Fix launching Snap-based Firefox

Author: pimterry

src/browsers.ts

@@ -81,6 +81,13 @@ export const getAvailableBrowsers = async (configPath: string) => {
     return (await getLauncher(configPath)).browsers;
 };
 
+export const getBrowserDetails = async (configPath: string, variant: string): Promise<Browser | undefined> => {
+    const browsers = await getAvailableBrowsers(configPath);
+
+    // Get the details for the first matching browsers that is installed:
+    return browsers.find(b => b.name === variant);
+};
+
 export { LaunchOptions };
 
 export const launchBrowser = async (url: string, options: LaunchOptions, configPath: string) => {

src/interceptors/chromium-based-interceptors.ts

@@ -4,10 +4,9 @@ import { generateSPKIFingerprint } from 'mockttp';
 import { HtkConfig } from '../config';
 
 import {
-    getAvailableBrowsers,
+    getBrowserDetails,
     launchBrowser,
     BrowserInstance,
-    Browser,
     LaunchOptions
 } from '../browsers';
 import { delay } from '../util/promise';
@@ -18,13 +17,6 @@ import { Interceptor } from '.';
 import { logError } from '../error-tracking';
 import { WEBEXTENSION_INSTALL } from '../webextension';
 
-const getBrowserDetails = async (config: HtkConfig, variant: string): Promise<Browser | undefined> => {
-    const browsers = await getAvailableBrowsers(config.configPath);
-
-    // Get the details for the first of these browsers that is installed.
-    return _.find(browsers, b => b.name === variant);
-};
-
 const getChromiumLaunchOptions = async (
     browser: string,
     config: HtkConfig,
@@ -91,7 +83,7 @@ abstract class FreshChromiumBasedInterceptor implements Interceptor {
     }
 
     async isActivable() {
-        const browserDetails = await getBrowserDetails(this.config, this.variantName)
+        const browserDetails = await getBrowserDetails(this.config.configPath, this.variantName)
         return !!browserDetails;
     }
 
@@ -101,7 +93,7 @@ abstract class FreshChromiumBasedInterceptor implements Interceptor {
         const hideWarningServer = new HideWarningServer(this.config);
         await hideWarningServer.start('https://amiusing.httptoolkit.tech');
 
-        const browserDetails = await getBrowserDetails(this.config, this.variantName);
+        const browserDetails = await getBrowserDetails(this.config.configPath, this.variantName);
 
         const browser = await launchBrowser(hideWarningServer.hideWarningUrl,
             await getChromiumLaunchOptions(
@@ -186,7 +178,7 @@ abstract class ExistingChromiumBasedInterceptor implements Interceptor {
     ) { }
 
     async browserDetails() {
-        return getBrowserDetails(this.config, this.variantName);
+        return getBrowserDetails(this.config.configPath, this.variantName);
     }
 
     isActive(proxyPort: number | string) {
@@ -273,7 +265,7 @@ abstract class ExistingChromiumBasedInterceptor implements Interceptor {
             }
         }
 
-        const browserDetails = await getBrowserDetails(this.config, this.variantName);
+        const browserDetails = await getBrowserDetails(this.config.configPath, this.variantName);
         const launchOptions = await getChromiumLaunchOptions(
             browserDetails ? browserDetails.name : this.variantName,
             this.config,

src/interceptors/fresh-firefox.ts

@@ -6,9 +6,11 @@ import { APP_ROOT } from '../constants';
 import { HtkConfig } from '../config';
 import { logError } from '../error-tracking';
 
-import { getAvailableBrowsers, launchBrowser, BrowserInstance } from '../browsers';
 import { delay } from '../util/promise';
 import { isErrorLike } from '../util/error';
+import { isSnap, getSnapConfigPath } from '../util/snap';
+
+import { launchBrowser, BrowserInstance, getBrowserDetails } from '../browsers';
 import { readFile, canAccess, deleteFolder } from '../util/fs';
 import { windowsKill, spawnToResult } from '../util/process-management';
 import { MessageServer } from '../message-server';
@@ -73,23 +75,20 @@ export class FreshFirefox implements Interceptor {
 
     constructor(private config: HtkConfig) { }
 
-    private readonly firefoxProfilePath = path.join(this.config.configPath, 'firefox-profile');
-
     isActive(proxyPort: number | string) {
         return browsers[proxyPort] != null && !!browsers[proxyPort].pid;
     }
 
     async isActivable() {
-        const availableBrowsers = await getAvailableBrowsers(this.config.configPath);
-
-        const firefoxBrowser = _.find(availableBrowsers, { name: 'firefox' });
+        const firefoxBrowser = await getBrowserDetails(this.config.configPath, 'firefox');
 
         return !!firefoxBrowser && // Must have Firefox installed
             parseInt(firefoxBrowser.version.split('.')[0], 0) >= 58 && // Must use cert9.db
             await getCertutilCommand().then(() => true).catch(() => false) // Must have certutil available
     }
 
     async startFirefox(
+        profilePath: string,
         initialServer: MessageServer | CertCheckServer,
         proxyPort?: number,
         existingPrefs = {}
@@ -98,7 +97,7 @@ export class FreshFirefox implements Interceptor {
 
         const browser = await launchBrowser(initialUrl, {
             browser: 'firefox',
-            profile: this.firefoxProfilePath,
+            profile: profilePath,
             proxy: proxyPort ? `127.0.0.1:${proxyPort}` : undefined,
             prefs: _.assign(
                 existingPrefs,
@@ -184,7 +183,7 @@ export class FreshFirefox implements Interceptor {
     }
 
