go away utf8 invalid byte sequence

gistfile1.txt

# config/applications.rb

config.middleware.use "Utf8Sanitizer::Middleware"


# lib/utf8_sanitizer.rb

module Utf8Sanitizer 
  class Middleware
    SANITIZE_ENV_KEYS = %w(
      HTTP_REFERER
      PATH_INFO
      REQUEST_URI
      REQUEST_PATH
      QUERY_STRING
    )
   
    def initialize(app)
      @app = app
    end
   
    def call(env)
      SANITIZE_ENV_KEYS.each do |key|
        string = env[key].to_s
        valid = URI.decode(string).force_encoding('UTF-8').valid_encoding?
        # Don't accept requests with invalid byte sequence
        return [ 400, { }, [ 'Bad request' ] ] unless valid
      end
   
      @app.call(env)
    end
  end
end