SessionController.cs

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using Byond.TopicSender;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using Serilog.Context;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Net;
using System.Threading;
using System.Threading.Tasks;
using Tgstation.Server.Api;
using Tgstation.Server.Api.Models;
using Tgstation.Server.Host.Components.Byond;
using Tgstation.Server.Host.Components.Chat;
using Tgstation.Server.Host.Components.Deployment;
using Tgstation.Server.Host.Components.Interop;
using Tgstation.Server.Host.Components.Interop.Bridge;
using Tgstation.Server.Host.Components.Interop.Topic;
using Tgstation.Server.Host.System;

namespace Tgstation.Server.Host.Components.Session
{
    sealed class SessionController : ISessionController, IBridgeHandler, IChannelSink
    {
        public DMApiParameters DMApiParameters => reattachInformation;

        public bool IsPrimary
        {
            get
            {
                CheckDisposed();
                return reattachInformation.IsPrimary;
            }
        }

        public ApiValidationStatus ApiValidationStatus
        {
            get
            {
                if (!Lifetime.IsCompleted)
                    throw new InvalidOperationException("ApiValidated cannot be checked while Lifetime is incomplete!");
                return apiValidationStatus;
            }
        }

        public IDmbProvider Dmb
        {
            get
            {
                CheckDisposed();
                return reattachInformation.Dmb;
            }
        }

        public ushort? Port
        {
            get
            {
                CheckDisposed();
                if (portClosedForReboot)
                    return null;
                return reattachInformation.Port;
            }
        }

        public RebootState RebootState
        {
            get
            {
                CheckDisposed();
                return reattachInformation.RebootState;
            }
        }

        public Version DMApiVersion { get; private set; }

        public bool ClosePortOnReboot { get; set; }

        public bool TerminationWasRequested { get; private set; }

        public Task<LaunchResult> LaunchResult { get; }

        public Task<int> Lifetime => process.Lifetime;

        public Task OnReboot => rebootTcs.Task;

        public Task OnPrime => primeTcs.Task;

        readonly ReattachInformation reattachInformation;

        readonly Api.Models.Instance metadata;

        readonly CancellationTokenSource reattachTopicCts;

        readonly ITopicClient byondTopicSender;

        readonly IBridgeRegistration bridgeRegistration;

        readonly IProcess process;

        readonly IByondExecutableLock byondLock;

        readonly IChatTrackingContext chatTrackingContext;

        readonly IChatManager chat;

        readonly ILogger<SessionController> logger;

        readonly object synchronizationLock;

        TaskCompletionSource<bool> portAssignmentTcs;

        ushort? nextPort;

        TaskCompletionSource<object> rebootTcs;

        TaskCompletionSource<object> primeTcs;

        bool portClosedForReboot;

        bool disposed;

        ApiValidationStatus apiValidationStatus;

        bool released;

        public SessionController(
            ReattachInformation reattachInformation,
            Api.Models.Instance metadata,
            IProcess process,
            IByondExecutableLock byondLock,
            ITopicClient byondTopicSender,
            IChatTrackingContext chatTrackingContext,
            IBridgeRegistrar bridgeRegistrar,
            IChatManager chat,
            IAssemblyInformationProvider assemblyInformationProvider,
            ILogger<SessionController> logger,
            uint? startupTimeout,
            bool reattached)
        {
            this.reattachInformation = reattachInformation ?? throw new ArgumentNullException(nameof(reattachInformation));
            this.metadata = metadata ?? throw new ArgumentNullException(nameof(metadata));
            this.process = process ?? throw new ArgumentNullException(nameof(process));
            this.byondLock = byondLock ?? throw new ArgumentNullException(nameof(byondLock));
            this.byondTopicSender = byondTopicSender ?? throw new ArgumentNullException(nameof(byondTopicSender));
            this.chatTrackingContext = chatTrackingContext ?? throw new ArgumentNullException(nameof(chatTrackingContext));
            bridgeRegistration = bridgeRegistrar?.RegisterHandler(this) ?? throw new ArgumentNullException(nameof(bridgeRegistrar));
            this.chat = chat ?? throw new ArgumentNullException(nameof(chat));
            this.logger = logger ?? throw new ArgumentNullException(nameof(logger));

            this.chatTrackingContext.SetChannelSink(this);

            portClosedForReboot = false;
            disposed = false;
            apiValidationStatus = ApiValidationStatus.NeverValidated;
            released = false;

            rebootTcs = new TaskCompletionSource<object>();
            primeTcs = new TaskCompletionSource<object>();
            reattachTopicCts = new CancellationTokenSource();
            synchronizationLock = new object();

