SEBWIN-917: Consolidated system (events) monitoring in sentinel.

SafeExamBrowser.Client.UnitTests/ClientControllerTests.cs

@@ -73,7 +73,6 @@ namespace SafeExamBrowser.Client.UnitTests
 		private AppSettings settings;
 		private Mock<Action> shutdown;
 		private Mock<ISplashScreen> splashScreen;
-		private Mock<ISystemMonitor> systemMonitor;
 		private Mock<ITaskbar> taskbar;
 		private Mock<IText> text;
 		private Mock<IUserInterfaceFactory> uiFactory;
@@ -108,7 +107,6 @@ namespace SafeExamBrowser.Client.UnitTests
 			settings = new AppSettings();
 			shutdown = new Mock<Action>();
 			splashScreen = new Mock<ISplashScreen>();
-			systemMonitor = new Mock<ISystemMonitor>();
 			taskbar = new Mock<ITaskbar>();
 			text = new Mock<IText>();
 			uiFactory = new Mock<IUserInterfaceFactory>();
@@ -134,7 +132,6 @@ namespace SafeExamBrowser.Client.UnitTests
 				runtimeProxy.Object,
 				shutdown.Object,
 				splashScreen.Object,
-				systemMonitor.Object,
 				sentinel.Object,
 				taskbar.Object,
 				text.Object,
@@ -1288,7 +1285,7 @@ namespace SafeExamBrowser.Client.UnitTests
 				.Returns(lockScreen.Object);
 
 			sut.TryStart();
-			systemMonitor.Raise(m => m.SessionChanged += null);
+			sentinel.Raise(s => s.SessionChanged += null);
 
 			coordinator.Verify(c => c.RequestSessionLock(), Times.Once);
 			coordinator.Verify(c => c.ReleaseSessionLock(), Times.Once);
@@ -1311,7 +1308,7 @@ namespace SafeExamBrowser.Client.UnitTests
 				.Returns(lockScreen.Object);
 
 			sut.TryStart();
-			systemMonitor.Raise(m => m.SessionChanged += null);
+			sentinel.Raise(s => s.SessionChanged += null);
 
 			coordinator.Verify(c => c.RequestSessionLock(), Times.Once);
 			coordinator.Verify(c => c.ReleaseSessionLock(), Times.Once);
@@ -1333,7 +1330,7 @@ namespace SafeExamBrowser.Client.UnitTests
 				.Returns(lockScreen.Object);
 
 			sut.TryStart();
-			systemMonitor.Raise(m => m.SessionChanged += null);
+			sentinel.Raise(s => s.SessionChanged += null);
 
 			lockScreen.Verify(l => l.Show(), Times.Never);
 		}

SafeExamBrowser.Client.UnitTests/Operations/SystemMonitorOperationTests.cs

@@ -1,53 +0,0 @@
-/*
- * Copyright (c) 2024 ETH Zürich, IT Services
- * 
- * 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 Microsoft.VisualStudio.TestTools.UnitTesting;
-using Moq;
-using SafeExamBrowser.Client.Operations;
-using SafeExamBrowser.Logging.Contracts;
-using SafeExamBrowser.Monitoring.Contracts.System;
-
-namespace SafeExamBrowser.Client.UnitTests.Operations
-{
-	[TestClass]
-	public class SystemMonitorOperationTests
-	{
-		private ClientContext context;
-		private Mock<ISystemMonitor> systemMonitor;
-		private Mock<ILogger> logger;
-		private SystemMonitorOperation sut;
-
-		[TestInitialize]
-		public void Initialize()
-		{
-			context = new ClientContext();
-			systemMonitor = new Mock<ISystemMonitor>();
-			logger = new Mock<ILogger>();
-
-			sut = new SystemMonitorOperation(context, systemMonitor.Object, logger.Object);
-		}
-
-		[TestMethod]
-		public void Perform_MustStartMonitor()
-		{
-			sut.Perform();
-
-			systemMonitor.Verify(s => s.Start(), Times.Once);
-			systemMonitor.VerifyNoOtherCalls();
-		}
-
-		[TestMethod]
-		public void Revert_MustStopMonitor()
-		{
-			sut.Revert();
-
-			systemMonitor.Verify(s => s.Stop(), Times.Once);
-			systemMonitor.VerifyNoOtherCalls();
-		}
-	}
-}

