Fix HTTP3 header decoder buffer allocation

src/libraries/Common/src/System/Net/Http/aspnetcore/Http3/QPack/QPackDecoder.cs

@@ -243,12 +243,11 @@ private void DecodeInternal(ReadOnlySpan<byte> data, IHttpStreamHeadersHandler h
  // will no longer be valid.
  if (_headerNameRange != null)
  {
- EnsureStringCapacity(ref _headerNameOctets, _stringLength, existingLength: 0);
+ EnsureStringCapacity(ref _headerNameOctets, _headerNameLength, existingLength: 0);
  _headerName = _headerNameOctets;
 
  ReadOnlySpan<byte> headerBytes = data.Slice(_headerNameRange.GetValueOrDefault().start, _headerNameRange.GetValueOrDefault().length);
  headerBytes.CopyTo(_headerName);
- _headerNameLength = headerBytes.Length;
  _headerNameRange = null;
  }
  }
@@ -294,6 +293,7 @@ private void ParseHeaderName(ReadOnlySpan<byte> data, ref int currentIndex, IHtt
  {
  // Fast path. Store the range rather than copying.
  _headerNameRange = (start: currentIndex, count);
+ _headerNameLength = _stringLength;
  currentIndex += count;
 
  _state = State.HeaderValueLength;

src/libraries/System.Net.Http/tests/UnitTests/QPack/QPackDecoderTest.cs

@@ -0,0 +1,116 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Linq;
+using System.Net.Http.QPack;
+using System.Net.Http.Unit.Tests.HPack;
+using System.Text;
+
+using Xunit;
+
+namespace System.Net.Http.Unit.Tests.QPack
+{
+ public class QPackDecoderTest
+ {
+ private const int MaxHeaderFieldSize = 8190;
+
+ // 4.5.6 - Literal Field Without Name Reference - (literal-header-field)
+ private static readonly byte[] _literalFieldWithoutNameReference = new byte[] { 0x37, 0x0d, 0x6c, 0x69, 0x74, 0x65, 0x72, 0x61, 0x6c, 0x2d, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x2d, 0x66, 0x69, 0x65, 0x6c, 0x64 };
+
+ private const string _headerNameString = "literal-header-field"; // 20 bytes
+ private const string _headerValueString = "should-not-break"; // 16 bytes
+
+ private static readonly byte[] _headerValueBytes = Encoding.ASCII.GetBytes(_headerValueString);
+
+ private static readonly byte[] _headerValue = new byte[] { (byte)_headerValueBytes.Length }
+ .Concat(_headerValueBytes)
+ .ToArray();
+
+ // The key take away here is that the header name length should be
+ // at least 2^n + 1 and the header value length less than or equal to 2^n.
+ // This is due to how System.Buffer buckets the arrays to be used by the decoder.
+ private static readonly byte[] _encodedLiteralField = _literalFieldWithoutNameReference
+ .Concat(_headerValue)
+ .ToArray();
+
+ private readonly QPackDecoder _decoder;
+ private readonly TestHttpHeadersHandler _handler = new TestHttpHeadersHandler();
+
+ public QPackDecoderTest()
+ {
+ _decoder = new QPackDecoder(MaxHeaderFieldSize);
+ }
+
+ [Fact]
+ public void LiteralFieldWithoutNameReferece_SingleBuffer()
+ {
+ _decoder.Decode(new byte[] { 0, 0 }, endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField, endHeaders: true, handler: _handler);
+
+ Assert.Equal(1, _handler.DecodedHeaders.Count);
+ Assert.Equal(_headerNameString, _handler.DecodedHeaders.Keys.First());
+ Assert.Equal(_headerValueString, _handler.DecodedHeaders.Values.First());
+ }
+
+ [Fact]
+ public void LiteralFieldWithoutNameReferece_NameLengthBrokenIntoSeparateBuffers()
+ {
+ _decoder.Decode(new byte[] { 0, 0 }, endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[..1], endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[1..], endHeaders: true, handler: _handler);
+
+ Assert.Equal(1, _handler.DecodedHeaders.Count);
+ Assert.Equal(_headerNameString, _handler.DecodedHeaders.Keys.First());
+ Assert.Equal(_headerValueString, _handler.DecodedHeaders.Values.First());
+ }
+
+ [Fact]
+ public void LiteralFieldWithoutNameReferece_NameBrokenIntoSeparateBuffers()
+ {
+ _decoder.Decode(new byte[] { 0, 0 }, endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[..(_headerNameString.Length / 2)], endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[(_headerNameString.Length / 2)..], endHeaders: true, handler: _handler);
+
+ Assert.Equal(1, _handler.DecodedHeaders.Count);
+ Assert.Equal(_headerNameString, _handler.DecodedHeaders.Keys.First());
+ Assert.Equal(_headerValueString, _handler.DecodedHeaders.Values.First());
+ }
+
+ [Fact]
+ public void LiteralFieldWithoutNameReferece_NameAndValueBrokenIntoSeparateBuffers()
+ {
+ _decoder.Decode(new byte[] { 0, 0 }, endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[..^_headerValue.Length], endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[^_headerValue.Length..], endHeaders: true, handler: _handler);
+
+ Assert.Equal(1, _handler.DecodedHeaders.Count);
+ Assert.Equal(_headerNameString, _handler.DecodedHeaders.Keys.First());
+ Assert.Equal(_headerValueString, _handler.DecodedHeaders.Values.First());
+ }
+
+ [Fact]
+ // Ideally should be ran with a value length of or bigger than 2 bytes
+ public void LiteralFieldWithoutNameReferece_ValueLengthBrokenIntoSeparateBuffers()
+ {
+ _decoder.Decode(new byte[] { 0, 0 }, endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[..^(_headerValue.Length - 1)], endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[^(_headerValue.Length - 1)..], endHeaders: true, handler: _handler);
+
+ Assert.Equal(1, _handler.DecodedHeaders.Count);
+ Assert.Equal(_headerNameString, _handler.DecodedHeaders.Keys.First());
+ Assert.Equal(_headerValueString, _handler.DecodedHeaders.Values.First());
+ }
+
+ [Fact]
+ public void LiteralFieldWithoutNameReferece_ValueBrokenIntoSeparateBuffers()
+ {
+ _decoder.Decode(new byte[] { 0, 0 }, endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[..^(_headerValueString.Length / 2)], endHeaders: false, handler: _handler);
+ _decoder.Decode(_encodedLiteralField[^(_headerValueString.Length / 2)..], endHeaders: true, handler: _handler);
+
+ Assert.Equal(1, _handler.DecodedHeaders.Count);
+ Assert.Equal(_headerNameString, _handler.DecodedHeaders.Keys.First());
+ Assert.Equal(_headerValueString, _handler.DecodedHeaders.Values.First());
+ }
+ }
+}

