From 751bfcb1446e9563ccb509ea76b6fa65ae526e5e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Damian=20B=C3=BCchel?= <damian.buechel@let.ethz.ch>
Date: Wed, 1 Nov 2023 13:52:39 +0100
Subject: [PATCH] SEBWIN-762: Added user identifier detection via Moodle plugin
 and overall renamed session to user identifier.

---
 ... => UserIdentifierDetectedEventHandler.cs} |   4 +-
 .../IBrowserApplication.cs                    |   8 +-
 .../SafeExamBrowser.Browser.Contracts.csproj  |   2 +-
 .../Handlers/ResourceHandlerTests.cs          |  38 ++--
 SafeExamBrowser.Browser/BrowserApplication.cs |   4 +-
 SafeExamBrowser.Browser/BrowserWindow.cs      |   6 +-
 .../Handlers/ResourceHandler.cs               | 194 +++++++++++-------
 .../ClientControllerTests.cs                  |   8 +-
 SafeExamBrowser.Client/ClientController.cs    |  16 +-
 .../IServerProxy.cs                           |   4 +-
 ...ierRequest.cs => UserIdentifierRequest.cs} |   4 +-
 .../SafeExamBrowser.Server.csproj             |   2 +-
 SafeExamBrowser.Server/ServerProxy.cs         |   8 +-
 13 files changed, 173 insertions(+), 125 deletions(-)
 rename SafeExamBrowser.Browser.Contracts/Events/{SessionIdentifierDetectedEventHandler.cs => UserIdentifierDetectedEventHandler.cs} (79%)
 rename SafeExamBrowser.Server/Requests/{SessionIdentifierRequest.cs => UserIdentifierRequest.cs} (91%)

diff --git a/SafeExamBrowser.Browser.Contracts/Events/SessionIdentifierDetectedEventHandler.cs b/SafeExamBrowser.Browser.Contracts/Events/UserIdentifierDetectedEventHandler.cs
similarity index 79%
rename from SafeExamBrowser.Browser.Contracts/Events/SessionIdentifierDetectedEventHandler.cs
rename to SafeExamBrowser.Browser.Contracts/Events/UserIdentifierDetectedEventHandler.cs
index dbbd52c3..2d44db5a 100644
--- a/SafeExamBrowser.Browser.Contracts/Events/SessionIdentifierDetectedEventHandler.cs
+++ b/SafeExamBrowser.Browser.Contracts/Events/UserIdentifierDetectedEventHandler.cs
@@ -9,7 +9,7 @@
 namespace SafeExamBrowser.Browser.Contracts.Events
 {
 	/// <summary>
-	/// Event handler used to indicate that the browser has detected a session identifier of a LMS.
+	/// Event handler used to indicate that the browser has detected a user identifier of an LMS.
 	/// </summary>
-	public delegate void SessionIdentifierDetectedEventHandler(string identifier);
+	public delegate void UserIdentifierDetectedEventHandler(string identifier);
 }
diff --git a/SafeExamBrowser.Browser.Contracts/IBrowserApplication.cs b/SafeExamBrowser.Browser.Contracts/IBrowserApplication.cs
index 8cb418f8..98ab461e 100644
--- a/SafeExamBrowser.Browser.Contracts/IBrowserApplication.cs
+++ b/SafeExamBrowser.Browser.Contracts/IBrowserApplication.cs
@@ -22,9 +22,9 @@ namespace SafeExamBrowser.Browser.Contracts
 		event DownloadRequestedEventHandler ConfigurationDownloadRequested;
 
 		/// <summary>
-		/// Event fired when the browser application detects a session identifier of an LMS.
+		/// Event fired when the user tries to focus the taskbar.
 		/// </summary>
-		event SessionIdentifierDetectedEventHandler SessionIdentifierDetected;
+		event LoseFocusRequestedEventHandler LoseFocusRequested;
 
 		/// <summary>
 		/// Event fired when the browser application detects a request to terminate SEB.
@@ -32,9 +32,9 @@ namespace SafeExamBrowser.Browser.Contracts
 		event TerminationRequestedEventHandler TerminationRequested;
 
 		/// <summary>
-		/// Event fired when the user tries to focus the taskbar.
+		/// Event fired when the browser application detects a user identifier of an LMS.
 		/// </summary>
-		event LoseFocusRequestedEventHandler LoseFocusRequested;
+		event UserIdentifierDetectedEventHandler UserIdentifierDetected;
 
