63a02fc04e
Motivation: There are various known issues in netty-codec-dns: - Message types are not interfaces, which can make it difficult for a user to implement his/her own message implementation. - Some class names and field names do not match with the terms in the RFC. - The support for decoding a DNS record was limited. A user had to encode and decode by him/herself. - The separation of DnsHeader from DnsMessage was unnecessary, although it is fine conceptually. - Buffer leak caused by DnsMessage was difficult to analyze, because the leak detector tracks down the underlying ByteBuf rather than the DnsMessage itself. - DnsMessage assumes DNS-over-UDP. - To send an EDNS message, a user have to create a new DNS record class instance unnecessarily. Modifications: - Make all message types interfaces and add default implementations - Rename some classes, properties, and constants to match the RFCs - DnsResource -> DnsRecord - DnsType -> DnsRecordType - and many more - Remove DnsClass and use an integer to support EDNS better - Add DnsRecordEncoder/DnsRecordDecoder and their default implementations - DnsRecord does not require RDATA to be ByteBuf anymore. - Add DnsRawRecord as the catch-all record type - Merge DnsHeader into DnsMessage - Make ResourceLeakDetector track AbstractDnsMessage - Remove DnsMessage.sender/recipient properties - Wrap DnsMessage with AddressedEnvelope - Add DatagramDnsQuest and DatagramDnsResponse for ease of use - Rename DnsQueryEncoder to DatagramDnsQueryEncoder - Rename DnsResponseDecoder to DatagramDnsResponseDecoder - Miscellaneous changes - Add StringUtil.TAB Result: - Cleaner APi - Can support DNS-over-TCP more easily in the future - Reduced memory footprint in the default DnsQuery/Response implementations - Better leak tracking for DnsMessages - Possibility to introduce new DnsRecord types in the future and provide full record encoder/decoder implementation. - No unnecessary instantiation for an EDNS pseudo resource record
112 lines
4.1 KiB
Java
112 lines
4.1 KiB
Java
/*
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* Copyright 2015 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.dns;
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import io.netty.buffer.ByteBuf;
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import io.netty.channel.ChannelHandler;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.socket.DatagramPacket;
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import io.netty.handler.codec.CorruptedFrameException;
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import io.netty.handler.codec.MessageToMessageDecoder;
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import java.net.InetSocketAddress;
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import java.util.List;
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import static io.netty.util.internal.ObjectUtil.checkNotNull;
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/**
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* Decodes a {@link DatagramPacket} into a {@link DatagramDnsResponse}.
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*/
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@ChannelHandler.Sharable
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public class DatagramDnsResponseDecoder extends MessageToMessageDecoder<DatagramPacket> {
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private final DnsRecordDecoder recordDecoder;
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/**
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* Creates a new decoder with {@linkplain DnsRecordDecoder#DEFAULT the default record decoder}.
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*/
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public DatagramDnsResponseDecoder() {
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this(DnsRecordDecoder.DEFAULT);
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}
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/**
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* Creates a new decoder with the specified {@code recordDecoder}.
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*/
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public DatagramDnsResponseDecoder(DnsRecordDecoder recordDecoder) {
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this.recordDecoder = checkNotNull(recordDecoder, "recordDecoder");
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}
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@Override
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protected void decode(ChannelHandlerContext ctx, DatagramPacket packet, List<Object> out) throws Exception {
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final InetSocketAddress sender = packet.sender();
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final ByteBuf buf = packet.content();
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final DnsResponse response = newResponse(sender, buf);
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boolean success = false;
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try {
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final int questionCount = buf.readUnsignedShort();
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final int answerCount = buf.readUnsignedShort();
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final int authorityRecordCount = buf.readUnsignedShort();
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final int additionalRecordCount = buf.readUnsignedShort();
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decodeQuestions(response, buf, questionCount);
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decodeRecords(response, DnsSection.ANSWER, buf, answerCount);
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decodeRecords(response, DnsSection.AUTHORITY, buf, authorityRecordCount);
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decodeRecords(response, DnsSection.ADDITIONAL, buf, additionalRecordCount);
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out.add(response);
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success = true;
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} finally {
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if (!success) {
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response.release();
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}
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}
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}
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private static DnsResponse newResponse(InetSocketAddress sender, ByteBuf buf) {
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final int id = buf.readUnsignedShort();
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final int flags = buf.readUnsignedShort();
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if (flags >> 15 == 0) {
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throw new CorruptedFrameException("not a response");
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}
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final DnsResponse response = new DatagramDnsResponse(
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sender, null,
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id, DnsOpCode.valueOf((byte) (flags >> 11 & 0xf)), DnsResponseCode.valueOf((byte) (flags & 0xf)));
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response.setRecursionDesired((flags >> 8 & 1) == 1);
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response.setAuthoritativeAnswer((flags >> 10 & 1) == 1);
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response.setTruncated((flags >> 9 & 1) == 1);
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response.setRecursionAvailable((flags >> 7 & 1) == 1);
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response.setZ(flags >> 4 & 0x7);
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return response;
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}
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private void decodeQuestions(DnsResponse response, ByteBuf buf, int questionCount) throws Exception {
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for (int i = questionCount; i > 0; i --) {
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response.addRecord(DnsSection.QUESTION, recordDecoder.decodeQuestion(buf));
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}
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}
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private void decodeRecords(
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DnsResponse response, DnsSection section, ByteBuf buf, int count) throws Exception {
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for (int i = count; i > 0; i --) {
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response.addRecord(section, recordDecoder.decodeRecord(buf));
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}
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}
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}
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