ApiClient.cs

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using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Net.Mime;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Web;
 
using Microsoft.AspNetCore.Http.Connections;
using Microsoft.AspNetCore.SignalR.Client;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Net.Http.Headers;
 
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;
using Newtonsoft.Json.Serialization;
 
using Tgstation.Server.Api;
using Tgstation.Server.Api.Models;
using Tgstation.Server.Api.Models.Response;
using Tgstation.Server.Client.Extensions;
using Tgstation.Server.Common.Extensions;
using Tgstation.Server.Common.Http;
 
namespace Tgstation.Server.Client
{
    class ApiClient : IApiClient
    {
        static readonly HttpMethod HttpPatch = new("PATCH");
 
        public Uri Url { get; }
 
        public ApiHeaders Headers
        {
            get => headers;
            set => headers = value ?? throw new InvalidOperationException("Cannot set null headers!");
        }
 
        public TimeSpan Timeout
        {
            get => httpClient.Timeout;
            set => httpClient.Timeout = value;
        }
 
        static readonly JsonSerializerSettings SerializerSettings = new()
        {
            ContractResolver = new CamelCasePropertyNamesContractResolver(),
            Converters = new[]
            {
                new VersionConverter(),
            },
        };
 
        readonly IHttpClient httpClient;
 
        readonly List<IRequestLogger> requestLoggers;
 
        readonly List<HubConnection> hubConnections;
 
        readonly ApiHeaders? tokenRefreshHeaders;
 
        readonly SemaphoreSlim semaphoreSlim;
 
        readonly bool authless;
 
        ApiHeaders headers;
 
        bool disposed;
 
        static void HandleBadResponse(HttpResponseMessage response, string json)
        {
            ErrorMessageResponse? errorMessage = null;
            try
            {
                // check if json serializes to an error message
                errorMessage = JsonConvert.DeserializeObject<ErrorMessageResponse>(json, SerializerSettings);
            }
            catch (JsonException)
            {
            }
 
#pragma warning disable IDE0010 // Add missing cases
            switch (response.StatusCode)
#pragma warning restore IDE0010 // Add missing cases
            {
                case HttpStatusCode.Unauthorized:
                    throw new UnauthorizedException(errorMessage, response);
                case HttpStatusCode.InternalServerError:
                    throw new ServerErrorException(errorMessage, response);
                case HttpStatusCode.NotImplemented:
                // unprocessable entity
                case (HttpStatusCode)422:
                    throw new MethodNotSupportedException(errorMessage, response);
                case HttpStatusCode.NotFound:
                case HttpStatusCode.Gone:
                case HttpStatusCode.Conflict:
                    throw new ConflictException(errorMessage, response);
                case HttpStatusCode.Forbidden:
                    throw new InsufficientPermissionsException(response);
                case HttpStatusCode.ServiceUnavailable:
                    throw new ServiceUnavailableException(response);
                case HttpStatusCode.RequestTimeout:
                    throw new RequestTimeoutException(response);
                case (HttpStatusCode)429:
                    throw new RateLimitException(errorMessage, response);
                default:
                    if (errorMessage?.ErrorCode == ErrorCode.ApiMismatch)
                        throw new VersionMismatchException(errorMessage, response);
 
                    throw new ApiConflictException(errorMessage, response);
            }
        }
 
        public ApiClient(
            IHttpClient httpClient,
            Uri url,
            ApiHeaders apiHeaders,
            ApiHeaders? tokenRefreshHeaders,
            bool authless)
        {
            this.httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
            Url = url ?? throw new ArgumentNullException(nameof(url));
            headers = apiHeaders ?? throw new ArgumentNullException(nameof(apiHeaders));
            this.tokenRefreshHeaders = tokenRefreshHeaders;
            this.authless = authless;
 
            requestLoggers = new List<IRequestLogger>();
            hubConnections = new List<HubConnection>();
            semaphoreSlim = new SemaphoreSlim(1);
        }
 
        public async ValueTask DisposeAsync()
        {
            List<HubConnection> localHubConnections;
            lock (hubConnections)
            {
                if (disposed)
                    return;
 
                disposed = true;
 
                localHubConnections = hubConnections.ToList();
                hubConnections.Clear();
            }
 
            await ValueTaskExtensions.WhenAll(hubConnections.Select(connection => connection.DisposeAsync()));
 
            httpClient.Dispose();
            semaphoreSlim.Dispose();
        }
 
        public ValueTask<TResult> Create<TResult>(string route, CancellationToken cancellationToken)
            => RunRequest<object, TResult>(route, new object(), HttpMethod.Put, null, false, cancellationToken);
 