SafeExamBrowser.Client.UnitTests/SafeExamBrowser.Client.UnitTests.csproj

@@ -163,7 +163,6 @@
     <Compile Include="Communication\ClientHostTests.cs" />
     <Compile Include="Notifications\AboutNotificationControllerTests.cs" />
     <Compile Include="Notifications\LogNotificationControllerTests.cs" />
-    <Compile Include="Operations\SystemMonitorOperationTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="ClientControllerTests.cs" />
     <Compile Include="CoordinatorTests.cs" />

SafeExamBrowser.Client/ClientController.cs

@@ -66,7 +66,6 @@ namespace SafeExamBrowser.Client
 		private readonly IRuntimeProxy runtime;
 		private readonly Action shutdown;
 		private readonly ISplashScreen splashScreen;
-		private readonly ISystemMonitor systemMonitor;
 		private readonly ISystemSentinel sentinel;
 		private readonly ITaskbar taskbar;
 		private readonly IText text;
@@ -97,7 +96,6 @@ namespace SafeExamBrowser.Client
 			IRuntimeProxy runtime,
 			Action shutdown,
 			ISplashScreen splashScreen,
-			ISystemMonitor systemMonitor,
 			ISystemSentinel sentinel,
 			ITaskbar taskbar,
 			IText text,
@@ -118,7 +116,6 @@ namespace SafeExamBrowser.Client
 			this.runtime = runtime;
 			this.shutdown = shutdown;
 			this.splashScreen = splashScreen;
-			this.systemMonitor = systemMonitor;
 			this.sentinel = sentinel;
 			this.taskbar = taskbar;
 			this.text = text;
@@ -144,6 +141,7 @@ namespace SafeExamBrowser.Client
 				ShowShell();
 				AutoStartApplications();
 				ScheduleIntegrityVerification();
+				StartMonitoring();
 
 				var communication = runtime.InformClientReady();
 
@@ -226,8 +224,8 @@ namespace SafeExamBrowser.Client
 			runtime.ConnectionLost += Runtime_ConnectionLost;
 			sentinel.CursorChanged += Sentinel_CursorChanged;
 			sentinel.EaseOfAccessChanged += Sentinel_EaseOfAccessChanged;
+			sentinel.SessionChanged += Sentinel_SessionChanged;
 			sentinel.StickyKeysChanged += Sentinel_StickyKeysChanged;
-			systemMonitor.SessionChanged += SystemMonitor_SessionChanged;
 			taskbar.LoseFocusRequested += Taskbar_LoseFocusRequested;
 			taskbar.QuitButtonClicked += Shell_QuitButtonClicked;
 
@@ -253,8 +251,8 @@ namespace SafeExamBrowser.Client
 			runtime.ConnectionLost -= Runtime_ConnectionLost;
 			sentinel.CursorChanged -= Sentinel_CursorChanged;
 			sentinel.EaseOfAccessChanged -= Sentinel_EaseOfAccessChanged;
+			sentinel.SessionChanged -= Sentinel_SessionChanged;
 			sentinel.StickyKeysChanged -= Sentinel_StickyKeysChanged;
-			systemMonitor.SessionChanged -= SystemMonitor_SessionChanged;
 			taskbar.LoseFocusRequested -= Taskbar_LoseFocusRequested;
 			taskbar.QuitButtonClicked -= Shell_QuitButtonClicked;
 
@@ -368,6 +366,11 @@ namespace SafeExamBrowser.Client
 			timer.Elapsed += (o, args) => VerifyApplicationIntegrity();
 			timer.Interval = TEN_MINUTES + (new Random().NextDouble() * FIVE_MINUTES);
 			timer.Start();
+		}
+
+		private void StartMonitoring()
+		{
+			sentinel.StartMonitoringSystemEvents();
 
 			if (!Settings.Security.AllowStickyKeys)
 			{
@@ -853,6 +856,47 @@ namespace SafeExamBrowser.Client
 			}
 		}
 
