this fixes #756

4 files changed, 169 insertions, 39 deletions

diff --git a/platform/firefox/frameModule.js b/platform/firefox/frameModule.js
index a11720e..98fc107 100644
--- a/platform/firefox/frameModule.js
+++ b/platform/firefox/frameModule.js
@@ -30,6 +30,7 @@ const {Services} = Cu.import('resource://gre/modules/Services.jsm', null);
 const {XPCOMUtils} = Cu.import('resource://gre/modules/XPCOMUtils.jsm', null);
 
 const hostName = Services.io.newURI(Components.stack.filename, null, null).host;
+const rpcEmitterName = hostName + ':child-process-message';
 
 //Cu.import('resource://gre/modules/devtools/Console.jsm');
 
@@ -239,9 +240,25 @@ const contentObserver = {
                 wantXHRConstructor: false
             });
 
+            if ( Services.cpmm ) {
+                sandbox.rpc = function(details) {
+                    var svc = Services;
+                    if ( svc === undefined ) { return; }
+                    var cpmm = svc.cpmm;
+                    if ( !cpmm ) { return; }
+                    var r = cpmm.sendSyncMessage(rpcEmitterName, details);
+                    if ( Array.isArray(r) ) {
+                        return r[0];
+                    }
+                };
+            } else {
+                sandbox.rpc = function() {};
+            }
+
             sandbox.injectScript = function(script) {
-                if ( Services !== undefined ) {
-                    Services.scriptloader.loadSubScript(script, sandbox);
+                var svc = Services;
+                if ( svc !== undefined ) {
+                    svc.scriptloader.loadSubScript(script, sandbox);
                 } else {
                     // Sandbox appears void.
                     // I've seen this happens, need to investigate why.
@@ -258,9 +275,10 @@ const contentObserver = {
                 sandbox.removeMessageListener();
                 sandbox.addMessageListener =
                 sandbox.injectScript =
+                sandbox.outerShutdown =
                 sandbox.removeMessageListener =
-                sandbox.sendAsyncMessage =
-                sandbox.outerShutdown = function(){};
+                sandbox.rpc =
+                sandbox.sendAsyncMessage = function(){};
                 sandbox.vAPI = {};
                 messager = null;
             };
@@ -412,13 +430,19 @@ const LocationChangeListener = function(docShell) {
 
     var requestor = docShell.QueryInterface(Ci.nsIInterfaceRequestor);
     var ds = requestor.getInterface(Ci.nsIWebProgress);
+    if ( !ds ) {
+        return;
+    }
     var mm = requestor.getInterface(Ci.nsIContentFrameMessageManager);
-
-    if ( ds && mm && typeof mm.sendAsyncMessage === 'function' ) {
-        this.docShell = ds;
-        this.messageManager = mm;
-        ds.addProgressListener(this, Ci.nsIWebProgress.NOTIFY_LOCATION);
+    if ( !mm ) {
+        return;
+    }
+    if ( typeof mm.sendAsyncMessage !== 'function' ) {
+        return;
     }
+    this.docShell = ds;
+    this.messageManager = mm;
+    ds.addProgressListener(this, Ci.nsIWebProgress.NOTIFY_LOCATION);
 };
 
 LocationChangeListener.prototype.QueryInterface = XPCOMUtils.generateQI([
diff --git a/platform/firefox/frameScript.js b/platform/firefox/frameScript.js
index fdee50c..17cd84f 100644
--- a/platform/firefox/frameScript.js
+++ b/platform/firefox/frameScript.js
@@ -19,13 +19,11 @@
     Home: https://github.com/gorhill/uBlock
 */
 
-/* global addMessageListener, removeMessageListener, docShell */
-
 /******************************************************************************/
 
-var locationChangeListener; // Keep alive while frameScript is alive
+// https://developer.mozilla.org/en-US/Firefox/Multiprocess_Firefox/Frame_script_environment
 
-(function() {
+(function(context) {
 
 'use strict';
 
@@ -52,25 +50,36 @@ let injectContentScripts = function(win) {
 };
 
 let onLoadCompleted = function() {
-    removeMessageListener('ublock0-load-completed', onLoadCompleted);
-    injectContentScripts(content);
+    context.removeMessageListener('ublock0-load-completed', onLoadCompleted);
+    injectContentScripts(context.content);
 };
+context.addMessageListener('ublock0-load-completed', onLoadCompleted);
 
-addMessageListener('ublock0-load-completed', onLoadCompleted);
+let shutdown = function(ev) {
+    if ( ev.target !== context ) {
+        return;
+    }
+    context.removeMessageListener('ublock0-load-completed', onLoadCompleted);
+    context.removeEventListener('unload', shutdown);
+    context.locationChangeListener = null;
+    LocationChangeListener = null;
+    contentObserver = null;
+};
+context.addEventListener('unload', shutdown);
 
