aspnetcore: Form key length limit 2048 exceeded.

After switching to preview 5、6, you often encounter the following error logs

2019-06-16 20:16:49.0768|1|ERROR|Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware|An unhandled exception has occurred while executing the request. System.IO.InvalidDataException: Form key length limit 2048 exceeded.
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ThrowKeyTooLargeException()
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseValuesSlow(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseFormValues(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ReadFormAsync(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.Controllers.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.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
2019-06-16 20:16:49.0768|1|ERROR|Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware|An unhandled exception has occurred while executing the request. System.IO.InvalidDataException: Form key length limit 2048 exceeded.
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ThrowKeyTooLargeException()
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseValuesSlow(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseFormValues(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ReadFormAsync(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.Controllers.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.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
2019-06-16 20:16:49.1097|3|ERROR|Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware|An exception was thrown attempting to execute the error handler. System.IO.InvalidDataException: Form key length limit 2048 exceeded.
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ThrowKeyTooLargeException()
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseValuesSlow(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseFormValues(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ReadFormAsync(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.Controllers.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.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.HandleException(HttpContext context, ExceptionDispatchInfo edi)
2019-06-16 20:16:49.1097|3|ERROR|Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware|An exception was thrown attempting to execute the error handler. System.IO.InvalidDataException: Form key length limit 2048 exceeded.
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ThrowKeyTooLargeException()
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseValuesSlow(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseFormValues(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ReadFormAsync(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.Controllers.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.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.HandleException(HttpContext context, ExceptionDispatchInfo edi)
2019-06-16 20:16:49.1097|13|ERROR|Microsoft.AspNetCore.Server.Kestrel|Connection id "0HLNIA5KOJDT0", Request id "0HLNIA5KOJDT0:00000ACE": An unhandled exception was thrown by the application. System.IO.InvalidDataException: Form key length limit 2048 exceeded.
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ThrowKeyTooLargeException()
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseValuesSlow(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseFormValues(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ReadFormAsync(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.Controllers.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.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.HandleException(HttpContext context, ExceptionDispatchInfo edi)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
   at Microsoft.AspNetCore.Server.IISIntegration.IISMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)
2019-06-16 20:16:49.1097|13|ERROR|Microsoft.AspNetCore.Server.Kestrel|Connection id "0HLNIA5KOJDT0", Request id "0HLNIA5KOJDT0:00000ACE": An unhandled exception was thrown by the application. System.IO.InvalidDataException: Form key length limit 2048 exceeded.
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ThrowKeyTooLargeException()
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseValuesSlow(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ParseFormValues(ReadOnlySequence`1& buffer, KeyValueAccumulator& accumulator, Boolean isFinalBlock)
   at Microsoft.AspNetCore.WebUtilities.FormPipeReader.ReadFormAsync(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.Controllers.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.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.HandleException(HttpContext context, ExceptionDispatchInfo edi)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
   at Microsoft.AspNetCore.Server.IISIntegration.IISMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

Tracking access logs found that the parameters of the web API requested by the client were normal and did not exceed the limit. Strangely, from 2.2, the code of the interface did not change, just upgraded to preview 5, and from that day on, there were constant error logs, sometimes several minutes, sometimes dozens of minutes, I am sure. Not when the user requests that the limit is exceeded.

The accepted parameter is an entity class, which is received through the [FromForm] form and works well, but requests are rejected from time to time.

I’m looking forward to Preview 6 solving this problem. The result is the same. It’s been going on for more than ten days. It’s strange.

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 42 (26 by maintainers)

Most upvoted comments

@tobiasbunyan see https://github.com/aspnet/AspNetCore/issues/13719 and lower your value length limit.

Tratcher on Sep 6, 2019

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Extensions.Options;
using Microsoft.Net.Http.Headers;

namespace WebApplication306
{
    /// <summary>
    /// Workaround for parsing issue https://github.com/aspnet/AspNetCore/issues/11262
    /// </summary>
    public class FormWorkaroundMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly FormOptions _formOptions;

        public FormWorkaroundMiddleware(RequestDelegate next, IOptions<FormOptions> options)
        {
            _next = next;
            _formOptions = options.Value;
        }

        public async Task Invoke(HttpContext httpContext)
        {
            if (httpContext.Request.HasFormContentType)
            {
                var previousFormFeature = httpContext.Features.Get<IFormFeature>();
                httpContext.Features.Set<IFormFeature>(new WorkaroundFormFeature(httpContext.Request, previousFormFeature, _formOptions));
            }

            await _next(httpContext);
        }

        private class WorkaroundFormFeature : IFormFeature
        {
            private readonly HttpRequest _request;
            private readonly IFormFeature _feature;
            private readonly FormOptions _options;

            public WorkaroundFormFeature(HttpRequest request, IFormFeature feature, FormOptions options)
            {
                _request = request;
                _feature = feature;
                _options = options;
            }

            private MediaTypeHeaderValue ContentType
            {
                get
                {
                    MediaTypeHeaderValue.TryParse(_request.ContentType, out MediaTypeHeaderValue mt);
                    return mt;
                }
            }

            private bool HasApplicationFormContentType =>
                ContentType?.MediaType.Equals("application/x-www-form-urlencoded", StringComparison.OrdinalIgnoreCase) == true;

            public bool HasFormContentType => _feature.HasFormContentType;

            public IFormCollection Form { get => _feature.Form; set => _feature.Form = value; }

            public IFormCollection ReadForm()
            {
                if (Form != null)
                {
                    return Form;
                }

                if (HasApplicationFormContentType)
                {
                    var encoding = FilterEncoding(ContentType.Encoding);
                    var formReader = new FormReader(_request.Body, encoding)
                    {
                        ValueCountLimit = _options.ValueCountLimit,
                        KeyLengthLimit = _options.KeyLengthLimit,
                        ValueLengthLimit = _options.ValueLengthLimit,
                    };
                    return Form = new FormCollection(formReader.ReadForm());
                }

                return _feature.ReadForm();
            }

            public async Task<IFormCollection> ReadFormAsync(CancellationToken cancellationToken)
            {
                if (Form != null)
                {
                    return Form;
                }

                if (HasApplicationFormContentType)
                {
                    var encoding = FilterEncoding(ContentType.Encoding);
                    var formReader = new FormReader(_request.Body, encoding)
                    {
                        ValueCountLimit = _options.ValueCountLimit,
                        KeyLengthLimit = _options.KeyLengthLimit,
                        ValueLengthLimit = _options.ValueLengthLimit,
                    };
                    return Form = new FormCollection(await formReader.ReadFormAsync());
                }
                return await _feature.ReadFormAsync(cancellationToken);
            }

            private Encoding FilterEncoding(Encoding encoding)
            {
                // UTF-7 is insecure and should not be honored. UTF-8 will succeed for most cases.
                if (encoding == null || Encoding.UTF7.Equals(encoding))
                {
                    return Encoding.UTF8;
                }
                return encoding;
            }
        }
    }

    // Extension method used to add the middleware to the HTTP request pipeline.
    public static class FormWorkaroundMiddlewareExtensions
    {
        public static IApplicationBuilder UseFormWorkaroundMiddleware(this IApplicationBuilder builder)
        {
            return builder.UseMiddleware<FormWorkaroundMiddleware>();
        }
    }
}

davidfowl on Jul 14, 2019

I can reproduce the issue.

davidfowl on Jul 12, 2019

Reply.txt

The text is too long. I go to txt.

sln162 on Jun 26, 2019