        public ValueTask<TResult> Read<TResult>(string route, CancellationToken cancellationToken)
            => RunRequest<object, TResult>(route, null, HttpMethod.Get, null, false, cancellationToken);
 
        public ValueTask<TResult> Update<TResult>(string route, CancellationToken cancellationToken)
            => RunRequest<object, TResult>(route, new object(), HttpMethod.Post, null, false, cancellationToken);
 
        public ValueTask<TResult> Update<TBody, TResult>(string route, TBody body, CancellationToken cancellationToken)
            where TBody : class
            => RunRequest<TBody, TResult>(route, body, HttpMethod.Post, null, false, cancellationToken);
 
        public ValueTask Patch(string route, CancellationToken cancellationToken) => RunRequest(route, HttpPatch, null, false, cancellationToken);
 
        public ValueTask Update<TBody>(string route, TBody body, CancellationToken cancellationToken)
            where TBody : class
            => RunResultlessRequest(route, body, HttpMethod.Post, null, false, cancellationToken);
 
        public ValueTask<TResult> Create<TBody, TResult>(string route, TBody body, CancellationToken cancellationToken)
            where TBody : class
            => RunRequest<TBody, TResult>(route, body, HttpMethod.Put, null, false, cancellationToken);
 
        public ValueTask Delete(string route, CancellationToken cancellationToken)
            => RunRequest(route, HttpMethod.Delete, null, false, cancellationToken);
 
        public ValueTask<TResult> Create<TBody, TResult>(string route, TBody body, long instanceId, CancellationToken cancellationToken)
            where TBody : class
            => RunRequest<TBody, TResult>(route, body, HttpMethod.Put, instanceId, false, cancellationToken);
 
        public ValueTask<TResult> Read<TResult>(string route, long instanceId, CancellationToken cancellationToken)
            => RunRequest<TResult>(route, null, HttpMethod.Get, instanceId, false, cancellationToken);
 
        public ValueTask<TResult> Update<TBody, TResult>(string route, TBody body, long instanceId, CancellationToken cancellationToken)
            where TBody : class
            => RunRequest<TBody, TResult>(route, body, HttpMethod.Post, instanceId, false, cancellationToken);
 
        public ValueTask Delete(string route, long instanceId, CancellationToken cancellationToken)
            => RunRequest(route, HttpMethod.Delete, instanceId, false, cancellationToken);
 
        public ValueTask Delete<TBody>(string route, TBody body, long instanceId, CancellationToken cancellationToken)
            where TBody : class
            => RunResultlessRequest(route, body, HttpMethod.Delete, instanceId, false, cancellationToken);
 
        public ValueTask<TResult> Delete<TResult>(string route, long instanceId, CancellationToken cancellationToken)
            => RunRequest<TResult>(route, null, HttpMethod.Delete, instanceId, false, cancellationToken);
 
        public ValueTask<TResult> Delete<TBody, TResult>(string route, TBody body, long instanceId, CancellationToken cancellationToken)
            where TBody : class
            => RunRequest<TBody, TResult>(route, body, HttpMethod.Delete, instanceId, false, cancellationToken);
 
        public ValueTask<TResult> Create<TResult>(string route, long instanceId, CancellationToken cancellationToken)
            => RunRequest<object, TResult>(route, new object(), HttpMethod.Put, instanceId, false, cancellationToken);
 
        public ValueTask<TResult> Patch<TResult>(string route, long instanceId, CancellationToken cancellationToken)
            => RunRequest<object, TResult>(route, new object(), HttpPatch, instanceId, false, cancellationToken);
 
        public void AddRequestLogger(IRequestLogger requestLogger) => requestLoggers.Add(requestLogger ?? throw new ArgumentNullException(nameof(requestLogger)));
 
        public ValueTask<Stream> Download(FileTicketResponse ticket, CancellationToken cancellationToken)
        {
            if (ticket == null)
                throw new ArgumentNullException(nameof(ticket));
 
            return RunRequest<Stream>(
                $"{Routes.Transfer}?ticket={HttpUtility.UrlEncode(ticket.FileTicket)}",
                null,
                HttpMethod.Get,
                null,
                false,
                cancellationToken);
        }
 
        public async ValueTask Upload(FileTicketResponse ticket, Stream? uploadStream, CancellationToken cancellationToken)
        {
            if (ticket == null)
                throw new ArgumentNullException(nameof(ticket));
 