+		private void Sentinel_SessionChanged()
+		{
+			var allow = !Settings.Service.IgnoreService && (!Settings.Service.DisableUserLock || !Settings.Service.DisableUserSwitch);
+			var disable = Settings.Security.DisableSessionChangeLockScreen;
+
+			if (allow || disable)
+			{
+				logger.Info($"Detected user session change, but {(allow ? "session locking and/or switching is allowed" : "lock screen is deactivated")}.");
+			}
+			else
+			{
+				var message = text.Get(TextKey.LockScreen_UserSessionMessage);
+				var title = text.Get(TextKey.LockScreen_Title);
+				var continueOption = new LockScreenOption { Text = text.Get(TextKey.LockScreen_UserSessionContinueOption) };
+				var terminateOption = new LockScreenOption { Text = text.Get(TextKey.LockScreen_UserSessionTerminateOption) };
+
+				logger.Warn("User session changed! Attempting to show lock screen...");
+
+				if (coordinator.RequestSessionLock())
+				{
+					var result = ShowLockScreen(message, title, new[] { continueOption, terminateOption });
+
+					if (result.OptionId == continueOption.Id)
+					{
+						logger.Info("The session will be allowed to resume as requested by the user...");
+					}
+					else if (result.OptionId == terminateOption.Id)
+					{
+						logger.Info("Attempting to shutdown as requested by the user...");
+						TryRequestShutdown();
+					}
+
+					coordinator.ReleaseSessionLock();
+				}
+				else
+				{
+					logger.Warn("User session changed but lock screen is already active.");
+				}
+			}
+		}
+
 		private void Sentinel_StickyKeysChanged(SentinelEventArgs args)
 		{
 			if (coordinator.RequestSessionLock())
@@ -919,42 +963,6 @@ namespace SafeExamBrowser.Client
 			ResumeActivators();
 		}
 
-		private void SystemMonitor_SessionChanged()
-		{
-			var allow = !Settings.Service.IgnoreService && (!Settings.Service.DisableUserLock || !Settings.Service.DisableUserSwitch);
-			var disable = Settings.Security.DisableSessionChangeLockScreen;
-			var message = text.Get(TextKey.LockScreen_UserSessionMessage);
-			var title = text.Get(TextKey.LockScreen_Title);
-			var continueOption = new LockScreenOption { Text = text.Get(TextKey.LockScreen_UserSessionContinueOption) };
-			var terminateOption = new LockScreenOption { Text = text.Get(TextKey.LockScreen_UserSessionTerminateOption) };
-
-			if (allow || disable)
-			{
-				logger.Info($"Detected user session change, but {(allow ? "session locking and/or switching is allowed" : "lock screen is deactivated")}.");
-			}
-			else
-			{
-				logger.Warn("Detected user session change!");
-
-				if (coordinator.RequestSessionLock())
-				{
-					var result = ShowLockScreen(message, title, new[] { continueOption, terminateOption });
-
-					if (result.OptionId == terminateOption.Id)
-					{
-						logger.Info("Attempting to shutdown as requested by the user...");
-						TryRequestShutdown();
-					}
-
-					coordinator.ReleaseSessionLock();
-				}
-				else
-				{
-					logger.Info("Lock screen is already active.");
-				}
-			}
-		}
-
 		private void Taskbar_LoseFocusRequested(bool forward)
 		{
 			Browser.Focus(forward);

SafeExamBrowser.Client/CompositionRoot.cs

@@ -121,7 +121,6 @@ namespace SafeExamBrowser.Client
 			var hashAlgorithm = new HashAlgorithm();
 			var sentinel = new SystemSentinel(ModuleLogger(nameof(SystemSentinel)), nativeMethods, registry);
 			var splashScreen = uiFactory.CreateSplashScreen();
-			var systemMonitor = new SystemMonitor(ModuleLogger(nameof(SystemMonitor)));
 
 			var operations = new Queue<IOperation>();
 
@@ -137,7 +136,6 @@ namespace SafeExamBrowser.Client
 			operations.Enqueue(new LazyInitializationOperation(BuildMouseInterceptorOperation));
 			operations.Enqueue(new ApplicationOperation(context, applicationFactory, applicationMonitor, logger, text));
 			operations.Enqueue(new DisplayMonitorOperation(context, displayMonitor, logger, taskbar));
-			operations.Enqueue(new SystemMonitorOperation(context, systemMonitor, logger));
 			operations.Enqueue(new LazyInitializationOperation(BuildShellOperation));
 			operations.Enqueue(new LazyInitializationOperation(BuildBrowserOperation));
 			operations.Enqueue(new LazyInitializationOperation(BuildServerOperation));
@@ -162,7 +160,6 @@ namespace SafeExamBrowser.Client
 				runtimeProxy,
 				shutdown,
 				splashScreen,
-				systemMonitor,
 				sentinel,
 				taskbar,
 				text,

SafeExamBrowser.Client/Operations/SystemMonitorOperation.cs

@@ -1,51 +0,0 @@
-/*
- * Copyright (c) 2024 ETH Zürich, IT Services
- * 
- * 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 SafeExamBrowser.Core.Contracts.OperationModel;
-using SafeExamBrowser.Core.Contracts.OperationModel.Events;
-using SafeExamBrowser.I18n.Contracts;
-using SafeExamBrowser.Logging.Contracts;
-using SafeExamBrowser.Monitoring.Contracts.System;
-
-namespace SafeExamBrowser.Client.Operations
-{
-	internal class SystemMonitorOperation : ClientOperation
-	{
-		private readonly ILogger logger;
-		private readonly ISystemMonitor systemMonitor;
-
-		public override event ActionRequiredEventHandler ActionRequired { add { } remove { } }
-		public override event StatusChangedEventHandler StatusChanged;
-
-		public SystemMonitorOperation(ClientContext context, ISystemMonitor systemMonitor, ILogger logger) : base(context)
-		{
-			this.logger = logger;
-			this.systemMonitor = systemMonitor;
-		}
-
-		public override OperationResult Perform()
-		{
-			logger.Info("Initializing system events...");
-			StatusChanged?.Invoke(TextKey.OperationStatus_InitializeSystemEvents);
-
-			systemMonitor.Start();
-
-			return OperationResult.Success;
-		}
-
-		public override OperationResult Revert()
-		{
-			logger.Info("Finalizing system events...");
-			StatusChanged?.Invoke(TextKey.OperationStatus_FinalizeSystemEvents);
-
-			systemMonitor.Stop();
-
-			return OperationResult.Success;
-		}
-	}
-}

SafeExamBrowser.Client/SafeExamBrowser.Client.csproj

@@ -97,7 +97,6 @@
     <Compile Include="Operations\ApplicationOperation.cs" />
     <Compile Include="Operations\ServerOperation.cs" />
     <Compile Include="Operations\ShellOperation.cs" />
-    <Compile Include="Operations\SystemMonitorOperation.cs" />
     <Compile Include="Properties\AssemblyInfo.cs">
       <SubType>Code</SubType>
     </Compile>

SafeExamBrowser.Monitoring.Contracts/SafeExamBrowser.Monitoring.Contracts.csproj

@@ -73,7 +73,6 @@
     <Compile Include="System\Events\SentinelEventArgs.cs" />
     <Compile Include="System\Events\SentinelEventHandler.cs" />
     <Compile Include="System\Events\SessionChangedEventHandler.cs" />
-    <Compile Include="System\ISystemMonitor.cs" />
     <Compile Include="System\ISystemSentinel.cs" />
   </ItemGroup>
   <ItemGroup>

SafeExamBrowser.Monitoring.Contracts/System/ISystemMonitor.cs

@@ -1,33 +0,0 @@
-/*
- * Copyright (c) 2024 ETH Zürich, IT Services
- * 
- * 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 SafeExamBrowser.Monitoring.Contracts.System.Events;
-
-namespace SafeExamBrowser.Monitoring.Contracts.System
-{
-	/// <summary>
-	/// Monitors the operating system, e.g. for user account related events.
-	/// </summary>
-	public interface ISystemMonitor
-	{
-		/// <summary>
-		/// Event fired when the active user session has changed.
-		/// </summary>
-		event SessionChangedEventHandler SessionChanged;
-
-		/// <summary>
-		/// Starts the monitoring.
-		/// </summary>
-		void Start();
-
-		/// <summary>
-		/// Stops the monitoring.
-		/// </summary>
-		void Stop();
-	}
-}

