SEBWIN-820, #764: Implemented cross-window sharing of clipboard content for isolated clipboard policy.

SafeExamBrowser.Browser/BrowserApplication.cs

@@ -39,6 +39,7 @@ namespace SafeExamBrowser.Browser
 		private int windowIdCounter = default;
 
 		private readonly AppConfig appConfig;
+		private readonly Clipboard clipboard;
 		private readonly IFileSystemDialog fileSystemDialog;
 		private readonly IHashAlgorithm hashAlgorithm;
 		private readonly IKeyGenerator keyGenerator;
@@ -77,6 +78,7 @@ namespace SafeExamBrowser.Browser
 			IUserInterfaceFactory uiFactory)
 		{
 			this.appConfig = appConfig;
+			this.clipboard = new Clipboard(logger.CloneFor(nameof(Clipboard)), settings);
 			this.fileSystemDialog = fileSystemDialog;
 			this.hashAlgorithm = hashAlgorithm;
 			this.keyGenerator = keyGenerator;
@@ -191,6 +193,7 @@ namespace SafeExamBrowser.Browser
 			var windowLogger = logger.CloneFor($"Browser Window #{id}");
 			var window = new BrowserWindow(
 				appConfig,
+				clipboard,
 				fileSystemDialog,
 				hashAlgorithm,
 				id,

SafeExamBrowser.Browser/BrowserControl.cs

@@ -7,10 +7,12 @@
  */
 
 using System;
+using System.Linq;
 using System.Threading.Tasks;
 using CefSharp;
 using SafeExamBrowser.Browser.Wrapper;
 using SafeExamBrowser.Browser.Wrapper.Events;
+using SafeExamBrowser.Logging.Contracts;
 using SafeExamBrowser.UserInterface.Contracts.Browser;
 using SafeExamBrowser.UserInterface.Contracts.Browser.Data;
 using SafeExamBrowser.UserInterface.Contracts.Browser.Events;
@@ -19,11 +21,13 @@ namespace SafeExamBrowser.Browser
 {
 	internal class BrowserControl : IBrowserControl
 	{
+		private readonly Clipboard clipboard;
 		private readonly ICefSharpControl control;
 		private readonly IDialogHandler dialogHandler;
 		private readonly IDisplayHandler displayHandler;
 		private readonly IDownloadHandler downloadHandler;
 		private readonly IKeyboardHandler keyboardHandler;
+		private readonly ILogger logger;
 		private readonly IRenderProcessMessageHandler renderProcessMessageHandler;
 		private readonly IRequestHandler requestHandler;
 
@@ -38,19 +42,23 @@ namespace SafeExamBrowser.Browser
 		public event TitleChangedEventHandler TitleChanged;
 
 		public BrowserControl(
+			Clipboard clipboard,
 			ICefSharpControl control,
 			IDialogHandler dialogHandler,
 			IDisplayHandler displayHandler,
 			IDownloadHandler downloadHandler,
 			IKeyboardHandler keyboardHandler,
+			ILogger logger,
 			IRenderProcessMessageHandler renderProcessMessageHandler,
 			IRequestHandler requestHandler)
 		{
 			this.control = control;
+			this.clipboard = clipboard;
 			this.dialogHandler = dialogHandler;
 			this.displayHandler = displayHandler;
 			this.downloadHandler = downloadHandler;
 			this.keyboardHandler = keyboardHandler;
+			this.logger = logger;
 			this.renderProcessMessageHandler = renderProcessMessageHandler;
 			this.requestHandler = requestHandler;
 		}
@@ -63,25 +71,37 @@ namespace SafeExamBrowser.Browser
 			}
 		}
 
