allow ON_SANITIZE plugins to modify the list of tags and attributes that are permissible

include/functions.php

@@ -2666,37 +2666,44 @@
 
 		}
 
+		$allowed_elements = array('a', 'address', 'audio', 'article',
+			'b', 'big', 'blockquote', 'body', 'br', 'cite', 'center',
+			'code', 'dd', 'del', 'details', 'div', 'dl', 'font',
+			'dt', 'em', 'footer', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
+			'header', 'html', 'i', 'img', 'ins', 'kbd',
+			'li', 'nav', 'ol', 'p', 'pre', 'q', 's','small',
+			'source', 'span', 'strike', 'strong', 'sub', 'summary',
+			'sup', 'table', 'tbody', 'td', 'tfoot', 'th', 'thead',
+			'tr', 'track', 'tt', 'u', 'ul', 'var', 'wbr', 'video' );
+
+		if ($_SESSION['hasSandbox']) $allowed_elements[] = 'iframe';
+
+		$disallowed_attributes = array('id', 'style', 'class');
+
 		global $pluginhost;
 
 		if (isset($pluginhost)) {
 			foreach ($pluginhost->get_hooks($pluginhost::HOOK_SANITIZE) as $plugin) {
-				$doc = $plugin->hook_sanitize($doc, $site_url);
+				$retval = $plugin->hook_sanitize($doc, $site_url, $allowed_elements, $disallowed_attributes);
+				if (is_array($retval)) {
+					$doc = $retval[0];
+					$allowed_elements = $retval[1];
+					$disallowed_attributes = $retval[2];
+				} else {
+					$doc = $retval;
+				}
 			}
 		}
 
 		$doc->removeChild($doc->firstChild); //remove doctype
-		$doc = strip_harmful_tags($doc);
+		$doc = strip_harmful_tags($doc, $allowed_elements, $disallowed_attributes);
 		$res = $doc->saveHTML();
 		return $res;
 	}
 
-	function strip_harmful_tags($doc) {
+	function strip_harmful_tags($doc, $allowed_elements, $disallowed_attributes) {
 		$entries = $doc->getElementsByTagName("*");
 
-		$allowed_elements = array('a', 'address', 'audio', 'article',
-			'b', 'big', 'blockquote', 'body', 'br', 'cite', 'center',
-			'code', 'dd', 'del', 'details', 'div', 'dl', 'font',
-			'dt', 'em', 'footer', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
-			'header', 'html', 'i', 'img', 'ins', 'kbd',
-			'li', 'nav', 'ol', 'p', 'pre', 'q', 's','small',
-			'source', 'span', 'strike', 'strong', 'sub', 'summary',
-			'sup', 'table', 'tbody', 'td', 'tfoot', 'th', 'thead',
-			'tr', 'track', 'tt', 'u', 'ul', 'var', 'wbr', 'video' );
-
-		if ($_SESSION['hasSandbox']) array_push($allowed_elements, 'iframe');
-
-		$disallowed_attributes = array('id', 'style', 'class');
-
 		foreach ($entries as $entry) {
 			if (!in_array($entry->nodeName, $allowed_elements)) {
 				$entry->parentNode->removeChild($entry);