91 lines
3.2 KiB
C#
91 lines
3.2 KiB
C#
/*
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* Copyright (c) 2019 ETH Zürich, Educational Development and Technology (LET)
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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using System;
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using System.Linq;
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using System.Windows.Input;
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using SafeExamBrowser.Logging.Contracts;
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using SafeExamBrowser.Monitoring.Contracts.Keyboard;
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using SafeExamBrowser.Settings.Monitoring;
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using SafeExamBrowser.WindowsApi.Contracts;
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using SafeExamBrowser.WindowsApi.Contracts.Events;
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namespace SafeExamBrowser.Monitoring.Keyboard
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{
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public class KeyboardInterceptor : IKeyboardInterceptor
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{
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private Guid? hookId;
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private ILogger logger;
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private INativeMethods nativeMethods;
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private KeyboardSettings settings;
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public KeyboardInterceptor(ILogger logger, INativeMethods nativeMethods, KeyboardSettings settings)
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{
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this.logger = logger;
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this.nativeMethods = nativeMethods;
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this.settings = settings;
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}
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public void Start()
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{
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hookId = nativeMethods.RegisterKeyboardHook(KeyboardHookCallback);
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}
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public void Stop()
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{
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if (hookId.HasValue)
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{
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nativeMethods.DeregisterKeyboardHook(hookId.Value);
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}
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}
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private bool KeyboardHookCallback(int keyCode, KeyModifier modifier, KeyState state)
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{
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var block = false;
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var key = KeyInterop.KeyFromVirtualKey(keyCode);
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block |= key == Key.Apps;
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block |= key == Key.Escape && modifier == KeyModifier.None && !settings.AllowEsc;
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block |= key == Key.F1 && !settings.AllowF1;
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block |= key == Key.F2 && !settings.AllowF2;
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block |= key == Key.F3 && !settings.AllowF3;
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block |= key == Key.F4 && !settings.AllowF4;
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block |= key == Key.F5 && !settings.AllowF5;
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block |= key == Key.F6 && !settings.AllowF6;
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block |= key == Key.F7 && !settings.AllowF7;
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block |= key == Key.F8 && !settings.AllowF8;
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block |= key == Key.F9 && !settings.AllowF9;
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block |= key == Key.F10 && !settings.AllowF10;
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block |= key == Key.F11 && !settings.AllowF11;
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block |= key == Key.F12 && !settings.AllowF12;
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block |= key == Key.LWin && !settings.AllowSystemKey;
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block |= key == Key.PrintScreen && !settings.AllowPrintScreen;
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block |= key == Key.RWin && !settings.AllowSystemKey;
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block |= modifier.HasFlag(KeyModifier.Alt) && key == Key.Escape && !settings.AllowAltEsc;
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block |= modifier.HasFlag(KeyModifier.Alt) && key == Key.F4 && !settings.AllowAltF4;
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block |= modifier.HasFlag(KeyModifier.Alt) && key == Key.Space;
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block |= modifier.HasFlag(KeyModifier.Alt) && key == Key.Tab && !settings.AllowAltTab;
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block |= modifier.HasFlag(KeyModifier.Ctrl) && key == Key.Escape && !settings.AllowCtrlEsc;
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if (block)
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{
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Log(key, keyCode, modifier, state);
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}
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return block;
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}
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private void Log(Key key, int keyCode, KeyModifier modifier, KeyState state)
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{
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var modifierFlags = Enum.GetValues(typeof(KeyModifier)).OfType<KeyModifier>().Where(m => m != KeyModifier.None && modifier.HasFlag(m));
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var modifiers = modifierFlags.Any() ? String.Join(" + ", modifierFlags) + " + " : string.Empty;
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logger.Info($"Blocked '{modifiers}{key}' ({key} = {keyCode}) when {state.ToString().ToLower()}.");
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}
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}
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}
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