System.IO.DirectoryNotFoundException 流式传输 9 MB 文件时 - .NET Core 2.2（使用 Kestrel）

Question

我正在使用此 link (https://docs.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-2.2#uploading-large-files-with-streaming) 中提到的代码来传输 9MB jpg/png 文件，但我最终在 EC2 实例上收到以下错误。

需要说明的是，我在本地主机上没有遇到这个问题，但是在 AWS EC2 上遇到了这个问题。正如您在附图中看到的那样，只有部分文件正在上传，但在收到 >28KB 的文件后会抛出异常，并且每次上传文件时都会发生这种情况。

    fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HLPPS3LVRBHR", Request id "0HLPPS3LVRBHR:00000004": An unhandled exception was thrown by the application.
System.IO.DirectoryNotFoundException: C:\Users\Administrator\AppData\Local\Temp\
   at Microsoft.AspNetCore.Http.Internal.BufferingHelper.get_TempDirectory()
   at Microsoft.AspNetCore.WebUtilities.FileBufferingReadStream.CreateTempFile()
   at Microsoft.AspNetCore.WebUtilities.FileBufferingReadStream.ReadAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.WebUtilities.BufferedReadStream.EnsureBufferedAsync(Int32 minCount, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.WebUtilities.MultipartReaderStream.ReadAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at System.IO.Stream.CopyToAsyncInternal(Stream destination, Int32 bufferSize, CancellationToken cancellationToken)
   at RenetalApi.Helpers.FileStreamingHelper.StreamFile(HttpRequest request, Stream targetStream)
   at RenetalApi.Controllers.ProductsController.Upload(Int32 productId)
   at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Cors.Infrastructure.CorsMiddleware.InvokeCore(HttpContext context)
   at Sentry.AspNetCore.SentryMiddleware.InvokeAsync(HttpContext context)
   at Sentry.AspNetCore.SentryMiddleware.InvokeAsync(HttpContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

我想了解为什么会出现这样的错误？但是，如果我手动创建丢失的文件夹，那么在 Kestrel 重新启动之前我不会遇到任何问题，这似乎不是一个永久的解决方案。

这是我的代码：

CustomersController.cs

[HttpPut]
[Route("{customerId}/upload-photo")]
[DisableFormValueModelBinding]
public async Task<IActionResult> UploadPhoto(int customerId)
{
    // Generates a new unique filename
    var fileName = $"{Guid.NewGuid().ToString()}.jpg";
    var filePath = Path.Combine("c:\files", fileName);

    FormValueProvider formModel;
    using (var stream = System.IO.File.Create(filePath))
    {
        formModel = await Request.StreamFile(stream);
    }

    Console.WriteLine("File received.");

    return Ok();
}

FileStreamingHelper.cs

public static class FileStreamingHelper
    {
        private static readonly FormOptions _defaultFormOptions = new FormOptions();

        public static async Task<FormValueProvider> StreamFile(this HttpRequest request, Stream targetStream)
        {
            if (!MultipartRequestHelper.IsMultipartContentType(request.ContentType))
            {
                throw new Exception($"Expected a multipart request, but got {request.ContentType}");
            }

            // Used to accumulate all the form url encoded key value pairs in the 
            // request.
            var formAccumulator = new KeyValueAccumulator();

            var boundary = MultipartRequestHelper.GetBoundary(MediaTypeHeaderValue.Parse(request.ContentType), _defaultFormOptions.MultipartBoundaryLengthLimit);
            var reader = new MultipartReader(boundary, request.Body);

            var section = await reader.ReadNextSectionAsync();
            while (section != null)
            {
                ContentDispositionHeaderValue contentDisposition;
                var hasContentDispositionHeader = ContentDispositionHeaderValue.TryParse(section.ContentDisposition, out contentDisposition);

                if (hasContentDispositionHeader)
                {
                    if (MultipartRequestHelper.HasFileContentDisposition(contentDisposition))
                    {
                        await section.Body.CopyToAsync(targetStream);
                    }
                    else if (MultipartRequestHelper.HasFormDataContentDisposition(contentDisposition))
                    {
                        // Content-Disposition: form-data; name="key"
                        //
                        // value

                        // Do not limit the key name length here because the 
                        // multipart headers length limit is already in effect.
                        var key = HeaderUtilities.RemoveQuotes(contentDisposition.Name);
                        var encoding = GetEncoding(section);
                        using (var streamReader = new StreamReader(
                            section.Body,
                            encoding,
                            detectEncodingFromByteOrderMarks: true,
                            bufferSize: 1024,
                            leaveOpen: true))
                        {
                            // The value length limit is enforced by MultipartBodyLengthLimit
                            var value = await streamReader.ReadToEndAsync();
                            if (String.Equals(value, "undefined", StringComparison.OrdinalIgnoreCase))
                            {
                                value = String.Empty;
                            }
                            formAccumulator.Append(key.Value, value); // For .NET Core <2.0 remove ".Value" from key

                            if (formAccumulator.ValueCount > _defaultFormOptions.ValueCountLimit)
                            {
                                throw new InvalidDataException($"Form key count limit {_defaultFormOptions.ValueCountLimit} exceeded.");
                            }
                        }
                    }
                }

