From 6ffffb7b2bb1386bb3fe97caa06baec729dc07de Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Mon, 31 Mar 2025 16:30:17 -0400
Subject: [PATCH] [mv3] Force real origin in `postMessage` so that
 `use_dynamic_url` can be used

Call to postMessage was failing in the zapper when using `use_dynamic_url` in
manifest. Manually overwriting the per-session dynamic hostname with the real
extension id fixes this.
---
 platform/mv3/chromium/manifest.json           | 3 ++-
 platform/mv3/extension/js/scripting/zapper.js | 8 +++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/platform/mv3/chromium/manifest.json b/platform/mv3/chromium/manifest.json
index a5ff0306f..d913bf1f6 100644
--- a/platform/mv3/chromium/manifest.json
+++ b/platform/mv3/chromium/manifest.json
@@ -63,7 +63,8 @@
       ],
       "matches": [
         "<all_urls>"
-      ]
+      ],
+      "use_dynamic_url": true
     }
   ]
 }
diff --git a/platform/mv3/extension/js/scripting/zapper.js b/platform/mv3/extension/js/scripting/zapper.js
index 038ea1601..fb37ee1cf 100644
--- a/platform/mv3/extension/js/scripting/zapper.js
+++ b/platform/mv3/extension/js/scripting/zapper.js
@@ -365,7 +365,7 @@ const onFrameMessage = function(msg) {
 // can remove the iframe.
 
 const bootstrap = async ( ) => {
-    const url = new URL(chrome.runtime.getURL('/zapper-ui.html'));
+    const dynamicURL = new URL(chrome.runtime.getURL('/zapper-ui.html'));
     return new Promise(resolve => {
         const frame = document.createElement('iframe');
         frame.setAttribute(zapperSecret, '');
@@ -381,9 +381,11 @@ const bootstrap = async ( ) => {
             port.onmessageerror = ( ) => {
                 quitZapper();
             };
+            const realURL = new URL(dynamicURL);
+            realURL.hostname = chrome.i18n.getMessage('@@extension_id');
             frame.contentWindow.postMessage(
                 { what: 'zapperStart' },
-                url.origin,
+                realURL.origin,
                 [ channel.port2 ]
             );
             frame.contentWindow.focus();
@@ -392,7 +394,7 @@ const bootstrap = async ( ) => {
                 zapperFramePort: port,
             });
         };
-        frame.contentWindow.location = url.href;
+        frame.contentWindow.location = dynamicURL.href;
     });
 };