get_string

# File lib/resolv.rb, line 1569
        def get_string
          raise DecodeError.new("limit exceeded") if @limit <= @index
          len = @data[@index].ord
          raise DecodeError.new("limit exceeded") if @limit < @index + 1 + len
          d = @data[@index + 1, len]
          @index += 1 + len
          return d
        end