SafeExamBrowser.Monitoring.Contracts/System/ISystemSentinel.cs

@@ -25,6 +25,11 @@ namespace SafeExamBrowser.Monitoring.Contracts.System
 		/// </summary>
 		event SentinelEventHandler EaseOfAccessChanged;
 
+		/// <summary>
+		/// Event fired when the active user session has changed.
+		/// </summary>
+		event SessionChangedEventHandler SessionChanged;
+
 		/// <summary>
 		/// Event fired when the sticky keys state has changed.
 		/// </summary>
@@ -60,6 +65,11 @@ namespace SafeExamBrowser.Monitoring.Contracts.System
 		/// </summary>
 		void StartMonitoringStickyKeys();
 
+		/// <summary>
+		/// Starts monitoring the system events.
+		/// </summary>
+		void StartMonitoringSystemEvents();
+
 		/// <summary>
 		/// Stops all monitoring operations.
 		/// </summary>

SafeExamBrowser.Monitoring/SafeExamBrowser.Monitoring.csproj

@@ -70,7 +70,7 @@
     <Compile Include="System\Components\Cursors.cs" />
     <Compile Include="System\Components\EaseOfAccess.cs" />
     <Compile Include="System\Components\StickyKeys.cs" />
-    <Compile Include="System\SystemMonitor.cs" />
+    <Compile Include="System\Components\SystemEvents.cs" />
     <Compile Include="System\SystemSentinel.cs" />
   </ItemGroup>
   <ItemGroup>

SafeExamBrowser.Monitoring/System/Components/SystemEvents.cs

@@ -10,46 +10,47 @@ using System;
 using System.Threading.Tasks;
 using Microsoft.Win32;
 using SafeExamBrowser.Logging.Contracts;
-using SafeExamBrowser.Monitoring.Contracts.System;
 using SafeExamBrowser.Monitoring.Contracts.System.Events;
 
-namespace SafeExamBrowser.Monitoring.System
+namespace SafeExamBrowser.Monitoring.System.Components
 {
-	public class SystemMonitor : ISystemMonitor
+	internal class SystemEvents
 	{
 		private readonly ILogger logger;
 
-		public event SessionChangedEventHandler SessionChanged;
+		internal event SessionChangedEventHandler SessionChanged;
 
-		public SystemMonitor(ILogger logger)
+		internal SystemEvents(ILogger logger)
 		{
 			this.logger = logger;
 		}
 
-		public void Start()
+		internal void StartMonitoring()
 		{
-			SystemEvents.EventsThreadShutdown += SystemEvents_EventsThreadShutdown;
+			Microsoft.Win32.SystemEvents.EventsThreadShutdown += SystemEvents_EventsThreadShutdown;
-			SystemEvents.InstalledFontsChanged += SystemEvents_InstalledFontsChanged;
+			Microsoft.Win32.SystemEvents.InstalledFontsChanged += SystemEvents_InstalledFontsChanged;
-			SystemEvents.PowerModeChanged += SystemEvents_PowerModeChanged;
+			Microsoft.Win32.SystemEvents.PowerModeChanged += SystemEvents_PowerModeChanged;
-			SystemEvents.SessionEnded += SystemEvents_SessionEnded;
+			Microsoft.Win32.SystemEvents.SessionEnded += SystemEvents_SessionEnded;
-			SystemEvents.SessionEnding += SystemEvents_SessionEnding;
+			Microsoft.Win32.SystemEvents.SessionEnding += SystemEvents_SessionEnding;
-			SystemEvents.SessionSwitch += SystemEvents_SessionChanged;
+			Microsoft.Win32.SystemEvents.SessionSwitch += SystemEvents_SessionChanged;
-			SystemEvents.TimeChanged += SystemEvents_TimeChanged;
+			Microsoft.Win32.SystemEvents.TimeChanged += SystemEvents_TimeChanged;
-			SystemEvents.UserPreferenceChanged += SystemEvents_UserPreferenceChanged;
+			Microsoft.Win32.SystemEvents.UserPreferenceChanged += SystemEvents_UserPreferenceChanged;
-			logger.Info("Started monitoring the operating system.");
+
+			logger.Info("Started monitoring system events.");
 		}
 