 		/// <summary>
 		/// Transfers the focus to the browser application. If the parameter is <c>true</c>, the first focusable element in the browser window
diff --git a/SafeExamBrowser.Browser.Contracts/SafeExamBrowser.Browser.Contracts.csproj b/SafeExamBrowser.Browser.Contracts/SafeExamBrowser.Browser.Contracts.csproj
index e74e58d5..e993bfcc 100644
--- a/SafeExamBrowser.Browser.Contracts/SafeExamBrowser.Browser.Contracts.csproj
+++ b/SafeExamBrowser.Browser.Contracts/SafeExamBrowser.Browser.Contracts.csproj
@@ -60,7 +60,7 @@
     <Compile Include="Events\DownloadRequestedEventHandler.cs" />
     <Compile Include="Events\TabPressedEventHandler.cs" />
     <Compile Include="Events\LoseFocusRequestedEventHandler.cs" />
-    <Compile Include="Events\SessionIdentifierDetectedEventHandler.cs" />
+    <Compile Include="Events\UserIdentifierDetectedEventHandler.cs" />
     <Compile Include="Events\TerminationRequestedEventHandler.cs" />
     <Compile Include="Filters\IRequestFilter.cs" />
     <Compile Include="Filters\IRule.cs" />
diff --git a/SafeExamBrowser.Browser.UnitTests/Handlers/ResourceHandlerTests.cs b/SafeExamBrowser.Browser.UnitTests/Handlers/ResourceHandlerTests.cs
index 06441071..c999b63e 100644
--- a/SafeExamBrowser.Browser.UnitTests/Handlers/ResourceHandlerTests.cs
+++ b/SafeExamBrowser.Browser.UnitTests/Handlers/ResourceHandlerTests.cs
@@ -166,7 +166,7 @@ namespace SafeExamBrowser.Browser.UnitTests.Handlers
 		[TestMethod]
 		public void MustLetOperatingSystemHandleUnknownProtocols()
 		{
-			Assert.IsTrue(sut.OnProtocolExecution(default(IWebBrowser), default(IBrowser), default(IFrame), default(IRequest)));
+			Assert.IsTrue(sut.OnProtocolExecution(default, default, default, default));
 		}
 
 		[TestMethod]
@@ -232,28 +232,28 @@ namespace SafeExamBrowser.Browser.UnitTests.Handlers
 			var newUrl = default(string);
 			var request = new Mock<IRequest>();
 			var response = new Mock<IResponse>();
-			var sessionId = default(string);
+			var userId = default(string);
 
 			headers.Add("X-LMS-USER-ID", "some-session-id-123");
 			request.SetupGet(r => r.Url).Returns("https://www.somelms.org");
 			response.SetupGet(r => r.Headers).Returns(headers);
-			sut.SessionIdentifierDetected += (id) =>
+			sut.UserIdentifierDetected += (id) =>
 			{
-				sessionId = id;
+				userId = id;
 				@event.Set();
 			};
 
 			sut.OnResourceRedirect(Mock.Of<IWebBrowser>(), Mock.Of<IBrowser>(), Mock.Of<IFrame>(), Mock.Of<IRequest>(), response.Object, ref newUrl);
 			@event.WaitOne();
-			Assert.AreEqual("some-session-id-123", sessionId);
+			Assert.AreEqual("some-session-id-123", userId);
 
 			headers.Clear();
 			headers.Add("X-LMS-USER-ID", "other-session-id-123");
-			sessionId = default(string);
+			userId = default;
 
 			sut.OnResourceResponse(Mock.Of<IWebBrowser>(), Mock.Of<IBrowser>(), Mock.Of<IFrame>(), request.Object, response.Object);
 			@event.WaitOne();
-			Assert.AreEqual("other-session-id-123", sessionId);
+			Assert.AreEqual("other-session-id-123", userId);
 		}
 
