From 6355a17187f70c288ff8354656835bdc0a1e13eb Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Wed, 20 Nov 2024 09:04:52 -0500
Subject: [PATCH] [mv3] Fix flaw breaking scriptlets injection in optimal/basic
 mode

Not all matching scriptlets were injected on a given site in Optimal
or Complete mode when default mode was set to Basic or less.

A high profile manifestation of this bug was that Youtube ads were
not being blocked when using Optimal on Youtube while default mode
was Basic.
---
 platform/mv3/extension/js/scripting-manager.js |  4 ++--
 platform/mv3/extension/js/utils.js             | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/platform/mv3/extension/js/scripting-manager.js b/platform/mv3/extension/js/scripting-manager.js
index 814343ebe..23a6444ea 100644
--- a/platform/mv3/extension/js/scripting-manager.js
+++ b/platform/mv3/extension/js/scripting-manager.js
@@ -450,8 +450,8 @@ function registerScriptlet(context, scriptletDetails) {
                     targetHostnames = permissionGrantedHostnames;
                 } else {
                     targetHostnames = ut.intersectHostnameIters(
-                        permissionGrantedHostnames,
-                        scriptletHostnames
+                        scriptletHostnames,
+                        permissionGrantedHostnames
                     );
                 }
             }
diff --git a/platform/mv3/extension/js/utils.js b/platform/mv3/extension/js/utils.js
index b32104f94..7bf6e1350 100644
--- a/platform/mv3/extension/js/utils.js
+++ b/platform/mv3/extension/js/utils.js
@@ -47,6 +47,13 @@ const isDescendantHostname = (hna, hnb) => {
     return hna.charCodeAt(hna.length - hnb.length - 1) === 0x2E /* '.' */;
 };
 
+/**
+ * Returns whether a hostname is part of a collection, or is descendant of an
+ * item in the collection.
+ * @param hna - the hostname representing the needle.
+ * @param iterb - an iterable representing the haystack of hostnames.
+ */
+
 const isDescendantHostnameOfIter = (hna, iterb) => {
     const setb = iterb instanceof Set ? iterb : new Set(iterb);
     if ( setb.has('all-urls') || setb.has('*') ) { return true; }
@@ -60,6 +67,13 @@ const isDescendantHostnameOfIter = (hna, iterb) => {
     return false;
 };
 
+/**
+ * Returns all hostnames in the first collection which are equal or descendant
+ * of hostnames in the second collection.
+ * @param itera - an iterable which hostnames must be filtered out.
+ * @param iterb - an iterable which hostnames must be matched.
+ */
+
 const intersectHostnameIters = (itera, iterb) => {
     const setb = iterb instanceof Set ? iterb : new Set(iterb);
     if ( setb.has('all-urls') || setb.has('*') ) { return Array.from(itera); }