Decompression

GenHTTP.Modules.Compression

This concern will analyze incoming requests for compressed content and will automatically decompress the body using a suitable decompression algorithm.

In contrast to automatic compression of responses, this concern is not enabled by default and needs to be activated on the host:

await Host.Create()
          .Handler(...)
          .Defaults(decompression: true)
          .RunAsync();

Custom Algorithms

The concern analyzes the Content-Encoding header of incoming requests and supports automatic decompression of gzip, br and zstd (.NET 11 only) compressed request bodies.

If you would like to add support for an additional algorithm, you need to implement and supply a ICompressionAlgorithm instance - the same interface used to compress responses, but only its Decompress(Stream) member is relevant here. The following example shows how to add deflate support to your server:

using System.IO.Compression;

using GenHTTP.Api.Content.IO;
using GenHTTP.Api.Protocol;

using GenHTTP.Engine.Internal;

using GenHTTP.Modules.Compression;
using GenHTTP.Modules.Compression.Providers;
using GenHTTP.Modules.Layouting;
using GenHTTP.Modules.Practices;

var decompression = DecompressedContent.Default()
                                       .Add(new DeflateAlgorithm());

var app = Layout.Create()
                .Add(decompression);

await Host.Create()
          .Handler(app)
          .Defaults()
          .Development()
          .RunAsync();

public class DeflateAlgorithm : ICompressionAlgorithm
{
    private static readonly AlgorithmName AlgorithmName = new("deflate");

    public AlgorithmName Name => AlgorithmName;

    public Priority Priority => Priority.Low;

    public IResponseContent Compress(IResponseContent content, CompressionLevel level)
    {
        throw new NotSupportedException("This algorithm is only used for decompression");
    }

    public Stream Decompress(Stream content)
    {
        return new DeflateStream(content, CompressionMode.Decompress, leaveOpen: true);
    }

}

Once a matching algorithm is found for the request’s Content-Encoding, the concern calls request.WrapBody(...) to transparently replace the request body with a DecompressedBody that decompresses on read - handlers downstream keep reading request.GetBody() as usual and never see the compressed bytes. WrapBody on IRequest is the same extension point other body-rewriting concerns can build on; only one wrapper can be active per request.