SEBWIN-477 implementation

SafeExamBrowser.Client/ClientController.cs

@@ -68,6 +68,7 @@ namespace SafeExamBrowser.Client
 		private IServerProxy Server => context.Server;
 		private AppSettings Settings => context.Settings;
 
+		private ILockScreen lockScreen;
 		private bool sessionLocked;
 
 		internal ClientController(
@@ -215,10 +216,25 @@ namespace SafeExamBrowser.Client
 
 			if (Server != null)
 			{
+				Server.LockScreenConfirmed += Server_LockScreenConfirmed;
 				Server.TerminationRequested += Server_TerminationRequested;
+				Server.LockScreenRequested += Server_LockScreenRequested;
 			}
 		}
 
+		private void Server_LockScreenRequested(string message)
+		{
+			logger.Info("Received lock screen event from SEB Server.");
+			var title = text.Get(TextKey.LockScreen_Title);
+			ShowLockScreen(message, title, Enumerable.Empty<LockScreenOption>());
+		}
+
+		private void Server_LockScreenConfirmed()
+		{
+			logger.Info("Closing lock screen as requested by the server...");
+			lockScreen?.Cancel();
+		}
+
 		private void Taskbar_LoseFocusRequested(bool forward)
 		{
 			Browser.Focus(forward);
@@ -260,7 +276,9 @@ namespace SafeExamBrowser.Client
 
 			if (Server != null)
 			{
+				Server.LockScreenConfirmed -= Server_LockScreenConfirmed;
 				Server.TerminationRequested -= Server_TerminationRequested;
+				Server.LockScreenRequested -= Server_LockScreenRequested;
 			}
 
 			foreach (var activator in context.Activators.OfType<ITerminationActivator>())
@@ -769,18 +787,33 @@ namespace SafeExamBrowser.Client
 		private LockScreenResult ShowLockScreen(string message, string title, IEnumerable<LockScreenOption> options)
 		{
 			var hasQuitPassword = !string.IsNullOrEmpty(Settings.Security.QuitPasswordHash);
-			var lockScreen = uiFactory.CreateLockScreen(message, title, options);
+			lockScreen = uiFactory.CreateLockScreen(message, title, options);
 			var result = default(LockScreenResult);
 
 			logger.Info("Showing lock screen...");
 			PauseActivators();
 			lockScreen.Show();
 
+			if (Settings.SessionMode == SessionMode.Server)
+			{
+				var response = Server.LockScreen(message);
+
+				if (!response.Success)
+				{
+					logger.Error($"Failed to send lock screen notification to server! Message: {response.Message}.");
+				}
+			}
+
 			for (var unlocked = false; !unlocked;)
 			{
 				result = lockScreen.WaitForResult();
 
-				if (hasQuitPassword)
+				if (result.Canceled) 
+				{
+					logger.Info("The lock screen has been automaticaly canceled.");
+					unlocked = true;
+				} 
+				else if (hasQuitPassword)
 				{
 					var passwordHash = hashAlgorithm.GenerateHashFor(result.Password);
 					var isCorrect = Settings.Security.QuitPasswordHash.Equals(passwordHash, StringComparison.OrdinalIgnoreCase);
@@ -807,6 +840,16 @@ namespace SafeExamBrowser.Client
 			ResumeActivators();
 			logger.Info("Closed lock screen.");
 
+			if (Settings.SessionMode == SessionMode.Server)
+			{
+				var response = Server.ConfirmLockScreen();
+
+				if (!response.Success)
+				{
+					logger.Error($"Failed to send lock screen confirm notification to server! Message: {response.Message}.");
+				}
+			}
+
 			return result;
 		}
 

SafeExamBrowser.Server.Contracts/Events/LockScreenRequestedEventHandler.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SafeExamBrowser.Server.Contracts.Events
+{
+	/// <summary>
+	/// Event handler used to handle a requested lock screen from SEB Server
+	/// </summary>
+	public delegate void LockScreenRequestedEventHandler(String message);
+	
+}