            MemoryStream? memoryStream = null;
            if (uploadStream == null)
                memoryStream = new MemoryStream();
 
            using (memoryStream)
            {
                var streamContent = new StreamContent(uploadStream ?? memoryStream);
                try
                {
                    await RunRequest<object>(
                        $"{Routes.Transfer}?ticket={HttpUtility.UrlEncode(ticket.FileTicket)}",
                        streamContent,
                        HttpMethod.Put,
                        null,
                        false,
                        cancellationToken)
                        .ConfigureAwait(false);
                    streamContent = null;
                }
                finally
                {
                    streamContent?.Dispose();
                }
            }
        }
 
        public async ValueTask<bool> RefreshToken(CancellationToken cancellationToken)
        {
            if (tokenRefreshHeaders == null)
                return false;
 
            var startingToken = headers.Token;
            await semaphoreSlim.WaitAsync(cancellationToken).ConfigureAwait(false);
            try
            {
                if (startingToken != headers.Token)
                    return true;
 
                var token = await RunRequest<object, TokenResponse>(Routes.ApiRoot, new object(), HttpMethod.Post, null, true, cancellationToken).ConfigureAwait(false);
                headers = new ApiHeaders(headers.UserAgent!, token);
            }
            finally
            {
                semaphoreSlim.Release();
            }
 
            return true;
        }
 
        public async ValueTask<IAsyncDisposable> CreateHubConnection<THubImplementation>(
            THubImplementation hubImplementation,
            IRetryPolicy? retryPolicy,
            Action<ILoggingBuilder>? loggingConfigureAction,
            CancellationToken cancellationToken)
            where THubImplementation : class
        {
            if (hubImplementation == null)
                throw new ArgumentNullException(nameof(hubImplementation));
 
            retryPolicy ??= new InfiniteThirtySecondMaxRetryPolicy();
 
            var wrappedPolicy = new ApiClientTokenRefreshRetryPolicy(this, retryPolicy);
 
            HubConnection? hubConnection = null;
            var hubConnectionBuilder = new HubConnectionBuilder()
                .AddNewtonsoftJsonProtocol(options =>
                {
                    options.PayloadSerializerSettings = SerializerSettings;
                })
                .WithAutomaticReconnect(wrappedPolicy)
                .WithUrl(
                    new Uri(Url, Routes.JobsHub),
                    HttpTransportType.ServerSentEvents,
                    options =>
                    {
                        options.AccessTokenProvider = async () =>
                        {
                            // DCT: None available.
                            if (Headers.Token == null
                                || (Headers.Token.ParseJwt().ValidTo <= DateTime.UtcNow
                                && !await RefreshToken(CancellationToken.None)))
                            {
                                _ = hubConnection!.StopAsync(); // DCT: None available.
                                return null;
                            }
 
                            return Headers.Token.Bearer;
                        };
 
                        options.CloseTimeout = Timeout;
 
                        Headers.SetHubConnectionHeaders(options.Headers);
                    });
 
            if (loggingConfigureAction != null)
                hubConnectionBuilder.ConfigureLogging(loggingConfigureAction);
 
            hubConnection = hubConnectionBuilder.Build();
            try
            {
                hubConnection.Closed += async (error) =>
                {
                    if (error is HttpRequestException httpRequestException)
                    {
                        // .StatusCode isn't in netstandard but fuck the police
                        var property = error.GetType().GetProperty("StatusCode");
                        if (property != null)
                        {
                            var statusCode = (HttpStatusCode?)property.GetValue(error);
                            if (statusCode == HttpStatusCode.Unauthorized
                                && !await RefreshToken(CancellationToken.None))
                                _ = hubConnection!.StopAsync();
                        }
                    }
                };
 
                hubConnection.ProxyOn(hubImplementation);
 
                Task startTask;
                lock (hubConnections)
                {
                    if (disposed)
                        throw new ObjectDisposedException(nameof(ApiClient));
 
                    hubConnections.Add(hubConnection);
                    startTask = hubConnection.StartAsync(cancellationToken);
                }
 
                await startTask;
 
                return hubConnection;
            }
            catch
            {
                bool needsDispose;
                lock (hubConnections)
                    needsDispose = hubConnections.Remove(hubConnection);
 
                if (needsDispose)
                    await hubConnection.DisposeAsync();
                throw;
            }
        }
 
