DNS compare

dns_compare.rb

#!/usr/bin/env ruby

NEW_NS_SERVER="ns-561.awsdns-06.net"
OLD_NS_SERVER="ns.udag.net"

def clean_up_answer(ns_answer)
  answer_section = nil
  ns_answer.match(%r{^;; ANSWER SECTION:\s*(.*?\n)\n}m) do |match|
    answer_section = match[1]
  end

  answer_section.lines.map do |line|
    hostname, _ttl, _in, type, *content = line.strip.split(/\s+/)
    next unless %w[A MX CNAME TXT].include?(type)

    "#{hostname} #{type} #{content.join(' ')}"
  end.compact.sort
end

ARGV.each do |hostname|
  (+hostname).strip!

  old_ns_answer = %x{host -a #{hostname} #{OLD_NS_SERVER}}
  new_ns_answer = %x{host -a #{hostname} #{NEW_NS_SERVER}}

  if clean_up_answer(old_ns_answer) == clean_up_answer(new_ns_answer)
    puts "Matched: #{hostname}"
  else
    puts "Difference for host #{hostname}:"
    puts "Old Raw:\n#{old_ns_answer}\n"
    puts "New Raw:\n#{new_ns_answer}\n"
    puts "Old Cleaned:\n#{clean_up_answer(old_ns_answer)}\n"
    puts "New Cleaned:\n#{clean_up_answer(new_ns_answer)}\n"
  end
end