            _ = process.Lifetime.ContinueWith(
                x =>
                {
                    lock (synchronizationLock)
                        if (!disposed)
                            reattachTopicCts.Cancel();
                    chatTrackingContext.Active = false;
                },
                TaskScheduler.Current);

            LaunchResult = GetLaunchResult(
                assemblyInformationProvider,
                startupTimeout,
                reattached);

            logger.LogDebug("Created session controller. Primary: {0}, CommsKey: {1}, Port: {2}", IsPrimary, reattachInformation.AccessIdentifier, Port);
        }

#pragma warning disable CA1821 // Remove empty Finalizers TODO: remove this when https://github.com/dotnet/roslyn-analyzers/issues/1241 is fixed
        ~SessionController() => Dispose(false);
#pragma warning restore CA1821 // Remove empty Finalizers

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        void Dispose(bool disposing)
        {
            lock (synchronizationLock)
            {
                if (disposed)
                    return;
                disposed = true;
                logger.LogTrace("Disposing...");
                if (disposing)
                {
                    if (!released)
                    {
                        process.Terminate();
                        byondLock.Dispose();
                    }

                    process.Dispose();
                    bridgeRegistration.Dispose();
                    reattachInformation.Dmb?.Dispose(); // will be null when released
                    chatTrackingContext.Dispose();
                    reattachTopicCts.Dispose();
                }
                else
                {
                    if (logger != null)
                        logger.LogError("Being disposed via finalizer!");
                    if (!released)
                        if (process != null)
                            process.Terminate();
                        else if (logger != null)
                            logger.LogCritical("Unable to terminate active DreamDaemon session due to finalizer ordering!");
                }
            }
        }

        async Task<LaunchResult> GetLaunchResult(
            IAssemblyInformationProvider assemblyInformationProvider,
            uint? startupTimeout,
            bool reattached)
        {
            var startTime = DateTimeOffset.Now;
            Task toAwait = process.Startup;

            if (startupTimeout.HasValue)
                toAwait = Task.WhenAny(process.Startup, Task.Delay(startTime.AddSeconds(startupTimeout.Value) - startTime));

            await toAwait.ConfigureAwait(false);

            var result = new LaunchResult
            {
                ExitCode = process.Lifetime.IsCompleted ? (int?)await process.Lifetime.ConfigureAwait(false) : null,
                StartupTime = process.Startup.IsCompleted ? (TimeSpan?)(DateTimeOffset.Now - startTime) : null
            };

            logger.LogTrace("Launch result: {0}", result);

            if (!result.ExitCode.HasValue && reattached && !disposed)
            {
                var reattachResponse = await SendCommand(
                    new TopicParameters(
                        assemblyInformationProvider.Version,
                        reattachInformation.RuntimeInformation.ServerPort),
                    reattachTopicCts.Token)
                    .ConfigureAwait(false);

                if (reattachResponse.InteropResponse?.CustomCommands != null)
                    chatTrackingContext.CustomCommands = reattachResponse.InteropResponse.CustomCommands;
                else if (reattachResponse.InteropResponse != null)
                    logger.LogWarning(
                        "DMAPI v{0} isn't returning the TGS custom commands list. Functionality added in v5.2.0.",
                        Dmb.CompileJob.DMApiVersion.Semver());
            }

            return result;
        }

        public async Task<BridgeResponse> ProcessBridgeRequest(BridgeParameters parameters, CancellationToken cancellationToken)
        {
            if (parameters == null)
                throw new ArgumentNullException(nameof(parameters));

            using (LogContext.PushProperty("Instance", metadata.Id))
            {
                logger.LogTrace("Handling bridge request...");
                var response = new BridgeResponse();
                switch (parameters.CommandType)
                {
                    case BridgeCommandType.ChatSend:
                        if (parameters.ChatMessage == null)
                            return new BridgeResponse
                            {
                                ErrorMessage = "Missing chatMessage field!"
                            };

                        if (parameters.ChatMessage.ChannelIds == null)
                            return new BridgeResponse
                            {
                                ErrorMessage = "Missing channelIds field in chatMessage!"
                            };

                        if (parameters.ChatMessage.ChannelIds.Any(channelIdString => !UInt64.TryParse(channelIdString, out var _)))
                            return new BridgeResponse
                            {
                                ErrorMessage = "Invalid channelIds in chatMessage!"
                            };

