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Sep 11, 2020
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Improve Http1ContentLengthMessageBody's reset logic #25799

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91 changes: 69 additions & 22 deletions src/Servers/Kestrel/Core/src/Internal/Http/Http1ContentLengthMessageBody.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,16 @@
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Diagnostics;
using System.IO.Pipelines;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Connections;

namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
{
using BadHttpRequestException = Microsoft.AspNetCore.Http.BadHttpRequestException;

internal sealed class Http1ContentLengthMessageBody : Http1MessageBody
{
private ReadResult _readResult;
Expand All @@ -18,6 +21,7 @@ internal sealed class Http1ContentLengthMessageBody : Http1MessageBody
private bool _isReading;
private int _userCanceled;
private bool _finalAdvanceCalled;
private bool _cannotResetInputPipe;

public Http1ContentLengthMessageBody(bool keepAlive, long contentLength, Http1Connection context)
: base(context)
Expand All @@ -35,15 +39,19 @@ public override ValueTask<ReadResult> ReadAsync(CancellationToken cancellationTo

public override async ValueTask<ReadResult> ReadAsyncInternal(CancellationToken cancellationToken = default)
{
if (_isReading)
{
throw new InvalidOperationException("Reading is already in progress.");
}
VerifyIsNotReading();

if (_readCompleted)
{
_isReading = true;
return new ReadResult(_readResult.Buffer, Interlocked.Exchange(ref _userCanceled, 0) == 1, _readResult.IsCompleted);
return new ReadResult(_readResult.Buffer, Interlocked.Exchange(ref _userCanceled, 0) == 1, isCompleted: true);
}

// The issue is that TryRead can get a canceled read result
// which is unknown to StartTimingReadAsync.
if (_context.RequestTimedOut)
{
KestrelBadHttpRequestException.Throw(RequestRejectionReason.RequestBodyTimeout);
}

TryStart();
Expand All @@ -54,12 +62,6 @@ public override async ValueTask<ReadResult> ReadAsyncInternal(CancellationToken
// We internally track an int for that.
while (true)
{
// The issue is that TryRead can get a canceled read result
// which is unknown to StartTimingReadAsync.
if (_context.RequestTimedOut)
{
KestrelBadHttpRequestException.Throw(RequestRejectionReason.RequestBodyTimeout);
}

try
{
Expand All @@ -76,10 +78,14 @@ public override async ValueTask<ReadResult> ReadAsyncInternal(CancellationToken

void ResetReadingState()
{
_isReading = false;
// Reset the timing read here for the next call to read.
StopTimingRead(0);
_context.Input.AdvanceTo(_readResult.Buffer.Start);

if (!_cannotResetInputPipe)
{
_isReading = false;
_context.Input.AdvanceTo(_readResult.Buffer.Start);
}
}

if (_context.RequestTimedOut)
Expand All @@ -95,7 +101,10 @@ void ResetReadingState()
}

// Ignore the canceled readResult if it wasn't canceled by the user.
if (!_readResult.IsCanceled || Interlocked.Exchange(ref _userCanceled, 0) == 1)
// Normally we do not return a canceled ReadResult unless CancelPendingRead was called on the request body PipeReader itself,
// but if the last call to AdvanceTo examined data it did not consume, we cannot reset the state of the Input pipe.
// https://github.com/dotnet/aspnetcore/issues/19476
if (!_readResult.IsCanceled || Interlocked.Exchange(ref _userCanceled, 0) == 1 || _cannotResetInputPipe)
{
var returnedReadResultLength = CreateReadResultFromConnectionReadResult();

Expand Down Expand Up @@ -124,18 +133,20 @@ public override bool TryRead(out ReadResult readResult)

public override bool TryReadInternal(out ReadResult readResult)
{
if (_isReading)
{
throw new InvalidOperationException("Reading is already in progress.");
}
VerifyIsNotReading();

if (_readCompleted)
{
_isReading = true;
readResult = new ReadResult(_readResult.Buffer, Interlocked.Exchange(ref _userCanceled, 0) == 1, _readResult.IsCompleted);
readResult = new ReadResult(_readResult.Buffer, Interlocked.Exchange(ref _userCanceled, 0) == 1, isCompleted: true);
return true;
}

if (_context.RequestTimedOut)
{
KestrelBadHttpRequestException.Throw(RequestRejectionReason.RequestBodyTimeout);
}

TryStart();

// The while(true) because we don't want to return a canceled ReadResult if the user themselves didn't cancel it.
Expand All @@ -147,7 +158,7 @@ public override bool TryReadInternal(out ReadResult readResult)
return false;
}

if (!_readResult.IsCanceled || Interlocked.Exchange(ref _userCanceled, 0) == 1)
if (!_readResult.IsCanceled || Interlocked.Exchange(ref _userCanceled, 0) == 1 || _cannotResetInputPipe)
{
break;
}
Expand All @@ -157,7 +168,15 @@ public override bool TryReadInternal(out ReadResult readResult)

if (_readResult.IsCompleted)
{
_context.Input.AdvanceTo(_readResult.Buffer.Start);
if (_cannotResetInputPipe)
{
_isReading = true;
}
else
{
_context.Input.AdvanceTo(_readResult.Buffer.Start);
}

