Question

我要做什么：

我正在尝试使用Postman将带有文件和JSON Blob的multipart/form-data上传到ASP.NET Core 2.2 APIController，并将文件流式传输到磁盘上的临时文件中，而不是完全导入到其中。由于文件的大小可能很大（20MB-2GB），因此内存不足。我从大文件示例开始遵循https://docs.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-2.2的两个示例，但是我也尝试过以相同的错误，相似但不同的堆栈跟踪测试小文件示例。服务器使用Kestrel。

大文件示例的堆栈跟踪（捕获在调试器中）：

Exception has occurred: CLR/System.IO.InvalidDataException
Exception thrown: 'System.IO.InvalidDataException' in System.Private.CoreLib.dll: 'Multipart body length limit 16384 exceeded.'
   at Microsoft.AspNetCore.WebUtilities.MultipartReaderStream.UpdatePosition(Int32 read)
   at Microsoft.AspNetCore.WebUtilities.MultipartReaderStream.<ReadAsync>d__36.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.AspNetCore.WebUtilities.StreamHelperExtensions.<DrainAsync>d__3.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.WebUtilities.MultipartReader.<ReadNextSectionAsync>d__20.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at LookupServiceAPI.Helpers.FileStreamingHelper.<StreamFile>d__1.MoveNext() in <hidden-path-to-project>\Helpers\FileStreamingHelper.cs:line 35

小文件示例的堆栈跟踪（作为响应返回，未遇到任何断点或调试器异常捕获）：

System.IO.InvalidDataException: Multipart body length limit 16384 exceeded.
   at Microsoft.AspNetCore.WebUtilities.MultipartReaderStream.UpdatePosition(Int32 read)
   at Microsoft.AspNetCore.WebUtilities.MultipartReaderStream.ReadAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.WebUtilities.StreamHelperExtensions.DrainAsync(Stream stream, ArrayPool`1 bytePool, Nullable`1 limit, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.WebUtilities.MultipartReader.ReadNextSectionAsync(CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Http.Features.FormFeature.InnerReadFormAsync(CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Mvc.ModelBinding.FormValueProviderFactory.AddValueProviderAsync(ValueProviderFactoryContext context)
   at Microsoft.AspNetCore.Mvc.ModelBinding.CompositeValueProvider.CreateAsync(ActionContext actionContext, IList`1 factories)
   at Microsoft.AspNetCore.Mvc.ModelBinding.CompositeValueProvider.CreateAsync(ControllerContext controllerContext)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerBinderDelegateProvider.<>c__DisplayClass0_0.<<CreateBinderDelegate>g__Bind|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   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.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

这是大文件示例的基本控制器代码和帮助程序类：

FileStreamingHelper.cs

using System;
using System.Globalization;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Http.Extensions;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Net.Http.Headers;

namespace LookupServiceAPI.Helpers
{
    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 = request.GetMultipartBoundary();
            var reader = new MultipartReader(boundary, request.Body);
            reader.BodyLengthLimit = Int32.MaxValue;
            reader.HeadersLengthLimit = Int32.MaxValue;
            var section = await reader.ReadNextSectionAsync(); //EXCEPTION HERE
            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;
        }

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

MultipartRequestHelper.cs

using System;
using System.IO;
using Microsoft.Net.Http.Headers;

namespace LookupServiceAPI.Helpers
{
    public static class MultipartRequestHelper
    {
        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)
                   && string.IsNullOrEmpty(contentDisposition.FileNameStar.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.ToString())
                       || !string.IsNullOrEmpty(contentDisposition.FileNameStar.ToString()));
        }
    }
}

最小控制器：

[Route("api/v0.1/data/excel")]
[ApiController]
public class DataExcelController : ControllerBase
{
    [HttpPost, DisableRequestSizeLimit]
    public async Task<IActionResult> ImportExcel()
    {
        var processID = Guid.NewGuid();
        FormValueProvider multipartContent;
        string tempFilePath = Path.GetTempPath() + processID;
        using(var tempStream = System.IO.File.OpenWrite(tempFilePath))
        {
            multipartContent = await Request.StreamFile(tempStream);
        }
        /** Other unnecessary code **/
        return Ok();
    }
}

Startup.cs

namespace LookupServiceAPI
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

            services.Configure<FormOptions>(x =>
            {
                x.MultipartHeadersLengthLimit = Int32.MaxValue;
                x.MultipartBoundaryLengthLimit = Int32.MaxValue;
                x.MultipartBodyLengthLimit = Int64.MaxValue;
                x.ValueLengthLimit = Int32.MaxValue;
                x.BufferBodyLengthLimit = Int64.MaxValue;
                x.MemoryBufferThreshold = Int32.MaxValue;
            });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseMvc();
        }
    }
}