                        if (parameters.ChatMessage.Text == null)
                            return new BridgeResponse
                            {
                                ErrorMessage = "Missing message field in chatMessage!"
                            };

                        await chat.SendMessage(
                            parameters.ChatMessage.Text,
                            parameters.ChatMessage.ChannelIds.Select(UInt64.Parse),
                            cancellationToken).ConfigureAwait(false);
                        break;
                    case BridgeCommandType.Prime:
                        var oldPrimeTcs = primeTcs;
                        primeTcs = new TaskCompletionSource<object>();
                        oldPrimeTcs.SetResult(null);
                        break;
                    case BridgeCommandType.Kill:
                        logger.LogInformation("Bridge requested process termination!");
                        TerminationWasRequested = true;
                        process.Terminate();
                        break;
                    case BridgeCommandType.PortUpdate:
                        lock (synchronizationLock)
                        {
                            if (!parameters.CurrentPort.HasValue)
                            {
                                logger.LogWarning("DreamDaemon sent new port command without providing it's own!");
                                return new BridgeResponse
                                {
                                    ErrorMessage = "Missing stringified port as data parameter!"
                                };
                            }

                            var currentPort = parameters.CurrentPort.Value;
                            if (!nextPort.HasValue)
                                reattachInformation.Port = parameters.CurrentPort.Value; // not ready yet, so what we'll do is accept the random port DD opened on for now and change it later when we decide to
                            else
                            {
                                // nextPort is ready, tell DD to switch to that
                                // if it fails it'll kill itself
                                response.NewPort = nextPort.Value;
                                reattachInformation.Port = nextPort.Value;
                                nextPort = null;

                                // we'll also get here from SetPort so complete that task
                                var tmpTcs = portAssignmentTcs;
                                portAssignmentTcs = null;
                                tmpTcs.SetResult(true);
                            }

                            portClosedForReboot = false;
                        }

                        break;
                    case BridgeCommandType.Startup:
                        apiValidationStatus = ApiValidationStatus.BadValidationRequest;
                        if (parameters.Version == null)
                            return new BridgeResponse
                            {
                                ErrorMessage = "Missing dmApiVersion field!"
                            };

                        DMApiVersion = parameters.Version;
                        switch (parameters.MinimumSecurityLevel)
                        {
                            case DreamDaemonSecurity.Ultrasafe:
                                apiValidationStatus = ApiValidationStatus.RequiresUltrasafe;
                                break;
                            case DreamDaemonSecurity.Safe:
                                apiValidationStatus = ApiValidationStatus.RequiresSafe;
                                break;
                            case DreamDaemonSecurity.Trusted:
                                apiValidationStatus = ApiValidationStatus.RequiresTrusted;
                                break;
                            case null:
                                return new BridgeResponse
                                {
                                    ErrorMessage = "Missing minimumSecurityLevel field!"
                                };
                            default:
                                return new BridgeResponse
                                {
                                    ErrorMessage = "Invalid minimumSecurityLevel!"
                                };
                        }

                        response.RuntimeInformation = reattachInformation.RuntimeInformation;

                        // Load custom commands
                        chatTrackingContext.CustomCommands = parameters.CustomCommands;
                        break;
                    case BridgeCommandType.Reboot:
                        if (ClosePortOnReboot)
                        {
                            chatTrackingContext.Active = false;
                            response.NewPort = 0;
                            portClosedForReboot = true;
                        }

                        var oldRebootTcs = rebootTcs;
                        rebootTcs = new TaskCompletionSource<object>();
                        oldRebootTcs.SetResult(null);
                        break;
                    case null:
                        response.ErrorMessage = "Missing commandType!";
                        break;
                    default:
                        response.ErrorMessage = "Requested commandType not supported!";
                        break;
                }

                return response;
            }
        }

        void CheckDisposed()
        {
            if (disposed)
                throw new ObjectDisposedException(nameof(SessionController));
        }

        public void EnableCustomChatCommands() => chatTrackingContext.Active = true;

        public ReattachInformation Release()
        {
            CheckDisposed();

