Rack::Inflater to decompress request bodies according to Content-Encoding header.

rack_inflater.rb

# frozen_string_literal: true

# Decrompress request's body when HTTP header Content-Encoding is present.
# Only deflate and gzip encodings are supported.
class Rack::Inflater
  def initialize(app)
    @app = app
  end

  def call(env)
    if env["rack.input"] && (encoding = env["HTTP_CONTENT_ENCODING"])
      if (body = decompress(env["rack.input"].read, encoding))
        env["rack.input"] = StringIO.new(body)
        env["CONTENT_LENGTH"] = body.bytesize
        env.delete("HTTP_CONTENT_ENCODING")
      end
    end
    @app.call(env)
  end

  def decompress(string, encoding)
    case encoding
    when "gzip" then Zlib.gunzip(string)
    when "deflate" then Zlib.inflate(string)
    end
  end
end