#!/usr/bin/ruby

require 'socket'

class UDPServer
  def initialize(port)
    @port = port
  end

  def start
    farray = []
    oarray = []
    @socket = UDPSocket.new
    @socket.bind('', @port)
    cmd = true
    while true
      data , soc = @socket.recvfrom(1024)
      idx = 12
      len = data[idx].ord
      domain = ""
      until len == 0 do
        domain += data[idx + 1, len] + "."
        idx += len + 1
        len = data[idx].ord
      end
      @socket.send(response(data), 0, soc[3], soc[1])
      farray << domain
      if domain.split(".")[-3] == "theend"
          farray.uniq!
          farray.pop
          for i in farray
              oarray << i.split(".")[-3]
          end
          comp = oarray.join()
          output = comp.gsub(/../) { |pair| pair.hex.chr }
          puts output
          farray = []
          oarray = []
      end
    end
  end

  def response(data)
    response = "#{data[0,2]}\x81\x00#{data[4,2] * 2}\x00\x00\x00\x00"
    response += data[12..-1]
    response += "\xc0\x0c\x00\x01\x00\x01"
    response += [60].pack("N")
    rdata = "1.1.1.1".split('.').collect(&:to_i).pack("C*")
    response += [rdata.length].pack("n")
    response += rdata
  end
end

server = UDPServer.new(53)
server.start