<?php class Sanitizer { private static function strip_harmful_tags($doc, $allowed_elements, $disallowed_attributes) { $xpath = new DOMXPath($doc); $entries = $xpath->query('//*'); foreach ($entries as $entry) { if (!in_array($entry->nodeName, $allowed_elements)) { $entry->parentNode->removeChild($entry); } if ($entry->hasAttributes()) { $attrs_to_remove = array(); foreach ($entry->attributes as $attr) { if (strpos($attr->nodeName, 'on') === 0) { array_push($attrs_to_remove, $attr); } if (strpos($attr->nodeName, "data-") === 0) { array_push($attrs_to_remove, $attr); } if ($attr->nodeName == 'href' && stripos($attr->value, 'javascript:') === 0) { array_push($attrs_to_remove, $attr); } if (in_array($attr->nodeName, $disallowed_attributes)) { array_push($attrs_to_remove, $attr); } } foreach ($attrs_to_remove as $attr) { $entry->removeAttributeNode($attr); } } } return $doc; } public static function iframe_whitelisted($entry) { $src = parse_url($entry->getAttribute("src"), PHP_URL_HOST); if (!empty($src)) return PluginHost::getInstance()->run_hooks_until(PluginHost::HOOK_IFRAME_WHITELISTED, true, $src); return false; } public static function sanitize($str, $force_remove_images = false, $owner = false, $site_url = false, $highlight_words = false, $article_id = false) { if (!$owner && isset($_SESSION["uid"])) $owner = $_SESSION["uid"]; $res = trim($str); if (!$res) return ''; $doc = new DOMDocument(); $doc->loadHTML('<?xml encoding="UTF-8">' . $res); $xpath = new DOMXPath($doc); $rewrite_base_url = $site_url ? $site_url : get_self_url_prefix(); $entries = $xpath->query('(//a[@href]|//img[@src]|//source[@srcset|@src])'); foreach ($entries as $entry) { if ($entry->hasAttribute('href')) { $entry->setAttribute('href', rewrite_relative_url($rewrite_base_url, $entry->getAttribute('href'))); $entry->setAttribute('rel', 'noopener noreferrer'); $entry->setAttribute("target", "_blank"); } if ($entry->hasAttribute('src')) { $entry->setAttribute('src', rewrite_relative_url($rewrite_base_url, $entry->getAttribute('src'))); } if ($entry->nodeName == 'img') { $entry->setAttribute('referrerpolicy', 'no-referrer'); $entry->setAttribute('loading', 'lazy'); } if ($entry->hasAttribute('srcset')) { $matches = RSSUtils::decode_srcset($entry->getAttribute('srcset')); for ($i = 0; $i < count($matches); $i++) { $matches[$i]["url"] = rewrite_relative_url($rewrite_base_url, $matches[$i]["url"]); } $entry->setAttribute("srcset", RSSUtils::encode_srcset($matches)); } if ($entry->hasAttribute('src') && ($owner && get_pref("STRIP_IMAGES", $owner)) || $force_remove_images || ($_SESSION["bw_limit"] ?? false)) { $p = $doc->createElement('p'); $a = $doc->createElement('a'); $a->setAttribute('href', $entry->getAttribute('src')); $a->appendChild(new DOMText($entry->getAttribute('src'))); $a->setAttribute('target', '_blank'); $a->setAttribute('rel', 'noopener noreferrer'); $p->appendChild($a); if ($entry->nodeName == 'source') { if ($entry->parentNode && $entry->parentNode->parentNode) $entry->parentNode->parentNode->replaceChild($p, $entry->parentNode); } else if ($entry->nodeName == 'img') { if ($entry->parentNode) $entry->parentNode->replaceChild($p, $entry); } } } $entries = $xpath->query('//iframe'); foreach ($entries as $entry) { if (!self::iframe_whitelisted($entry)) { $entry->setAttribute('sandbox', 'allow-scripts'); } else { if (is_prefix_https()) { $entry->setAttribute("src", str_replace("http://", "https://", $entry->getAttribute("src"))); } } } $allowed_elements = array('a', 'abbr', 'address', 'acronym', 'audio', 'article', 'aside', 'b', 'bdi', 'bdo', 'big', 'blockquote', 'body', 'br', 'caption', 'cite', 'center', 'code', 'col', 'colgroup', 'data', 'dd', 'del', 'details', 'description', 'dfn', 'div', 'dl', 'font', 'dt', 'em', 'footer', 'figure', 'figcaption', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'header', 'hr', 'html', 'i', 'img', 'ins', 'kbd', 'li', 'main', 'mark', 'nav', 'noscript', 'ol', 'p', 'picture', 'pre', 'q', 'ruby', 'rp', 'rt', 's', 'samp', 'section', 'small', 'source', 'span', 'strike', 'strong', 'sub', 'summary', 'sup', 'table', 'tbody', 'td', 'tfoot', 'th', 'thead', 'time', 'tr', 'track', 'tt', 'u', 'ul', 'var', 'wbr', 'video', 'xml:namespace' ); if ($_SESSION['hasSandbox'] ?? false) $allowed_elements[] = 'iframe'; $disallowed_attributes = array('id', 'style', 'class', 'width', 'height', 'allow'); PluginHost::getInstance()->chain_hooks_callback(PluginHost::HOOK_SANITIZE, function ($result) use (&$doc, &$allowed_elements, &$disallowed_attributes) { if (is_array($result)) { $doc = $result[0]; $allowed_elements = $result[1]; $disallowed_attributes = $result[2]; } else { $doc = $result; } }, $doc, $site_url, $allowed_elements, $disallowed_attributes, $article_id); $doc->removeChild($doc->firstChild); //remove doctype $doc = self::strip_harmful_tags($doc, $allowed_elements, $disallowed_attributes); $entries = $xpath->query('//iframe'); foreach ($entries as $entry) { $div = $doc->createElement('div'); $div->setAttribute('class', 'embed-responsive'); $entry->parentNode->replaceChild($div, $entry); $div->appendChild($entry); } if ($highlight_words && is_array($highlight_words)) { foreach ($highlight_words as $word) { // http://stackoverflow.com/questions/4081372/highlight-keywords-in-a-paragraph $elements = $xpath->query("//*/text()"); foreach ($elements as $child) { $fragment = $doc->createDocumentFragment(); $text = $child->textContent; while (($pos = mb_stripos($text, $word)) !== false) { $fragment->appendChild(new DOMText(mb_substr($text, 0, (int)$pos))); $word = mb_substr($text, (int)$pos, mb_strlen($word)); $highlight = $doc->createElement('span'); $highlight->appendChild(new DOMText($word)); $highlight->setAttribute('class', 'highlight'); $fragment->appendChild($highlight); $text = mb_substr($text, $pos + mb_strlen($word)); } if (!empty($text)) $fragment->appendChild(new DOMText($text)); $child->parentNode->replaceChild($fragment, $child); } } } $res = $doc->saveHTML(); /* strip everything outside of <body>...</body> */ $res_frag = array(); if (preg_match('/<body>(.*)<\/body>/is', $res, $res_frag)) { return $res_frag[1]; } else { return $res; } } }