') { return $result; } else { return $options[core_media_manager::OPTION_ORIGINAL_TEXT]; } } /** * Replaces