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

def get_length16
  len, = self.get_unpack('n')
  save_limit = @limit
  @limit = @index + len
  d = yield(len)
  if @index < @limit
    raise DecodeError.new("junk exists")
  elsif @limit < @index
    raise DecodeError.new("limit exceeded")
  end
  @limit = save_limit
  return d
end