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| 1 | +using System.Net; |
| 2 | +using System.Text; |
| 3 | +using System.Text.Json; |
| 4 | +using JetBrains.Annotations; |
| 5 | +using JsonApiDotNetCore.AtomicOperations; |
| 6 | +using JsonApiDotNetCore.Configuration; |
| 7 | +using JsonApiDotNetCore.Errors; |
| 8 | +using JsonApiDotNetCore.Serialization.Objects; |
| 9 | +using JsonApiDotNetCore.Serialization.Response; |
| 10 | +using Microsoft.AspNetCore.Http; |
| 11 | +using Microsoft.AspNetCore.Http.Extensions; |
| 12 | +using Microsoft.AspNetCore.WebUtilities; |
| 13 | +using Microsoft.IO; |
| 14 | +using Microsoft.Net.Http.Headers; |
| 15 | +using SysNotNull = System.Diagnostics.CodeAnalysis.NotNullAttribute; |
| 16 | + |
| 17 | +namespace JsonApiDotNetCore.Middleware; |
| 18 | + |
| 19 | +// IMPORTANT: In your Program.cs, make sure app.UseDeveloperExceptionPage() is called BEFORE this! |
| 20 | + |
| 21 | +public sealed class IdempotencyMiddleware |
| 22 | +{ |
| 23 | + private static readonly RecyclableMemoryStreamManager MemoryStreamManager = new(); |
| 24 | + |
| 25 | + private readonly IJsonApiOptions _options; |
| 26 | + private readonly IFingerprintGenerator _fingerprintGenerator; |
| 27 | + private readonly RequestDelegate _next; |
| 28 | + |
| 29 | + public IdempotencyMiddleware(IJsonApiOptions options, IFingerprintGenerator fingerprintGenerator, RequestDelegate next) |
| 30 | + { |
| 31 | + ArgumentGuard.NotNull(options, nameof(options)); |
| 32 | + ArgumentGuard.NotNull(fingerprintGenerator, nameof(fingerprintGenerator)); |
| 33 | + |
| 34 | + _options = options; |
| 35 | + _fingerprintGenerator = fingerprintGenerator; |
| 36 | + _next = next; |
| 37 | + } |
| 38 | + |
| 39 | + public async Task InvokeAsync(HttpContext httpContext, IIdempotencyProvider idempotencyProvider) |
| 40 | + { |
| 41 | + try |
| 42 | + { |
| 43 | + await InnerInvokeAsync(httpContext, idempotencyProvider); |
| 44 | + } |
| 45 | + catch (JsonApiException exception) |
| 46 | + { |
| 47 | + await FlushResponseAsync(httpContext.Response, _options.SerializerWriteOptions, exception.Errors.Single()); |
| 48 | + } |
| 49 | + } |
| 50 | + |
| 51 | + public async Task InnerInvokeAsync(HttpContext httpContext, IIdempotencyProvider idempotencyProvider) |
| 52 | + { |
| 53 | + string? idempotencyKey = GetIdempotencyKey(httpContext.Request.Headers); |
| 54 | + |
| 55 | + if (idempotencyKey != null && idempotencyProvider is NoIdempotencyProvider) |
| 56 | + { |
| 57 | + throw new JsonApiException(new ErrorObject(HttpStatusCode.BadRequest) |
| 58 | + { |
| 59 | + Title = $"Invalid '{HeaderConstants.IdempotencyKey}' HTTP header.", |
| 60 | + Detail = "Idempotency is currently disabled.", |
| 61 | + Source = new ErrorSource |
| 62 | + { |
| 63 | + Header = HeaderConstants.IdempotencyKey |
| 64 | + } |
| 65 | + }); |
| 66 | + } |
| 67 | + |
| 68 | + if (!idempotencyProvider.IsSupported(httpContext.Request)) |
| 69 | + { |
| 70 | + await _next(httpContext); |
| 71 | + return; |
| 72 | + } |
| 73 | + |
| 74 | + AssertIdempotencyKeyIsValid(idempotencyKey); |
| 75 | + |
| 76 | + await BufferRequestBodyAsync(httpContext); |
| 77 | + |
| 78 | + string requestFingerprint = await GetRequestFingerprintAsync(httpContext); |
| 79 | + IdempotentResponse? idempotentResponse = await idempotencyProvider.GetResponseFromCacheAsync(idempotencyKey, httpContext.RequestAborted); |
| 80 | + |
| 81 | + if (idempotentResponse != null) |
| 82 | + { |
| 83 | + if (idempotentResponse.RequestFingerprint != requestFingerprint) |
| 84 | + { |
| 85 | + throw new JsonApiException(new ErrorObject(HttpStatusCode.UnprocessableEntity) |
| 86 | + { |
| 87 | + Title = $"Invalid '{HeaderConstants.IdempotencyKey}' HTTP header.", |
