Restore SEBPatch

SafeExamBrowser.Lockdown/FeatureConfigurations/RegistryConfigurations/RegistryConfiguration.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.Collections.Generic;
+using System.Linq;
+using Microsoft.Win32;
+using SafeExamBrowser.Lockdown.Contracts;
+using SafeExamBrowser.Logging.Contracts;
+
+namespace SafeExamBrowser.Lockdown.FeatureConfigurations.RegistryConfigurations
+{
+	[Serializable]
+	internal abstract class RegistryConfiguration : FeatureConfiguration
+	{
+		private IList<RegistryDataItem> itemsToDelete;
+		private IList<RegistryDataItem> itemsToRestore;
+
+		protected abstract IEnumerable<RegistryConfigurationItem> Items { get; }
+		protected abstract RegistryKey RootKey { get; }
+
+		public RegistryConfiguration(Guid groupId, ILogger logger) : base(groupId, logger)
+		{
+			itemsToDelete = new List<RegistryDataItem>();
+			itemsToRestore = new List<RegistryDataItem>();
+		}
+
+		protected abstract bool IsHiveAvailable(RegistryDataItem item);
+
+		public override bool DisableFeature()
+		{
+			var success = true;
+
+			foreach (var item in Items)
+			{
+				success &= TrySet(new RegistryDataItem { Key = item.Key, Value = item.Value, Data = item.Disabled });
+			}
+
+			if (success)
+			{
+				logger.Info("Successfully disabled feature.");
+			}
+			else
+			{
+				logger.Warn("Failed to disable feature!");
+			}
+
+			return success;
+		}
+
+		public override bool EnableFeature()
+		{
+			var success = true;
+
+			foreach (var item in Items)
+			{
+				success &= TrySet(new RegistryDataItem { Key = item.Key, Value = item.Value, Data = item.Enabled });
+			}
+
+			if (success)
+			{
+				logger.Info("Successfully enabled feature.");
+			}
+			else
+			{
+				logger.Warn("Failed to enable feature!");
+			}
+
+			return success;
+		}
+
+		public override void Initialize()
+		{
+			foreach (var item in Items)
+			{
+				var original = ReadItem(item.Key, item.Value);
+
+				if (original.Data == null)
+				{
+					itemsToDelete.Add(original);
+				}
+				else
+				{
+					itemsToRestore.Add(original);
+				}
+			}
+		}
+
+		public override FeatureConfigurationStatus GetStatus()
+		{
+			var status = FeatureConfigurationStatus.Undefined;
+
+			foreach (var item in Items)
+			{
+				var current = ReadItem(item.Key, item.Value);
+
+				if (current.Data?.Equals(item.Disabled) == true && status != FeatureConfigurationStatus.Enabled)
+				{
+					status = FeatureConfigurationStatus.Disabled;
+				}
+				else if (current.Data?.Equals(item.Enabled) == true && status != FeatureConfigurationStatus.Disabled)
+				{
+					status = FeatureConfigurationStatus.Enabled;
+				}
+				else
+				{
+					status = FeatureConfigurationStatus.Undefined;
+
+					break;
+				}
+			}
+
+			return status;
+		}
+
+		public override bool Restore()
+		{
+			foreach (var item in new List<RegistryDataItem>(itemsToDelete))
+			{
+				if (TryDelete(item))
+				{
+					itemsToDelete.Remove(item);
+				}
+			}
+
+			foreach (var item in new List<RegistryDataItem>(itemsToRestore))
+			{
+				if (TrySet(item))
+				{
+					itemsToRestore.Remove(item);
+				}
+			}
+
+			var success = !itemsToDelete.Any() && !itemsToRestore.Any();
+
+			if (success)
+			{
+				logger.Info("Successfully restored feature.");
+			}
+			else
+			{
+				logger.Warn("Failed to restore feature!");
+			}
+
+			return success;
+		}
+
+		protected bool DeleteConfiguration()
+		{
+			var success = true;
+
+			foreach (var item in Items)
+			{
+				success &= TryDelete(new RegistryDataItem { Key = item.Key, Value = item.Value });
+			}
+
+			if (success)
+			{
+				logger.Info("Successfully deleted feature configuration.");
+			}
+			else
+			{
+				logger.Warn("Failed to delete feature configuration!");
+			}
+
+			return success;
+		}
+
+		private RegistryDataItem ReadItem(string key, string value)
+		{
+			var data = Registry.GetValue(key, value, null);
+			var original = new RegistryDataItem { Key = key, Value = value, Data = data };
+
+			return original;
+		}
+
+		private bool TryDelete(RegistryDataItem item)
+		{
+			var success = false;
+
+			try
+			{
+				if (IsHiveAvailable(item))
+				{
+					var keyWithoutRoot = item.Key.Substring(item.Key.IndexOf('\\') + 1);
+
+					using (var key = RootKey.OpenSubKey(keyWithoutRoot, true))
+					{
+						if (key.GetValue(item.Value) != null)
+						{
+							key.DeleteValue(item.Value);
+							logger.Debug($"Successfully deleted registry item {item}.");
+						}
+						else
+						{
+							logger.Debug($"No need to delete registry item {item} as it does not exist.");
+						}
+
+						success = true;
+					}
+				}
+				else
+				{
+					logger.Warn($"Cannot delete item {item} as its registry hive is not available!");
+				}
+			}
+			catch (Exception e)
+			{
+				logger.Error($"Failed to delete registry item {item}!", e);
+			}
+
+			return success;
+		}
+
+		private bool TrySet(RegistryDataItem item)
+		{
+			var success = false;
+
+			try
+			{
+				if (IsHiveAvailable(item))
+				{
+					Registry.SetValue(item.Key, item.Value, item.Data);
+					logger.Debug($"Successfully set registry item {item}.");
+					success = true;
+				}
+				else
+				{
+					logger.Warn($"Cannot set item {item} as its registry hive is not available!");
+				}
+			}
+			catch (Exception e)
+			{
+				logger.Error($"Failed to set registry item {item}!", e);
+			}
+
+			return success;
+		}
+	}
+}