Restore SEBPatch

SafeExamBrowser.SystemComponents/UserInfo.cs

@@ -0,0 +1,112 @@
+/*
+ * 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.Diagnostics;
+using System.Security.Principal;
+using System.Text.RegularExpressions;
+using SafeExamBrowser.Logging.Contracts;
+using SafeExamBrowser.SystemComponents.Contracts;
+
+namespace SafeExamBrowser.SystemComponents
+{
+	public class UserInfo : IUserInfo
+	{
+		private const string SID_REGEX_PATTERN = @"S-\d(-\d+)+";
+
+		private ILogger logger;
+
+		public UserInfo(ILogger logger)
+		{
+			this.logger = logger;
+		}
+
+		public string GetUserName()
+		{
+			return Environment.UserName;
+		}
+
+		public string GetUserSid()
+		{
+			return WindowsIdentity.GetCurrent().User.Value;
+		}
+
+		public bool TryGetSidForUser(string userName, out string sid)
+		{
+			var strategies = new Func<string, string>[] { NtAccount, Wmi };
+			var success = false;
+
+			sid = default(string);
+
+			foreach (var strategy in strategies)
+			{
+				try
+				{
+					sid = strategy.Invoke(userName);
+
+					if (IsValid(sid))
+					{
+						logger.Info($"Found SID '{sid}' via '{strategy.Method.Name}' for user name '{userName}'!");
+						success = true;
+
+						break;
+					}
+
+					logger.Warn($"Retrieved invalid SID '{sid}' via '{strategy.Method.Name}' for user name '{userName}'!");
+				}
+				catch (Exception e)
+				{
+					logger.Error($"Failed to get SID via '{strategy.Method.Name}' for user name '{userName}'!", e);
+				}
+			}
+
+			if (!success)
+			{
+				logger.Error($"All attempts to retrieve SID for user name '{userName}' failed!");
+			}
+
+			return success;
+		}
+
+		private string NtAccount(string userName)
+		{
+			var account = new NTAccount(userName);
+
+			if (account.IsValidTargetType(typeof(SecurityIdentifier)))
+			{
+				return account.Translate(typeof(SecurityIdentifier)).Value;
+			}
+
+			return null;
+		}
+
+		private string Wmi(string userName)
+		{
+			var process = new Process();
+
+			process.StartInfo.Arguments = $"/c \"wmic useraccount where name='{userName}' get sid\"";
+			process.StartInfo.CreateNoWindow = true;
+			process.StartInfo.FileName = "cmd.exe";
+			process.StartInfo.RedirectStandardOutput = true;
+			process.StartInfo.UseShellExecute = false;
+			process.StartInfo.WorkingDirectory = Environment.GetFolderPath(Environment.SpecialFolder.Windows);
+			process.Start();
+			process.WaitForExit(5000);
+
+			var output = process.StandardOutput.ReadToEnd();
+			var match = Regex.Match(output, SID_REGEX_PATTERN);
+
+			return match.Success ? match.Value : null;
+		}
+
+		private bool IsValid(string sid)
+		{
+			return !String.IsNullOrWhiteSpace(sid) && Regex.IsMatch(sid, $"^{SID_REGEX_PATTERN}$");
+		}
+	}
+}