AsyncDNS-cr  Diff

          end
          handle_packet(buf[0, len], addr)
        end
      end
    end

    def handle_packet(packet : Bytes, sender : Socket::IPAddress) : Nil
      io = IO::Memory.new(packet, writeable: false)
      begin
        id = packet[0].to_u16 << 8 | packet[1]
        id = io.read_bytes(UInt16, IO::ByteFormat::BigEndian)

        begin
          context = @queries[id]
        rescue KeyError
          return
        end

        return if sender != context.used_ns

        @queries.delete(id)

        byte = io.read_bytes(UInt8)
        if packet[2] & 0x80 == 0 ||                       # QR
           packet[2] & 0x78 != context.raw_data[2] & 0x78 # Opcode
        if byte & 0x80 == 0 ||                       # QR
           byte & 0x78 != context.raw_data[2] & 0x78 # Opcode
          context.block.call(Error::INVALID_REPLY)
          return
        end

        if packet[2] & 0x02 != 0 # TC
        if byte & 0x02 != 0 # TC
          # TODO: Switch to TCP
          context.block.call(Error::TRUNCATED)
          return
        end

        case packet[3] & 0x0F # RCODE
        case io.read_bytes(UInt8) & 0x0F # RCODE
        when 0
          error = nil
          try_next_ns = false
        when 1
          error = Error::SERVER_INVALID_FORMAT
          try_next_ns = false
        when 2

        end

        if error
          context.block.call(error)
          return
        end

        io = IO::Memory.new(packet[4, packet.size - 4], writeable: false)
        qdcount = io.read_bytes(UInt16, IO::ByteFormat::BigEndian)
        adcount = io.read_bytes(UInt16, IO::ByteFormat::BigEndian)
        nscount = io.read_bytes(UInt16, IO::ByteFormat::BigEndian)
        arcount = io.read_bytes(UInt16, IO::ByteFormat::BigEndian)
      rescue IndexError
      rescue IO::EOFError
      end
    end

    def stop : Nil
      @v6_sock.try { |s| s.close }
      @v4_sock.try { |s| s.close }
    end
  end
end