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[Http] Remove some unsafe code and save a string allocation #31267

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Mar 30, 2021
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61 changes: 46 additions & 15 deletions src/Http/Headers/src/ContentDispositionHeaderValue.cs
Original file line number Diff line number Diff line change
Expand Up @@ -3,11 +3,13 @@

using System;
using System.Buffers;
using System.Buffers.Text;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Diagnostics.Contracts;
using System.Globalization;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using Microsoft.Extensions.Primitives;

Expand All @@ -30,6 +32,9 @@ public class ContentDispositionHeaderValue
private const string SizeString = "size";
private static readonly char[] QuestionMark = new char[] { '?' };
private static readonly char[] SingleQuote = new char[] { '\'' };
private static readonly char[] EscapeChars = new char[] { '\\', '"' };
private static ReadOnlySpan<byte> MimePrefix => new byte[] { (byte)'"', (byte)'=', (byte)'?', (byte)'u', (byte)'t', (byte)'f', (byte)'-', (byte)'8', (byte)'?', (byte)'B', (byte)'?' };
private static ReadOnlySpan<byte> MimeSuffix => new byte[] { (byte)'?', (byte)'=', (byte)'"' };

private static readonly HttpHeaderParser<ContentDispositionHeaderValue> Parser
= new GenericHeaderParser<ContentDispositionHeaderValue>(false, GetDispositionTypeLength);
Expand Down Expand Up @@ -466,8 +471,10 @@ private StringSegment EncodeAndQuoteMime(StringSegment input)

if (RequiresEncoding(result))
{
needsQuotes = true; // Encoded data must always be quoted, the equals signs are invalid in tokens
result = EncodeMime(result); // =?utf-8?B?asdfasdfaesdf?=
// EncodeMimeWithQuotes will Base64 encode any quotes in the input, and surround the payload in quotes
// so there is no need to add quotes
needsQuotes = false;
result = EncodeMimeWithQuotes(result); // "=?utf-8?B?asdfasdfaesdf?="
}
else if (!needsQuotes && HttpRuleParser.GetTokenLength(result, 0) != result.Length)
{
Expand All @@ -476,8 +483,11 @@ private StringSegment EncodeAndQuoteMime(StringSegment input)

if (needsQuotes)
{
// '\' and '"' must be escaped in a quoted string
result = result.ToString().Replace(@"\", @"\\").Replace(@"""", @"\""");
if (result.IndexOfAny(EscapeChars) != -1)
{
// '\' and '"' must be escaped in a quoted string
result = result.ToString().Replace(@"\", @"\\").Replace(@"""", @"\""");
}
// Re-add quotes "value"
result = string.Format(CultureInfo.InvariantCulture, "\"{0}\"", result);
}
Expand Down Expand Up @@ -531,20 +541,41 @@ private bool RequiresEncoding(StringSegment input)
return false;
}

// Encode using MIME encoding
private unsafe string EncodeMime(StringSegment input)
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int GetBase64Length(int inputLength)
{
fixed (char* chars = input.Buffer)
// Copied from https://github.com/dotnet/runtime/blob/82ca681cbac89d813a3ce397e0c665e6c051ed67/src/libraries/System.Private.CoreLib/src/System/Convert.cs#L2530
long outlen = ((long)inputLength) / 3 * 4; // the base length - we want integer division here.
outlen += ((inputLength % 3) != 0) ? 4 : 0; // at most 4 more chars for the remainder

if (outlen > int.MaxValue)
{
var byteCount = Encoding.UTF8.GetByteCount(chars + input.Offset, input.Length);
var buffer = new byte[byteCount];
fixed (byte* bytes = buffer)
{
Encoding.UTF8.GetBytes(chars + input.Offset, input.Length, bytes, byteCount);
}
var encodedName = Convert.ToBase64String(buffer);
return "=?utf-8?B?" + encodedName + "?=";
throw new OutOfMemoryException();
}

return (int)outlen;
}

// Encode using MIME encoding
// And adds surrounding quotes, Encoded data must always be quoted, the equals signs are invalid in tokens
private string EncodeMimeWithQuotes(StringSegment input)
{
var requiredLength = MimePrefix.Length +
GetBase64Length(Encoding.UTF8.GetByteCount(input.AsSpan())) +
MimeSuffix.Length;
Span<byte> buffer = requiredLength <= 256
? (stackalloc byte[256]).Slice(0, requiredLength)
: new byte[requiredLength];

