class RuboCop::Cop::Style::IpAddresses

def offense?(node)
  contents = node.source[1...-1]
  return false if contents.empty?
  return false if whitelist.include?(contents.downcase)
  # To try to avoid doing two regex checks on every string,
  # shortcut out if the string does not look like an IP address
  return false unless could_be_ip?(contents)
  contents =~ ::Resolv::IPv4::Regex || contents =~ ::Resolv::IPv6::Regex
end