     // Create the profile. We need to run FF to do its setup, then close it & edit more ourselves.
-    async setupFirefoxProfile() {
+    async setupFirefoxProfile(profilePath: string) {
         const messageServer = new MessageServer(
             this.config,
             `HTTP Toolkit is preparing a Firefox profile, please wait...`
@@ -193,15 +192,15 @@ export class FreshFirefox implements Interceptor {
 
         let messageShown: Promise<void> | true = messageServer.waitForSuccess().catch(logError);
 
-        profileSetupBrowser = await this.startFirefox(messageServer);
+        profileSetupBrowser = await this.startFirefox(profilePath, messageServer);
         profileSetupBrowser.process.once('close', (exitCode) => {
             console.log("Profile setup Firefox closed");
             messageServer.stop();
             profileSetupBrowser = undefined;
 
             if (messageShown !== true) {
                 logError(`Firefox profile setup failed with code ${exitCode}`);
-                deleteFolder(this.firefoxProfilePath).catch(console.warn);
+                deleteFolder(profilePath).catch(console.warn);
             }
         });
 
@@ -222,7 +221,7 @@ export class FreshFirefox implements Interceptor {
         const certUtilResult = await spawnToResult(
             certutil.command, [
                 '-A',
-                '-d', `sql:${this.firefoxProfilePath}`,
+                '-d', `sql:${profilePath}`,
                 '-t', 'C,,',
                 '-i', this.config.https.certPath,
                 '-n', 'HTTP Toolkit'
@@ -240,7 +239,14 @@ export class FreshFirefox implements Interceptor {
     async activate(proxyPort: number) {
         if (this.isActive(proxyPort) || !!profileSetupBrowser) return;
 
-        const firefoxPrefsFile = path.join(this.firefoxProfilePath, 'prefs.js');
+        const browserDetails = await getBrowserDetails(this.config.configPath, 'firefox');
+        if (!browserDetails) throw new Error('Firefox could not be detected');
+
+        const profilePath = await isSnap(browserDetails.command)
+            ? path.join(getSnapConfigPath('firefox'), 'profile')
+            : path.join(this.config.configPath, 'firefox-profile');
+
+        const firefoxPrefsFile = path.join(profilePath, 'prefs.js');
 
         let existingPrefs: _.Dictionary<any> = {};
 
@@ -250,7 +256,7 @@ export class FreshFirefox implements Interceptor {
             This helps avoid initial Firefox profile setup request noise, and tidies up some awkward UX where
             firefox likes to open extra welcome windows/tabs on first run.
             */
-            await this.setupFirefoxProfile();
+            await this.setupFirefoxProfile(profilePath);
         }
 
         // We need to preserve & reuse any existing preferences, to avoid issues
@@ -272,7 +278,7 @@ export class FreshFirefox implements Interceptor {
         const certCheckServer = new CertCheckServer(this.config);
         await certCheckServer.start("https://amiusing.httptoolkit.tech");
 
-        const browser = await this.startFirefox(certCheckServer, proxyPort, existingPrefs);
+        const browser = await this.startFirefox(profilePath, certCheckServer, proxyPort, existingPrefs);
 
         let certCheckSuccessful: boolean | undefined;
         certCheckServer.waitForSuccess().then(() => {
@@ -300,7 +306,7 @@ export class FreshFirefox implements Interceptor {
                         ? "failed"
                         : "did not complete"
                 } with FF exit code ${exitCode}`);
-                deleteFolder(this.firefoxProfilePath).catch(console.warn);
+                deleteFolder(profilePath).catch(console.warn);
             }
         });
 

src/util/fs.ts

@@ -56,8 +56,11 @@ export const deleteFolder = promisify(rimraf);
 export const ensureDirectoryExists = (path: string) =>
     checkAccess(path).catch(() => mkDir(path, { recursive: true }));
 
+export const resolveCommandPath = (path: string): Promise<string | undefined> =>
+    lookpath(path);
+
 export const commandExists = (path: string): Promise<boolean> =>
-    lookpath(path).then((result) => result !== undefined);
+    resolveCommandPath(path).then((result) => result !== undefined);
 
 export const createTmp = (options: tmp.Options = {}) => new Promise<{
     path: string,

src/util/snap.ts

@@ -0,0 +1,37 @@
+import os = require('os');
+import path = require('path');
+
+import fs = require('./fs');
+
+export async function isSnap(bin: string) {
+    if (os.platform() !== 'linux') return false;
+
+    const binPath = await fs.resolveCommandPath(bin);
+    if (!binPath) {
+        throw new Error(`Can't resolve command ${bin}`);
+    }
+
+    // Most snaps directly run from the Snap bin folder:
+    if (binPath.startsWith('/snap/bin/')) return true;
+
+    // Firefox is the only known example that doesn't - it uses a
+    // wrapper script, so we just look for that:
+    if (binPath === '/usr/bin/firefox') {
+        const content = await fs.readFile(binPath);
+        return content.includes('exec /snap/bin/firefox');
+    }
+
+    return false;
+}
+
+// For all Snaps, any data we want to inject needs to live inside the
+// Snap's data directory - we put it in a .httptoolkit folder.
+export const getSnapConfigPath = (appName: string) => {
+    return path.join(
+        os.homedir(),
+        'snap',
+        appName,
+        'current',
+        '.httptoolkit'
+    );
+}