112 lines
3.1 KiB
C#
112 lines
3.1 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.Runtime.InteropServices;
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using SafeExamBrowser.Contracts.Monitoring;
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using SafeExamBrowser.WindowsApi.Constants;
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using SafeExamBrowser.WindowsApi.Delegates;
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using SafeExamBrowser.WindowsApi.Types;
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namespace SafeExamBrowser.WindowsApi.Hooks
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{
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internal class MouseHook
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{
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private HookDelegate hookDelegate;
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internal IntPtr Handle { get; private set; }
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internal IMouseInterceptor Interceptor { get; private set; }
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internal MouseHook(IMouseInterceptor interceptor)
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{
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Interceptor = interceptor;
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}
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internal void Attach()
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{
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var process = System.Diagnostics.Process.GetCurrentProcess();
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var module = process.MainModule;
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var moduleHandle = Kernel32.GetModuleHandle(module.ModuleName);
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// IMPORTANT:
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// Ensures that the hook delegate does not get garbage collected prematurely, as it will be passed to unmanaged code.
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// Not doing so will result in a <c>CallbackOnCollectedDelegate</c> error and subsequent application crash!
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hookDelegate = new HookDelegate(LowLevelMouseProc);
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Handle = User32.SetWindowsHookEx(HookType.WH_MOUSE_LL, hookDelegate, moduleHandle, 0);
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}
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internal bool Detach()
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{
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return User32.UnhookWindowsHookEx(Handle);
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}
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private IntPtr LowLevelMouseProc(int nCode, IntPtr wParam, IntPtr lParam)
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{
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if (nCode >= 0 && !Ignore(wParam.ToInt32()))
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{
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var mouseData = (MSLLHOOKSTRUCT) Marshal.PtrToStructure(lParam, typeof(MSLLHOOKSTRUCT));
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var button = GetButton(wParam.ToInt32());
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var state = GetState(wParam.ToInt32());
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if (Interceptor.Block(button, state))
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{
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return (IntPtr) 1;
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}
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}
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return User32.CallNextHookEx(Handle, nCode, wParam, lParam);
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}
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private bool Ignore(int wParam)
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{
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// For performance reasons, ignore mouse movement and wheel rotation...
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return wParam == Constant.WM_MOUSEMOVE || wParam == Constant.WM_MOUSEWHEEL;
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}
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private MouseButton GetButton(int wParam)
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{
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switch (wParam)
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{
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case Constant.WM_LBUTTONDOWN:
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case Constant.WM_LBUTTONUP:
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return MouseButton.Left;
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case Constant.WM_MBUTTONDOWN:
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case Constant.WM_MBUTTONUP:
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return MouseButton.Middle;
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case Constant.WM_RBUTTONDOWN:
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case Constant.WM_RBUTTONUP:
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return MouseButton.Right;
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case Constant.WM_XBUTTONDOWN:
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case Constant.WM_XBUTTONUP:
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return MouseButton.Auxiliary;
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default:
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return MouseButton.Unknown;
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}
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}
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private KeyState GetState(int wParam)
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{
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switch (wParam)
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{
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case Constant.WM_LBUTTONDOWN:
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case Constant.WM_MBUTTONDOWN:
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case Constant.WM_RBUTTONDOWN:
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case Constant.WM_XBUTTONDOWN:
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return KeyState.Pressed;
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case Constant.WM_LBUTTONUP:
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case Constant.WM_MBUTTONUP:
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case Constant.WM_RBUTTONUP:
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case Constant.WM_XBUTTONUP:
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return KeyState.Released;
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default:
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return KeyState.Unknown;
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}
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}
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}
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}
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