Transform AST manually

Author: leo60228

lib/background.js

@@ -1,8 +1,8 @@
 import browser from 'webextension-polyfill';
 import transform from './transform.js';
 
-function jsHandler(details) {
-    let filter = browser.webRequest.filterResponseData(details.requestId);
+function jsHandler(event) {
+    let filter = browser.webRequest.filterResponseData(event.requestId);
 
     let buf = '';
     let decoder = new TextDecoder('utf-8');
@@ -12,19 +12,26 @@ function jsHandler(details) {
         buf += decoder.decode(event.data, { stream: true });
     };
 
-    filter.onstop = async () => {
-        const script = await transform(buf);
+    filter.onstop = () => {
+        const script = transform(buf);
         filter.write(encoder.encode(script));
         filter.disconnect();
     };
 
     return {};
 }
 
-browser.webRequest.onBeforeRequest.addListener(
-    jsHandler,
-    {
-        urls: ["https://d35iw2jmbg6ut8.cloudfront.net/static/js/*.js"]
-    },
-    ["blocking"]
-);
+function requestCacheHandler(event) {
+    return {
+        requestHeaders: event.requestHeaders.filter(x => !['if-none-match', 'if-modified-since'].includes(x.name.toLowerCase()))
+    };
+}
+
+const filter = {
+    urls: ['https://d35iw2jmbg6ut8.cloudfront.net/static/js/main.*.chunk.js']
+};
+
+browser.webRequest.onBeforeRequest.addListener(jsHandler, filter, ['blocking']);
+browser.webRequest.onBeforeSendHeaders.addListener(requestCacheHandler, filter, ['blocking', 'requestHeaders']);
+
+browser.webRequest.handlerBehaviorChanged();

lib/transform.js

@@ -1,16 +1,28 @@
-import { transformAsync } from '@babel/core';
 import alwaysFk from './transforms/alwaysFk.js';
+import { parseScript } from 'meriyah';
+import { walk } from 'estree-walker';
+import { generate } from 'astring';
 
-const options = {
-    plugins: [alwaysFk],
-    generatorOpts: {
-        compact: true
-    }
-};
-
-export default async function transform(source) {
+export default function transform(source) {
     console.time('transforming');
-    const { code } = await transformAsync(source, options);
+
+    console.time('parsing');
+    const ast = parseScript(source);
+    console.timeEnd('parsing');
+
+    console.time('walking');
+    walk(ast, {
+        enter(node) {
+            alwaysFk(node, this);
+        }
+    });
+    console.timeEnd('walking');
+
+    console.time('writing');
+    const transformed = generate(ast);
+    console.timeEnd('writing');
+
     console.timeEnd('transforming');
-    return code;
+
+    return transformed;
 }

lib/transforms/alwaysFk.js

@@ -1,27 +1,23 @@
-export default function({ types: t }) {
-    return {
-        visitor: {
-            ConditionalExpression(path) {
-                if (t.isLogicalExpression(path.node.test)) {
-                    if (path.node.test.operator !== '&&') return;
-                    if (!t.isBinaryExpression(path.node.test.left)) return;
-                    if (!t.isMemberExpression(path.node.test.left.right)) return;
-                    if (path.node.test.left.right.computed) return;
-                    if (path.node.test.left.right.property.name !== 'Forbidden_Knowledge_Access') return;
+export default function alwaysFk(node, ctx) {
+    if (node.type !== 'ConditionalExpression') return;
 
-                    if (t.isBinaryExpression(path.node.test.right) && t.isStringLiteral(path.node.test.right.left)) {
-                        path.node.test = path.node.test.right;
-                    } else {
-                        path.replaceWith(path.node.consequent);
-                    }
-                } else if (t.isBinaryExpression(path.node.test)) {
-                    if (!t.isMemberExpression(path.node.test.right)) return;
-                    if (path.node.test.right.computed) return;
-                    if (path.node.test.right.property.name !== 'Forbidden_Knowledge_Access') return;
+    if (node.test.type === 'LogicalExpression') {
+        if (node.test.operator !== '&&') return;
+        if (node.test.left.type !== 'BinaryExpression') return;
+        if (node.test.left.right.type !== 'MemberExpression') return;
+        if (node.test.left.right.computed) return;
+        if (node.test.left.right.property.name !== 'Forbidden_Knowledge_Access') return;
 
-                    path.replaceWith(path.node.consequent);
-                }
-            }
+        if (node.test.right.type === 'BinaryExpression' && node.test.right.left.type === 'Literal') {
+            node.test = node.test.right;
+        } else {
+            ctx.replace(node.consequent);
         }
+    } else if (node.test.type === 'BinaryExpression') {
+        if (node.test.right.type !== 'MemberExpression') return;
+        if (node.test.right.computed) return;
+        if (node.test.right.property.name !== 'Forbidden_Knowledge_Access') return;
+
+        ctx.replace(node.consequent);
     }
 }

package.json

@@ -30,13 +30,11 @@
         "webpack-cli": "^4.5.0"
     },
     "dependencies": {
-        "@babel/core": "^7.13.15",
         "@popperjs/core": "^2.8.6",
-        "assert": "^2.0.0",
-        "buffer": "^6.0.3",
+        "astring": "^1.7.4",
         "camelcase": "^6.2.0",
-        "path-browserify": "^1.0.1",
-        "process": "^0.11.10",
+        "estree-walker": "^3.0.0",
+        "meriyah": "^4.1.5",
         "webextension-polyfill": "^0.7.0"
     },
     "type": "module"

webpack.config.mjs

@@ -1,10 +1,6 @@
 import { dirname, resolve } from 'path';
 import { fileURLToPath } from 'url';
 import WebExtWebpackPlugin from '@leo60228/web-ext-webpack-plugin';
-import { createRequire } from 'module';
-import webpack from 'webpack';
-
-const require = createRequire(import.meta.url);
 
 const cwd = dirname(fileURLToPath(import.meta.url));
 const addonDir = resolve(cwd, 'addon');
@@ -31,10 +27,6 @@ const config = env => ({
             firefoxProfile: resolve(cwd, '.ff-profile'),
             profileCreateIfMissing: true,
             keepProfileChanges: true
-        }),
-        new webpack.ProvidePlugin({
-            process: 'process/browser',
-            Buffer: 'buffer/'
         })
     ],
     node: {
@@ -51,13 +43,6 @@ const config = env => ({
                 type: 'asset/source'
             }
         ]
-    },
-    resolve: {
-        fallback: {
-            path: require.resolve('path-browserify'),
-            assert: require.resolve('assert/'),
-            fs: false
-        }
     }
 });