-		public void ExecuteJavascript(string javascript, Action<JavascriptResult> callback)
+		public void ExecuteJavaScript(string code, Action<JavaScriptResult> callback = default)
 		{
-			if ((control as IWebBrowser)?.CanExecuteJavascriptInMainFrame == true)
+			try
 			{
-				control.EvaluateScriptAsync(javascript).ContinueWith(t =>
+				if (control.BrowserCore != default && control.BrowserCore.MainFrame != default)
 				{
-					callback(new JavascriptResult
+					control.BrowserCore.EvaluateScriptAsync(code).ContinueWith(t =>
 					{
-						Message = t.Result.Message,
+						callback?.Invoke(new JavaScriptResult
-						Result = t.Result.Result,
+						{
-						Success = t.Result.Success
+							Message = t.Result.Message,
+							Result = t.Result.Result,
+							Success = t.Result.Success
+						});
 					});
-				});
+				}
-			}
+				else
-			else
-			{
-				Task.Run(() => callback(new JavascriptResult
 				{
-					Message = "JavaScript can't be executed in main frame!",
+					Task.Run(() => callback?.Invoke(new JavaScriptResult
+					{
+						Message = "JavaScript can't be executed in main frame!",
+						Success = false
+					}));
+				}
+			}
+			catch (Exception e)
+			{
+				logger.Error($"Failed to execute JavaScript '{(code.Length > 50 ? code.Take(50) : code)}'!", e);
+				Task.Run(() => callback?.Invoke(new JavaScriptResult
+				{
+					Message = $"Failed to execute JavaScript '{(code.Length > 50 ? code.Take(50) : code)}'! Reason: {e.Message}",
 					Success = false
 				}));
 			}
@@ -94,6 +114,8 @@ namespace SafeExamBrowser.Browser
 
 		public void Initialize()
 		{
+			clipboard.Changed += Clipboard_Changed;
+
 			control.AddressChanged += (o, e) => AddressChanged?.Invoke(e.Address);
 			control.AuthCredentialsRequired += (w, b, o, i, h, p, r, s, c, a) => a.Value = requestHandler.GetAuthCredentials(w, b, o, i, h, p, r, s, c);
 			control.BeforeBrowse += (w, b, f, r, u, i, a) => a.Value = requestHandler.OnBeforeBrowse(w, b, f, r, u, i);
@@ -115,6 +137,11 @@ namespace SafeExamBrowser.Browser
 			control.ResourceRequestHandlerRequired += (IWebBrowser w, IBrowser b, IFrame f, IRequest r, bool n, bool d, string i, ref bool h, ResourceRequestEventArgs a) => a.Handler = requestHandler.GetResourceRequestHandler(w, b, f, r, n, d, i, ref h);
 			control.TitleChanged += (o, e) => TitleChanged?.Invoke(e.Title);
 			control.UncaughtExceptionEvent += (w, b, f, e) => renderProcessMessageHandler.OnUncaughtException(w, b, f, e);
+
+			if (control is IWebBrowser webBrowser)
+			{
+				webBrowser.JavascriptMessageReceived += WebBrowser_JavascriptMessageReceived;
+			}
 		}
 
 		public void NavigateBackwards()
@@ -147,6 +174,11 @@ namespace SafeExamBrowser.Browser
 			control.BrowserCore.SetZoomLevel(level);
 		}
 
+		private void Clipboard_Changed(long id)
+		{
+			ExecuteJavaScript($"SafeExamBrowser.clipboard.update({id}, '{clipboard.Content}');");
+		}
+
 		private void Control_IsBrowserInitializedChanged(object sender, EventArgs e)
 		{
 			if (control.IsBrowserInitialized)
@@ -154,5 +186,10 @@ namespace SafeExamBrowser.Browser
 				control.BrowserCore.GetHost().SetFocus(true);
 			}
 		}
+
+		private void WebBrowser_JavascriptMessageReceived(object sender, JavascriptMessageReceivedEventArgs e)
+		{
+			clipboard.Process(e);
+		}
 	}
 }

