Restore SEBPatch
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270
SafeExamBrowser.Runtime/Operations/ClientOperation.cs
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270
SafeExamBrowser.Runtime/Operations/ClientOperation.cs
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/*
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* Copyright (c) 2024 ETH Zürich, IT Services
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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.Text;
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using System.Threading;
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using SafeExamBrowser.Communication.Contracts;
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using SafeExamBrowser.Communication.Contracts.Events;
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using SafeExamBrowser.Communication.Contracts.Hosts;
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using SafeExamBrowser.Communication.Contracts.Proxies;
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using SafeExamBrowser.Core.Contracts.OperationModel;
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using SafeExamBrowser.Core.Contracts.OperationModel.Events;
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using SafeExamBrowser.I18n.Contracts;
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using SafeExamBrowser.Logging.Contracts;
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using SafeExamBrowser.WindowsApi.Contracts;
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using SafeExamBrowser.WindowsApi.Contracts.Events;
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namespace SafeExamBrowser.Runtime.Operations
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{
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internal class ClientOperation : SessionOperation
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{
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private readonly ILogger logger;
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private readonly IProcessFactory processFactory;
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private readonly IProxyFactory proxyFactory;
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private readonly IRuntimeHost runtimeHost;
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private readonly int timeout_ms;
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private IProcess ClientProcess
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{
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get { return Context.ClientProcess; }
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set { Context.ClientProcess = value; }
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}
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private IClientProxy ClientProxy
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{
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get { return Context.ClientProxy; }
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set { Context.ClientProxy = value; }
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}
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public override event ActionRequiredEventHandler ActionRequired { add { } remove { } }
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public override event StatusChangedEventHandler StatusChanged;
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public ClientOperation(
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ILogger logger,
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IProcessFactory processFactory,
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IProxyFactory proxyFactory,
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IRuntimeHost runtimeHost,
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SessionContext sessionContext,
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int timeout_ms) : base(sessionContext)
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{
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this.logger = logger;
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this.processFactory = processFactory;
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this.proxyFactory = proxyFactory;
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this.runtimeHost = runtimeHost;
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this.timeout_ms = timeout_ms;
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}
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public override OperationResult Perform()
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{
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StatusChanged?.Invoke(TextKey.OperationStatus_StartClient);
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var success = TryStartClient();
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if (success)
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{
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logger.Info("Successfully started new client instance.");
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}
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else
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{
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logger.Error("Failed to start new client instance! Aborting procedure...");
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}
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return success ? OperationResult.Success : OperationResult.Failed;
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}
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public override OperationResult Repeat()
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{
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return Perform();
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}
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public override OperationResult Revert()
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{
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var success = true;
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if (ClientProcess != null && !ClientProcess.HasTerminated)
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{
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StatusChanged?.Invoke(TextKey.OperationStatus_StopClient);
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success = TryStopClient();
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}
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return success ? OperationResult.Success : OperationResult.Failed;
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}
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private bool TryStartClient()
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{
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var authenticationToken = Context.Next.ClientAuthenticationToken.ToString("D");
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var executablePath = Context.Next.AppConfig.ClientExecutablePath;
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var logFilePath = $"{'"' + Convert.ToBase64String(Encoding.UTF8.GetBytes(Context.Next.AppConfig.ClientLogFilePath)) + '"'}";
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var logLevel = Context.Next.Settings.LogLevel.ToString();
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var runtimeHostUri = Context.Next.AppConfig.RuntimeAddress;
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var uiMode = Context.Next.Settings.UserInterface.Mode.ToString();
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var clientReady = false;
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var clientReadyEvent = new AutoResetEvent(false);
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var clientReadyEventHandler = new CommunicationEventHandler(() => clientReadyEvent.Set());
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var clientTerminated = false;
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var clientTerminatedEventHandler = new ProcessTerminatedEventHandler(_ => { clientTerminated = true; clientReadyEvent.Set(); });
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logger.Info("Starting new client process...");
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runtimeHost.AllowConnection = true;
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runtimeHost.AuthenticationToken = Context.Next.ClientAuthenticationToken;
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runtimeHost.ClientReady += clientReadyEventHandler;
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ClientProcess = processFactory.StartNew(executablePath, logFilePath, logLevel, runtimeHostUri, authenticationToken, uiMode);
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ClientProcess.Terminated += clientTerminatedEventHandler;
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logger.Info("Waiting for client to complete initialization...");
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clientReady = clientReadyEvent.WaitOne();
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runtimeHost.AllowConnection = false;
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runtimeHost.AuthenticationToken = default(Guid?);