src/libraries/System.Net.Http/tests/UnitTests/System.Net.Http.Unit.Tests.csproj

@@ -325,6 +325,7 @@
  <Compile Include="HttpContentTest.cs" />
  <Compile Include="HttpRuleParserTest.cs" />
  <Compile Include="MockContent.cs" />
+ <Compile Include="QPack\QPackDecoderTest.cs" />
  <Compile Include="RuntimeSettingParserTest.cs" />
  <Compile Include="StreamToStreamCopyTest.cs" />
  <Compile Include="HttpEnvironmentProxyTest.cs" />
@@ -393,8 +394,12 @@
  Link="Common\System\Net\Http\aspnetcore\Http3\QPack\HeaderField.cs" />
  <Compile Include="$(CommonPath)System\Net\Http\aspnetcore\Http3\QPack\QPackEncoder.cs"
  Link="Common\System\Net\Http\aspnetcore\Http3\QPack\QPackEncoder.cs" />
+ <Compile Include="$(CommonPath)System\Net\Http\aspnetcore\Http3\QPack\QPackDecoder.cs"
+ Link="Common\System\Net\Http\aspnetcore\Http3\QPack\QPackDecoder.cs" />
  <Compile Include="$(CommonPath)System\Net\Http\aspnetcore\Http3\QPack\QPackEncodingException.cs"
  Link="Common\System\Net\Http\aspnetcore\Http3\QPack\QPackEncodingException.cs" />
+ <Compile Include="$(CommonPath)System\Net\Http\aspnetcore\Http3\QPack\QPackDecodingException.cs"
+ Link="Common\System\Net\Http\aspnetcore\Http3\QPack\QPackDecodingException.cs" />
  <Compile Include="$(CommonPath)System\Text\ValueStringBuilder.cs"
  Link="Common\System\Text\ValueStringBuilder.cs" />
  <Compile Include="$(CommonPath)System\Text\ValueStringBuilder.AppendSpanFormattable.cs"