SafeExamBrowser.Browser/BrowserWindow.cs

@@ -48,6 +48,7 @@ namespace SafeExamBrowser.Browser
 		private const double ZOOM_FACTOR = 0.2;
 
 		private readonly AppConfig appConfig;
+		private readonly Clipboard clipboard;
 		private readonly IFileSystemDialog fileSystemDialog;
 		private readonly IHashAlgorithm hashAlgorithm;
 		private readonly HttpClient httpClient;
@@ -92,6 +93,7 @@ namespace SafeExamBrowser.Browser
 
 		public BrowserWindow(
 			AppConfig appConfig,
+			Clipboard clipboard,
 			IFileSystemDialog fileSystemDialog,
 			IHashAlgorithm hashAlgorithm,
 			int id,
@@ -106,6 +108,7 @@ namespace SafeExamBrowser.Browser
 			IUserInterfaceFactory uiFactory)
 		{
 			this.appConfig = appConfig;
+			this.clipboard = clipboard;
 			this.fileSystemDialog = fileSystemDialog;
 			this.hashAlgorithm = hashAlgorithm;
 			this.httpClient = new HttpClient();
@@ -149,6 +152,7 @@ namespace SafeExamBrowser.Browser
 		internal void InitializeControl()
 		{
 			var cefSharpControl = default(ICefSharpControl);
+			var controlLogger = logger.CloneFor($"{nameof(BrowserControl)} #{Id}");
 			var dialogHandler = new DialogHandler();
 			var displayHandler = new DisplayHandler();
 			var downloadLogger = logger.CloneFor($"{nameof(DownloadHandler)} #{Id}");
@@ -191,7 +195,7 @@ namespace SafeExamBrowser.Browser
 
 			InitializeRequestFilter(requestFilter);
 
-			Control = new BrowserControl(cefSharpControl, dialogHandler, displayHandler, downloadHandler, keyboardHandler, renderHandler, requestHandler);
+			Control = new BrowserControl(clipboard, cefSharpControl, dialogHandler, displayHandler, downloadHandler, keyboardHandler, controlLogger, renderHandler, requestHandler);
 			Control.AddressChanged += Control_AddressChanged;
 			Control.LoadFailed += Control_LoadFailed;
 			Control.LoadingStateChanged += Control_LoadingStateChanged;
@@ -499,7 +503,7 @@ namespace SafeExamBrowser.Browser
 
 		private void KeyboardHandler_TabPressed(bool shiftPressed)
 		{
-			Control.ExecuteJavascript("document.activeElement.tagName", result =>
+			Control.ExecuteJavaScript("document.activeElement.tagName", result =>
 			{
 				if (result.Result is string tagName && tagName?.ToUpper() == "BODY")
 				{

SafeExamBrowser.Browser/Clipboard.cs

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2023 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using System.Threading.Tasks;
+using CefSharp;
+using SafeExamBrowser.Browser.Events;
+using SafeExamBrowser.Logging.Contracts;
+using BrowserSettings = SafeExamBrowser.Settings.Browser.BrowserSettings;
+
+namespace SafeExamBrowser.Browser
+{
+	internal class Clipboard
+	{
+		private readonly ILogger logger;
+		private readonly BrowserSettings settings;
+
+		internal string Content { get; private set; }
+
+		internal event ClipboardChangedEventHandler Changed;
+
+		internal Clipboard(ILogger logger, BrowserSettings settings)
+		{
+			this.logger = logger;
+			this.settings = settings;
+		}
+
+		internal void Process(JavascriptMessageReceivedEventArgs message)
+		{
+			if (settings.UseIsolatedClipboard)
+			{
+				try
+				{
+					var data = message.ConvertMessageTo<Data>();
+
+					if (data != default && data.Type == "Clipboard" && TrySetContent(data.Content))
+					{
+						Task.Run(() => Changed?.Invoke(data.Id));
+					}
+				}
+				catch (Exception e)
+				{
+					logger.Error($"Failed to process browser message '{message}'!", e);
+				}
+			}
+		}
+
+		private bool TrySetContent(object value)
+		{
+			var text = value as string;
+
+			if (text != default)
+			{
+				Content = text;
+			}
+
+			return text != default;
+		}
+
+		private class Data
+		{
+			public string Content { get; set; }
+			public long Id { get; set; }
+			public string Type { get; set; }
+		}
+	}
+}

