Restore SEBPatch

2025-06-01 11:56:28 +02:00
parent 8c656e3137
commit 00707825b4
1009 changed files with 5005 additions and 6502 deletions
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Buffer.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Buffer.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
@@ -47,6 +47,15 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			}
 		}

+		internal void Clear()
+		{
+			lock (@lock)
+			{
+				list.Clear();
+				logger.Debug("Cleared all data.");
+			}
+		}
+
 		internal void Dequeue()
 		{
 			lock (@lock)
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Cache.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Cache.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
@@ -23,19 +23,27 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 {
 	internal class Cache
 	{
-		private const string DATA_FILE_EXTENSION = "xml";
+		private const string DATA_FILE_EXTENSION = "spsdat";
+		private const string IMAGE_FILE_EXTENSION = "spsimg";

 		private readonly AppConfig appConfig;
+		private readonly Lazy<string> directory;
+		private readonly Encryptor encryptor;
 		private readonly ILogger logger;
+		private readonly ScreenProctoringSettings settings;
 		private readonly ConcurrentQueue<(string fileName, int checksum, string hash)> queue;

 		internal int Count => queue.Count;
-		internal string Directory { get; private set; }
+		internal string Directory => directory.Value;
+		internal long Size { get; private set; }

-		public Cache(AppConfig appConfig, ILogger logger)
+		public Cache(AppConfig appConfig, ILogger logger, ScreenProctoringSettings settings)
 		{
 			this.appConfig = appConfig;
+			this.directory = new Lazy<string>(InitializeDirectory);
+			this.encryptor = new Encryptor(settings);
 			this.logger = logger;
+			this.settings = settings;
 			this.queue = new ConcurrentQueue<(string, int, string)>();
 		}

@@ -44,6 +52,24 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			return queue.Any();
 		}

+		internal void Clear()
+		{
+			while (queue.Any())
+			{
+				if (queue.TryDequeue(out var item))
+				{
+					var (dataPath, imagePath) = BuildPathsFor(item.fileName);
+
+					File.Delete(dataPath);
+					File.Delete(imagePath);
+				}
+			}
+
+			Size = 0;
+
+			logger.Debug("Cleared all data.");
+		}
+
 		internal bool TryEnqueue(MetaData metaData, ScreenShot screenShot)
 		{
 			var fileName = $"{screenShot.CaptureTime:yyyy-MM-dd HH\\hmm\\mss\\sfff\\m\\s}";
@@ -51,14 +77,22 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring

 			try
 			{
-				InitializeDirectory();
-				SaveData(fileName, metaData, screenShot);
-				SaveImage(fileName, screenShot);
-				Enqueue(fileName, metaData, screenShot);
+				var (dataPath, imagePath) = BuildPathsFor(fileName);
+
+				if (Size <= settings.CacheSize * 1000000)
+				{
+					SaveData(dataPath, metaData, screenShot);
+					SaveImage(imagePath, screenShot);
+					Enqueue(fileName, metaData, screenShot);
+
+					logger.Debug($"Cached data for '{fileName}', now holding {Count} item(s) counting {Size / 1000000.0:N1} MB.");
+				}
+				else
+				{
+					logger.Debug($"The maximum cache size of {settings.CacheSize:N1} MB has been reached, dropping data for '{fileName}'!");
+				}

 				success = true;
-
-				logger.Debug($"Cached data for '{fileName}', now holding {Count} item(s).");
 			}
 			catch (Exception e)
 			{
@@ -79,13 +113,15 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			{
 				try
 				{
-					LoadData(item.fileName, out metaData, out screenShot);
-					LoadImage(item.fileName, screenShot);
-					Dequeue(item.fileName, item.checksum, item.hash, metaData, screenShot);
+					var (dataPath, imagePath) = BuildPathsFor(item.fileName);
+
+					LoadData(dataPath, out metaData, out screenShot);
+					LoadImage(imagePath, screenShot);
+					Dequeue(item.checksum, dataPath, item.fileName, item.hash, imagePath, metaData, screenShot);

 					success = true;

