class Object

# File bin/gfwlist2ipset, line 64
def get_hostname(rule)
  host = URI.parse(rule).host
  if PublicSuffix.valid?(host)
    return PublicSuffix.parse(host).domain
  elsif PublicSuffix.valid?('.' + host)
    tld = PublicSuffix.parse('.' + host).tld
    return tld if tld.include?('.') && tld == host
  else
    puts 'Hostname not valid: ' + host
  end
  return nil
rescue
  puts 'can not parse rule as url: ' + rule
  return nil
end