feat: add the slim mode for disabling performance-heavy evasions (#263)

* feat: add the slim mode for disabling performance-heavy evasions * chore: naming conventions
apify · Jan 24, 2024 · 1c8b0f5 · 1c8b0f5
1 parent 7e37117
commit 1c8b0f5
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Showing 3 changed files with 48 additions and 6 deletions.
diff --git a/packages/fingerprint-generator/src/fingerprint-generator.ts b/packages/fingerprint-generator/src/fingerprint-generator.ts
@@ -63,6 +63,7 @@ export type Fingerprint = {
     multimediaDevices: string[];
     fonts: string[];
     mockWebRTC: boolean;
+    slim?: boolean;
 }
 
 export type BrowserFingerprintWithHeaders = {
@@ -82,6 +83,13 @@ export interface FingerprintGeneratorOptions extends HeaderGeneratorOptions {
         maxHeight?: number;
     };
     mockWebRTC?: boolean;
+    /**
+     * Enables the slim mode for the fingerprint injection.
+     * This disables some performance-heavy evasions, but might decrease benchmark scores.
+     *
+     * Try enabling this if you are experiencing performance issues with the fingerprint injection.
+     */
+    slim?: boolean;
 }
 
 /**
@@ -99,6 +107,7 @@ export class FingerprintGenerator extends HeaderGenerator {
         this.fingerprintGlobalOptions = {
             screen: options.screen,
             mockWebRTC: options.mockWebRTC,
+            slim: options.slim,
         };
         this.fingerprintGeneratorNetwork = new BayesianNetwork({ path: `${__dirname}/data_files/fingerprint-network-definition.zip` });
     }
@@ -181,6 +190,7 @@ export class FingerprintGenerator extends HeaderGenerator {
                 fingerprint: {
                     ...this.transformFingerprint(fingerprint),
                     mockWebRTC: options.mockWebRTC ?? this.fingerprintGlobalOptions.mockWebRTC ?? false,
+                    slim: options.slim ?? this.fingerprintGlobalOptions.slim ?? false,
                 },
                 headers,
             };

diff --git a/packages/fingerprint-injector/src/fingerprint-injector.ts b/packages/fingerprint-injector/src/fingerprint-injector.ts
@@ -160,6 +160,7 @@ export class FingerprintInjector {
                 audioCodecs,
                 videoCodecs,
                 mockWebRTC,
+                slim,
                 // @ts-expect-error internal browser code
             } = fp as EnhancedFingerprint;
 
@@ -203,6 +204,12 @@ export class FingerprintInjector {
 
             if (mockWebRTC) blockWebRTC();
 
+            if (slim) {
+                // @ts-expect-error internal browser code
+                // eslint-disable-next-line dot-notation
+                window['slim'] = true;
+            }
+
             overrideIntlAPI(navigatorProps.language);
             overrideStatic();
 

diff --git a/packages/fingerprint-injector/src/utils.js b/packages/fingerprint-injector/src/utils.js
@@ -1,7 +1,19 @@
-const isHeadlessChromium = () => /headless/i.test(navigator.userAgent) && navigator.plugins.length === 0;
-const isChrome = () => navigator.userAgent.includes("Chrome");
-const isFirefox = () => navigator.userAgent.includes("Firefox");
-const isSafari = () => navigator.userAgent.includes("Safari") && !navigator.userAgent.includes("Chrome");
+const isHeadlessChromium = /headless/i.test(navigator.userAgent) && navigator.plugins.length === 0;
+const isChrome = navigator.userAgent.includes("Chrome");
+const isFirefox = navigator.userAgent.includes("Firefox");
+const isSafari = navigator.userAgent.includes("Safari") && !navigator.userAgent.includes("Chrome");
+
+let slim = null;
+function getSlim() {
+    if(slim === null) {
+        slim = window.slim || false;
+        if(typeof window.slim !== 'undefined') {
+            delete window.slim;
+        }
+    }
+
+    return slim;
+}
 
 // This file contains utils that are build and included on the window object with some randomized prefix.
 
@@ -102,7 +114,14 @@ function overrideInstancePrototype(instance, overrideObj) {
     }
 }
 
+/**
+ * Updates the .toString method in Function.prototype to return a native string representation of the function.
+ * @param {*} proxyObj 
+ * @param {*} originalObj 
+ */
 function redirectToString(proxyObj, originalObj) {
+    if(getSlim()) return;
+
     const handler = {
         setPrototypeOf: (target, newProto) => {
             try {
@@ -131,6 +150,7 @@ function redirectToString(proxyObj, originalObj) {
             const hasSameProto = Object.getPrototypeOf(
                 Function.prototype.toString,
             ).isPrototypeOf(ctx.toString); // eslint-disable-line no-prototype-builtins
+
             if (!hasSameProto) {
                 // Pass the call on to the local Function.prototype.toString instead
                 return ctx.toString();
@@ -194,6 +214,11 @@ function redefineProperty(masterObject, propertyName, descriptorOverrides = {})
     });
 }
 
+/**
+ * For all the traps in the passed proxy handler, we wrap them in a try/catch and modify the error stack if they throw.
+ * @param {*} handler A proxy handler object
+ * @returns A new proxy handler object with error stack modifications
+ */
 function stripProxyFromErrors(handler) {
     const newHandler = {};
     // We wrap each trap in the handler in a try/catch and modify the error stack if they throw
@@ -535,7 +560,7 @@ function overrideUserAgentData(userAgentData) {
 };
 
 function fixWindowChrome(){
-    if( isChrome() && !window.chrome ){
+    if(isChrome && !window.chrome){
         Object.defineProperty(window, 'chrome', {
             writable: true,
             enumerable: true,
@@ -704,7 +729,7 @@ function fixPluginArray() {
 
 function runHeadlessFixes(){
     try {
-        if( isHeadlessChromium() ){
+        if( isHeadlessChromium ){
             fixWindowChrome();
             fixPermissions();
             fixIframeContentWindow();