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Make GetFinalTransferCoding "safe" #21202

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Merged
merged 2 commits into from
Apr 28, 2020
Merged

Make GetFinalTransferCoding "safe" #21202

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Make GetFinalTransferCoding "safe"
benaadams Apr 25, 2020
650f7d9
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benaadams Apr 28, 2020
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141 changes: 105 additions & 36 deletions src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,12 @@
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Buffers.Binary;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Intrinsics.X86;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
Expand Down Expand Up @@ -377,70 +379,137 @@ public static unsafe ConnectionOptions ParseConnection(StringValues connection)
return connectionOptions;
}

public static unsafe TransferCoding GetFinalTransferCoding(StringValues transferEncoding)
private static char ToLowerCase(char value) => (char)(value | (char)0x0020);

public static TransferCoding GetFinalTransferCoding(StringValues transferEncoding)
{
const ulong chunkedStart = 0x006b_006e_0075_0068; // 4 chars "hunk"
const uint chunkedEnd = 0x0064_0065; // 2 chars "ed"

var transferEncodingOptions = TransferCoding.None;

var transferEncodingCount = transferEncoding.Count;
for (var i = 0; i < transferEncodingCount; i++)
{
var value = transferEncoding[i];
fixed (char* ptr = value)
{
var ch = ptr;
var tokenEnd = ch;
var end = ch + value.Length;
var values = transferEncoding[i].AsSpan();

while (ch < end)
while (values.Length > 0)
{
int offset;
char c = '\0';
// Skip any spaces and empty values.
for (offset = 0; offset < values.Length; offset++)
{
while (tokenEnd < end && *tokenEnd != ',')
c = values[offset];
if (c != ' ' && c != ',')
{
tokenEnd++;
break;
}
}

while (ch < tokenEnd && *ch == ' ')
// Skip last read char.
offset++;
if ((uint)offset > (uint)values.Length)
{
// Consumed entire string, move to next.
break;
}

// Remove leading spaces or empty values.
values = values.Slice(offset);
offset = 0;

var byteValue = MemoryMarshal.AsBytes(values);

if (ToLowerCase(c) == 'c' &&
TryReadLowerCaseUInt64(byteValue, out var result64) && result64 == chunkedStart)
{
offset += sizeof(ulong) / 2;
byteValue = byteValue.Slice(sizeof(ulong));

if (TryReadLowerCaseUInt32(byteValue, out var result32) && result32 == chunkedEnd)
{
ch++;
offset += sizeof(uint) / 2;
transferEncodingOptions = TransferCoding.Chunked;
}
}

var tokenLength = tokenEnd - ch;
if ((uint)offset >= (uint)values.Length)
{
// Consumed entire string, move to next string.
break;
}
else
{
values = values.Slice(offset);
}

if (tokenLength >= 7 && (*ch | 0x20) == 'c')
for (offset = 0; offset < values.Length; offset++)
{
c = values[offset];
if (c == ',')
{
if ((*++ch | 0x20) == 'h' &&
(*++ch | 0x20) == 'u' &&
(*++ch | 0x20) == 'n' &&
(*++ch | 0x20) == 'k' &&
(*++ch | 0x20) == 'e' &&
(*++ch | 0x20) == 'd')
{
ch++;
while (ch < tokenEnd && *ch == ' ')
{
ch++;
}

if (ch == tokenEnd)
{
transferEncodingOptions = TransferCoding.Chunked;
}
}
break;
}

if (tokenLength > 0 && ch != tokenEnd)
else if (c != ' ')
{
// Value contains extra chars; Chunked is not the matched one.
transferEncodingOptions = TransferCoding.Other;
}
}

tokenEnd++;
ch = tokenEnd;
if ((uint)offset >= (uint)values.Length)
{
// Consumed entire string, move to next string.
break;
}
else if (c == ',')
{
// Consumed value, move to next value.
offset++;
if ((uint)offset >= (uint)values.Length)
{
// Consumed entire string, move to next string.
break;
}
else
{
values = values.Slice(offset);
continue;
}
}
}
}

return transferEncodingOptions;
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool TryReadLowerCaseUInt64(ReadOnlySpan<byte> byteValue, out ulong value)
{
if (BinaryPrimitives.TryReadUInt64LittleEndian(byteValue, out var result))
{
value = result | 0x0020_0020_0020_0020;
return true;
}

value = 0;
return false;
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool TryReadLowerCaseUInt32(ReadOnlySpan<byte> byteValue, out uint value)
{
if (BinaryPrimitives.TryReadUInt32LittleEndian(byteValue, out var result))
{
value = result | 0x0020_0020;
return true;
}

value = 0;
return false;
}

private static void ThrowInvalidContentLengthException(long value)
{
throw new ArgumentOutOfRangeException(CoreStrings.FormatInvalidContentLength_InvalidNumber(value));
Expand Down