Various changes in order to make startup and error handling more robust.

html/offline.html

@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Offline</title>
+    <style>
+        html,
+        body {
+            width: 100%;
+            height: 100%;
+            margin: 0;
+            background: #000;
+        }
+    </style>
+</head>
+
+<body></body>
+
+</html>

html/onboarding.html

@@ -30,6 +30,7 @@
             line-height: 1;
             margin: 1rem 0 1.333rem 0;
         }
+
         h2 {
             margin-bottom: 2.25rem;
         }
@@ -113,7 +114,8 @@
         }
 
 
-        td, th {
+        td,
+        th {
             margin: 0;
             padding: 1rem;
             border-top: 1px solid lightblue;

main.js

@@ -1,9 +1,10 @@
 const { app, BrowserWindow, nativeTheme, Menu, MenuItem } = require('electron/main');
 const path = require('node:path');
+const { fileURLToPath } = require('node:url');
 const fs = require('fs');
 const log = require('electron-log/main');
-const isReachable = require('is-reachable');
-const { setInterval } = require('node:timers/promises');
+const { default: isReachable } = require('is-reachable');
+const { setTimeout: delay } = require('node:timers/promises');
 const config = require('./js/config.js');
 const { Config } = require('./js/config.js');
 
@@ -14,6 +15,17 @@ const { Config } = require('./js/config.js');
 
 let win;
 let menu;
+let navigationController;
+let navigationRequest = 0;
+let restartScheduled = false;
+let rendererRecoveryScheduled = false;
+let restartTimer;
+
+const restartArgument = '--tooloop-restart-count=';
+const restartCount = Number(
+    process.argv.find(argument => argument.startsWith(restartArgument))?.slice(restartArgument.length) || 0
+);
+const maxAutomaticRestarts = 3;
 
 const isMac = process.platform === 'darwin';
 
@@ -56,7 +68,34 @@ function createMainWindow() {
         }
         return { action: 'deny' };
     });
-    win.webContents.on("did-fail-load", (event) => log.error(event));
+    win.webContents.on("did-fail-load", (event) => {
+        log.error(event);
+        if (event.isMainFrame && event.errorCode !== -3 && config.data?.url) {
+            loadOfflinePage();
+        }
+    });
+    win.webContents.on("render-process-gone", (_event, details) => {
+        rendererRecoveryScheduled = false;
+        log.error('Renderer process gone: ' + JSON.stringify(details));
+        loadOfflinePage();
+    });
+    win.webContents.on("unresponsive", () => {
+        log.error('Renderer became unresponsive');
+        if (rendererRecoveryScheduled || win.isDestroyed()) return;
+
+        rendererRecoveryScheduled = true;
+        try {
+            win.webContents.forcefullyCrashRenderer();
+        } catch (error) {
+            rendererRecoveryScheduled = false;
+            log.error('Could not restart renderer: ' + (error?.stack || error));
+            loadOfflinePage();
+        }
+    });
+    win.webContents.on("responsive", () => {
+        rendererRecoveryScheduled = false;
+        log.info('Renderer became responsive');
+    });
     win.on("page-title-updated", (event) => event.preventDefault());
 
     // Load page from config file
@@ -74,6 +113,13 @@ function createMainWindow() {
     }
 }
 
+function loadOfflinePage() {
+    log.warn('Loading offline page');
+    if (win && !win.isDestroyed()) {
+        win.loadFile(path.join(__dirname, 'html/offline.html'));
+    }
+}
+
 
 /**
  * Creates all available keyboard shortcuts
@@ -117,14 +163,17 @@ function createMenu() {
  * @returns `true` if the url is allowed, `false` otherwise
  */
 function validateDomain(event) {
-    if (config == undefined) return true;
+    if (config == undefined || config.data == undefined) return true;
 
     let url = new URL(event.url);
 
     // allow local urls
     if (['file:', 'file'].includes(url.protocol)) return true;
 
-    if ('whitelist' in config && !config.whitelist.includes(url.hostname)) {
+    if ('whitelist' in config.data &&
+        Array.isArray(config.data.whitelist) &&
+        config.data.whitelist.length > 0 &&
+        !config.data.whitelist.includes(url.hostname)) {
         event.preventDefault();
         log.info("Navigation to " + event.url + " prevented");
         return false;
@@ -140,47 +189,96 @@ function validateDomain(event) {
  * @param {string} testurl 
  */
 async function loadUrlAsync(testurl) {
+    const request = ++navigationRequest;
+    navigationController?.abort();
+    navigationController = new AbortController();
+    const { signal } = navigationController;
+
     try {
         let url = new URL(testurl);
         // If it’s an online url, test whether it’s reachable
         if (['https:', 'http:', 'https', 'http'].includes(url.protocol)) {
+            let fallbackShown = false;
 
