DatagramDnsResponseEncoder Class — netty Architecture

Source Code

codec-dns/src/main/java/io/netty/handler/codec/dns/DatagramDnsResponseEncoder.java lines 34–76

@ChannelHandler.Sharable
public class DatagramDnsResponseEncoder
    extends MessageToMessageEncoder<AddressedEnvelope<DnsResponse, InetSocketAddress>> {

    private final DnsRecordEncoder recordEncoder;

    /**
     * Creates a new encoder with {@linkplain DnsRecordEncoder#DEFAULT the default record encoder}.
     */
    public DatagramDnsResponseEncoder() {
        this(DnsRecordEncoder.DEFAULT);
    }

    /**
     * Creates a new encoder with the specified {@code recordEncoder}.
     */
    public DatagramDnsResponseEncoder(DnsRecordEncoder recordEncoder) {
        this.recordEncoder = checkNotNull(recordEncoder, "recordEncoder");
    }

    @Override
    protected void encode(ChannelHandlerContext ctx,
                          AddressedEnvelope<DnsResponse, InetSocketAddress> in, List<Object> out) throws Exception {

        final InetSocketAddress recipient = in.recipient();
        final DnsResponse response = in.content();
        final ByteBuf buf = allocateBuffer(ctx, in);

        DnsMessageUtil.encodeDnsResponse(recordEncoder, response, buf);

        out.add(new DatagramPacket(buf, recipient, null));
    }

    /**
     * Allocate a {@link ByteBuf} which will be used for constructing a datagram packet.
     * Sub-classes may override this method to return a {@link ByteBuf} with a perfect matching initial capacity.
     */
    protected ByteBuf allocateBuffer(
        ChannelHandlerContext ctx,
        @SuppressWarnings("unused") AddressedEnvelope<DnsResponse, InetSocketAddress> msg) throws Exception {
        return ctx.alloc().ioBuffer(1024);
    }
}