 		[TestMethod]
@@ -264,28 +264,28 @@ namespace SafeExamBrowser.Browser.UnitTests.Handlers
 			var newUrl = default(string);
 			var request = new Mock<IRequest>();
 			var response = new Mock<IResponse>();
-			var sessionId = default(string);
+			var userId = default(string);
 
 			headers.Add("Set-Cookie", "edx-user-info=\"{\\\"username\\\": \\\"edx-123\\\"}\"; expires");
 			request.SetupGet(r => r.Url).Returns("https://www.somelms.org");
 			response.SetupGet(r => r.Headers).Returns(headers);
-			sut.SessionIdentifierDetected += (id) =>
+			sut.UserIdentifierDetected += (id) =>
 			{
-				sessionId = id;
+				userId = id;
 				@event.Set();
 			};
 
 			sut.OnResourceRedirect(Mock.Of<IWebBrowser>(), Mock.Of<IBrowser>(), Mock.Of<IFrame>(), Mock.Of<IRequest>(), response.Object, ref newUrl);
 			@event.WaitOne();
-			Assert.AreEqual("edx-123", sessionId);
+			Assert.AreEqual("edx-123", userId);
 
 			headers.Clear();
 			headers.Add("Set-Cookie", "edx-user-info=\"{\\\"username\\\": \\\"edx-345\\\"}\"; expires");
-			sessionId = default(string);
+			userId = default;
 
 			sut.OnResourceResponse(Mock.Of<IWebBrowser>(), Mock.Of<IBrowser>(), Mock.Of<IFrame>(), request.Object, response.Object);
 			@event.WaitOne();
-			Assert.AreEqual("edx-345", sessionId);
+			Assert.AreEqual("edx-345", userId);
 		}
 
 		[TestMethod]
@@ -296,28 +296,28 @@ namespace SafeExamBrowser.Browser.UnitTests.Handlers
 			var newUrl = default(string);
 			var request = new Mock<IRequest>();
 			var response = new Mock<IResponse>();
-			var sessionId = default(string);
+			var userId = default(string);
 
 			headers.Add("Location", "https://www.some-moodle-instance.org/moodle/login/index.php?testsession=123");
 			request.SetupGet(r => r.Url).Returns("https://www.some-moodle-instance.org");
 			response.SetupGet(r => r.Headers).Returns(headers);
-			sut.SessionIdentifierDetected += (id) =>
+			sut.UserIdentifierDetected += (id) =>
 			{
-				sessionId = id;
+				userId = id;
 				@event.Set();
 			};
 
 			sut.OnResourceRedirect(Mock.Of<IWebBrowser>(), Mock.Of<IBrowser>(), Mock.Of<IFrame>(), Mock.Of<IRequest>(), response.Object, ref newUrl);
 			@event.WaitOne();
-			Assert.AreEqual("123", sessionId);
+			Assert.AreEqual("123", userId);
 
 			headers.Clear();
 			headers.Add("Location", "https://www.some-moodle-instance.org/moodle/login/index.php?testsession=456");
-			sessionId = default(string);
+			userId = default;
 
 			sut.OnResourceResponse(Mock.Of<IWebBrowser>(), Mock.Of<IBrowser>(), Mock.Of<IFrame>(), request.Object, response.Object);
 			@event.WaitOne();
-			Assert.AreEqual("456", sessionId);
+			Assert.AreEqual("456", userId);
 		}
 
 		private class TestableResourceHandler : ResourceHandler
diff --git a/SafeExamBrowser.Browser/BrowserApplication.cs b/SafeExamBrowser.Browser/BrowserApplication.cs
index f5ef88b9..fb8513f0 100644
--- a/SafeExamBrowser.Browser/BrowserApplication.cs
+++ b/SafeExamBrowser.Browser/BrowserApplication.cs
@@ -59,9 +59,9 @@ namespace SafeExamBrowser.Browser
 		public string Tooltip { get; private set; }
 
 		public event DownloadRequestedEventHandler ConfigurationDownloadRequested;
-		public event SessionIdentifierDetectedEventHandler SessionIdentifierDetected;
 		public event LoseFocusRequestedEventHandler LoseFocusRequested;
 		public event TerminationRequestedEventHandler TerminationRequested;
+		public event UserIdentifierDetectedEventHandler UserIdentifierDetected;
 		public event WindowsChangedEventHandler WindowsChanged;
 