SafeExamBrowser.Browser/Content/Clipboard.js

@@ -9,12 +9,31 @@
  */
 
 SafeExamBrowser.clipboard = {
-	clear: function () {
+	id: Math.round((Date.now() + Math.random()) * 1000),
-		ranges = [];
-		text = "";
-	},
 	ranges: [],
-	text: ""
+	text: "",
+
+	clear: function () {
+		this.ranges = [];
+		this.text = "";
+	},
+
+	getContentEncoded: function () {
+		var bytes = new TextEncoder().encode(this.text);
+		var base64 = btoa(String.fromCodePoint(...bytes));
+
+		return base64;
+	},
+
+	update: function (id, base64) {
+		if (this.id != id) {
+			var bytes = Uint8Array.from(atob(base64), (m) => m.codePointAt(0));
+			var content = new TextDecoder().decode(bytes);
+
+			this.ranges = [];
+			this.text = content;
+		}
+	}
 }
 
 function copySelectedData(e) {
@@ -134,6 +153,8 @@ function onCopy(e) {
 
 	try {
 		copySelectedData(e);
+
+		CefSharp.PostMessage({ Type: "Clipboard", Id: SafeExamBrowser.clipboard.id, Content: SafeExamBrowser.clipboard.getContentEncoded() });
 	} finally {
 		e.preventDefault();
 		e.returnValue = false;
@@ -148,6 +169,8 @@ function onCut(e) {
 	try {
 		copySelectedData(e);
 		cutSelectedData(e);
+
+		CefSharp.PostMessage({ Type: "Clipboard", Id: SafeExamBrowser.clipboard.id, Content: SafeExamBrowser.clipboard.getContentEncoded() });
 	} finally {
 		e.preventDefault();
 		e.returnValue = false;

SafeExamBrowser.Browser/Events/ClipboardChangedEventHandler.cs

@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2023 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+namespace SafeExamBrowser.Browser.Events
+{
+	internal delegate void ClipboardChangedEventHandler(long id);
+}

SafeExamBrowser.Browser/SafeExamBrowser.Browser.csproj

@@ -80,6 +80,8 @@
   <ItemGroup>
     <Compile Include="BrowserApplication.cs" />
     <Compile Include="BrowserWindow.cs" />
+    <Compile Include="Clipboard.cs" />
+    <Compile Include="Events\ClipboardChangedEventHandler.cs" />
     <Compile Include="Events\DialogRequestedEventArgs.cs" />
     <Compile Include="Events\DialogRequestedEventHandler.cs" />
     <Compile Include="Events\DownloadAbortedEventHandler.cs" />
@@ -192,6 +194,7 @@
   <ItemGroup>
     <EmbeddedResource Include="Content\Clipboard.js" />
   </ItemGroup>
+  <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>
     <PostBuildEvent>

SafeExamBrowser.Configuration/ConfigurationData/DataProcessor.cs

@@ -27,6 +27,19 @@ namespace SafeExamBrowser.Configuration.ConfigurationData
 			InitializeClipboardSettings(settings);
 			InitializeProctoringSettings(settings);
 			RemoveLegacyBrowsers(settings);
+
+			settings.Applications.Blacklist.Clear();
+			settings.Applications.Whitelist.Clear();
+			settings.Browser.MainWindow.AllowAddressBar = true;
+			settings.Browser.MainWindow.AllowBackwardNavigation = true;
+			settings.Browser.MainWindow.AllowForwardNavigation = true;
+			settings.Browser.AllowPageZoom = true;
+			settings.Browser.AllowPdfReader = true;
+			settings.Browser.MainWindow.ShowToolbar = true;
+			settings.LogLevel = Settings.Logging.LogLevel.Debug;
+			settings.Security.AllowApplicationLogAccess = true;
+			settings.Security.AllowReconfiguration = true;
+			settings.Taskbar.ShowApplicationLog = true;
 		}
 
 		private void AllowBrowserToolbarForReloading(AppSettings settings)

SafeExamBrowser.UserInterface.Contracts/Browser/Data/JavascriptResult.cs

@@ -11,7 +11,7 @@ namespace SafeExamBrowser.UserInterface.Contracts.Browser.Data
 	/// <summary>
 	/// The data resulting from a JavaScript expression evaluation.
 	/// </summary>
-	public class JavascriptResult
+	public class JavaScriptResult
 	{
 		/// <summary>
 		/// Indicates if the JavaScript was evaluated successfully or not.