-					logger.Debug($"Removed data for '{item.fileName}', {Count} item(s) remaining.");
+					logger.Debug($"Removed data for '{item.fileName}', {Count} item(s) counting {Size / 1000000.0:N1} MB remaining.");
 				}
 				catch (Exception e)
 				{
@@ -96,12 +132,16 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			return success;
 		}

-		private void Dequeue(string fileName, int checksum, string hash, MetaData metaData, ScreenShot screenShot)
+		private (string dataPath, string imagePath) BuildPathsFor(string fileName)
 		{
 			var dataPath = Path.Combine(Directory, $"{fileName}.{DATA_FILE_EXTENSION}");
-			var extension = screenShot.Format.ToString().ToLower();
-			var imagePath = Path.Combine(Directory, $"{fileName}.{extension}");
+			var imagePath = Path.Combine(Directory, $"{fileName}.{IMAGE_FILE_EXTENSION}");

+			return (dataPath, imagePath);
+		}
+
+		private void Dequeue(int checksum, string dataPath, string fileName, string hash, string imagePath, MetaData metaData, ScreenShot screenShot)
+		{
 			if (checksum != GenerateChecksum(screenShot))
 			{
 				logger.Warn($"The checksum for '{fileName}' does not match, the image data may be manipulated!");
@@ -157,24 +197,25 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			return hash;
 		}

-		private void InitializeDirectory()
+		private string InitializeDirectory()
 		{
-			if (Directory == default)
+			var path = Path.Combine(appConfig.TemporaryDirectory, nameof(ScreenProctoring));
+
+			if (!System.IO.Directory.Exists(path))
 			{
-				Directory = Path.Combine(appConfig.TemporaryDirectory, nameof(ScreenProctoring));
+				System.IO.Directory.CreateDirectory(path);
+				logger.Debug($"Created caching directory '{path}'.");
 			}

-			if (!System.IO.Directory.Exists(Directory))
-			{
-				System.IO.Directory.CreateDirectory(Directory);
-				logger.Debug($"Created caching directory '{Directory}'.");
-			}
+			return path;
 		}

-		private void LoadData(string fileName, out MetaData metaData, out ScreenShot screenShot)
+		private void LoadData(string filePath, out MetaData metaData, out ScreenShot screenShot)
 		{
-			var dataPath = Path.Combine(Directory, $"{fileName}.{DATA_FILE_EXTENSION}");
-			var document = XDocument.Load(dataPath);
+			var encrypted = File.ReadAllBytes(filePath);
+			var data = encryptor.Decrypt(encrypted);
+			var text = Encoding.UTF8.GetString(data);
+			var document = XDocument.Parse(text);
 			var xml = document.Descendants(nameof(MetaData)).First();

 			metaData = new MetaData();
@@ -193,22 +234,24 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			screenShot.Format = (ImageFormat) Enum.Parse(typeof(ImageFormat), xml.Descendants(nameof(ScreenShot.Format)).First().Value);
 			screenShot.Height = int.Parse(xml.Descendants(nameof(ScreenShot.Height)).First().Value);
 			screenShot.Width = int.Parse(xml.Descendants(nameof(ScreenShot.Width)).First().Value);
+
+			Size -= encrypted.Length;
 		}

-		private void LoadImage(string fileName, ScreenShot screenShot)
+		private void LoadImage(string filePath, ScreenShot screenShot)
 		{
-			var extension = screenShot.Format.ToString().ToLower();
-			var imagePath = Path.Combine(Directory, $"{fileName}.{extension}");
+			var encrypted = File.ReadAllBytes(filePath);
+			var image = encryptor.Decrypt(encrypted);

-			screenShot.Data = File.ReadAllBytes(imagePath);
+			screenShot.Data = image;
+			Size -= encrypted.Length;
 		}

-		private void SaveData(string fileName, MetaData metaData, ScreenShot screenShot)
+		private void SaveData(string filePath, MetaData metaData, ScreenShot screenShot)
 		{
-			var data = new XDocument(new XDeclaration("1.0", "utf-8", "yes"));
-			var dataPath = Path.Combine(Directory, $"{fileName}.{DATA_FILE_EXTENSION}");
+			var xml = new XDocument(new XDeclaration("1.0", "utf-8", "yes"));