 		public BrowserApplication(
@@ -209,7 +209,7 @@ namespace SafeExamBrowser.Browser
 			window.ConfigurationDownloadRequested += (f, a) => ConfigurationDownloadRequested?.Invoke(f, a);
 			window.PopupRequested += Window_PopupRequested;
 			window.ResetRequested += Window_ResetRequested;
-			window.SessionIdentifierDetected += (i) => SessionIdentifierDetected?.Invoke(i);
+			window.UserIdentifierDetected += (i) => UserIdentifierDetected?.Invoke(i);
 			window.TerminationRequested += () => TerminationRequested?.Invoke();
 			window.LoseFocusRequested += (forward) => LoseFocusRequested?.Invoke(forward);
 
diff --git a/SafeExamBrowser.Browser/BrowserWindow.cs b/SafeExamBrowser.Browser/BrowserWindow.cs
index 38897998..849ef68c 100644
--- a/SafeExamBrowser.Browser/BrowserWindow.cs
+++ b/SafeExamBrowser.Browser/BrowserWindow.cs
@@ -81,11 +81,11 @@ namespace SafeExamBrowser.Browser
 
 		internal event WindowClosedEventHandler Closed;
 		internal event DownloadRequestedEventHandler ConfigurationDownloadRequested;
+		internal event LoseFocusRequestedEventHandler LoseFocusRequested;
 		internal event PopupRequestedEventHandler PopupRequested;
 		internal event ResetRequestedEventHandler ResetRequested;
-		internal event SessionIdentifierDetectedEventHandler SessionIdentifierDetected;
-		internal event LoseFocusRequestedEventHandler LoseFocusRequested;
 		internal event TerminationRequestedEventHandler TerminationRequested;
+		internal event UserIdentifierDetectedEventHandler UserIdentifierDetected;
 
 		public event IconChangedEventHandler IconChanged;
 		public event TitleChangedEventHandler TitleChanged;
@@ -185,9 +185,9 @@ namespace SafeExamBrowser.Browser
 			keyboardHandler.ZoomInRequested += ZoomInRequested;
 			keyboardHandler.ZoomOutRequested += ZoomOutRequested;
 			keyboardHandler.ZoomResetRequested += ZoomResetRequested;
-			resourceHandler.SessionIdentifierDetected += (id) => SessionIdentifierDetected?.Invoke(id);
 			requestHandler.QuitUrlVisited += RequestHandler_QuitUrlVisited;
 			requestHandler.RequestBlocked += RequestHandler_RequestBlocked;
+			resourceHandler.UserIdentifierDetected += (id) => UserIdentifierDetected?.Invoke(id);
 
 			InitializeRequestFilter(requestFilter);
 
diff --git a/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs b/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs
index e92cdd02..d779c940 100644
--- a/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs
+++ b/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs
@@ -44,9 +44,9 @@ namespace SafeExamBrowser.Browser.Handlers
 
 		private IResourceHandler contentHandler;
 		private IResourceHandler pageHandler;
-		private string sessionIdentifier;
+		private string userIdentifier;
 
-		internal event SessionIdentifierDetectedEventHandler SessionIdentifierDetected;
+		internal event UserIdentifierDetectedEventHandler UserIdentifierDetected;
 
 		internal ResourceHandler(
 			AppConfig appConfig,
@@ -100,7 +100,7 @@ namespace SafeExamBrowser.Browser.Handlers
 		{
 			if (sessionMode == SessionMode.Server)
 			{
-				SearchSessionIdentifiers(request, response);
+				SearchUserIdentifier(request, response);
 			}
 
 			base.OnResourceRedirect(chromiumWebBrowser, browser, frame, request, response, ref newUrl);
@@ -117,7 +117,7 @@ namespace SafeExamBrowser.Browser.Handlers
 
 			if (sessionMode == SessionMode.Server)
 			{
-				SearchSessionIdentifiers(request, response);
+				SearchUserIdentifier(request, response);
 			}
 
 			return base.OnResourceResponse(webBrowser, browser, frame, request, response);
@@ -233,41 +233,46 @@ namespace SafeExamBrowser.Browser.Handlers
 			}
 		}
 
-		private void SearchSessionIdentifiers(IRequest request, IResponse response)
+		private void SearchUserIdentifier(IRequest request, IResponse response)
 		{
-			var success = TrySearchGenericSessionIdentifier(response);
+			var success = TrySearchGenericUserIdentifier(response);
 
 			if (!success)
 			{
-				SearchEdxIdentifier(response);
-				SearchMoodleIdentifier(request, response);
+				success = TrySearchEdxUserIdentifier(response);
+			}
+
+			if (!success)
+			{
+				TrySearchMoodleUserIdentifier(request, response);
 			}
 		}
 