| 88 | + Detail = $"The provided idempotency key '{idempotencyKey}' is in use for another request.", |
| 89 | + Source = new ErrorSource |
| 90 | + { |
| 91 | + Header = HeaderConstants.IdempotencyKey |
| 92 | + } |
| 93 | + }); |
| 94 | + } |
| 95 | + |
| 96 | + httpContext.Response.StatusCode = (int)idempotentResponse.ResponseStatusCode; |
| 97 | + httpContext.Response.Headers[HeaderConstants.IdempotencyKey] = $"\"{idempotencyKey}\""; |
| 98 | + httpContext.Response.Headers[HeaderNames.Location] = idempotentResponse.ResponseLocationHeader; |
| 99 | + |
| 100 | + if (idempotentResponse.ResponseContentTypeHeader != null) |
| 101 | + { |
| 102 | + // Workaround for invalid nullability annotation in HttpResponse.ContentType |
| 103 | + // Fixed after ASP.NET 6 release, see https://github.com/dotnet/aspnetcore/commit/8bb128185b58a26065d0f29e695a2410cf0a3c68#diff-bbfd771a8ef013a9921bff36df0d69f424910e079945992f1dccb24de54ca717 |
| 104 | + httpContext.Response.ContentType = idempotentResponse.ResponseContentTypeHeader; |
| 105 | + } |
| 106 | + |
| 107 | + await using TextWriter writer = new HttpResponseStreamWriter(httpContext.Response.Body, Encoding.UTF8); |
| 108 | + await writer.WriteAsync(idempotentResponse.ResponseBody); |
| 109 | + await writer.FlushAsync(); |
| 110 | + |
| 111 | + return; |
| 112 | + } |
| 113 | + |
| 114 | + await using IOperationsTransaction transaction = |
| 115 | + await idempotencyProvider.BeginRequestAsync(idempotencyKey, requestFingerprint, httpContext.RequestAborted); |
| 116 | + |
| 117 | + string responseBody = await CaptureResponseBodyAsync(httpContext, _next); |
| 118 | + |
| 119 | + idempotentResponse = new IdempotentResponse(requestFingerprint, (HttpStatusCode)httpContext.Response.StatusCode, |
| 120 | + httpContext.Response.Headers[HeaderNames.Location], httpContext.Response.ContentType, responseBody); |
| 121 | + |
| 122 | + await idempotencyProvider.CompleteRequestAsync(idempotencyKey, idempotentResponse, transaction, httpContext.RequestAborted); |
| 123 | + } |
| 124 | + |
| 125 | + private static string? GetIdempotencyKey(IHeaderDictionary requestHeaders) |
| 126 | + { |
| 127 | + if (!requestHeaders.ContainsKey(HeaderConstants.IdempotencyKey)) |
| 128 | + { |
| 129 | + return null; |
| 130 | + } |
| 131 | + |
| 132 | + string headerValue = requestHeaders[HeaderConstants.IdempotencyKey]; |
| 133 | + |
| 134 | + if (headerValue.Length >= 2 && headerValue[0] == '\"' && headerValue[^1] == '\"') |
| 135 | + { |
| 136 | + return headerValue[1..^1]; |
| 137 | + } |
| 138 | + |
| 139 | + return string.Empty; |
| 140 | + } |
| 141 | + |
| 142 | + [AssertionMethod] |
| 143 | + private static void AssertIdempotencyKeyIsValid([SysNotNull] string? idempotencyKey) |
| 144 | + { |
| 145 | + if (idempotencyKey == null) |
| 146 | + { |
| 147 | + throw new JsonApiException(new ErrorObject(HttpStatusCode.BadRequest) |
| 148 | + { |
| 149 | + Title = $"Missing '{HeaderConstants.IdempotencyKey}' HTTP header.", |
| 150 | + Detail = "An idempotency key is a unique value generated by the client, which the server uses to recognize subsequent retries " + |
| 151 | + "of the same request. This should be a random string with enough entropy to avoid collisions." |
| 152 | + }); |
| 153 | + } |
| 154 | + |
| 155 | + if (idempotencyKey == string.Empty) |
| 156 | + { |
| 157 | + throw new JsonApiException(new ErrorObject(HttpStatusCode.BadRequest) |
| 158 | + { |
| 159 | + Title = $"Invalid '{HeaderConstants.IdempotencyKey}' HTTP header.", |
| 160 | + Detail = "Expected non-empty value surrounded by double quotes.", |
| 161 | + Source = new ErrorSource |
| 162 | + { |
| 163 | + Header = HeaderConstants.IdempotencyKey |
| 164 | + } |
| 165 | + }); |
