From 3059db77c4a4e8a9a44931b0aa1989c272b07dc4 Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Wed, 14 Oct 2020 13:37:09 -0400
Subject: [PATCH] Use proxy detection code path only on Firefox 79 and less

Related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/911

This was fixed in Firefox 80:
- https://bugzilla.mozilla.org/show_bug.cgi?id=1618271
---
 platform/firefox/vapi-webrequest.js | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/platform/firefox/vapi-webrequest.js b/platform/firefox/vapi-webrequest.js
index a7c14c24c..eaa74b34f 100644
--- a/platform/firefox/vapi-webrequest.js
+++ b/platform/firefox/vapi-webrequest.js
@@ -125,19 +125,21 @@
             this.cnameFlushTime = Date.now() + this.cnameMaxTTL * 60000;
             // https://github.com/uBlockOrigin/uBlock-issues/issues/911
             //   Install/remove proxy detector.
-            const wrohr = browser.webRequest.onHeadersReceived;
-            if ( cnameUncloak === false || cnameUncloakProxied ) {
-                if ( wrohr.hasListener(proxyDetector) ) {
-                    wrohr.removeListener(proxyDetector);
+            if ( vAPI.webextFlavor.major < 80 ) {
+                const wrohr = browser.webRequest.onHeadersReceived;
+                if ( cnameUncloak === false || cnameUncloakProxied ) {
+                    if ( wrohr.hasListener(proxyDetector) ) {
+                        wrohr.removeListener(proxyDetector);
+                    }
+                } else if ( wrohr.hasListener(proxyDetector) === false ) {
+                    wrohr.addListener(
+                        proxyDetector,
+                        { urls: [ '*://*/*' ] },
+                        [ 'blocking' ]
+                    );
                 }
-            } else if ( wrohr.hasListener(proxyDetector) === false ) {
-                wrohr.addListener(
-                    proxyDetector,
-                    { urls: [ '*://*/*' ] },
-                    [ 'blocking' ]
-                );
+                proxyDetectorTryCount = 32;
             }
-            proxyDetectorTryCount = 32;
         }
         normalizeDetails(details) {
             if ( mustPunycode && !reAsciiHostname.test(details.url) ) {