-		private bool TrySearchGenericSessionIdentifier(IResponse response)
+		private bool TrySearchGenericUserIdentifier(IResponse response)
 		{
 			var ids = response.Headers.GetValues("X-LMS-USER-ID");
+			var success = false;
 
 			if (ids != default(string[]))
 			{
 				var userId = ids.FirstOrDefault();
 
-				if (userId != default && sessionIdentifier != userId)
+				if (userId != default && userIdentifier != userId)
 				{
-					sessionIdentifier = userId;
-					Task.Run(() => SessionIdentifierDetected?.Invoke(sessionIdentifier));
-					logger.Info("Generic LMS session detected.");
-
-					return true;
+					userIdentifier = userId;
+					Task.Run(() => UserIdentifierDetected?.Invoke(userIdentifier));
+					logger.Info("Generic LMS user identifier detected.");
+					success = true;
 				}
 			}
 
-			return false;
+			return success;
 		}
 
-		private void SearchEdxIdentifier(IResponse response)
+		private bool TrySearchEdxUserIdentifier(IResponse response)
 		{
 			var cookies = response.Headers.GetValues("Set-Cookie");
+			var success = false;
 
 			if (cookies != default(string[]))
 			{
@@ -284,32 +289,42 @@ namespace SafeExamBrowser.Browser.Handlers
 						var json = JsonConvert.DeserializeObject(sanitized) as JObject;
 						var userName = json["username"].Value<string>();
 
-						if (sessionIdentifier != userName)
+						if (userIdentifier != userName)
 						{
-							sessionIdentifier = userName;
-							Task.Run(() => SessionIdentifierDetected?.Invoke(sessionIdentifier));
-							logger.Info("EdX session detected.");
+							userIdentifier = userName;
+							Task.Run(() => UserIdentifierDetected?.Invoke(userIdentifier));
+							logger.Info("EdX user identifier detected.");
+							success = true;
 						}
 					}
 				}
 				catch (Exception e)
 				{
-					logger.Error("Failed to parse edX session identifier!", e);
+					logger.Error("Failed to parse edX user identifier!", e);
 				}
 			}
+
+			return success;
 		}
 
-		private void SearchMoodleIdentifier(IRequest request, IResponse response)
+		private bool TrySearchMoodleUserIdentifier(IRequest request, IResponse response)
 		{
-			var success = TrySearchByLocation(response);
+			var success = TrySearchMoodleUserIdentifierByLocation(response);
 
 			if (!success)
 			{
-				TrySearchBySession(request, response);
+				success = TrySearchMoodleUserIdentifierByRequest(MoodleRequestType.Plugin, request, response);
 			}
+
+			if (!success)
+			{
+				success = TrySearchMoodleUserIdentifierByRequest(MoodleRequestType.Theme, request, response);
+			}
+
+			return success;
 		}
 
-		private bool TrySearchByLocation(IResponse response)
+		private bool TrySearchMoodleUserIdentifierByLocation(IResponse response)
 		{
 			var locations = response.Headers.GetValues("Location");
 
@@ -323,11 +338,11 @@ namespace SafeExamBrowser.Browser.Handlers
 					{
 						var userId = location.Substring(location.IndexOf("=") + 1);
 
-						if (sessionIdentifier != userId)
+						if (userIdentifier != userId)
 						{
-							sessionIdentifier = userId;
-							Task.Run(() => SessionIdentifierDetected?.Invoke(sessionIdentifier));
-							logger.Info("Moodle session detected.");
+							userIdentifier = userId;
+							Task.Run(() => UserIdentifierDetected?.Invoke(userIdentifier));
+							logger.Info("Moodle user identifier detected by location.");
 						}
 
 						return true;
@@ -335,16 +350,17 @@ namespace SafeExamBrowser.Browser.Handlers
 				}
 				catch (Exception e)
 				{
-					logger.Error("Failed to parse Moodle session identifier!", e);
+					logger.Error("Failed to parse Moodle user identifier by location!", e);
 				}
 			}
 
 			return false;
 		}
 
-		private void TrySearchBySession(IRequest request, IResponse response)
+		private bool TrySearchMoodleUserIdentifierByRequest(MoodleRequestType type, IRequest request, IResponse response)
 		{
 			var cookies = response.Headers.GetValues("Set-Cookie");
+			var success = false;
 
 			if (cookies != default(string[]))
 			{
@@ -352,51 +368,83 @@ namespace SafeExamBrowser.Browser.Handlers
 
 				if (session != default)
 				{
-					var requestUrl = request.Url;
+					var userId = ExecuteMoodleUserIdentifierRequest(request.Url, session, type);
 