-if ( docShell ) {
+if ( context.docShell ) {
     let Ci = Components.interfaces;
-    let wp = docShell.QueryInterface(Ci.nsIInterfaceRequestor)
-                     .getInterface(Ci.nsIWebProgress);
+    let wp = context.docShell.QueryInterface(Ci.nsIInterfaceRequestor)
+                             .getInterface(Ci.nsIWebProgress);
     let dw = wp.DOMWindow;
 
     if ( dw === dw.top ) {
-        locationChangeListener = new LocationChangeListener(docShell);
+        context.locationChangeListener = new LocationChangeListener(context.docShell);
     }
 }
 
 /******************************************************************************/
 
-})();
+})(this);
 
 /******************************************************************************/
diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index bf531c0..8bc110b 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -70,7 +70,7 @@ vAPI.localStorage.setDefaultBool('forceLegacyToolbarButton', false);
 var cleanupTasks = [];
 
 // This must be updated manually, every time a new task is added/removed
-var expectedNumberOfCleanups = 7;
+var expectedNumberOfCleanups = 8;
 
 window.addEventListener('unload', function() {
     if ( typeof vAPI.app.onShutdown === 'function' ) {
@@ -90,10 +90,11 @@ window.addEventListener('unload', function() {
     }
 
     // frameModule needs to be cleared too
+    var frameModuleURL = vAPI.getURL('frameModule.js');
     var frameModule = {};
-    Cu.import(vAPI.getURL('frameModule.js'), frameModule);
+    Cu.import(frameModuleURL, frameModule);
     frameModule.contentObserver.unregister();
-    Cu.unload(vAPI.getURL('frameModule.js'));
+    Cu.unload(frameModuleURL);
 });
 
 /******************************************************************************/
@@ -987,15 +988,15 @@ var tabWatcher = (function() {
     };
 
     // https://developer.mozilla.org/en-US/docs/Web/Events/TabOpen
-    var onOpen = function({target}) {
-        var tabId = tabIdFromTarget(target);
-        var browser = browserFromTabId(tabId);
-        vAPI.tabs.onNavigation({
-            frameId: 0,
-            tabId: tabId,
-            url: browser.currentURI.asciiSpec,
-        });
-    };
+    //var onOpen = function({target}) {
+    //    var tabId = tabIdFromTarget(target);
+    //    var browser = browserFromTabId(tabId);
+    //    vAPI.tabs.onNavigation({
+    //        frameId: 0,
+    //        tabId: tabId,
+    //        url: browser.currentURI.asciiSpec,
+    //    });
+    //};
 
     // https://developer.mozilla.org/en-US/docs/Web/Events/TabShow
     var onShow = function({target}) {
@@ -1208,7 +1209,7 @@ vAPI.messaging = {
         return Cc['@mozilla.org/globalmessagemanager;1']
                 .getService(Ci.nsIMessageListenerManager);
     },
-    frameScript: vAPI.getURL('frameScript.js'),
+    frameScriptURL: vAPI.getURL('frameScript.js'),
     listeners: {},
     defaultHandler: null,
     NOOPFUNC: function(){},
@@ -1438,7 +1439,7 @@ vAPI.messaging.setup = function(defaultHandler) {
         this.onMessage
     );
 
-    this.globalMessageManager.loadFrameScript(this.frameScript, true);
+    this.globalMessageManager.loadFrameScript(this.frameScriptURL, true);
 
     cleanupTasks.push(function() {
         var gmm = vAPI.messaging.globalMessageManager;
@@ -1452,7 +1453,7 @@ vAPI.messaging.setup = function(defaultHandler) {
             })
         );
 
-        gmm.removeDelayedFrameScript(vAPI.messaging.frameScript);
+        gmm.removeDelayedFrameScript(vAPI.messaging.frameScriptURL);
         gmm.removeMessageListener(
             location.host + ':background',
             vAPI.messaging.onMessage
@@ -1472,6 +1473,60 @@ vAPI.messaging.broadcast = function(message) {
 };
 