-            reachable = await isReachable(url.href);
-            if (reachable) {
-                log.info("Successfull access to " + url.hostname);
-                log.info("Loading " + config.data.url);
-                win.loadURL(config.data.url);
-            } else {
-                log.warn("Could not reach " + url.hostname);
+            while (!signal.aborted && request === navigationRequest) {
+                const timeoutSignal = AbortSignal.timeout(3000);
+                const reachable = await isReachable(url.href, {
+                    signal: AbortSignal.any([signal, timeoutSignal])
+                });
 
-                for await (_ of setInterval(1000)) {
-                    reachable = await isReachable(url.href);
-                    if (reachable) {
-                        log.info("Successfull access to " + url.hostname);
-                        log.info("Loading " + config.data.url);
-                        win.loadURL(config.data.url);
-                        // break the interval
-                        break;
-                    } else {
-                        log.warn("Could not reach " + url.hostname);
-                    }
+                if (signal.aborted || request !== navigationRequest) return;
+
+                if (reachable) {
+                    log.info("Successful access to " + url.hostname);
+                    log.info("Loading " + testurl);
+                    if (!win.isDestroyed()) win.loadURL(testurl);
+                    return;
                 }
 
+                log.warn("Could not reach " + url.hostname);
+                if (!fallbackShown && !win.isDestroyed()) {
+                    loadOfflinePage();
+                    fallbackShown = true;
+                }
+                await delay(1000, undefined, { signal });
             }
 
         }
-        // Load other protocols (i. e. offline) immedately
+        // Load local files and other protocols immediately
+        else if (url.protocol === 'file:') {
+            if (!signal.aborted && request === navigationRequest && !win.isDestroyed()) {
+                await win.loadFile(fileURLToPath(url), {
+                    search: url.search,
+                    hash: url.hash
+                });
+            }
+        }
         else {
-            win.loadURL(config.data.url);
+            if (!signal.aborted && request === navigationRequest && !win.isDestroyed()) {
+                win.loadURL(testurl);
+            }
         }
 
     } catch (err) {
+        if (signal.aborted || request !== navigationRequest) return;
         log.error(err.message);
         // Load fallback page
-        win.loadFile('./html/onboarding.html');
+        loadOfflinePage();
     }
 }
 
+function resolveLogPath() {
+    if (config.data != undefined && 'logPath' in config.data) {
+        if (fs.existsSync(config.data.logPath)) {
+            return config.data.logPath;
+        } else {
+            return "tooloop-kiosk-browser.log";
+        }
+    }
+}
+
+
+function restartAfterFatalError(error) {
+    log.error('Fatal main-process error: ' + (error?.stack || error));
+    if (restartScheduled) return;
+    restartScheduled = true;
+
+    if (restartCount >= maxAutomaticRestarts) {
+        log.error('Automatic restart limit reached; exiting');
+        app.exit(1);
+        return;
+    }
+
+    const relaunchArgs = process.argv.slice(1)
+        .filter(argument => !argument.startsWith(restartArgument));
+    relaunchArgs.push(restartArgument + (restartCount + 1));
+    log.warn('Restarting application in 5 seconds (attempt ' + (restartCount + 1) + '/' + maxAutomaticRestarts + ')');
+    restartTimer = setTimeout(() => {
+        app.relaunch({ args: relaunchArgs });
+        app.exit(1);
+    }, 5000);
+}
+
 
 //------------------------------------------------------------------------------
 // Init electron app
@@ -195,12 +293,11 @@ app.whenReady().then(() => {
     config.load();
 
     log.initialize();
-    if (config.data != undefined && 'logPath' in config.data) {
-        log.transports.file.resolvePathFn = () => config.data.logPath;
-    }
+    log.transports.file.resolvePathFn = resolveLogPath;
 
     log.info('----------------------------------------------');
     log.info('Starting Tooloop Kiosk Browser...');
+    log.info('Logging to ' + log.transports.file.resolvePathFn());
 
     createMenu();
     createMainWindow();
@@ -221,6 +318,5 @@ app.on('quit', () => {
 });
 
 // prevent error dialogs in case of exceptions
-process.on('uncaughtException', function (error) {
-    log.error(error);
-});
+process.on('uncaughtException', restartAfterFatalError);
+process.on('unhandledRejection', restartAfterFatalError);