110 lines
3.9 KiB
C#
110 lines
3.9 KiB
C#
/*
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* Copyright (c) 2018 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.Threading.Tasks;
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using SafeExamBrowser.Contracts.Communication;
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using SafeExamBrowser.Contracts.Communication.Data;
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using SafeExamBrowser.Contracts.Communication.Hosts;
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using SafeExamBrowser.Contracts.Configuration;
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using SafeExamBrowser.Contracts.Configuration.Settings;
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using SafeExamBrowser.Contracts.Logging;
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using SafeExamBrowser.Core.Communication.Hosts;
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namespace SafeExamBrowser.Runtime.Communication
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{
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internal class RuntimeHost : BaseHost, IRuntimeHost
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{
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private bool allowConnection = true;
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private IConfigurationRepository configuration;
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public Guid StartupToken { private get; set; }
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public event CommunicationEventHandler ClientDisconnected;
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public event CommunicationEventHandler ClientReady;
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public event CommunicationEventHandler ReconfigurationRequested;
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public event CommunicationEventHandler ShutdownRequested;
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public RuntimeHost(string address, IConfigurationRepository configuration, IHostObjectFactory factory, ILogger logger) : base(address, factory, logger)
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{
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this.configuration = configuration;
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}
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protected override bool OnConnect(Guid? token = null)
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{
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var authenticated = StartupToken == token;
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var accepted = allowConnection && authenticated;
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if (accepted)
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{
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allowConnection = false;
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}
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return accepted;
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}
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protected override void OnDisconnect()
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{
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ClientDisconnected?.Invoke();
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// TODO: Handle client crash scenario!
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// If a client crashes or hangs when terminating (which should not happen!), it could be that it never gets to disconnect from
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// the RuntimeHost - in that case, allowConnection prohibits restarting a new session as long as it's only set here!
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// -> Move AllowConnection to interface and reset it in SessionController?
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// -> Only possible as long as just the client connects, with service and client a more elaborate solution will be needed!
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// -> E.g. ClientId and ServiceId, and then AllowClientConnection and AllowServiceConnection?
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allowConnection = true;
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}
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protected override Response OnReceive(Message message)
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{
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switch (message)
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{
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case ReconfigurationMessage reconfigurationMessage:
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// TODO: Not the job of the host, fire event or alike!
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return Handle(reconfigurationMessage);
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}
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return new SimpleResponse(SimpleResponsePurport.UnknownMessage);
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}
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protected override Response OnReceive(SimpleMessagePurport message)
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{
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switch (message)
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{
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case SimpleMessagePurport.ClientIsReady:
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ClientReady?.Invoke();
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return new SimpleResponse(SimpleResponsePurport.Acknowledged);
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case SimpleMessagePurport.ConfigurationNeeded:
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// TODO: Not the job of the host, fire event or alike!
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return new ConfigurationResponse { Configuration = configuration.BuildClientConfiguration() };
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case SimpleMessagePurport.RequestShutdown:
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ShutdownRequested?.Invoke();
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return new SimpleResponse(SimpleResponsePurport.Acknowledged);
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}
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return new SimpleResponse(SimpleResponsePurport.UnknownMessage);
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}
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private Response Handle(ReconfigurationMessage message)
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{
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var isExam = configuration.CurrentSettings.ConfigurationMode == ConfigurationMode.Exam;
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var isValidUri = Uri.TryCreate(message.ConfigurationUrl, UriKind.Absolute, out _);
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var allowed = !isExam && isValidUri;
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Logger.Info($"Received reconfiguration request for '{message.ConfigurationUrl}', {(allowed ? "accepted" : "denied")} it.");
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if (allowed)
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{
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configuration.ReconfigurationUrl = message.ConfigurationUrl;
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Task.Run(() => ReconfigurationRequested?.Invoke());
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}
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return new ReconfigurationResponse { Accepted = allowed };
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}
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}
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}
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