| 166 | + } |
| 167 | + } |
| 168 | + |
| 169 | + /// <summary> |
| 170 | + /// Enables to read the HTTP request stream multiple times, without risking GC Gen2/LOH promotion. |
| 171 | + /// </summary> |
| 172 | + private static async Task BufferRequestBodyAsync(HttpContext httpContext) |
| 173 | + { |
| 174 | + // Above this threshold, EnableBuffering() switches to a temporary file on disk. |
| 175 | + // Source: Microsoft.AspNetCore.Http.BufferingHelper.DefaultBufferThreshold |
| 176 | + const int enableBufferingThreshold = 1024 * 30; |
| 177 | + |
| 178 | + if (httpContext.Request.ContentLength > enableBufferingThreshold) |
| 179 | + { |
| 180 | + httpContext.Request.EnableBuffering(enableBufferingThreshold); |
| 181 | + } |
| 182 | + else |
| 183 | + { |
| 184 | + MemoryStream memoryRequestBodyStream = MemoryStreamManager.GetStream(); |
| 185 | + await httpContext.Request.Body.CopyToAsync(memoryRequestBodyStream, httpContext.RequestAborted); |
| 186 | + memoryRequestBodyStream.Seek(0, SeekOrigin.Begin); |
| 187 | + |
| 188 | + httpContext.Request.Body = memoryRequestBodyStream; |
| 189 | + httpContext.Response.RegisterForDispose(memoryRequestBodyStream); |
| 190 | + } |
| 191 | + } |
| 192 | + |
| 193 | + private async Task<string> GetRequestFingerprintAsync(HttpContext httpContext) |
| 194 | + { |
| 195 | + using var reader = new StreamReader(httpContext.Request.Body, leaveOpen: true); |
| 196 | + string requestBody = await reader.ReadToEndAsync(); |
| 197 | + httpContext.Request.Body.Seek(0, SeekOrigin.Begin); |
| 198 | + |
| 199 | + return _fingerprintGenerator.Generate(ArrayFactory.Create(httpContext.Request.GetEncodedUrl(), requestBody)); |
| 200 | + } |
| 201 | + |
| 202 | + /// <summary> |
| 203 | + /// Executes the specified action and returns what it wrote to the HTTP response stream. |
| 204 | + /// </summary> |
| 205 | + private static async Task<string> CaptureResponseBodyAsync(HttpContext httpContext, RequestDelegate nextAction) |
| 206 | + { |
| 207 | + // Loosely based on https://elanderson.net/2019/12/log-requests-and-responses-in-asp-net-core-3/. |
| 208 | + |
| 209 | + Stream previousResponseBodyStream = httpContext.Response.Body; |
| 210 | + |
| 211 | + try |
| 212 | + { |
| 213 | + await using MemoryStream memoryResponseBodyStream = MemoryStreamManager.GetStream(); |
| 214 | + httpContext.Response.Body = memoryResponseBodyStream; |
| 215 | + |
| 216 | + try |
| 217 | + { |
| 218 | + await nextAction(httpContext); |
| 219 | + } |
| 220 | + finally |
| 221 | + { |
| 222 | + memoryResponseBodyStream.Seek(0, SeekOrigin.Begin); |
| 223 | + await memoryResponseBodyStream.CopyToAsync(previousResponseBodyStream); |
| 224 | + } |
| 225 | + |
| 226 | + memoryResponseBodyStream.Seek(0, SeekOrigin.Begin); |
| 227 | + using var streamReader = new StreamReader(memoryResponseBodyStream, leaveOpen: true); |
| 228 | + return await streamReader.ReadToEndAsync(); |
| 229 | + } |
| 230 | + finally |
| 231 | + { |
| 232 | + httpContext.Response.Body = previousResponseBodyStream; |
| 233 | + } |
| 234 | + } |
| 235 | + |
| 236 | + private static async Task FlushResponseAsync(HttpResponse httpResponse, JsonSerializerOptions serializerOptions, ErrorObject error) |
| 237 | + { |
| 238 | + httpResponse.ContentType = HeaderConstants.MediaType; |
| 239 | + httpResponse.StatusCode = (int)error.StatusCode; |
| 240 | + |
| 241 | + var errorDocument = new Document |
| 242 | + { |
| 243 | + Errors = error.AsList() |
| 244 | + }; |
| 245 | + |
| 246 | + await JsonSerializer.SerializeAsync(httpResponse.Body, errorDocument, serializerOptions); |
| 247 | + await httpResponse.Body.FlushAsync(); |
| 248 | + } |
| 249 | +} |
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