commit e6fca496862eb2f13b0dc38da6a378cc540771a1
Author: Wojtek Kosior <koszko@koszko.org>
Date:   Wed Aug 24 12:21:24 2022 +0200

    force <noscript> tags

diff --git a/content/policy_enforcing.js b/content/policy_enforcing.js
index e230537..639a92a 100644
--- a/content/policy_enforcing.js
+++ b/content/policy_enforcing.js
@@ -162,6 +162,41 @@ function desanitize_script(script) {
     delete script.haketilo_blocked_type;
 }
 
+/* The following will only be run on pages without payload. */
+function force_noscript_tag(element) {
+    if (element.tagName !== "NOSCRIPT")
+	return;
+
+    let under_head = false;
+    let ancestor = element;
+    while (true) {
+	ancestor = ancestor.parentElement;
+
+	if (ancestor === null)
+	    break;
+
+	if (ancestor === document.head) {
+	    under_head = true;
+	    break;
+	}
+    }
+
+    const replacement = document.createElement('haketilo-noscript');
+    replacement.innerHTML = element.innerHTML;
+
+    for (const script of [...replacement.querySelectorAll('script')])
+	script.remove();
+
+    if (under_head) {
+	for (const child of replacement.childNodes)
+	    element.before(child);
+
+	element.remove();
+    } else {
+	element.replaceWith(replacement);
+    }
+}
+
 /*
  * Blocking certain attributes that might allow 'javascript:' URLs. Some of
  * these are: <iframe>'s 'src' attributes (would normally execute js in URL upon
@@ -254,7 +289,8 @@ function sanitize_tree_onevent(root) {
 #ENDIF
 
 /*
- * Sanitize elements on-the-fly as they appear using MutationObserver.
+ * Sanitize elements on-the-fly and force <noscript> tags visible as they appear
+ * using MutationObserver.
  *
  * Under Abrowser 97 it was observed that MutationObserver does not always work
  * as is should. When trying to observe nodes of an XMLDocument the behavior was
@@ -262,8 +298,9 @@ function sanitize_tree_onevent(root) {
  * around this we avoid using the "subtree" option altogether and have the same
  * code work in all scenarios.
  */
-function MOSanitizer(root) {
-    this.root = root;
+function MOSanitizer(root, payload_present) {
+    this.root            = root;
+    this.payload_present = payload_present;
 
     this.recursively_sanitize(root);
 
@@ -305,6 +342,8 @@ MOSanitizer.prototype.recursively_sanitize = function(elem) {
 #IF MOZILLA
 	sanitize_element_onevent(current_elem);
 #ENDIF
+	if (!this.payload_present)
+	    force_noscript_tag(current_elem);
     }
 }
 
@@ -391,7 +430,7 @@ async function sanitize_document(doc, policy) {
     substitute_doc.documentElement.replaceWith(root);
 #ENDIF
 
-    const sanitizer = new MOSanitizer(root);
+    const sanitizer = new MOSanitizer(root, !!policy.payload);
     sanitizer.start();
     wait_loaded(doc).then(() => sanitizer.stop());