From 0f9c2205d5f1f7f1a64900ed4540e33fc1d7a443 Mon Sep 17 00:00:00 2001
From: Matt Gibson <mgibson@bitwarden.com>
Date: Tue, 26 Oct 2021 08:45:32 -0500
Subject: [PATCH] Dynamically set electron user agent (#524)

* Dynamically set electron user agent

* PR review

* linter fixes

* Test agent static version does not change

* Fix formatting
---
 electron/src/utils.ts       | 16 ++++++++++++++++
 electron/src/window.main.ts | 18 +++++++++++-------
 spec/electron/utils.spec.ts | 27 +++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 7 deletions(-)
 create mode 100644 spec/electron/utils.spec.ts

diff --git a/electron/src/utils.ts b/electron/src/utils.ts
index 80eb09794f..ce4de6058d 100644
--- a/electron/src/utils.ts
+++ b/electron/src/utils.ts
@@ -46,3 +46,19 @@ export function isSnapStore() {
 export function isWindowsPortable() {
     return process.platform === 'win32' && process.env.PORTABLE_EXECUTABLE_DIR != null;
 }
+
+/**
+ * Sanitize user agent so external resources used by the app can't built data on our users.
+ */
+export function cleanUserAgent(userAgent: string): string {
+    const userAgentItem = (startString: string, endString: string) => {
+        const startIndex = userAgent.indexOf(startString);
+        return userAgent.substring(startIndex, userAgent.indexOf(endString, startIndex) + 1);
+    };
+    const systemInformation = '(Windows NT 10.0; Win64; x64)';
+
+    // Set system information, remove bitwarden, and electron information
+    return userAgent.replace(userAgentItem('(', ')'), systemInformation)
+        .replace(userAgentItem('Bitwarden', ' '), '')
+        .replace(userAgentItem('Electron', ' '), '');
+}
diff --git a/electron/src/window.main.ts b/electron/src/window.main.ts
index 28b3ca0abe..f51dc11410 100644
--- a/electron/src/window.main.ts
+++ b/electron/src/window.main.ts
@@ -11,6 +11,7 @@ import { StorageService } from 'jslib-common/abstractions/storage.service';
 
 import { ElectronConstants } from './electronConstants';
 import {
+    cleanUserAgent,
     isDev,
     isMacAppStore,
     isSnapStore,
@@ -139,13 +140,16 @@ export class WindowMain {
         this.win.show();
 
         // and load the index.html of the app.
-        this.win.loadURL(url.format({
-            protocol: 'file:',
-            pathname: path.join(__dirname, '/index.html'),
-            slashes: true,
-        }), {
-                userAgent: 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:74.0) Gecko/20100101 Firefox/74.0',
-            });
+        this.win.loadURL(url.format(
+            {
+                protocol: 'file:',
+                pathname: path.join(__dirname, '/index.html'),
+                slashes: true,
+            }),
+            {
+                userAgent: cleanUserAgent(this.win.webContents.userAgent),
+            }
+        );
 
         // Open the DevTools.
         if (isDev()) {
diff --git a/spec/electron/utils.spec.ts b/spec/electron/utils.spec.ts
new file mode 100644
index 0000000000..b350a82da9
--- /dev/null
+++ b/spec/electron/utils.spec.ts
@@ -0,0 +1,27 @@
+import { cleanUserAgent } from 'jslib-electron/utils';
+
+const expectedUserAgent = `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/${process.versions.chrome} Safari/537.36`;
+
+describe('cleanUserAgent', () => {
+    it('cleans mac agent', () => {
+        const initialMacAgent = `Mozilla/5.0 (Macintosh; Intel Mac OS X 11_6_0) AppleWebKit/537.36 (KHTML, like Gecko) Bitwarden/${process.version} Chrome/${process.versions.chrome} Electron/${process.versions.electron} Safari/537.36`;
+        expect(cleanUserAgent(initialMacAgent)).toEqual(expectedUserAgent);
+    });
+
+    it('cleans windows agent', () => {
+        const initialWindowsAgent = `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Bitwarden/${process.version} Chrome/${process.versions.chrome} Electron/${process.versions.electron} Safari/537.36`;
+        expect(cleanUserAgent(initialWindowsAgent)).toEqual(expectedUserAgent);
+    });
+
+    it('cleans linux agent', () => {
+        const initialWindowsAgent = `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Bitwarden/${process.version} Chrome/${process.versions.chrome} Electron/${process.versions.electron} Safari/537.36`;
+        expect(cleanUserAgent(initialWindowsAgent)).toEqual(expectedUserAgent);
+    });
+
+    it('does not change version numbers', () => {
+        const expected = `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Safari/537.36`;
+        const initialAgent = `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Bitwarden/1.28.3 Chrome/87.0.4280.141 Electron/11.4.5 Safari/537.36`;
+
+        expect(cleanUserAgent(initialAgent)).toEqual(expected);
+    });
+});