-					Task.Run(async () =>
+					if (int.TryParse(userId, out var id) && id > 0 && userIdentifier != userId)
 					{
-						try
-						{
-							var start = session.IndexOf("=") + 1;
-							var end = session.IndexOf(";");
-							var value = session.Substring(start, end - start);
-							var uri = new Uri(requestUrl);
-							var message = new HttpRequestMessage(HttpMethod.Get, $"{uri.Scheme}{Uri.SchemeDelimiter}{uri.Host}/theme/boost_ethz/sebuser.php");
-
-							using (var handler = new HttpClientHandler { UseCookies = false })
-							using (var client = new HttpClient(handler))
-							{
-								message.Headers.Add("Cookie", $"MoodleSession={value}");
-
-								var result = await client.SendAsync(message);
-
-								if (result.IsSuccessStatusCode)
-								{
-									var userId = await result.Content.ReadAsStringAsync();
-
-									if (int.TryParse(userId, out var id) && id > 0 && sessionIdentifier != userId)
-									{
-#pragma warning disable CS4014
-										sessionIdentifier = userId;
-										Task.Run(() => SessionIdentifierDetected?.Invoke(sessionIdentifier));
-										logger.Info("Moodle session detected.");
-#pragma warning restore CS4014
-									}
-								}
-								else
-								{
-									logger.Error($"Failed to retrieve Moodle session identifier! Response: {result.StatusCode} {result.ReasonPhrase}");
-								}
-							}
-						}
-						catch (Exception e)
-						{
-							logger.Error("Failed to parse Moodle session identifier!", e);
-						}
-					});
+						userIdentifier = userId;
+						Task.Run(() => UserIdentifierDetected?.Invoke(userIdentifier));
+						logger.Info($"Moodle user identifier detected by request ({type}).");
+						success = true;
+					}
 				}
 			}
+
+			return success;
+		}
+
+		private string ExecuteMoodleUserIdentifierRequest(string requestUrl, string session, MoodleRequestType type)
+		{
+			var userId = default(string);
+
+			try
+			{
+				Task.Run(async () =>
+				{
+					try
+					{
+						var endpointUrl = default(string);
+						var start = session.IndexOf("=") + 1;
+						var end = session.IndexOf(";");
+						var value = session.Substring(start, end - start);
+						var uri = new Uri(requestUrl);
+
+						if (type == MoodleRequestType.Plugin)
+						{
+							endpointUrl = $"{uri.Scheme}{Uri.SchemeDelimiter}{uri.Host}/mod/quiz/accessrule/sebserver/classes/external/user.php";
+						}
+						else
+						{
+							endpointUrl = $"{uri.Scheme}{Uri.SchemeDelimiter}{uri.Host}/theme/boost_ethz/sebuser.php";
+						}
+
+						var message = new HttpRequestMessage(HttpMethod.Get, endpointUrl);
+
+						using (var handler = new HttpClientHandler { UseCookies = false })
+						using (var client = new HttpClient(handler))
+						{
+							message.Headers.Add("Cookie", $"MoodleSession={value}");
+
+							var result = await client.SendAsync(message);
+
+							if (result.IsSuccessStatusCode)
+							{
+								userId = await result.Content.ReadAsStringAsync();
+							}
+							else if (result.StatusCode != HttpStatusCode.NotFound)
+							{
+								logger.Error($"Failed to retrieve Moodle user identifier by request ({type})! Response: {(int) result.StatusCode} {result.ReasonPhrase}");
+							}
+						}
+					}
+					catch (Exception e)
+					{
+						logger.Error($"Failed to parse Moodle user identifier by request ({type})!", e);
+					}
+				}).GetAwaiter().GetResult();
+			}
+			catch (Exception e)
+			{
+				logger.Error($"Failed to execute Moodle user identifier request ({type})!", e);
+			}
+
+			return userId;
+		}
+
+		private enum MoodleRequestType
+		{
+			Plugin,
+			Theme
 		}
 	}
 }
diff --git a/SafeExamBrowser.Client.UnitTests/ClientControllerTests.cs b/SafeExamBrowser.Client.UnitTests/ClientControllerTests.cs
index cbdbb523..ca4a46cc 100644
--- a/SafeExamBrowser.Client.UnitTests/ClientControllerTests.cs
+++ b/SafeExamBrowser.Client.UnitTests/ClientControllerTests.cs
@@ -324,18 +324,18 @@ namespace SafeExamBrowser.Client.UnitTests
 		}
 