MimePrefix.CopyTo(buffer);
var bufferContent = buffer.Slice(MimePrefix.Length);
var contentLength = Encoding.UTF8.GetBytes(input.AsSpan(), bufferContent);

Base64.EncodeToUtf8InPlace(bufferContent, contentLength, out var base64ContentLength);

MimeSuffix.CopyTo(bufferContent.Slice(base64ContentLength));

return Encoding.UTF8.GetString(buffer.Slice(0, MimePrefix.Length + base64ContentLength + MimeSuffix.Length));
}

// Attempt to decode MIME encoded strings
Expand Down
78 changes: 7 additions & 71 deletions src/Http/Headers/src/HeaderUtilities.cs
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,6 @@ namespace Microsoft.Net.Http.Headers
/// </summary>
public static class HeaderUtilities
{
private static readonly int _int64MaxStringLength = 19;
private static readonly int _qualityValueMaxCharCount = 10; // Little bit more permissive than RFC7231 5.3.1
private const string QualityName = "q";
internal const string BytesUnit = "bytes";
Expand Down Expand Up @@ -325,7 +324,7 @@ public static bool ContainsCacheDirective(StringValues cacheControlDirectives, s
return false;
}

private static unsafe bool TryParseNonNegativeInt64FromHeaderValue(int startIndex, string headerValue, out long result)
private static bool TryParseNonNegativeInt64FromHeaderValue(int startIndex, string headerValue, out long result)
{
// Trim leading whitespace
startIndex += HttpRuleParser.GetWhitespaceLength(headerValue, startIndex);
Expand Down Expand Up @@ -366,40 +365,15 @@ private static unsafe bool TryParseNonNegativeInt64FromHeaderValue(int startInde
/// result will be overwritten.
/// </param>
/// <returns><see langword="true" /> if parsing succeeded; otherwise, <see langword="false" />.</returns>
public static unsafe bool TryParseNonNegativeInt32(StringSegment value, out int result)
public static bool TryParseNonNegativeInt32(StringSegment value, out int result)
{
if (string.IsNullOrEmpty(value.Buffer) || value.Length == 0)
{
result = 0;
return false;
}

result = 0;
fixed (char* ptr = value.Buffer)
{
var ch = (ushort*)ptr + value.Offset;
var end = ch + value.Length;

ushort digit = 0;
while (ch < end && (digit = (ushort)(*ch - 0x30)) <= 9)
{
// Check for overflow
if ((result = result * 10 + digit) < 0)
{
result = 0;
return false;
}

ch++;
}

if (ch != end)
{
result = 0;
return false;
}
return true;
}
return int.TryParse(value.AsSpan(), NumberStyles.None, NumberFormatInfo.InvariantInfo, out result);
}

/// <summary>
Expand All @@ -417,40 +391,14 @@ public static unsafe bool TryParseNonNegativeInt32(StringSegment value, out int
/// originally supplied in result will be overwritten.
/// </param>
/// <returns><see langword="true" /> if parsing succeeded; otherwise, <see langword="false" />.</returns>
public static unsafe bool TryParseNonNegativeInt64(StringSegment value, out long result)
public static bool TryParseNonNegativeInt64(StringSegment value, out long result)
{
if (string.IsNullOrEmpty(value.Buffer) || value.Length == 0)
{
result = 0;
return false;
}

result = 0;
fixed (char* ptr = value.Buffer)
{
var ch = (ushort*)ptr + value.Offset;
var end = ch + value.Length;

ushort digit = 0;
while (ch < end && (digit = (ushort)(*ch - 0x30)) <= 9)
{
// Check for overflow
if ((result = result * 10 + digit) < 0)
{
result = 0;
return false;
}

ch++;
}

if (ch != end)
{
result = 0;
return false;
}
return true;
}
return long.TryParse(value.AsSpan(), NumberStyles.None, NumberFormatInfo.InvariantInfo, out result);
}