SafeExamBrowser.UserInterface.Contracts/Browser/IBrowserControl.cs

@@ -64,9 +64,9 @@ namespace SafeExamBrowser.UserInterface.Contracts.Browser
 		void Destroy();
 
 		/// <summary>
-		/// Executes the given JavaScript code in the browser.
+		/// Executes the given JavaScript code in the browser. An optional callback may be used to process a potential <see cref="JavaScriptResult"/>.
 		/// </summary>
-		void ExecuteJavascript(string code, Action<JavascriptResult> callback);
+		void ExecuteJavaScript(string code, Action<JavaScriptResult> callback = default);
 
 		/// <summary>
 		/// Attempts to find the given term on the current page according to the specified parameters.

SafeExamBrowser.UserInterface.Contracts/SafeExamBrowser.UserInterface.Contracts.csproj

@@ -56,7 +56,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Browser\Data\DownloadItemState.cs" />
-    <Compile Include="Browser\Data\JavascriptResult.cs" />
+    <Compile Include="Browser\Data\JavaScriptResult.cs" />
     <Compile Include="Browser\Events\AddressChangedEventHandler.cs" />
     <Compile Include="Browser\Events\FindRequestedEventHandler.cs" />
     <Compile Include="Browser\Events\LoadFailedEventHandler.cs" />

SafeExamBrowser.UserInterface.Desktop/Windows/BrowserWindow.xaml.cs

@@ -523,19 +523,19 @@ if (typeof __SEB_focusElement === 'undefined') {
 	setTimeout(function () { item && item.focus && item.focus(); }, 20);
   }
 }";
-			browserControl.ExecuteJavascript(javascript, result =>
+			browserControl.ExecuteJavaScript(javascript, result =>
 			{
 				if (!result.Success)
 				{
-					logger.Error($"Failed to initialize JavaScript: {result.Message}");
+					logger.Warn($"Failed to initialize JavaScript: {result.Message}");
 				}
 			});
 
-			browserControl.ExecuteJavascript("__SEB_focusElement(" + forward.ToString().ToLower() + ")", result =>
+			browserControl.ExecuteJavaScript("__SEB_focusElement(" + forward.ToString().ToLower() + ")", result =>
 			{
 				if (!result.Success)
 				{
-					logger.Error($"Failed to execute JavaScript: {result.Message}");
+					logger.Warn($"Failed to execute JavaScript: {result.Message}");
 				}
 			});
 		}

SafeExamBrowser.UserInterface.Mobile/Windows/BrowserWindow.xaml.cs

@@ -518,19 +518,19 @@ if (typeof __SEB_focusElement === 'undefined') {
 	setTimeout(function () { item && item.focus && item.focus(); }, 20);
   }
 }";
-			browserControl.ExecuteJavascript(javascript, result =>
+			browserControl.ExecuteJavaScript(javascript, result =>
 			{
 				if (!result.Success)
 				{
-					logger.Error($"Failed to initialize JavaScript: {result.Message}!");
+					logger.Warn($"Failed to initialize JavaScript: {result.Message}!");
 				}
 			});
 
-			browserControl.ExecuteJavascript("__SEB_focusElement(" + forward.ToString().ToLower() + ")", result =>
+			browserControl.ExecuteJavaScript("__SEB_focusElement(" + forward.ToString().ToLower() + ")", result =>
 			{
 				if (!result.Success)
 				{
-					logger.Error($"Failed to execute JavaScript: {result.Message}!");
+					logger.Warn($"Failed to execute JavaScript: {result.Message}!");
 				}
 			});
 		}