-			data.Add(
+			xml.Add(
 				new XElement("Data",
 					new XElement(nameof(MetaData),
 						new XElement(nameof(MetaData.ApplicationInfo), metaData.ApplicationInfo),
@@ -227,15 +270,25 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 				)
 			);

-			data.Save(dataPath);
+			using (var stream = new MemoryStream())
+			using (var writer = new StreamWriter(stream, new UTF8Encoding(false)))
+			{
+				xml.Save(writer);
+
+				var data = stream.ToArray();
+				var encrypted = encryptor.Encrypt(data);
+
+				File.WriteAllBytes(filePath, encrypted);
+				Size += encrypted.Length;
+			}
 		}

-		private void SaveImage(string fileName, ScreenShot screenShot)
+		private void SaveImage(string filePath, ScreenShot screenShot)
 		{
-			var extension = screenShot.Format.ToString().ToLower();
-			var imagePath = Path.Combine(Directory, $"{fileName}.{extension}");
+			var encrypted = encryptor.Encrypt(screenShot.Data);

-			File.WriteAllBytes(imagePath, screenShot.Data);
+			File.WriteAllBytes(filePath, encrypted);
+			Size += encrypted.Length;
 		}
 	}
 }
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Data/IntervalTrigger.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Data/IntervalTrigger.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Data/KeyboardTrigger.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Data/KeyboardTrigger.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Data/MetaDataAggregator.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Data/MetaDataAggregator.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Data/Metadata.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Data/Metadata.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Data/MouseTrigger.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Data/MouseTrigger.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/DataCollector.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/DataCollector.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
@@ -66,8 +66,8 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			mouseHookId = nativeMethods.RegisterMouseHook(MouseHookCallback);

 			timer.AutoReset = false;
-			timer.Elapsed += MaxIntervalElapsed;
-			timer.Interval = settings.MaxInterval;
+			timer.Elapsed += IntervalMaximumElapsed;
+			timer.Interval = settings.IntervalMaximum;
 			timer.Start();

 			logger.Debug("Started.");
@@ -90,7 +90,7 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			keyboardHookId = default;
 			mouseHookId = default;

-			timer.Elapsed -= MaxIntervalElapsed;
+			timer.Elapsed -= IntervalMaximumElapsed;
 			timer.Stop();

 			logger.Debug("Stopped.");
@@ -110,11 +110,11 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			return false;
 		}

-		private void MaxIntervalElapsed(object sender, ElapsedEventArgs args)
+		private void IntervalMaximumElapsed(object sender, ElapsedEventArgs args)
 		{
 			var trigger = new IntervalTrigger
 			{
-				ConfigurationValue = settings.MaxInterval,
+				ConfigurationValue = settings.IntervalMaximum,
 			};

 			TryCollect(interval: trigger);
@@ -136,7 +136,7 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring

 		private void TryCollect(IntervalTrigger interval = default, KeyboardTrigger keyboard = default, MouseTrigger mouse = default)
 		{
-			if (MinIntervalElapsed() && Monitor.TryEnter(@lock))
+			if (HasIntervalMinimumElapsed() && Monitor.TryEnter(@lock))
 			{
 				var elapsed = DateTime.Now.Subtract(last);

@@ -169,9 +169,9 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			}
 		}

-		private bool MinIntervalElapsed()
+		private bool HasIntervalMinimumElapsed()
 		{
-			return DateTime.Now.Subtract(last) >= new TimeSpan(0, 0, 0, 0, settings.MinInterval);
+			return DateTime.Now.Subtract(last) >= new TimeSpan(0, 0, 0, 0, settings.IntervalMinimum);
 		}
 	}
 }
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Events/DataCollectedEventHandler.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Events/DataCollectedEventHandler.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Imaging/Extensions.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Imaging/Extensions.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Imaging/ProcessingOrder.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Imaging/ProcessingOrder.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Imaging/ScreenShot.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Imaging/ScreenShot.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Imaging/ScreenShotProcessor.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Imaging/ScreenShotProcessor.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/ScreenProctoringImplementation.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/ScreenProctoringImplementation.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
@@ -47,7 +47,7 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			this.logger = logger;
 			this.service = service;
 			this.settings = settings.ScreenProctoring;
-			this.spooler = new TransmissionSpooler(appConfig, logger.CloneFor(nameof(TransmissionSpooler)), service);
+			this.spooler = new TransmissionSpooler(appConfig, logger.CloneFor(nameof(TransmissionSpooler)), service, settings.ScreenProctoring);
 			this.text = text;
 		}