邮递员配置映像（映像中仅设置了值，标头中未设置任何值）：

邮递员控制台输出：

我尝试过的事情：

来自Multipart body length limit 16384 exceeded：

设置MemoryBufferThreshold
设置MultipartBodyLengthLimit
确保邮递员配置的标头没有将Content-Type手动设置为multipart/form-data

来自Multipart body length limit exceeded exception：

设置ValueLengthLimit
使用过的[DisableRequestSizeLimit]

我认为问题出在哪里，但是我不确定解决方法或导致问题的原因： https://github.com/aspnet/AspNetCore/blob/master/src/Http/WebUtilities/src/MultipartReader.cs#L48-L50

似乎我的请求的序言超出了1024 * 16设置的DefaultHeadersLengthLimit（16384）的大小限制，但是我不知道为什么会这样。或者，如果序言应该大于该序言，那么如何在不重新实现整个类集的情况下解决该问题，或者如何等待Microsoft推出似乎没有进展的修复程序： https://github.com/aspnet/Mvc/issues/7019 https://github.com/aspnet/HttpAbstractions/issues/736

显然有人在这里解决了与我的问题（https://github.com/aspnet/Mvc/issues/5128#issuecomment-307675219）非常相似的问题： https://github.com/aspnet/Mvc/issues/5128#issuecomment-307962922，但我似乎不知道该如何解决甚至适用。

希望这是足够的信息。如果没有，请告诉我您的需求，我们很乐意提供或测试任何建议。我一直坚持研究这个问题，并尝试了6个小时以上可以找到的所有内容。

Answer 1

我有类似的问题，我发现问题与 Visual Studio 中的调试断点有关，因为我认为 Visual Studio 尝试读取流，然后尝试中断流，

所以尝试在 Watch 中跳过查看 Request.From 或调试快速查看

Answer 2

添加[FromForm]解决了我的问题。

例如

[HttpPost]
[RequestFormLimits(ValueLengthLimit = int.MaxValue, MultipartBodyLengthLimit = int.MaxValue)]
[Route("far")]
public SingleResponseModel<bool> UploadFar([FromForm] IFormFile file)
{
    return _fileUploadService.UploadFar(file);
}

Answer 3

我已经解决了我的问题。原来那是我使用的URL。

要解决我的问题，我意识到我发送给http端点而不是https端点，从而导致重定向。我将网址从http://localhost:5000/更改为https://localhost:5001/，一切立即开始起作用。

有趣的是，这也导致cURL出现问题，日志如下所示：

== Info: Connected to localhost (::1) port 5000 (#0)
=> Send header, 257 bytes (0x101)
0000: POST /api/v0.1/data/excel HTTP/1.1
0024: Host: localhost:5000
003a: User-Agent: curl/7.64.0
0053: Accept: */*
0060: cache-control: no-cache
0079: Content-Length: 13286446
0093: Content-Type: multipart/form-data; boundary=--------------------
00d3: ----7b12fc7773ed7878
00e9: Expect: 100-continue
00ff: 
== Info: Expire in 1000 ms for 0 (transfer 0xa6aa80)
<= Recv header, 33 bytes (0x21)
0000: HTTP/1.1 307 Temporary Redirect
<= Recv header, 37 bytes (0x25)
0000: Date: Tue, 09 Apr 2019 18:04:24 GMT
<= Recv header, 17 bytes (0x11)
0000: Server: Kestrel
<= Recv header, 19 bytes (0x13)
0000: Content-Length: 0
<= Recv header, 54 bytes (0x36)
0000: Location: https://localhost:5001/api/v0.1/data/excel
== Info: HTTP error before end of send, stop sending
<= Recv header, 2 bytes (0x2)
0000: 
== Info: Closing connection 0

更改端点也可以解决此问题。

不知道为什么multipart/form-data的上传由于该重定向而中断。如果有人对为什么有任何想法，我将很高兴学习。

Answer 4

我使用的是 asp.net core 3.1，我也遇到了这种情况。

当我将一个大文件传递给 api 时，它总是会导致 System.IO.InvalidDataException: Multipart body length limit 16384 exceeded.

现在，我找到了这个问题并阅读了@Sylex 的回答，所以我使用 https://localhost:5001 来请求 api，它有效！！！

知道发生了重定向，于是我去掉了app.UseHttpsRedirection();中的Startup.cs -> void Configure()，重新使用了http://localhost:5000/，现在可以正常请求了。

InvalidDataException：多部分主体长度限制超过16384

4 个答案: