120 lines
No EOL
3.7 KiB
C#
120 lines
No EOL
3.7 KiB
C#
using System.IO.Compression;
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using Microsoft.Extensions.Primitives;
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using Microsoft.Net.Http.Headers;
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namespace Iceshrimp.Backend.Core.Middleware;
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internal sealed class ContentEncodingNegotiator(RequestDelegate next, IWebHostEnvironment webHostEnvironment)
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{
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private static readonly StringSegment[] PreferredEncodings = ["br", "gzip"];
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private static readonly Dictionary<StringSegment, string> EncodingExtensionMap =
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new(StringSegmentComparer.OrdinalIgnoreCase) { ["br"] = ".br", ["gzip"] = ".gz" };
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public Task InvokeAsync(HttpContext context)
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{
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NegotiateEncoding(context);
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return HookTransparentDecompression(context);
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}
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private async Task HookTransparentDecompression(HttpContext ctx)
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{
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if (ctx.Response.Headers.ContentEncoding.Count != 0 || !ResourceExists(ctx, ".br") || ResourceExists(ctx, ""))
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{
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await next(ctx);
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return;
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}
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var responseStream = ctx.Response.Body;
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using var tempStream = new MemoryStream();
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await using var brotliStream = new BrotliStream(tempStream, CompressionMode.Decompress);
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ctx.Response.Body = tempStream;
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ctx.Request.Path = (PathString)(ctx.Request.Path + ".br");
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ctx.Response.OnStarting(() =>
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{
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ctx.Response.Headers.ContentLength = null;
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return Task.CompletedTask;
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});
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await next(ctx);
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tempStream.Seek(0, SeekOrigin.Begin);
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await brotliStream.CopyToAsync(responseStream);
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}
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private void NegotiateEncoding(HttpContext context)
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{
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var acceptEncoding = context.Request.Headers.AcceptEncoding;
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if (StringValues.IsNullOrEmpty(acceptEncoding) ||
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!StringWithQualityHeaderValue.TryParseList(acceptEncoding, out var parsedValues) ||
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parsedValues.Count == 0)
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return;
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var stringSegment1 = StringSegment.Empty;
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var num = 0.0;
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foreach (var encoding in parsedValues)
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{
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var stringSegment2 = encoding.Value;
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var valueOrDefault = encoding.Quality.GetValueOrDefault(1.0);
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if (!(valueOrDefault >= double.Epsilon) || !(valueOrDefault >= num)) continue;
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if (Math.Abs(valueOrDefault - num) < 0.001)
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{
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stringSegment1 = PickPreferredEncoding(context, stringSegment1, encoding);
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}
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else
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{
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if (EncodingExtensionMap.TryGetValue(stringSegment2, out var extension) &&
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ResourceExists(context, extension))
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{
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stringSegment1 = stringSegment2;
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num = valueOrDefault;
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}
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}
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if (StringSegment.Equals("*", stringSegment2, StringComparison.Ordinal))
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{
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stringSegment1 = PickPreferredEncoding(context, new StringSegment(), encoding);
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num = valueOrDefault;
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}
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if (!StringSegment.Equals("identity", stringSegment2, StringComparison.OrdinalIgnoreCase))
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continue;
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stringSegment1 = StringSegment.Empty;
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num = valueOrDefault;
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}
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if (!EncodingExtensionMap.TryGetValue(stringSegment1, out var str))
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return;
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context.Request.Path += str;
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context.Response.Headers.ContentEncoding = stringSegment1.Value;
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context.Response.Headers.Append(HeaderNames.Vary, HeaderNames.ContentEncoding);
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return;
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StringSegment PickPreferredEncoding(
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HttpContext innerContext,
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StringSegment selectedEncoding,
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StringWithQualityHeaderValue encoding
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)
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{
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foreach (var preferredEncoding in PreferredEncodings)
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{
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if (preferredEncoding == selectedEncoding)
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return selectedEncoding;
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if ((preferredEncoding == encoding.Value || encoding.Value == "*") &&
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ResourceExists(innerContext, EncodingExtensionMap[preferredEncoding]))
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return preferredEncoding;
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}
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return StringSegment.Empty;
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}
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}
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private bool ResourceExists(HttpContext context, string extension)
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{
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return webHostEnvironment.WebRootFileProvider.GetFileInfo(context.Request.Path + extension).Exists;
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}
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} |