@@ -112,6 +112,7 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 				{
 					settings.ClientId = instruction.ClientId;
 					settings.ClientSecret = instruction.ClientSecret;
+					settings.EncryptionSecret = instruction.EncryptionSecret;
 					settings.GroupId = instruction.GroupId;
 					settings.ServiceUrl = instruction.ServiceUrl;

--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Api.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Api.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
@@ -19,10 +19,10 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring.Service

 		internal Api()
 		{
-			AccessTokenEndpoint = "/oauth/token";
-			HealthEndpoint = "/health";
-			ScreenShotEndpoint = $"/seb-api/v1/session/{SESSION_ID}/screenshot";
-			SessionEndpoint = "/seb-api/v1/session";
+			AccessTokenEndpoint = "oauth/token";
+			HealthEndpoint = "health";
+			ScreenShotEndpoint = $"seb-api/v1/session/{SESSION_ID}/screenshot";
+			SessionEndpoint = "seb-api/v1/session";
 		}
 	}
 }
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Parser.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Parser.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/ContentType.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/ContentType.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/CreateSessionRequest.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/CreateSessionRequest.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/Extensions.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/Extensions.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/Header.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/Header.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/HealthRequest.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/HealthRequest.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/OAuth2TokenRequest.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/OAuth2TokenRequest.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/Request.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/Request.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/ScreenShotRequest.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/ScreenShotRequest.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/TerminateSessionRequest.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/Requests/TerminateSessionRequest.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/ServiceProxy.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/ServiceProxy.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
@@ -20,6 +20,7 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring.Service
 		private readonly Api api;
 		private readonly ILogger logger;
 		private readonly Parser parser;
+		private readonly Sanitizer sanitizer;

 		private HttpClient httpClient;

@@ -31,16 +32,19 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring.Service
 			this.api = new Api();
 			this.logger = logger;
 			this.parser = new Parser(logger);
+			this.sanitizer = new Sanitizer();
 		}

 		internal ServiceResponse Connect(string clientId, string clientSecret, string serviceUrl)
 		{
 			httpClient = new HttpClient
 			{
-				BaseAddress = new Uri(serviceUrl),
+				BaseAddress = sanitizer.Sanitize(serviceUrl),
 				Timeout = TimeSpan.FromSeconds(10)
 			};

+			sanitizer.Sanitize(api);
+
 			var request = new OAuth2TokenRequest(api, httpClient, logger, parser);
 			var success = request.TryExecute(clientId, clientSecret, out var message);

--- a/SafeExamBrowser.Proctoring/ScreenProctoring/Service/ServiceResponse.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/Service/ServiceResponse.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
--- a/SafeExamBrowser.Proctoring/ScreenProctoring/TransmissionSpooler.cs
+++ b/SafeExamBrowser.Proctoring/ScreenProctoring/TransmissionSpooler.cs
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 ETH Zürich, IT Services
+ * Copyright (c) 2025 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
@@ -16,6 +16,7 @@ using SafeExamBrowser.Proctoring.Contracts.Events;
 using SafeExamBrowser.Proctoring.ScreenProctoring.Data;
 using SafeExamBrowser.Proctoring.ScreenProctoring.Imaging;
 using SafeExamBrowser.Proctoring.ScreenProctoring.Service;
+using SafeExamBrowser.Settings.Proctoring;
 using Timer = System.Timers.Timer;

 namespace SafeExamBrowser.Proctoring.ScreenProctoring
@@ -40,10 +41,10 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 		private Thread thread;
 		private CancellationTokenSource token;