            // we still don't want to dispose the dmb yet, even though we're keeping it alive
            var tmpProvider = reattachInformation.Dmb;
            reattachInformation.Dmb = null;
            released = true;
            Dispose();
            byondLock.DoNotDeleteThisSession();
            tmpProvider.KeepAlive();
            reattachInformation.Dmb = tmpProvider;
            return reattachInformation;
        }

        public async Task<CombinedTopicResponse> SendCommand(TopicParameters parameters, CancellationToken cancellationToken)
        {
            if (Lifetime.IsCompleted)
            {
                logger.LogWarning(
                    "Attempted to send a command to an inactive SessionController: {0}",
                    parameters.CommandType);
                return null;
            }

            parameters.AccessIdentifier = reattachInformation.AccessIdentifier;

            var json = JsonConvert.SerializeObject(parameters, DMApiConstants.SerializerSettings);
            logger.LogTrace("Topic request: {0}", json);
            try
            {
                var commandString = String.Format(CultureInfo.InvariantCulture,
                    "?{0}={1}",
                    byondTopicSender.SanitizeString(DMApiConstants.TopicData),
                    byondTopicSender.SanitizeString(json));

                var targetPort = reattachInformation.Port;

                var topicResponse = await byondTopicSender.SendTopic(
                    new IPEndPoint(IPAddress.Loopback, targetPort),
                    commandString,
                    cancellationToken).ConfigureAwait(false);

                var topicReturn = topicResponse.StringData;

                Interop.Topic.TopicResponse interopResponse = null;
                if (topicReturn != null)
                    try
                    {
                        interopResponse = JsonConvert.DeserializeObject<Interop.Topic.TopicResponse>(topicReturn, DMApiConstants.SerializerSettings);
                        if (interopResponse.ErrorMessage != null)
                        {
                            logger.LogWarning("Errored topic response for command {0}: {1}", parameters.CommandType, interopResponse.ErrorMessage);
                        }

                        logger.LogTrace("Interop response: {0}", topicReturn);
                    }
                    catch
                    {
                        logger.LogWarning("Invalid interop response: {0}", topicReturn);
                    }

                return new CombinedTopicResponse(topicResponse, interopResponse);
            }
            catch (OperationCanceledException)
            {
                logger.LogTrace(
                    "Topic request {0}!",
                    cancellationToken.IsCancellationRequested
                        ? "aborted"
                        : "timed out");
                cancellationToken.ThrowIfCancellationRequested();
            }
            catch (Exception e)
            {
                logger.LogWarning("Send command exception:{0}{1}", Environment.NewLine, e);
            }

            return null;
        }

        public Task<bool> SetPort(ushort port, CancellationToken cancellationToken)
        {
            CheckDisposed();

            if (port == 0)
                throw new ArgumentOutOfRangeException(nameof(port), port, "port must not be zero!");

            async Task<bool> ImmediateTopicPortChange()
            {
                var commandResult = await SendCommand(
                    new TopicParameters(port),
                    cancellationToken)
                    .ConfigureAwait(false);

                if (commandResult.InteropResponse?.ErrorMessage != null)
                    return false;

                reattachInformation.Port = port;
                return true;
            }

            lock (synchronizationLock)
                if (portClosedForReboot)
                {
                    if (portAssignmentTcs != null)
                        throw new InvalidOperationException("A port change operation is already in progress!");
                    nextPort = port;
                    portAssignmentTcs = new TaskCompletionSource<bool>();
                    return portAssignmentTcs.Task;
                }
                else
                    return ImmediateTopicPortChange();
        }

        public async Task<bool> SetRebootState(RebootState newRebootState, CancellationToken cancellationToken)
        {
            if (RebootState == newRebootState)
                return true;

            logger.LogTrace("Changing reboot state to {0}", newRebootState);

            reattachInformation.RebootState = newRebootState;
            var result = await SendCommand(
                new TopicParameters(newRebootState),
                cancellationToken)
                .ConfigureAwait(false);

            return result?.InteropResponse != null && result.InteropResponse?.ErrorMessage == null;
        }

        public void ResetRebootState()
        {
            CheckDisposed();
            logger.LogTrace("Resetting reboot state...");
            reattachInformation.RebootState = RebootState.Normal;
        }

        public void SetHighPriority() => process.SetHighPriority();

        public void Suspend() => process.Suspend();

        public void Resume() => process.Resume();

        public void ReplaceDmbProvider(IDmbProvider dmbProvider)
        {
            var oldDmb = reattachInformation.Dmb;
            reattachInformation.Dmb = dmbProvider ?? throw new ArgumentNullException(nameof(dmbProvider));
            oldDmb.Dispose();
        }

        public Task InstanceRenamed(string newInstanceName, CancellationToken cancellationToken)
            => SendCommand(new TopicParameters(newInstanceName), cancellationToken);

        public Task UpdateChannels(IEnumerable<ChannelRepresentation> newChannels, CancellationToken cancellationToken)
            => SendCommand(
                new TopicParameters(
                    new ChatUpdate(newChannels)),
                cancellationToken);
    }
}