SafeExamBrowser.Server.Contracts/IServerProxy.cs

@@ -24,6 +24,16 @@ namespace SafeExamBrowser.Server.Contracts
 		/// </summary>
 		event ServerEventHandler HandConfirmed;
 
+		/// <summary>
+		/// Event fired when the proxy receives a confirmation for a lock screen notification.
+		/// </summary>
+		event ServerEventHandler LockScreenConfirmed;
+
+		/// <summary>
+		/// Event fired when proxy receives a lock screen instruction.
+		/// </summary>
+		event LockScreenRequestedEventHandler LockScreenRequested;
+
 		/// <summary>
 		/// Event fired when the proxy receives new proctoring configuration values.
 		/// </summary>
@@ -79,6 +89,11 @@ namespace SafeExamBrowser.Server.Contracts
 		/// </summary>
 		ServerResponse LowerHand();
 
+		/// <summary>
+		/// Sends a lock screen confirm notification to the server.
+		/// </summary>
+		ServerResponse ConfirmLockScreen();
+
 		/// <summary>
 		/// Sends the given user session identifier of a LMS and thus establishes a connection with the server.
 		/// </summary>
@@ -98,5 +113,10 @@ namespace SafeExamBrowser.Server.Contracts
 		/// Sends a raise hand notification to the server.
 		/// </summary>
 		ServerResponse RaiseHand(string message = default(string));
+
+		/// <summary>
+		/// Sends a lock screen notification to the server.
+		/// </summary>
+		ServerResponse LockScreen(string message = default(string));
 	}
 }

SafeExamBrowser.Server.Contracts/SafeExamBrowser.Server.Contracts.csproj

@@ -56,6 +56,7 @@
   <ItemGroup>
     <Compile Include="Data\ConnectionInfo.cs" />
     <Compile Include="Data\Exam.cs" />
+    <Compile Include="Events\LockScreenRequestedEventHandler.cs" />
     <Compile Include="Events\ProctoringConfigurationReceivedEventHandler.cs" />
     <Compile Include="Events\ProctoringInstructionEventArgs.cs" />
     <Compile Include="Events\ProctoringInstructionReceivedEventHandler.cs" />

SafeExamBrowser.Server/Data/Attributes.cs

@@ -19,6 +19,8 @@ namespace SafeExamBrowser.Server.Data
 		internal bool ReceiveVideo { get; set; }
 		internal string Type { get; set; }
 
+		internal string Message { get; set; }
+
 		internal Attributes()
 		{
 			Instruction = new ProctoringInstructionEventArgs();

SafeExamBrowser.Server/Data/Instructions.cs

@@ -14,5 +14,6 @@ namespace SafeExamBrowser.Server.Data
 		internal const string PROCTORING = "SEB_PROCTORING";
 		internal const string PROCTORING_RECONFIGURATION = "SEB_RECONFIGURE_SETTINGS";
 		internal const string QUIT = "SEB_QUIT";
+		internal const string LOCK_SCREEN = "SEB_FORCE_LOCK_SCREEN";
 	}
 }

SafeExamBrowser.Server/Parser.cs

@@ -180,7 +180,7 @@ namespace SafeExamBrowser.Server
 							instructionConfirmation = attributesJson["instruction-confirm"].Value<string>();
 						}
 
-						attributes = ParseProctoringAttributes(attributesJson, instruction);
+						attributes = ParseAttributes(attributesJson, instruction);
 					}
 				}
 			}
@@ -210,7 +210,7 @@ namespace SafeExamBrowser.Server
 			return oauth2Token != default;
 		}
 
-		private Attributes ParseProctoringAttributes(JObject attributesJson, string instruction)
+		private Attributes ParseAttributes(JObject attributesJson, string instruction)
 		{
 			var attributes = new Attributes();
 
