Rack アプリで、URL のパス(PATH_INFO)中に `%FF` が入っていたり、クエリ文字列(QUERY_STRING)中に `%FF=hoge` が入っていても Invalid byte sequence で落ちないようにするパッチ

avoid_invalid_byte_sequence_patch.rb

require 'rack/utils'
require 'rack/protection/path_traversal'

module Rack
  module Utils
    orig_normalize_params_singleton = method(:normalize_params)
    define_singleton_method(:normalize_params) do |params, name, *args|
      return unless name && name.valid_encoding?
      orig_normalize_params_singleton.call(params, name, *args)
    end

    orig_normalize_params = instance_method(:normalize_params)
    define_method(:normalize_params) do |params, name, *args|
      return unless name && name.valid_encoding?
      orig_normalize_params.bind(self).call(params, name, *args)
    end
  end

  module Protection
    class PathTraversal
      orig_cleanup = instance_method(:cleanup)
      define_method(:cleanup) do |path|
        orig_cleanup.bind(self).call(path).force_encoding('ASCII-8BIT')
      end
    end
  end
end