-		internal TransmissionSpooler(AppConfig appConfig, IModuleLogger logger, ServiceProxy service)
+		internal TransmissionSpooler(AppConfig appConfig, IModuleLogger logger, ServiceProxy service, ScreenProctoringSettings settings)
 		{
 			this.buffer = new Buffer(logger.CloneFor(nameof(Buffer)));
-			this.cache = new Cache(appConfig, logger.CloneFor(nameof(Cache)));
+			this.cache = new Cache(appConfig, logger.CloneFor(nameof(Cache)), settings);
 			this.logger = logger;
 			this.queue = new ConcurrentQueue<(MetaData, ScreenShot)>();
 			this.random = new Random();
@@ -56,13 +57,14 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 			queue.Enqueue((metaData, screenShot));
 		}

-		internal void ExecuteRemainingWork(Action<RemainingWorkUpdatedEventArgs> updateStatus)
+		internal void ExecuteRemainingWork(Action<RemainingWorkUpdatedEventArgs> handler)
 		{
 			var previous = buffer.Count + cache.Count;
 			var progress = 0;
+			var start = DateTime.Now;
 			var total = previous;

-			while (HasRemainingWork() && service.IsConnected && (!networkIssue || recovering || DateTime.Now < resume))
+			while (HasRemainingWork() && service.IsConnected)
 			{
 				var remaining = buffer.Count + cache.Count;

@@ -78,26 +80,19 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 				previous = remaining;
 				progress = total - remaining;

-				updateStatus(new RemainingWorkUpdatedEventArgs
+				var args = UpdateStatus(handler, progress, start, total);
+
+				if (args.CancellationRequested)
 				{
-					IsWaiting = recovering || networkIssue,
-					Next = buffer.TryPeek(out _, out var schedule, out _) ? schedule : default(DateTime?),
-					Progress = progress,
-					Resume = resume,
-					Total = total
-				});
+					logger.Warn($"The execution of the remaining work has been cancelled and {remaining} item(s) will not be transmitted!");
+
+					break;
+				}

 				Thread.Sleep(100);
 			}

-			if (networkIssue)
-			{
-				updateStatus(new RemainingWorkUpdatedEventArgs { HasFailed = true, CachePath = cache.Directory });
-			}
-			else
-			{
-				updateStatus(new RemainingWorkUpdatedEventArgs { IsFinished = true });
-			}
+			UpdateStatus(handler);
 		}

 		internal bool HasRemainingWork()
@@ -163,6 +158,9 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring
 				thread = default;
 				token = default;
 			}
+
+			buffer.Clear();
+			cache.Clear();
 		}

 		private void Execute()
@@ -417,5 +415,34 @@ namespace SafeExamBrowser.Proctoring.ScreenProctoring

 			return current;
 		}
+
+		private RemainingWorkUpdatedEventArgs UpdateStatus(Action<RemainingWorkUpdatedEventArgs> handler, int progress, DateTime start, int total)
+		{
+			var args = new RemainingWorkUpdatedEventArgs
+			{
+				AllowCancellation = start.Add(new TimeSpan(0, 1, 15)) < DateTime.Now,
+				IsWaiting = health == BAD || networkIssue || recovering || DateTime.Now < resume,
+				Next = buffer.TryPeek(out _, out var schedule, out _) ? schedule : default(DateTime?),
+				Progress = progress,
+				Resume = DateTime.Now < resume ? resume : default(DateTime?),
+				Total = total
+			};
+
+			handler.Invoke(args);
+
+			return args;
+		}
+
+		private void UpdateStatus(Action<RemainingWorkUpdatedEventArgs> handler)
+		{
+			if (HasRemainingWork())
+			{
+				handler.Invoke(new RemainingWorkUpdatedEventArgs { HasFailed = true, CachePath = cache.Directory });
+			}
+			else
+			{
+				handler.Invoke(new RemainingWorkUpdatedEventArgs { IsFinished = true });
+			}
+		}
 	}
 }