1 /*
2 * Copyright 2019 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.handler.codec.dns;
17
18 import io.netty.buffer.ByteBuf;
19 import io.netty.channel.ChannelHandler;
20 import io.netty.channel.ChannelHandlerContext;
21 import io.netty.handler.codec.MessageToByteEncoder;
22 import io.netty.util.internal.UnstableApi;
23
24 @ChannelHandler.Sharable
25 @UnstableApi
26 public final class TcpDnsQueryEncoder extends MessageToByteEncoder<DnsQuery> {
27
28 private final DnsQueryEncoder encoder;
29
30 /**
31 * Creates a new encoder with {@linkplain DnsRecordEncoder#DEFAULT the default record encoder}.
32 */
33 public TcpDnsQueryEncoder() {
34 this(DnsRecordEncoder.DEFAULT);
35 }
36
37 /**
38 * Creates a new encoder with the specified {@code recordEncoder}.
39 */
40 public TcpDnsQueryEncoder(DnsRecordEncoder recordEncoder) {
41 this.encoder = new DnsQueryEncoder(recordEncoder);
42 }
43
44 @Override
45 protected void encode(ChannelHandlerContext ctx, DnsQuery msg, ByteBuf out) throws Exception {
46 // Length is two octets as defined by RFC-7766
47 // See https://tools.ietf.org/html/rfc7766#section-8
48 out.writerIndex(out.writerIndex() + 2);
49 encoder.encode(msg, out);
50
51 // Now fill in the correct length based on the amount of data that we wrote the ByteBuf.
52 out.setShort(0, out.readableBytes() - 2);
53 }
54
55 @Override
56 protected ByteBuf allocateBuffer(ChannelHandlerContext ctx, @SuppressWarnings("unused") DnsQuery msg,
57 boolean preferDirect) {
58 if (preferDirect) {
59 return ctx.alloc().ioBuffer(1024);
60 } else {
61 return ctx.alloc().heapBuffer(1024);
62 }
63 }
64 }