 		[TestMethod]
-		public void Browser_MustHandleSessionIdentifierDetection()
+		public void Browser_MustHandleUserIdentifierDetection()
 		{
 			var counter = 0;
 			var identifier = "abc123";
 
 			settings.SessionMode = SessionMode.Server;
-			server.Setup(s => s.SendSessionIdentifier(It.IsAny<string>())).Returns(() => new ServerResponse(++counter == 3));
+			server.Setup(s => s.SendUserIdentifier(It.IsAny<string>())).Returns(() => new ServerResponse(++counter == 3));
 
 			sut.TryStart();
-			browser.Raise(b => b.SessionIdentifierDetected += null, identifier);
+			browser.Raise(b => b.UserIdentifierDetected += null, identifier);
 
-			server.Verify(s => s.SendSessionIdentifier(It.Is<string>(id => id == identifier)), Times.Exactly(3));
+			server.Verify(s => s.SendUserIdentifier(It.Is<string>(id => id == identifier)), Times.Exactly(3));
 		}
 
 		[TestMethod]
diff --git a/SafeExamBrowser.Client/ClientController.cs b/SafeExamBrowser.Client/ClientController.cs
index ad497c28..fda26380 100644
--- a/SafeExamBrowser.Client/ClientController.cs
+++ b/SafeExamBrowser.Client/ClientController.cs
@@ -200,9 +200,9 @@ namespace SafeExamBrowser.Client
 			applicationMonitor.ExplorerStarted += ApplicationMonitor_ExplorerStarted;
 			applicationMonitor.TerminationFailed += ApplicationMonitor_TerminationFailed;
 			Browser.ConfigurationDownloadRequested += Browser_ConfigurationDownloadRequested;
-			Browser.SessionIdentifierDetected += Browser_SessionIdentifierDetected;
-			Browser.TerminationRequested += Browser_TerminationRequested;
 			Browser.LoseFocusRequested += Browser_LoseFocusRequested;
+			Browser.TerminationRequested += Browser_TerminationRequested;
+			Browser.UserIdentifierDetected += Browser_UserIdentifierDetected;
 			ClientHost.ExamSelectionRequested += ClientHost_ExamSelectionRequested;
 			ClientHost.MessageBoxRequested += ClientHost_MessageBoxRequested;
 			ClientHost.PasswordRequested += ClientHost_PasswordRequested;
@@ -254,9 +254,9 @@ namespace SafeExamBrowser.Client
 			if (Browser != null)
 			{
 				Browser.ConfigurationDownloadRequested -= Browser_ConfigurationDownloadRequested;
-				Browser.SessionIdentifierDetected -= Browser_SessionIdentifierDetected;
-				Browser.TerminationRequested -= Browser_TerminationRequested;
 				Browser.LoseFocusRequested -= Browser_LoseFocusRequested;
+				Browser.TerminationRequested -= Browser_TerminationRequested;
+				Browser.UserIdentifierDetected -= Browser_UserIdentifierDetected;
 			}
 
 			if (ClientHost != null)
@@ -531,17 +531,17 @@ namespace SafeExamBrowser.Client
 			}
 		}
 