                // Drains any remaining section body that has not been consumed and
                // reads the headers for the next section.
                section = await reader.ReadNextSectionAsync();
            }

            // Bind form data to a model
            var formValueProvider = new FormValueProvider(
                BindingSource.Form,
                new FormCollection(formAccumulator.GetResults()),
                CultureInfo.CurrentCulture);

            return formValueProvider;
        }

        static Encoding GetEncoding(MultipartSection section)
        {
            var hasMediaTypeHeader = MediaTypeHeaderValue.TryParse(section.ContentType, out MediaTypeHeaderValue mediaType);
            // UTF-7 is insecure and should not be honored. UTF-8 will succeed in 
            // most cases.
            if (!hasMediaTypeHeader || Encoding.UTF7.Equals(mediaType.Encoding))
            {
                return Encoding.UTF8;
            }

            return mediaType.Encoding;
        }
    }

DisableFormValueModelBindingAttribute.cs

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
    public class DisableFormValueModelBindingAttribute : Attribute, IResourceFilter
    {
        public void OnResourceExecuting(ResourceExecutingContext context)
        {
            var formValueProviderFactory = context.ValueProviderFactories
                .OfType<FormValueProviderFactory>()
                .FirstOrDefault();
            if (formValueProviderFactory != null)
            {
                context.ValueProviderFactories.Remove(formValueProviderFactory);
            }

            var jqueryFormValueProviderFactory = context.ValueProviderFactories
                .OfType<JQueryFormValueProviderFactory>()
                .FirstOrDefault();
            if (jqueryFormValueProviderFactory != null)
            {
                context.ValueProviderFactories.Remove(jqueryFormValueProviderFactory);
            }
        }

        public void OnResourceExecuted(ResourceExecutedContext context)
        {
        }
    }

MultipartRequestHelper.cs

public static class MultipartRequestHelper
    {
        // Content-Type: multipart/form-data; boundary="----WebKitFormBoundarymx2fSWqWSd0OxQqq"
        // The spec says 70 characters is a reasonable limit.
        public static string GetBoundary(MediaTypeHeaderValue contentType, int lengthLimit)
        {
            //var boundary = Microsoft.Net.Http.Headers.HeaderUtilities.RemoveQuotes(contentType.Boundary);// .NET Core <2.0
            var boundary = HeaderUtilities.RemoveQuotes(contentType.Boundary).Value; //.NET Core 2.0
            if (string.IsNullOrWhiteSpace(boundary))
            {
                throw new InvalidDataException("Missing content-type boundary.");
            }

            if (boundary.Length > lengthLimit)
            {
                throw new InvalidDataException(
                    $"Multipart boundary length limit {lengthLimit} exceeded.");
            }

            return boundary;
        }

        public static bool IsMultipartContentType(string contentType)
        {
            return !string.IsNullOrEmpty(contentType)
                    && contentType.IndexOf("multipart/", StringComparison.OrdinalIgnoreCase) >= 0;
        }

        public static bool HasFormDataContentDisposition(ContentDispositionHeaderValue contentDisposition)
        {
            // Content-Disposition: form-data; name="key";
            return contentDisposition != null
                    && contentDisposition.DispositionType.Equals("form-data")
                    && string.IsNullOrEmpty(contentDisposition.FileName.Value) // For .NET Core <2.0 remove ".Value"
                    && string.IsNullOrEmpty(contentDisposition.FileNameStar.Value); // For .NET Core <2.0 remove ".Value"
        }

        public static bool HasFileContentDisposition(ContentDispositionHeaderValue contentDisposition)
        {
            // Content-Disposition: form-data; name="myfile1"; filename="Misc 002.jpg"
            return contentDisposition != null
                    && contentDisposition.DispositionType.Equals("form-data")
                    && (!string.IsNullOrEmpty(contentDisposition.FileName.Value) // For .NET Core <2.0 remove ".Value"
                        || !string.IsNullOrEmpty(contentDisposition.FileNameStar.Value)); // For .NET Core <2.0 remove ".Value"
        }
    }

Answer 1

如错误所示，您的文件夹 files 似乎不存在。尝试在下面添加代码来检查文件夹是否存在。

public async Task<IActionResult> UploadPhoto(int customerId)
{
    // Generates a new unique filename
    var fileName = $"{Guid.NewGuid().ToString()}.jpg";
    var filePath = Path.Combine("c:\files", fileName);
    FormValueProvider formModel;
    if (!Directory.Exists(Path.GetDirectoryName(filePath)))
    {
        Directory.CreateDirectory(Path.GetDirectoryName(filePath));
    }
    using (var stream = System.IO.File.Create(filePath))
    {
        formModel = await Request.StreamFile(stream);
    }

    Console.WriteLine("File received.");

    return Ok();
}

Answer 2

只是为了提供更新 - 我通过配置 环境变量 ASPNETCORE_TEMP 解决了这个问题。可以在 this 文章中找到详细信息。

System.IO.DirectoryNotFoundException 流式传输 9 MB 文件时 - .NET Core 2.2（使用 Kestrel）

System.IO.DirectoryNotFoundException while streaming 9 MB file - .NET Core 2.2 (using Kestrel)

.net

filestream

.net-core

kestrel-http-server

asp.net-core