@@ -225,11 +225,22 @@ namespace SafeExamBrowser.Server
 				case Instructions.PROCTORING_RECONFIGURATION:
 					ParseReconfigurationInstruction(attributes, attributesJson);
 					break;
+				case Instructions.LOCK_SCREEN:
+					ParseLockScreenInstruction(attributes, attributesJson);
+					break;
 			}
 
 			return attributes;
 		}
 
+		private void ParseLockScreenInstruction(Attributes attributes, JObject attributesJson)
+		{
+			if (attributesJson.ContainsKey("message"))
+			{
+				attributes.Message = attributesJson["message"].Value<string>();
+			}
+		}
+
 		private void ParseNotificationConfirmation(Attributes attributes, JObject attributesJson)
 		{
 			if (attributesJson.ContainsKey("id"))

SafeExamBrowser.Server/ServerProxy.cs

@@ -54,16 +54,21 @@ namespace SafeExamBrowser.Server
 		private bool connectedToPowergrid;
 		private int currentWlanValue;
 		private string examId;
-		private int handNotificationId;
+		private int notificationId;
+		private int currentRaisHandId;
+		private int currentLockScreenId;
+
 		private HttpClient httpClient;
 		private string oauth2Token;
 		private int pingNumber;
 		private ServerSettings settings;
 
 		public event ServerEventHandler HandConfirmed;
+		public event ServerEventHandler LockScreenConfirmed;
 		public event ProctoringConfigurationReceivedEventHandler ProctoringConfigurationReceived;
 		public event ProctoringInstructionReceivedEventHandler ProctoringInstructionReceived;
 		public event TerminationRequestedEventHandler TerminationRequested;
+		public event LockScreenRequestedEventHandler LockScreenRequested;
 
 		public ServerProxy(
 			AppConfig appConfig,
@@ -242,7 +247,7 @@ namespace SafeExamBrowser.Server
 			{
 				["type"] = "NOTIFICATION_CONFIRMED",
 				["timestamp"] = DateTime.Now.ToUnixTimestamp(),
-				["numericValue"] = handNotificationId,
+				["numericValue"] = currentRaisHandId,
 			};
 			var content = json.ToString();
 			var success = TryExecute(HttpMethod.Post, api.LogEndpoint, out var response, content, contentType, authorization, token);
@@ -259,6 +264,32 @@ namespace SafeExamBrowser.Server
 			return new ServerResponse(success, response.ToLogString());
 		}
 
+		public ServerResponse ConfirmLockScreen()
+		{
+			var authorization = ("Authorization", $"Bearer {oauth2Token}");
+			var contentType = "application/json;charset=UTF-8";
+			var token = ("SEBConnectionToken", connectionToken);
+			var json = new JObject
+			{
+				["type"] = "NOTIFICATION_CONFIRMED",
+				["timestamp"] = DateTime.Now.ToUnixTimestamp(),
+				["numericValue"] = currentLockScreenId,
+			};
+			var content = json.ToString();
+			var success = TryExecute(HttpMethod.Post, api.LogEndpoint, out var response, content, contentType, authorization, token);
+
+			if (success)
+			{
+				logger.Info("Successfully sent lock screen confirm notification.");
+			}
+			else
+			{
+				logger.Error("Failed to send lock screen confirm notification!");
+			}
+
+			return new ServerResponse(success, response.ToLogString());
+		}
+
 		public void Notify(ILogContent content)
 		{
 			logContent.Enqueue(content);
@@ -273,7 +304,7 @@ namespace SafeExamBrowser.Server
 			{
 				["type"] = "NOTIFICATION",
 				["timestamp"] = DateTime.Now.ToUnixTimestamp(),
-				["numericValue"] = ++handNotificationId,
+				["numericValue"] = currentRaisHandId = ++notificationId,
 				["text"] = $"<raisehand> {message}"
 			};
 			var content = json.ToString();
@@ -291,6 +322,33 @@ namespace SafeExamBrowser.Server
 			return new ServerResponse(success, response.ToLogString());
 		}
 
+		public ServerResponse LockScreen(string message = null)
+		{
+			var authorization = ("Authorization", $"Bearer {oauth2Token}");
+			var contentType = "application/json;charset=UTF-8";
+			var token = ("SEBConnectionToken", connectionToken);
+			var json = new JObject
+			{
+				["type"] = "NOTIFICATION",
+				["timestamp"] = DateTime.Now.ToUnixTimestamp(),
+				["numericValue"] = currentLockScreenId = ++notificationId,
+				["text"] = $"<lockscreen> {message}"
+			};
+			var content = json.ToString();
+			var success = TryExecute(HttpMethod.Post, api.LogEndpoint, out var response, content, contentType, authorization, token);
+
+			if (success)
+			{
+				logger.Info("Successfully sent lock screen notification.");
+			}
+			else
+			{
+				logger.Error("Failed to send lock screen notification!");
+			}
+
+			return new ServerResponse(success, response.ToLogString());
+		}
+
 		public ServerResponse SendSessionIdentifier(string identifier)
 		{
 			var authorization = ("Authorization", $"Bearer {oauth2Token}");
@@ -414,9 +472,12 @@ namespace SafeExamBrowser.Server
 					{
 						switch (instruction)
 						{
-							case Instructions.NOTIFICATION_CONFIRM when attributes.Type == "raisehand" && attributes.Id == handNotificationId:
+							case Instructions.NOTIFICATION_CONFIRM when attributes.Type == "raisehand":
 								Task.Run(() => HandConfirmed?.Invoke());
 								break;
+							case Instructions.NOTIFICATION_CONFIRM when attributes.Type == "lockscreen":
+								Task.Run(() => LockScreenConfirmed?.Invoke());
+								break;
 							case Instructions.PROCTORING:
 								Task.Run(() => ProctoringInstructionReceived?.Invoke(attributes.Instruction));
 								break;
@@ -426,6 +487,9 @@ namespace SafeExamBrowser.Server
 							case Instructions.QUIT:
 								Task.Run(() => TerminationRequested?.Invoke());
 								break;
+							case Instructions.LOCK_SCREEN:
+								Task.Run(() => LockScreenRequested?.Invoke(attributes.Message));
+								break;
 						}
 
 						if (instructionConfirmation != default)

SafeExamBrowser.UserInterface.Contracts/Windows/Data/LockScreenResult.cs

@@ -15,6 +15,12 @@ namespace SafeExamBrowser.UserInterface.Contracts.Windows.Data
 	/// </summary>
 	public class LockScreenResult
 	{
+
+		/// <summary>
+		/// This is been set if the lock screen was canceled from another process (E.g.: from SEB Server instruction)
+		/// </summary>
+		public bool Canceled { get; set; }
+
 		/// <summary>
 		/// The identifier of the option selected by the user, if available.
 		/// </summary>

SafeExamBrowser.UserInterface.Contracts/Windows/ILockScreen.cs

@@ -19,5 +19,9 @@ namespace SafeExamBrowser.UserInterface.Contracts.Windows
 		/// Waits for the user to provide the required input to unlock the application.
 		/// </summary>
 		LockScreenResult WaitForResult();
+		/// <summary>
+		/// This cancel a waiting thread for LockScreenResult and force the lock screen to close
+		/// </summary>
+		void Cancel();
 	}
 }

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

@@ -27,6 +27,7 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 	{
 		private readonly AutoResetEvent autoResetEvent;
 		private readonly IText text;
+		private bool canceled = false;
 
 		private IList<Window> windows;
 
@@ -85,6 +86,7 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 				}
 			});
 
+			result.Canceled = canceled;
 			return result;
 		}
 
@@ -172,5 +174,11 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 				autoResetEvent.Set();
 			}
 		}
+
+		public void Cancel()
+		{
+			canceled = true;
+			autoResetEvent.Set();
+		}
 	}
 }

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

@@ -27,6 +27,7 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 	{
 		private readonly AutoResetEvent autoResetEvent;
 		private readonly IText text;
+		private bool canceled = false;
 
 		private IList<Window> windows;
 
@@ -85,6 +86,7 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 				}
 			});
 
+			result.Canceled = canceled;
 			return result;
 		}
 
@@ -172,5 +174,11 @@ namespace SafeExamBrowser.UserInterface.Mobile.Windows
 				autoResetEvent.Set();
 			}
 		}
+
+		public void Cancel()
+		{
+			canceled = true;
+			autoResetEvent.Set();
+		}
 	}
 }