-		private void Browser_SessionIdentifierDetected(string identifier)
+		private void Browser_UserIdentifierDetected(string identifier)
 		{
 			if (Settings.SessionMode == SessionMode.Server)
 			{
-				var response = Server.SendSessionIdentifier(identifier);
+				var response = Server.SendUserIdentifier(identifier);
 
 				while (!response.Success)
 				{
-					logger.Error($"Failed to communicate session identifier with server! {response.Message}");
+					logger.Error($"Failed to communicate user identifier with server! {response.Message}");
 					Thread.Sleep(Settings.Server.RequestAttemptInterval);
-					response = Server.SendSessionIdentifier(identifier);
+					response = Server.SendUserIdentifier(identifier);
 				}
 			}
 		}
diff --git a/SafeExamBrowser.Server.Contracts/IServerProxy.cs b/SafeExamBrowser.Server.Contracts/IServerProxy.cs
index fc227b25..4ea7c0ff 100644
--- a/SafeExamBrowser.Server.Contracts/IServerProxy.cs
+++ b/SafeExamBrowser.Server.Contracts/IServerProxy.cs
@@ -110,9 +110,9 @@ namespace SafeExamBrowser.Server.Contracts
 		ServerResponse<string> SendSelectedExam(Exam exam);
 
 		/// <summary>
-		/// Sends the given user session identifier of a LMS and thus establishes a connection with the server.
+		/// Sends the given user identifier of an LMS and thus establishes a connection with the server.
 		/// </summary>
-		ServerResponse SendSessionIdentifier(string identifier);
+		ServerResponse SendUserIdentifier(string identifier);
 
 		/// <summary>
 		/// Starts sending ping and log data to the server.
diff --git a/SafeExamBrowser.Server/Requests/SessionIdentifierRequest.cs b/SafeExamBrowser.Server/Requests/UserIdentifierRequest.cs
similarity index 91%
rename from SafeExamBrowser.Server/Requests/SessionIdentifierRequest.cs
rename to SafeExamBrowser.Server/Requests/UserIdentifierRequest.cs
index 31dd7c33..a41394ab 100644
--- a/SafeExamBrowser.Server/Requests/SessionIdentifierRequest.cs
+++ b/SafeExamBrowser.Server/Requests/UserIdentifierRequest.cs
@@ -13,9 +13,9 @@ using SafeExamBrowser.Settings.Server;
 
 namespace SafeExamBrowser.Server.Requests
 {
-	internal class SessionIdentifierRequest : BaseRequest
+	internal class UserIdentifierRequest : BaseRequest
 	{
-		internal SessionIdentifierRequest(
+		internal UserIdentifierRequest(
 			ApiVersion1 api,
 			HttpClient httpClient,
 			ILogger logger,
diff --git a/SafeExamBrowser.Server/SafeExamBrowser.Server.csproj b/SafeExamBrowser.Server/SafeExamBrowser.Server.csproj
index 7ee62560..1bcd192a 100644
--- a/SafeExamBrowser.Server/SafeExamBrowser.Server.csproj
+++ b/SafeExamBrowser.Server/SafeExamBrowser.Server.csproj
@@ -85,7 +85,7 @@
     <Compile Include="Requests\PowerSupplyRequest.cs" />
     <Compile Include="Requests\RaiseHandRequest.cs" />
     <Compile Include="Requests\SelectExamRequest.cs" />
-    <Compile Include="Requests\SessionIdentifierRequest.cs" />
+    <Compile Include="Requests\UserIdentifierRequest.cs" />
     <Compile Include="ServerProxy.cs" />
   </ItemGroup>
   <ItemGroup>
diff --git a/SafeExamBrowser.Server/ServerProxy.cs b/SafeExamBrowser.Server/ServerProxy.cs
index 45173efe..f2473d82 100644
--- a/SafeExamBrowser.Server/ServerProxy.cs
+++ b/SafeExamBrowser.Server/ServerProxy.cs
@@ -310,18 +310,18 @@ namespace SafeExamBrowser.Server
 			return new ServerResponse<string>(success, browserExamKey, message);
 		}
 
-		public ServerResponse SendSessionIdentifier(string identifier)
+		public ServerResponse SendUserIdentifier(string identifier)
 		{
-			var request = new SessionIdentifierRequest(api, httpClient, logger, parser, settings);
+			var request = new UserIdentifierRequest(api, httpClient, logger, parser, settings);
 			var success = request.TryExecute(examId, identifier, out var message);
 
 			if (success)
 			{
-				logger.Info("Successfully sent session identifier.");
+				logger.Info("Successfully sent user identifier.");
 			}
 			else
 			{
-				logger.Error("Failed to send session identifier!");
+				logger.Error("Failed to send user identifier!");
 			}
 
 			return new ServerResponse(success, message);