duplicati/Duplicati/Library/RemoteControl/RegisterForRemote.cs

// Copyright (C) 2024, The Duplicati Team
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// 
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// 
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using System.Net.Http.Json;
using Duplicati.Library.Logging;
using Duplicati.Library.Utility;

namespace Duplicati.Library.RemoteControl;

/// <summary>
/// Implementation of the remote control enrollment process
/// </summary>
public class RegisterForRemote : IDisposable
{
    /// <summary>
    /// The log tag for messages from this class
    /// </summary>
    private static readonly string LogTag = Log.LogTagFromType<RegisterForRemote>();

    /// <summary>
    /// The interval between retries when registering the machine
    /// </summary>
    private static readonly TimeSpan ClientRegisterRetryInterval = TimeSpan.FromSeconds(30);
    /// <summary>
    /// The maximum number of retries when registering the machine
    /// </summary>
    private static readonly int ClientRegisterMaxRetries = 10;

    /// <summary>
    /// A random ID for this client instance
    /// </summary>
    private static readonly string ClientInstanceId = Guid.NewGuid().ToString();

    /// <summary>
    /// The states that the process can be in
    /// </summary>
    public enum States
    {
        /// <summary>
        /// The process has not started
        /// </summary>
        NotStarted,
        /// <summary>
        /// The machine is being registered
        /// </summary>
        Registering,
        /// <summary>
        /// The machine has been registered
        /// </summary>
        Registered,
        /// <summary>
        /// The machine is waiting for the user to claim it
        /// </summary>
        WaitingForClaim,
        /// <summary>
        /// The machine has been claimed
        /// </summary>
        Claimed,
        /// <summary>
        /// The process has failed
        /// </summary>
        Failed,
        /// <summary>
        /// The process has been disposed
        /// </summary>
        Disposed
    }

    /// <summary>
    /// The current state of the registration process
    /// </summary>
    private States _state;
    /// <summary>
    /// The URL to register the machine with
    /// </summary>
    private readonly string _registrationUrl;
    /// <summary>
    /// The cancellation token source for the process
    /// </summary>
    private readonly CancellationTokenSource _cancellationTokenSource;
    /// <summary>
    /// The HTTP client to use for requests
    /// </summary>
    private readonly HttpClient _httpClient;

    /// <summary>
    /// The data returned when registering the machine
    /// </summary>
    private RegisterClientData? _registerClientData;
    /// <summary>
    /// The data returned when claiming the machine
    /// </summary>
    private ClaimedClientData? _claimedClientData;

    /// <summary>
    /// Creates a new instance of the registration process
    /// </summary>
    /// <param name="registrationUrl">The URL to register the machine with</param>
    /// <param name="httpClient">The HTTP client to use for requests</param>
    /// <param name="cancellationToken">The cancellation token to use for the process</param>
    public RegisterForRemote(string registrationUrl, HttpClient? httpClient, CancellationToken cancellationToken)
    {
        _state = States.NotStarted;
        _registrationUrl = registrationUrl;
        _cancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
        _httpClient = httpClient ?? new HttpClient();
    }

    /// <summary>
    /// The current state of the registration process
    /// </summary>
    public States State => _state;

    /// <summary>
    /// Starts the registration process and returns the data needed to claim the machine
    /// </summary>
    /// <param name="maxRetries">The maximum number of retries when registering the machine</param>
    /// <param name="retryInterval">The interval between retries when registering the machine</param>
    /// <returns>The data needed to claim the machine</returns>
    /// <exception cref="InvalidOperationException">Thrown if the class is not in the correct state</exception>
    /// <exception cref="Exception">Thrown if the machine could not be registered</exception>
    public async Task<RegisterClientData> Register(int? maxRetries = null, TimeSpan? retryInterval = null)
    {
        if (_state != States.NotStarted)
            throw new InvalidOperationException("Registration process has already started");

        _state = States.Registering;
        try
        {
            _registerClientData = await RetryHelper.Retry(() => RegisterClient(), maxRetries ?? ClientRegisterMaxRetries, retryInterval ?? ClientRegisterRetryInterval, _cancellationTokenSource.Token);
        }
        catch (Exception ex)
        {
            if (_state != States.Disposed)
                _state = States.Failed;
            Log.WriteMessage(LogMessageType.Error, LogTag, "ClientRegistrationFailed", ex, $"Failed to register machine with server: {_registrationUrl}");
            throw;
        }


        if (_state != States.Disposed)
            _state = States.Registered;
        return _registerClientData!;
    }

    /// <summary>
    /// Registers the machine with the server
    /// </summary>
    /// <returns>The data needed to claim the machine</returns>
    private async Task<RegisterClientData> RegisterClient()
    {
        var response = await _httpClient.PostAsync(_registrationUrl, JsonContent.Create(new
        {
            InstanceId = ClientInstanceId,
            MachineId = AutoUpdater.UpdaterManager.MachineID,
            InstallId = AutoUpdater.UpdaterManager.InstallID,
            LocalTime = DateTimeOffset.Now
        }), _cancellationTokenSource.Token);

        response.EnsureSuccessStatusCode();
        return await response.Content.ReadFromJsonAsync<RegisterClientData>()
            ?? throw new Exception("Failed to read client registration data");
    }

    /// <summary>
    /// Claims the machine with the server
    /// </summary>
    /// <returns>The settings for the machine</returns>
    /// <exception cref="InvalidOperationException">Thrown if the class is not in the correct state</exception>
    /// <exception cref="Exception">Thrown if the machine could not be registered</exception>
    public async Task<ClaimedClientData> Claim()
    {
        if (_state != States.Registered)
            throw new InvalidOperationException("Resgistration process is not in the registered state");

        _state = States.WaitingForClaim;
        _cancellationTokenSource.CancelAfter(TimeSpan.FromSeconds(_registerClientData!.MaxLifetimeSeconds));
        try
        {
            _claimedClientData = await RetryHelper.Retry(() => CheckClientClaimed(), _registerClientData!.MaxRetries, TimeSpan.FromSeconds(_registerClientData!.RetrySeconds), _cancellationTokenSource.Token);
        }
        catch (Exception ex)
        {
            if (_state != States.Disposed)
                _state = States.Failed;
            Log.WriteMessage(LogMessageType.Error, LogTag, "ClientClaimFailed", ex, "Failed to claim machine with server");
            throw;
        }

        _state = States.Claimed;
        return _claimedClientData;
    }

    /// <summary>
    /// Checks if the machine has been claimed
    /// </summary>
    /// <returns>The data for the claimed machine</returns>
    /// <exception cref="Exception">Thrown if the machine could not be claimed</exception>
    private async Task<ClaimedClientData> CheckClientClaimed()
    {
        var response = await _httpClient.PostAsync(_registerClientData!.StatusLink, JsonContent.Create(new
        {
            InstanceId = ClientInstanceId,
            MachineId = AutoUpdater.UpdaterManager.MachineID,
            InstallId = AutoUpdater.UpdaterManager.InstallID,
            LocalTime = DateTimeOffset.Now
        }), _cancellationTokenSource.Token);

        response.EnsureSuccessStatusCode();
        return await response.Content.ReadFromJsonAsync<ClaimedClientData>()
            ?? throw new Exception("Failed to read machine claim data");
    }

    /// </inheritdoc>
    public void Dispose()
    {
        _cancellationTokenSource.Cancel();
        _httpClient.Dispose();
        _state = States.Disposed;
    }
}