class Gem::Resolv::DNS::Message::MessageDecoder

def get_unpack(template)
  len = 0
  template.each_byte {|byte|
    byte = "%c" % byte
    case byte
    when ?c, ?C
      len += 1
    when ?n
      len += 2
    when ?N
      len += 4
    else
      raise StandardError.new("unsupported template: '#{byte.chr}' in '#{template}'")
    end
  }
  raise DecodeError.new("limit exceeded") if @limit < @index + len
  arr = @data.unpack("@#{@index}#{template}")
  @index += len
  return arr
end