From 335709bc5084d53135350e12b1bdc64fc3e74c06 Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Sun, 4 Feb 2018 09:10:17 -0500
Subject: [PATCH] fix #940

---
 src/js/background.js |  1 +
 src/js/traffic.js    | 26 +++++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/js/background.js b/src/js/background.js
index cc5661b..e07164e 100644
--- a/src/js/background.js
+++ b/src/js/background.js
@@ -103,6 +103,7 @@ var requestStatsFactory = function() {
 var rawSettingsDefault = {
     contributorMode: false,
     disableCSPReportInjection: false,
+    enforceEscapedFragment: true,
     placeholderBackground:
         [
             'url("data:image/png;base64,',
diff --git a/src/js/traffic.js b/src/js/traffic.js
index fea9965..3610c43 100644
--- a/src/js/traffic.js
+++ b/src/js/traffic.js
@@ -53,7 +53,10 @@ var onBeforeRootFrameRequestHandler = function(details) {
 
     // Not blocked
     if ( !block ) {
-        // rhill 2013-11-07: Senseless to do this for behind-the-scene requests.
+        let redirectURL = maybeRedirectRootFrame(requestHostname, requestURL);
+        if ( redirectURL !== requestURL ) {
+            return { redirectUrl: redirectURL };
+        }
         µm.cookieHunter.recordPageCookies(pageStore);
         return;
     }
@@ -72,6 +75,27 @@ var onBeforeRootFrameRequestHandler = function(details) {
 
 /******************************************************************************/
 
+// https://twitter.com/thatcks/status/958776519765225473
+
+var maybeRedirectRootFrame = function(hostname, url) {
+    let µm = µMatrix;
+    if ( µm.rawSettings.enforceEscapedFragment !== true ) { return url; }
+    let block1pScripts = µm.mustBlock(hostname, hostname, 'script');
+    let reEscapedFragment = /[?&]_escaped_fragment_=/;
+    if ( reEscapedFragment.test(url) ) {
+        return block1pScripts ? url : url.replace(reEscapedFragment, '#!') ;
+    }
+    if ( block1pScripts === false ) { return url; }
+    let pos = url.indexOf('#!');
+    if ( pos === -1 ) { return url; }
+    let separator = url.lastIndexOf('?', pos) === -1 ? '?' : '&';
+    return url.slice(0, pos) +
+           separator + '_escaped_fragment_=' +
+           url.slice(pos + 2);
+};
+
+/******************************************************************************/
+
 // Intercept and filter web requests according to white and black lists.
 
 var onBeforeRequestHandler = function(details) {