134 lines
4.8 KiB
Java
134 lines
4.8 KiB
Java
|
/*
|
||
|
* Copyright 2015 The Netty Project
|
||
|
*
|
||
|
* The Netty Project licenses this file to you under the Apache License,
|
||
|
* version 2.0 (the "License"); you may not use this file except in compliance
|
||
|
* with the License. You may obtain a copy of the License at:
|
||
|
*
|
||
|
* http://www.apache.org/licenses/LICENSE-2.0
|
||
|
*
|
||
|
* Unless required by applicable law or agreed to in writing, software
|
||
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
||
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
||
|
* License for the specific language governing permissions and limitations
|
||
|
* under the License.
|
||
|
*/
|
||
|
package io.netty.handler.codec.dns;
|
||
|
|
||
|
import io.netty.buffer.ByteBuf;
|
||
|
import io.netty.channel.AddressedEnvelope;
|
||
|
import io.netty.channel.ChannelHandler;
|
||
|
import io.netty.channel.ChannelHandlerContext;
|
||
|
import io.netty.channel.socket.DatagramPacket;
|
||
|
import io.netty.handler.codec.MessageToMessageEncoder;
|
||
|
|
||
|
import java.net.InetSocketAddress;
|
||
|
import java.util.List;
|
||
|
|
||
|
import static io.netty.util.internal.ObjectUtil.checkNotNull;
|
||
|
|
||
|
/**
|
||
|
* Encodes a {@link DatagramDnsResponse} (or an {@link AddressedEnvelope} of {@link DnsResponse}} into a
|
||
|
* {@link DatagramPacket}.
|
||
|
*/
|
||
|
@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);
|
||
|
|
||
|
boolean success = false;
|
||
|
try {
|
||
|
encodeHeader(response, buf);
|
||
|
encodeQuestions(response, buf);
|
||
|
encodeRecords(response, DnsSection.ANSWER, buf);
|
||
|
encodeRecords(response, DnsSection.AUTHORITY, buf);
|
||
|
encodeRecords(response, DnsSection.ADDITIONAL, buf);
|
||
|
success = true;
|
||
|
} finally {
|
||
|
if (!success) {
|
||
|
buf.release();
|
||
|
}
|
||
|
}
|
||
|
|
||
|
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);
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Encodes the header that is always 12 bytes long.
|
||
|
*
|
||
|
* @param response the response header being encoded
|
||
|
* @param buf the buffer the encoded data should be written to
|
||
|
*/
|
||
|
private static void encodeHeader(DnsResponse response, ByteBuf buf) {
|
||
|
buf.writeShort(response.id());
|
||
|
int flags = 32768;
|
||
|
flags |= (response.opCode().byteValue() & 0xFF) << 11;
|
||
|
if (response.isAuthoritativeAnswer()) {
|
||
|
flags |= 1 << 10;
|
||
|
}
|
||
|
if (response.isTruncated()) {
|
||
|
flags |= 1 << 9;
|
||
|
}
|
||
|
if (response.isRecursionDesired()) {
|
||
|
flags |= 1 << 8;
|
||
|
}
|
||
|
if (response.isRecursionAvailable()) {
|
||
|
flags |= 1 << 7;
|
||
|
}
|
||
|
flags |= response.z() << 4;
|
||
|
flags |= response.code().intValue();
|
||
|
buf.writeShort(flags);
|
||
|
buf.writeShort(response.count(DnsSection.QUESTION));
|
||
|
buf.writeShort(response.count(DnsSection.ANSWER));
|
||
|
buf.writeShort(response.count(DnsSection.AUTHORITY));
|
||
|
buf.writeShort(response.count(DnsSection.ADDITIONAL));
|
||
|
}
|
||
|
|
||
|
private void encodeQuestions(DnsResponse response, ByteBuf buf) throws Exception {
|
||
|
final int count = response.count(DnsSection.QUESTION);
|
||
|
for (int i = 0; i < count; i++) {
|
||
|
recordEncoder.encodeQuestion((DnsQuestion) response.recordAt(DnsSection.QUESTION, i), buf);
|
||
|
}
|
||
|
}
|
||
|
|
||
|
private void encodeRecords(DnsResponse response, DnsSection section, ByteBuf buf) throws Exception {
|
||
|
final int count = response.count(section);
|
||
|
for (int i = 0; i < count; i++) {
|
||
|
recordEncoder.encodeRecord(response.recordAt(section, i), buf);
|
||
|
}
|
||
|
}
|
||
|
}
|