#pragma warning disable CA1506 // TODO: Decomplexify
        protected virtual async ValueTask<TResult> RunRequest<TResult>(
            string route,
            HttpContent? content,
            HttpMethod method,
            long? instanceId,
            bool tokenRefresh,
            CancellationToken cancellationToken)
        {
            if (route == null)
                throw new ArgumentNullException(nameof(route));
            if (method == null)
                throw new ArgumentNullException(nameof(method));
            if (content == null && (method == HttpMethod.Post || method == HttpMethod.Put))
                throw new InvalidOperationException("content cannot be null for POST or PUT!");
 
            if (disposed)
                throw new ObjectDisposedException(nameof(ApiClient));
 
            HttpResponseMessage response;
            var fullUri = new Uri(Url, route);
            var serializerSettings = SerializerSettings;
            var fileDownload = typeof(TResult) == typeof(Stream);
            using (var request = new HttpRequestMessage(method, fullUri))
            {
                if (content != null)
                    request.Content = content;
 
                try
                {
                    var headersToUse = tokenRefresh ? tokenRefreshHeaders! : headers;
                    headersToUse.SetRequestHeaders(request.Headers, instanceId);
 
                    if (authless)
                        request.Headers.Remove(HeaderNames.Authorization);
                    else
                    {
                        var bearer = headersToUse.Token?.Bearer;
                        if (bearer != null)
                        {
                            var parsed = headersToUse.Token!.ParseJwt();
                            var nbf = parsed.ValidFrom;
                            var now = DateTime.UtcNow;
                            if (nbf >= now)
                            {
                                var delay = (nbf - now).Add(TimeSpan.FromMilliseconds(1));
                                await Task.Delay(delay, cancellationToken);
                            }
                        }
                    }
 
                    if (fileDownload)
                        request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue(MediaTypeNames.Application.Octet));
 
                    await ValueTaskExtensions.WhenAll(requestLoggers.Select(x => x.LogRequest(request, cancellationToken))).ConfigureAwait(false);
 
                    response = await httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationToken).ConfigureAwait(false);
                }
                finally
                {
                    // prevent content param from getting disposed
                    request.Content = null;
                }
            }
 
            try
            {
                await ValueTaskExtensions.WhenAll(requestLoggers.Select(x => x.LogResponse(response, cancellationToken))).ConfigureAwait(false);
 
                // just stream
                if (fileDownload && response.IsSuccessStatusCode)
                    return (TResult)(object)await CachedResponseStream.Create(response).ConfigureAwait(false);
            }
            catch
            {
                response.Dispose();
                throw;
            }
 
            using (response)
            {
                var json = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
 
                if (!response.IsSuccessStatusCode)
                {
                    if (!tokenRefresh
                        && response.StatusCode == HttpStatusCode.Unauthorized
                        && await RefreshToken(cancellationToken).ConfigureAwait(false))
                        return await RunRequest<TResult>(route, content, method, instanceId, false, cancellationToken).ConfigureAwait(false);
                    HandleBadResponse(response, json);
                }
 
                if (String.IsNullOrWhiteSpace(json))
                    json = JsonConvert.SerializeObject(new object());
 
                try
                {
                    var result = JsonConvert.DeserializeObject<TResult>(json, serializerSettings);
                    return result!;
                }
                catch (JsonException)
                {
                    throw new UnrecognizedResponseException(response);
                }
            }
        }
#pragma warning restore CA1506
 
        async ValueTask<TResult> RunRequest<TBody, TResult>(
            string route,
            TBody? body,
            HttpMethod method,
            long? instanceId,
            bool tokenRefresh,
            CancellationToken cancellationToken)
            where TBody : class
        {
            HttpContent? content = null;
            if (body != null)
                content = new StringContent(
                    JsonConvert.SerializeObject(body, typeof(TBody), Formatting.None, SerializerSettings),
                    Encoding.UTF8,
                    ApiHeaders.ApplicationJsonMime);
 
            using (content)
                return await RunRequest<TResult>(
                    route,
                    content,
                    method,
                    instanceId,
                    tokenRefresh,
                    cancellationToken)
                    .ConfigureAwait(false);
        }
 
        async ValueTask RunResultlessRequest<TBody>(
            string route,
            TBody? body,
            HttpMethod method,
            long? instanceId,
            bool tokenRefresh,
            CancellationToken cancellationToken)
            where TBody : class
            => await RunRequest<TBody, object>(
                route,
                body,
                method,
                instanceId,
                tokenRefresh,
                cancellationToken);
 
        ValueTask RunRequest(
            string route,
            HttpMethod method,
            long? instanceId,
            bool tokenRefresh,
            CancellationToken cancellationToken)
            => RunResultlessRequest<object>(
                route,
                null,
                method,
                instanceId,
                tokenRefresh,
                cancellationToken);
    }
}