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Merged
MihaZupan merged 3 commits into from
Mar 16, 2026
Merged

Sync shared HPack/QPack changes from aspnetcore #125526

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e536cc6
Initial plan
Copilot Mar 13, 2026
4fc70e6
Apply HPack/QPack Huffman decoded header length check fix from workfl…
Copilot Mar 13, 2026
2b12054
Merge branch 'main' into copilot/apply-auth-issues-fix
MihaZupan Mar 16, 2026
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8 changes: 7 additions & 1 deletion src/libraries/Common/src/System/Net/Http/aspnetcore/Http2/Hpack/HPackDecoder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -596,10 +596,16 @@ int Decode(ref byte[] dst)
{
if (_huffman)
{
return Huffman.Decode(new ReadOnlySpan<byte>(_stringOctets, 0, _stringLength), ref dst);
int decodedLength = Huffman.Decode(new ReadOnlySpan<byte>(_stringOctets, 0, _stringLength), ref dst);
if (decodedLength > _maxHeadersLength)
{
throw new HPackDecodingException(SR.Format(SR.net_http_headers_exceeded_length, _maxHeadersLength));
}
return decodedLength;
}
else
{
Debug.Assert(_stringLength <= _maxHeadersLength, "String length should have been checked prior to decode.");
EnsureStringCapacity(ref dst);
Buffer.BlockCopy(_stringOctets, 0, dst, 0, _stringLength);
return _stringLength;
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8 changes: 7 additions & 1 deletion src/libraries/Common/src/System/Net/Http/aspnetcore/Http3/QPack/QPackDecoder.cs
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Expand Up @@ -634,10 +634,16 @@ int Decode(ref byte[]? dst)

if (_huffman)
{
return Huffman.Decode(new ReadOnlySpan<byte>(_stringOctets, 0, _stringLength), ref dst);
int decodedLength = Huffman.Decode(new ReadOnlySpan<byte>(_stringOctets, 0, _stringLength), ref dst);
if (decodedLength > _maxHeadersLength)
{
throw new QPackDecodingException(SR.Format(SR.net_http_headers_exceeded_length, _maxHeadersLength));
}
return decodedLength;
}
else
{
Debug.Assert(_stringLength <= _maxHeadersLength, "String length should have been checked prior to decode.");
Buffer.BlockCopy(_stringOctets, 0, dst, 0, _stringLength);
return _stringLength;
}
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39 changes: 39 additions & 0 deletions src/libraries/Common/tests/Tests/System/Net/aspnetcore/Http2/HPackDecoderTest.cs
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Expand Up @@ -678,6 +678,45 @@ public void DecodesStringLength_GreaterThanLimit_Error()
Assert.Empty(_handler.DecodedHeaders);
}

[Fact]
public void HuffmanDecodedHeaderName_ExceedsLimitAfterDecoding_Throws()
{
// '0' (ASCII 48) has a 5-bit Huffman code (00000).
// 16 '0' characters = 80 Huffman bits = 10 encoded bytes, but decodes to 16 bytes.
// Encoded length (10) passes the pre-decode check (<= 10), but decoded length (16) exceeds the limit.
HPackDecoder decoder = new HPackDecoder(DynamicTableInitialMaxSize, maxHeadersLength: 10);

byte[] encoded = [
0x00, // Literal header field without indexing, new name
0x8a, // Huffman flag set (0x80) + string length 10 (7-bit prefix)
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 10 bytes Huffman -> 16 '0' chars
0x01, // String length = 1 (no Huffman)
0x61 // Value = "a"
];

HPackDecodingException exception = Assert.Throws<HPackDecodingException>(() => decoder.Decode(encoded, endHeaders: true, handler: _handler));
Assert.Equal(SR.Format(SR.net_http_headers_exceeded_length, 10), exception.Message);
Assert.Empty(_handler.DecodedHeaders);
}

[Fact]
public void HuffmanDecodedHeaderValue_ExceedsLimitAfterDecoding_Throws()
{
HPackDecoder decoder = new HPackDecoder(DynamicTableInitialMaxSize, maxHeadersLength: 10);

byte[] encoded = [
0x00, // Literal header field without indexing, new name
0x01, // String length = 1 (no Huffman)
0x61, // Name = "a"
0x8a, // Huffman flag set (0x80) + string length 10 (7-bit prefix)
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 // 10 bytes Huffman -> 16 '0' chars
];

HPackDecodingException exception = Assert.Throws<HPackDecodingException>(() => decoder.Decode(encoded, endHeaders: true, handler: _handler));
Assert.Equal(SR.Format(SR.net_http_headers_exceeded_length, 10), exception.Message);
Assert.Empty(_handler.DecodedHeaders);
}

[Fact]
public void DecodesStringLength_LimitConfigurable()
{
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43 changes: 43 additions & 0 deletions src/libraries/Common/tests/Tests/System/Net/aspnetcore/Http3/QPackDecoderTest.cs
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Expand Up @@ -273,6 +273,49 @@ public void LiteralFieldWithoutNameReference_ValueBrokenIntoSeparateBuffers()
Assert.Equal(_headerValueString, _handler.DecodedHeaders[_literalHeaderFieldString]);
}

[Fact]
public void HuffmanDecodedHeaderName_ExceedsLimitAfterDecoding_Throws()
{
// '0' (ASCII 48) has a 5-bit Huffman code (00000).
// 16 '0' characters = 80 Huffman bits = 10 encoded bytes, but decodes to 16 bytes.
// Encoded length (10) passes the pre-decode check (<= 10), but decoded length (16) exceeds the limit.
using QPackDecoder decoder = new QPackDecoder(maxHeadersLength: 10);
TestHttpHeadersHandler handler = new TestHttpHeadersHandler();

byte[] encoded = new byte[]
{
0x00, 0x00, // Required insert count (0) and base (0)
0x2f, 0x03, // Literal field with literal name: N=0, H=1, name length = 10 (3-bit prefix: 7 + 3)
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 10 bytes Huffman -> 16 '0' chars
0x01, // Value length = 1 (no Huffman)
0x61 // Value = "a"
};

QPackDecodingException exception = Assert.Throws<QPackDecodingException>(() => decoder.Decode(encoded, endHeaders: true, handler: handler));
Assert.Equal(SR.Format(SR.net_http_headers_exceeded_length, 10), exception.Message);
Assert.Empty(handler.DecodedHeaders);
}

[Fact]
public void HuffmanDecodedHeaderValue_ExceedsLimitAfterDecoding_Throws()
{
using QPackDecoder decoder = new QPackDecoder(maxHeadersLength: 10);
TestHttpHeadersHandler handler = new TestHttpHeadersHandler();

byte[] encoded = new byte[]
{
0x00, 0x00, // Required insert count (0) and base (0)
0x21, // Literal field with literal name: N=0, H=0, name length = 1 (3-bit prefix)
0x61, // Name = "a"
0x8a, // Huffman flag set (0x80) + value length 10 (7-bit prefix)
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 // 10 bytes Huffman -> 16 '0' chars
};

QPackDecodingException exception = Assert.Throws<QPackDecodingException>(() => decoder.Decode(encoded, endHeaders: true, handler: handler));
Assert.Equal(SR.Format(SR.net_http_headers_exceeded_length, 10), exception.Message);
Assert.Empty(handler.DecodedHeaders);
}

public static readonly TheoryData<byte[]> _incompleteHeaderBlockData = new TheoryData<byte[]>
{
// Incomplete header
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