 /******************************************************************************/
+/******************************************************************************/
+
+// Synchronous messaging: Firefox allows this. Chromium does not allow this.
+
+// Sometimes there is no way around synchronous messaging, as long as:
+// - the code at the other end execute fast and return quickly.
+// - it's not abused.
+// Original rationale is <https://github.com/gorhill/uBlock/issues/756>.
+// Synchronous messaging is a good solution for this case because:
+// - It's done only *once* per page load. (Keep in mind there is already a
+//   sync message sent for each single network request on a page and it's not
+//   an issue, because the code executed is trivial, which is the key -- see
+//   shouldLoadListener below).
+// - The code at the other end is fast.
+// Though vAPI.rpcReceiver was brought forth because of this one case, I
+// generalized the concept for whatever future need for synchronous messaging
+// which might arise.
+
+// https://developer.mozilla.org/en-US/Firefox/Multiprocess_Firefox/Message_Manager/Message_manager_overview#Content_frame_message_manager
+
+vAPI.rpcReceiver = (function() {
+    var calls = Object.create(null);
+    var childProcessMessageName = location.host + ':child-process-message';
+
+    var onChildProcessMessage = function(ev) {
+        var msg = ev.data;
+        if ( !msg ) { return; }
+        var fn = calls[msg.fnName];
+        if ( typeof fn === 'function' ) {
+            return fn(msg);
+        }
+    };
+
+    if ( Services.ppmm ) {
+        Services.ppmm.addMessageListener(
+            childProcessMessageName,
+            onChildProcessMessage
+        );
+    }
+
+    cleanupTasks.push(function() {
+        if ( Services.ppmm ) {
+            Services.ppmm.removeMessageListener(
+                childProcessMessageName,
+                onChildProcessMessage
+            );
+        }
+    });
+
+    return calls;
+})();
+
+/******************************************************************************/
+/******************************************************************************/
 
 var httpObserver = {
     classDescription: 'net-channel-event-sinks for ' + location.host,
@@ -1865,7 +1920,11 @@ vAPI.net.registerListeners = function() {
         var tabId = tabWatcher.tabIdFromTarget(e.target);
         var sourceTabId = null;
 
-        // Popup candidate
+        // Popup candidate: this code path is taken only for when a new top
+        // document loads, i.e. only once per document load. TODO: evaluate for
+        // popup filtering in an asynchrous manner -- it's not really required
+        // to evaluate on the spot. Still, there is currently no harm given
+        // this code path is typically taken only once per page load.
         if ( details.openerURL ) {
             for ( var browser of tabWatcher.browsers() ) {
                 var URI = browser.currentURI;
@@ -1899,8 +1958,9 @@ vAPI.net.registerListeners = function() {
             }
         }
 
-        //console.log('shouldLoadListener:', details.url);
-
+        // We are being called synchronously from the content process, so we
+        // must return ASAP. The code below merely record the details of the
+        // request into a ring buffer for later retrieval by the HTTP observer.
         var pendingReq = httpObserver.createPendingRequest(details.url);
         pendingReq.frameId = details.frameId;
         pendingReq.parentFrameId = details.parentFrameId;
diff --git a/platform/firefox/vapi-client.js b/platform/firefox/vapi-client.js
index bd6facd..07da7c8 100644
--- a/platform/firefox/vapi-client.js
+++ b/platform/firefox/vapi-client.js
@@ -31,6 +31,13 @@
 
 /******************************************************************************/
 
+// Not all sandbox are given an rpc function, so assign a dummy one it is
+// missing -- this avoids the need for constantly testing before use.
+
+self.rpc = self.rpc || function(){};
+
+/******************************************************************************/
+
 var vAPI = self.vAPI = self.vAPI || {};
 vAPI.firefox = true;
 vAPI.sessionId = String.fromCharCode(Date.now() % 26 + 97) +
@@ -67,6 +74,30 @@ vAPI.shutdown = (function() {
 
 /******************************************************************************/
 
+(function() {
+    var hostname = location.hostname;
+    if ( !hostname ) {
+        return;
+    }
+    var filters = self.rpc({
+        fnName: 'getScriptTagFilters',
+        url: location.href,
+        hostname: hostname
+    });
+    if ( typeof filters !== 'string' || filters === '' ) {
+        return;
+    }
+    var reFilters = new RegExp(filters);
+    document.addEventListener('beforescriptexecute', function(ev) {
+        if ( reFilters.test(ev.target.textContent) ) {
+            ev.preventDefault();
+            ev.stopPropagation();
+        }
+    });
+})();
+
+/******************************************************************************/
+
 vAPI.messaging = {
     channels: {},
     pending: {},
@@ -254,6 +285,12 @@ MessagingChannel.prototype.send = function(message, callback) {
 
 MessagingChannel.prototype.sendTo = function(message, toTabId, toChannel, callback) {
     var messaging = vAPI.messaging;
+    if ( !messaging ) {
+        if ( typeof callback === 'function' ) {
+            callback();
+        }
+        return;
+    }
     // Too large a gap between the last request and the last response means
     // the main process is no longer reachable: memory leaks and bad
     // performance become a risk -- especially for long-lived, dynamic