DelegatingHandler for GZip in ASP.NET Web API

GzipHandler.cs

public class GzipHandler : DelegatingHandler
{
  protected async override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
  {
    if (request.Content != null &&
      request.Content.Headers.ContentType != null &&
      (request.Content.Headers.ContentType.MediaType == "application/gzip" ||
      request.Content.Headers.ContentType.MediaType == "application/deflate"))
    {
      string encodingType = request.Content.Headers.ContentType.MediaType.Split('/').Last();
      Stream stream;
      if (encodingType == "gzip")
      {
        stream = new GZipStream(await request.Content.ReadAsStreamAsync(), CompressionMode.Decompress);
      }
      else if (encodingType == "deflate")
      {
        stream = new DeflateStream(await request.Content.ReadAsStreamAsync(), CompressionMode.Decompress);
      }
      else
      {
        throw new HttpException(HttpStatusCode.UnsupportedMediaType, string.Format("Encoding '{0}' is not supported. Only supports gzip or deflate encoding.", encodingType));
      }
      request.Content = new DecompressedContent(request.Content, stream);
    }

    var response = await base.SendAsync(request, cancellationToken);
    if (response.Content != null &&
      response.RequestMessage.Headers.AcceptEncoding != null &&
      response.RequestMessage.Headers.AcceptEncoding.Count > 0)
    {
      string encodingType = response.RequestMessage.Headers.AcceptEncoding.First().Value;

      response.Content = new CompressedContent(response.Content, encodingType);
    }
    return response;
  }
}

public class CompressedContent : HttpContent
{
  private HttpContent _content;
  private string _encodingType;

  public CompressedContent(HttpContent content, string encodingType)
  {
    _content = content;
    _encodingType = encodingType.ToLowerInvariant();

    if (_encodingType != "gzip" && _encodingType != "deflate")
    {
      throw new HttpException(HttpStatusCode.UnsupportedMediaType, string.Format("Encoding '{0}' is not supported. Only supports gzip or deflate encoding.", _encodingType));
    }

    // copy the headers from the original content
    foreach (KeyValuePair<string, IEnumerable<string>> header in _content.Headers)
    {
      Headers.TryAddWithoutValidation(header.Key, header.Value);
    }

    Headers.ContentEncoding.Add(encodingType);
  }

  protected override bool TryComputeLength(out long length)
  {
    length = -1;

    return false;
  }

  protected override async Task SerializeToStreamAsync(Stream stream, TransportContext context)
  {
    Stream compressedStream = null;

    if (_encodingType == "gzip")
    {
        compressedStream = new GZipStream(stream, CompressionMode.Compress, leaveOpen: true);
    }
    else if (_encodingType == "deflate")
    {
        compressedStream = new DeflateStream(stream, CompressionMode.Compress, leaveOpen: true);
    }

    try
    {
        await _content.CopyToAsync(compressedStream);
    }
    finally
    {
        compressedStream.Dispose();
    }
  }
}

public class DecompressedContent : StreamContent
{
  public DecompressedContent(HttpContent content, Stream stream) : base(stream)
  {
    // copy the headers from the original content
    foreach (KeyValuePair<string, IEnumerable<string>> header in content.Headers)
    {
        Headers.TryAddWithoutValidation(header.Key, header.Value);
    }

    Headers.Remove("Content-Type");
    Headers.Add("Content-Type", "application/json");
  }
}