[xss] Refactor for non-persistence.

src/bg/Settings.js

@@ -188,12 +188,6 @@ var Settings = {
 
     if (xssUserChoices) await XSS.saveUserChoices(xssUserChoices);
 
-    if (ns.sync.xss) {
-      XSS.start();
-    } else {
-      XSS.stop();
-    }
-
     if (reloadOptionsUI) await this.reloadOptionsUI();
   },
 

src/bg/main.js

@@ -89,12 +89,6 @@
     }
 
     await RequestGuard.start();
-    await XSS.start(); // we must start it anyway to initialize sub-objects
-    if (!ns.sync.xss) {
-      XSS.stop();
-    }
-
-
 
     try {
       await Messages.send("started");

src/xss/Exceptions.js

@@ -24,13 +24,6 @@ XSS.Exceptions = (() => {
 
   var Exceptions = {
 
-    async getWhitelist() {
-      return (await Storage.get("sync", "xssWhitelist")).xssWhitelist;
-    },
-    async setWhitelist(xssWhitelist) {
-      await Storage.set("sync", {xssWhitelist});
-    },
-
     async shouldIgnore(xssReq) {
       function logEx(...args) {
         debug("[XSS preprocessing] Ignoring %o", xssReq, ...args);

src/xss/XSS.js

@@ -22,6 +22,8 @@
 
 var XSS = (() => {
 
+  let initializing;
+
   const ABORT = {cancel: true}, ALLOW = {};
 
   let baseTTL = 20000; // timeout in milliseconds for each worker to perform
@@ -78,6 +80,8 @@ var XSS = (() => {
   }
 
   async function requestListener(request) {
+    await initializing; // depends also on ns.initializing
+    if (!ns.sync.xss) return;
 
     {
       let {type} = request;
@@ -88,8 +92,10 @@ var XSS = (() => {
         }
       }
     }
+
     let xssReq = XSS.parseRequest(request);
     if (!xssReq) return null;
+
     let userResponse = await getUserResponse(xssReq);
     if (userResponse) return userResponse;
 
@@ -190,49 +196,31 @@ var XSS = (() => {
     };
   }
 
-  return {
-    async start() {
-      if (!UA.isMozilla) return; // async webRequest is supported on Mozilla only
-
-      let {onBeforeRequest, onCompleted, onErrorOccurred} = browser.webRequest;
-
-      if (onBeforeRequest.hasListener(requestListener)) return;
+  if (UA.isMozilla) {
+    // async webRequest is supported on Mozilla only
+    const {onBeforeRequest, onCompleted, onErrorOccurred} = browser.webRequest;
+    const filter = {
+      urls: ["*://*/*"],
+      types: ["main_frame", "sub_frame", "object"]
+    };
 
+    initializing = (async () => {
       await include([
         "/nscl/common/AsyncRegExp.js",
         "/xss/Exceptions.js"
       ]);
 
-      this._userChoices = (await Storage.get("sync", "xssUserChoices")).xssUserChoices || {};
+      XSS._userChoices = (await Storage.get("sync", "xssUserChoices")).xssUserChoices || {};
+      await ns.initializing;
+    })();
 
-      // convert old style whitelist if stored
-      let oldWhitelist = await XSS.Exceptions.getWhitelist();
-      if (oldWhitelist) {
-        for (let [destOrigin, sources] of Object.entries(oldWhitelist)) {
-          for (let srcOrigin of sources) {
-            this._userChoices[`${srcOrigin}>${destOrigin}`] = "allow";
-          }
-        }
-        XSS.Exceptions.setWhitelist(null);
-      }
-      let filter = {
-        urls: ["*://*/*"],
-        types: ["main_frame", "sub_frame", "object"]
-      };
-      onBeforeRequest.addListener(requestListener, filter, ["blocking", "requestBody"]);
-      if (!onCompleted.hasListener(doneListener)) {
-        onCompleted.addListener(doneListener, filter);
-        onErrorOccurred.addListener(doneListener, filter);
-      }
-    },
+    onBeforeRequest.addListener(requestListener, filter, ["blocking", "requestBody"]);
+    onCompleted.addListener(doneListener, filter);
+    onErrorOccurred.addListener(doneListener, filter);
+  }
 
-    stop() {
-      let {onBeforeRequest} = browser.webRequest;
-      if (onBeforeRequest.hasListener(requestListener)) {
-        onBeforeRequest.removeListener(requestListener);
-      }
-    },
 
+  return {
     parseRequest(request) {
       let {
         requestId,