Rack Middleware to automatically unzip gzipped/deflated POST data

compress_requests.rb

class CompressedRequests
  def initialize(app)
    @app = app
  end

  def method_handled?(env)
    !!(env['REQUEST_METHOD'] =~ /(POST|PUT)/)
  end

  def encoding_handled?(env)
    ['gzip', 'deflate'].include? env['HTTP_CONTENT_ENCODING']
  end
  
  def call(env)
    if method_handled?(env) && encoding_handled?(env)
      extracted = decode(env['rack.input'], env['HTTP_CONTENT_ENCODING'])

      env.delete('HTTP_CONTENT_ENCODING')
      env['CONTENT_LENGTH'] = extracted.bytesize
      env['rack.input'] = StringIO.new(extracted)
    end

    status, headers, response = @app.call(env)
    return [status, headers, response]
  end
  
  def decode(input, content_encoding)
    case content_encoding
      when 'gzip' then Zlib::GzipReader.new(input).read
      when 'deflate' then Zlib::Inflate.inflate(input.read)
    end
  end
end

Awesome! To get this to work with Rails 3, I had to insert it before ActionDispatch::ParamsParser:

config.middleware.insert_before ActionDispatch::ParamsParser, "CompressedRequests"

Thanks for adding that!

Can this be used in Rails 2?

Sorry to miss this question. It should be usable on anything that supports standard Rack middleware, including Rails 2.

Thanks for this gist! It’s working great.

I found that for a payload that uses multibyte strings, the content length was not getting set correctly. The solution is to use .bytesize instead of .length.

env['CONTENT_LENGTH'] = extracted.bytesize

Here's my fork with the fix: https://gist.github.com/mbrictson/9106778

It looks like the account name above moved, the updated location is:

https://gist.github.com/mattbrictson/9106778

config.middleware.insert_before ActionDispatch::ParamsParser, "CompressedRequests"

this does not work with rails 5.

This is fixed for the CONTENT_LENGTH issue now. I don't know Rails 5 @plentz, so if you knew what needs to go there instead, please post that here.

It's working for me in rails 6 with config.middleware.insert_after ::Rack::Sendfile, ::CompressedRequests

-    status, headers, response = @app.call(env)
-    return [status, headers, response]
+    @app.call(env)

had a similar effect 💚

Used an index in insert_before which worked in rails 5 in all envs.

    config.middleware.insert_before 0, CompressedRequests