// Strict and fast RFC7231 5.3.1 Quality value parser (and without memory allocation)
Expand Down Expand Up @@ -553,7 +501,7 @@ internal static bool TryParseQualityDouble(StringSegment input, int startIndex,
/// <returns>
/// The string representation of the value of this instance, consisting of a sequence of digits ranging from 0 to 9 with no leading zeroes.
/// </returns>
public unsafe static string FormatNonNegativeInt64(long value)
public static string FormatNonNegativeInt64(long value)
{
if (value < 0)
{
Expand All @@ -565,19 +513,7 @@ public unsafe static string FormatNonNegativeInt64(long value)
return "0";
}

var position = _int64MaxStringLength;
char* charBuffer = stackalloc char[_int64MaxStringLength];

do
{
// Consider using Math.DivRem() if available
var quotient = value / 10;
charBuffer[--position] = (char)(0x30 + (value - quotient * 10)); // 0x30 = '0'
value = quotient;
}
while (value != 0);

return new string(charBuffer, position, _int64MaxStringLength - position);
return ((ulong)value).ToString(NumberFormatInfo.InvariantInfo);
}

/// <summary>
Expand Down
3 changes: 2 additions & 1 deletion src/Http/Headers/src/MediaTypeHeaderValue.cs
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
using System.Diagnostics.Contracts;
using System.Globalization;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.Extensions.Primitives;

Expand Down Expand Up @@ -645,7 +646,7 @@ private static int GetMediaTypeExpressionLength(StringSegment input, int startIn
}
else
{
mediaType = input.Substring(startIndex, typeLength) + ForwardSlashCharacter + input.Substring(current, subtypeLength);
mediaType = string.Concat(input.AsSpan().Slice(startIndex, typeLength), "/", input.AsSpan().Slice(current, subtypeLength));
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@BrennanConroy can you propose an API StringSegment.AsSpan(int start, int length) on dotnet/runtime

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}

return mediaTypeLength;
Expand Down
3 changes: 1 addition & 2 deletions src/Http/Headers/src/Microsoft.Net.Http.Headers.csproj
Original file line number Diff line number Diff line change
@@ -1,10 +1,9 @@
<Project Sdk="Microsoft.NET.Sdk">
<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<Description>HTTP header parser implementations.</Description>
<TargetFramework>$(DefaultNetCoreTargetFramework)</TargetFramework>
<IsAspNetCoreApp>true</IsAspNetCoreApp>
<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
<GenerateDocumentationFile>true</GenerateDocumentationFile>
<PackageTags>http</PackageTags>
<IsPackable>false</IsPackable>
Expand Down
4 changes: 2 additions & 2 deletions src/Http/Routing/src/Matching/SingleEntryAsciiJumpTable.cs
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright (c) .NET Foundation. All rights reserved.
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
Expand Down Expand Up @@ -27,7 +27,7 @@ public SingleEntryAsciiJumpTable(
_destination = destination;
}

public unsafe override int GetDestination(string path, PathSegment segment)
public override int GetDestination(string path, PathSegment segment)
{
var length = segment.Length;
if (length == 0)
Expand Down
1 change: 0 additions & 1 deletion src/Http/Routing/src/Microsoft.AspNetCore.Routing.csproj
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,6 @@ Microsoft.AspNetCore.Routing.RouteCollection</Description>
<IsAspNetCoreApp>true</IsAspNetCoreApp>
<GenerateDocumentationFile>true</GenerateDocumentationFile>
<PackageTags>aspnetcore;routing</PackageTags>
<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
<IsPackable>false</IsPackable>
<Nullable>enable</Nullable>
</PropertyGroup>
Expand Down