rack attack, whitelist cloudflare

rack_attack.rb

class Rack::Attack
  
  CLOUDFLARE_SUBNETS = [
    IPAddr.new("103.21.244.0/22"),
    IPAddr.new("103.22.200.0/22"),
    IPAddr.new("103.31.4.0/22"),
    IPAddr.new("104.16.0.0/12"),
    IPAddr.new("108.162.192.0/18"),
    IPAddr.new("131.0.72.0/22"),
    IPAddr.new("141.101.64.0/18"),
    IPAddr.new("162.158.0.0/15"),
    IPAddr.new("172.64.0.0/13"),
    IPAddr.new("173.245.48.0/20"),
    IPAddr.new("188.114.96.0/20"),
    IPAddr.new("190.93.240.0/20"),
    IPAddr.new("197.234.240.0/22"),
    IPAddr.new("198.41.128.0/17"),
    IPAddr.new("199.27.128.0/21")
  ]

  whitelist("Always allow CloudFlare") do |req|
    !!CLOUDFLARE_SUBNETS.find { |subnet| subnet === req.ip }
  end

end