-		public void Stop()
+		internal void StopMonitoring()
 		{
-			SystemEvents.EventsThreadShutdown -= SystemEvents_EventsThreadShutdown;
+			Microsoft.Win32.SystemEvents.EventsThreadShutdown -= SystemEvents_EventsThreadShutdown;
-			SystemEvents.InstalledFontsChanged -= SystemEvents_InstalledFontsChanged;
+			Microsoft.Win32.SystemEvents.InstalledFontsChanged -= SystemEvents_InstalledFontsChanged;
-			SystemEvents.PowerModeChanged -= SystemEvents_PowerModeChanged;
+			Microsoft.Win32.SystemEvents.PowerModeChanged -= SystemEvents_PowerModeChanged;
-			SystemEvents.SessionEnded -= SystemEvents_SessionEnded;
+			Microsoft.Win32.SystemEvents.SessionEnded -= SystemEvents_SessionEnded;
-			SystemEvents.SessionEnding -= SystemEvents_SessionEnding;
+			Microsoft.Win32.SystemEvents.SessionEnding -= SystemEvents_SessionEnding;
-			SystemEvents.SessionSwitch -= SystemEvents_SessionChanged;
+			Microsoft.Win32.SystemEvents.SessionSwitch -= SystemEvents_SessionChanged;
-			SystemEvents.TimeChanged -= SystemEvents_TimeChanged;
+			Microsoft.Win32.SystemEvents.TimeChanged -= SystemEvents_TimeChanged;
-			SystemEvents.UserPreferenceChanged -= SystemEvents_UserPreferenceChanged;
+			Microsoft.Win32.SystemEvents.UserPreferenceChanged -= SystemEvents_UserPreferenceChanged;
-			logger.Info("Stopped monitoring the operating system.");
+
+			logger.Info("Stopped monitoring system events.");
 		}
 
 		private void SystemEvents_EventsThreadShutdown(object sender, EventArgs e)

SafeExamBrowser.Monitoring/System/SystemSentinel.cs

@@ -20,16 +20,19 @@ namespace SafeExamBrowser.Monitoring.System
 		private readonly Cursors cursors;
 		private readonly EaseOfAccess easeOfAccess;
 		private readonly StickyKeys stickyKeys;
+		private readonly SystemEvents systemEvents;
 
 		public event SentinelEventHandler CursorChanged;
 		public event SentinelEventHandler EaseOfAccessChanged;
 		public event SentinelEventHandler StickyKeysChanged;
+		public event SessionChangedEventHandler SessionChanged;
 
 		public SystemSentinel(ILogger logger, INativeMethods nativeMethods, IRegistry registry)
 		{
-			this.cursors = new Cursors(logger, registry);
+			cursors = new Cursors(logger, registry);
-			this.easeOfAccess = new EaseOfAccess(logger, registry);
+			easeOfAccess = new EaseOfAccess(logger, registry);
-			this.stickyKeys = new StickyKeys(logger, nativeMethods);
+			stickyKeys = new StickyKeys(logger, nativeMethods);
+			systemEvents = new SystemEvents(logger);
 		}
 
 		public bool DisableStickyKeys()
@@ -65,11 +68,18 @@ namespace SafeExamBrowser.Monitoring.System
 			stickyKeys.StartMonitoring();
 		}
 
+		public void StartMonitoringSystemEvents()
+		{
+			systemEvents.SessionChanged += () => SessionChanged?.Invoke();
+			systemEvents.StartMonitoring();
+		}
+
 		public void StopMonitoring()
 		{
 			cursors.StopMonitoring();
 			easeOfAccess.StopMonitoring();
 			stickyKeys.StopMonitoring();
+			systemEvents.StopMonitoring();
 		}
 
 		public bool VerifyCursors()