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runtimeHost.ClientReady -= clientReadyEventHandler;
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ClientProcess.Terminated -= clientTerminatedEventHandler;
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if (clientReady && !clientTerminated)
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{
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return TryStartCommunication();
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}
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if (!clientReady)
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{
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logger.Error($"Failed to start client!");
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}
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if (clientTerminated)
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{
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logger.Error("Client instance terminated unexpectedly during initialization!");
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}
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return false;
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}
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private bool TryStartCommunication()
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{
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var success = false;
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logger.Info("Client has been successfully started and initialized. Creating communication proxy for client host...");
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ClientProxy = proxyFactory.CreateClientProxy(Context.Next.AppConfig.ClientAddress, Interlocutor.Runtime);
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if (ClientProxy.Connect(Context.Next.ClientAuthenticationToken))
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{
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logger.Info("Connection with client has been established. Requesting authentication...");
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var communication = ClientProxy.RequestAuthentication();
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var response = communication.Value;
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success = communication.Success && ClientProcess.Id == response?.ProcessId;
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if (success)
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{
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logger.Info("Authentication of client has been successful, client is ready to operate.");
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}
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else
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{
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logger.Error("Failed to verify client integrity!");
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}
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}
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else
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{
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logger.Error("Failed to connect to client!");
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}
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return success;
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}
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private bool TryStopClient()
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{
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var success = false;
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var disconnected = false;
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var disconnectedEvent = new AutoResetEvent(false);
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var disconnectedEventHandler = new CommunicationEventHandler(() => disconnectedEvent.Set());
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var terminated = false;
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var terminatedEvent = new AutoResetEvent(false);
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var terminatedEventHandler = new ProcessTerminatedEventHandler((_) => terminatedEvent.Set());
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if (ClientProxy != null)
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{
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runtimeHost.ClientDisconnected += disconnectedEventHandler;
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ClientProcess.Terminated += terminatedEventHandler;
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logger.Info("Instructing client to initiate shutdown procedure.");
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ClientProxy.InitiateShutdown();
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logger.Info("Disconnecting from client communication host.");
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ClientProxy.Disconnect();
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logger.Info("Waiting for client to disconnect from runtime communication host...");
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disconnected = disconnectedEvent.WaitOne(timeout_ms / 2);
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if (!disconnected)
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{
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logger.Error($"Client failed to disconnect within {timeout_ms / 2 / 1000} seconds!");
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}
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logger.Info("Waiting for client process to terminate...");
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terminated = terminatedEvent.WaitOne(timeout_ms / 2);
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if (!terminated)
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{
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logger.Error($"Client failed to terminate within {timeout_ms / 2 / 1000} seconds!");
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}
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runtimeHost.ClientDisconnected -= disconnectedEventHandler;
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ClientProcess.Terminated -= terminatedEventHandler;
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}
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if (disconnected && terminated)
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{
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logger.Info("Client has been successfully terminated.");
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success = true;
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}
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else
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{
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logger.Warn("Attempting to kill client process since graceful termination failed!");
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success = TryKillClient();
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}
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if (success)
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{
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ClientProcess = null;
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ClientProxy = null;
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}
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return success;
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}
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private bool TryKillClient()
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{
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const int MAX_ATTEMPTS = 5;
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for (var attempt = 1; attempt <= MAX_ATTEMPTS; attempt++)
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{
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logger.Info($"Attempt {attempt}/{MAX_ATTEMPTS} to kill client process with ID = {ClientProcess.Id}.");
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if (ClientProcess.TryKill(500))
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{
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break;
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}
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}
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if (ClientProcess.HasTerminated)
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{
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logger.Info("Client process has terminated.");
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}
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else
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{
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logger.Error($"Failed to kill client process within {MAX_ATTEMPTS} attempts!");
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}
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return ClientProcess.HasTerminated;
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}
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}
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}
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