89 lines
2.2 KiB
C#
89 lines
2.2 KiB
C#
/*
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* Copyright (c) 2023 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 System.Timers;
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using SafeExamBrowser.Logging.Contracts;
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using SafeExamBrowser.WindowsApi.Constants;
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using SafeExamBrowser.WindowsApi.Contracts;
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namespace SafeExamBrowser.WindowsApi
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{
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public class DesktopMonitor : IDesktopMonitor
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{
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private readonly ILogger logger;
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private readonly Timer timer;
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private IDesktop desktop;
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public DesktopMonitor(ILogger logger)
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{
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this.logger = logger;
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this.timer = new Timer(1000);
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}
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public void Start(IDesktop desktop)
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{
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this.desktop = desktop;
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timer.AutoReset = false;
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timer.Elapsed += Timer_Elapsed;
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timer.Start();
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logger.Info($"Started monitoring desktop {desktop}.");
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}
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public void Stop()
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{
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timer.Stop();
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timer.Elapsed -= Timer_Elapsed;
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logger.Info($"Stopped monitoring desktop {desktop}.");
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}
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private void Timer_Elapsed(object sender, ElapsedEventArgs e)
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{
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var handle = User32.OpenInputDesktop(0, false, (uint) AccessMask.DESKTOP_NONE);
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var name = string.Empty;
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var nameLength = 0;
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if (handle != IntPtr.Zero)
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{
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User32.GetUserObjectInformation(handle, Constant.UOI_NAME, IntPtr.Zero, 0, ref nameLength);
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var namePointer = Marshal.AllocHGlobal(nameLength);
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var success = User32.GetUserObjectInformation(handle, Constant.UOI_NAME, namePointer, nameLength, ref nameLength);
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if (success)
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{
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name = Marshal.PtrToStringAnsi(namePointer);
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Marshal.FreeHGlobal(namePointer);
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if (name?.Equals(desktop.Name, StringComparison.OrdinalIgnoreCase) != true)
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{
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logger.Warn($"Detected desktop switch to '{name}' [{handle}], trying to reactivate {desktop}...");
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desktop.Activate();
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}
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}
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else
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{
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logger.Warn("Failed to get name of currently active desktop!");
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}
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User32.CloseDesktop(handle);
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}
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else
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{
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logger.Warn("Failed to get currently active desktop!");
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}
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timer.Start();
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}
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}
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}
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