ThrowUnexpectedEndOfRequestContent();
}

Expand Down Expand Up @@ -214,7 +233,7 @@ public override void AdvanceTo(SequencePosition consumed, SequencePosition exami
if (_readCompleted)
{
// If the old stored _readResult was canceled, it's already been observed. Do not store a canceled read result permanently.
_readResult = new ReadResult(_readResult.Buffer.Slice(consumed, _readResult.Buffer.End), isCanceled: false, _readCompleted);
_readResult = new ReadResult(_readResult.Buffer.Slice(consumed, _readResult.Buffer.End), isCanceled: false, isCompleted: true);

if (!_finalAdvanceCalled && _readResult.Buffer.Length == 0)
{
Expand All @@ -226,6 +245,10 @@ public override void AdvanceTo(SequencePosition consumed, SequencePosition exami
return;
}

// If consumed != examined, we cannot reset _context.Input back to a non-reading state after the next call to ReadAsync
// simply by calling _context.Input.AdvanceTo(_readResult.Buffer.Start) because the DefaultPipeReader will complain that
// "The examined position cannot be less than the previously examined position."
_cannotResetInputPipe = !consumed.Equals(examined);
_unexaminedInputLength -= TrackConsumedAndExaminedBytes(_readResult, consumed, examined);
_context.Input.AdvanceTo(consumed, examined);
}
Expand Down Expand Up @@ -255,5 +278,29 @@ protected override Task OnStopAsync()
Complete(null);
return Task.CompletedTask;
}

[StackTraceHidden]
private void VerifyIsNotReading()
{
if (!_isReading)
{
return;
}

if (_cannotResetInputPipe)
{
if (_readResult.IsCompleted)
{
KestrelBadHttpRequestException.Throw(RequestRejectionReason.UnexpectedEndOfRequestContent);
}

if (_context.RequestTimedOut)
{
KestrelBadHttpRequestException.Throw(RequestRejectionReason.RequestBodyTimeout);
}
}

throw new InvalidOperationException("Reading is already in progress.");
}
}
}
2 changes: 1 addition & 1 deletion src/Servers/Kestrel/Core/src/Internal/Http/Http1MessageBody.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -89,7 +89,7 @@ protected async Task OnConsumeAsyncAwaited()
AdvanceTo(result.Buffer.End);
} while (!result.IsCompleted);
}
catch (Microsoft.AspNetCore.Http.BadHttpRequestException ex)
catch (BadHttpRequestException ex)
{
_context.SetBadRequestState(ex);
}
Expand Down
33 changes: 33 additions & 0 deletions src/Servers/Kestrel/Core/test/MessageBodyTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1226,6 +1226,39 @@ public async Task UnexpectedEndOfRequestContentIsRepeatedlyThrownForContentLengt

input.Application.Output.Complete();

#pragma warning disable CS0618 // Type or member is obsolete
var ex0 = Assert.Throws<BadHttpRequestException>(() => reader.TryRead(out var readResult));
var ex1 = Assert.Throws<BadHttpRequestException>(() => reader.TryRead(out var readResult));
var ex2 = await Assert.ThrowsAsync<BadHttpRequestException>(() => reader.ReadAsync().AsTask());
var ex3 = await Assert.ThrowsAsync<BadHttpRequestException>(() => reader.ReadAsync().AsTask());
#pragma warning restore CS0618 // Type or member is obsolete

Assert.Equal(RequestRejectionReason.UnexpectedEndOfRequestContent, ex0.Reason);
Assert.Equal(RequestRejectionReason.UnexpectedEndOfRequestContent, ex1.Reason);
Assert.Equal(RequestRejectionReason.UnexpectedEndOfRequestContent, ex2.Reason);
Assert.Equal(RequestRejectionReason.UnexpectedEndOfRequestContent, ex3.Reason);

await body.StopAsync();
}
}

[Fact]
public async Task UnexpectedEndOfRequestContentIsRepeatedlyThrownForContentLengthBodyAfterExaminingButNotConsumingBytes()
{
using (var input = new TestInput())
{
var body = Http1MessageBody.For(HttpVersion.Http11, new HttpRequestHeaders { HeaderContentLength = "5" }, input.Http1Connection);
var reader = new HttpRequestPipeReader();
reader.StartAcceptingReads(body);

await input.Application.Output.WriteAsync(new byte[] { 0 });

var readResult = await reader.ReadAsync();

reader.AdvanceTo(readResult.Buffer.Start, readResult.Buffer.End);

input.Application.Output.Complete();

#pragma warning disable CS0618 // Type or member is obsolete
var ex0 = Assert.Throws<BadHttpRequestException>(() => reader.TryRead(out var readResult));
var ex1 = Assert.Throws<BadHttpRequestException>(() => reader.TryRead(out var readResult));
Expand Down