Restore SEBPatch

SafeExamBrowser.Monitoring/Keyboard/KeyboardInterceptor.cs

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+/*
+ * 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 System;
+using System.Linq;
+using System.Windows.Input;
+using SafeExamBrowser.Logging.Contracts;
+using SafeExamBrowser.Monitoring.Contracts.Keyboard;
+using SafeExamBrowser.Settings.Monitoring;
+using SafeExamBrowser.WindowsApi.Contracts;
+using SafeExamBrowser.WindowsApi.Contracts.Events;
+
+namespace SafeExamBrowser.Monitoring.Keyboard
+{
+	public class KeyboardInterceptor : IKeyboardInterceptor
+	{
+		private Guid? hookId;
+		private readonly ILogger logger;
+		private readonly INativeMethods nativeMethods;
+		private readonly KeyboardSettings settings;
+
+		public KeyboardInterceptor(ILogger logger, INativeMethods nativeMethods, KeyboardSettings settings)
+		{
+			this.logger = logger;
+			this.nativeMethods = nativeMethods;
+			this.settings = settings;
+		}
+
+		public void Start()
+		{
+			hookId = nativeMethods.RegisterKeyboardHook(KeyboardHookCallback);
+		}
+
+		public void Stop()
+		{
+			if (hookId.HasValue)
+			{
+				nativeMethods.DeregisterKeyboardHook(hookId.Value);
+			}
+		}
+
+		private bool KeyboardHookCallback(int keyCode, KeyModifier modifier, KeyState state)
+		{
+			var block = false;
+
+			return block;
+		}
+
+		private void Log(Key key, int keyCode, KeyModifier modifier, KeyState state)
+		{
+			var modifierFlags = Enum.GetValues(typeof(KeyModifier)).OfType<KeyModifier>().Where(m => m != KeyModifier.None && modifier.HasFlag(m));
+			var modifiers = modifierFlags.Any() ? String.Join(" + ", modifierFlags) + " + " : string.Empty;
+
+			logger.Info($"Blocked '{modifiers}{key}' ({key} = {keyCode}) when {state.ToString().ToLower()}.");
+		}
+	}
+}