Motivation: When decoding DnsRecord, if the record contains compression pointers, and not all compression pointers are decompressed, but part of the pointers are decompressed. Then when encoding the record, the compressed pointer will point to the wrong location, resulting in bad label problem. Modification: Pre-decompressed record RData that may contain compression pointers. Result: Fixes #8962
169 lines
6.2 KiB
Java
169 lines
6.2 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.socket.InternetProtocolFamily;
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import io.netty.handler.codec.UnsupportedMessageTypeException;
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import io.netty.util.internal.StringUtil;
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import io.netty.util.internal.UnstableApi;
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/**
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* The default {@link DnsRecordEncoder} implementation.
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*
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* @see DefaultDnsRecordDecoder
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*/
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@UnstableApi
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public class DefaultDnsRecordEncoder implements DnsRecordEncoder {
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private static final int PREFIX_MASK = Byte.SIZE - 1;
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/**
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* Creates a new instance.
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*/
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protected DefaultDnsRecordEncoder() { }
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@Override
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public final void encodeQuestion(DnsQuestion question, ByteBuf out) throws Exception {
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encodeName(question.name(), out);
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out.writeShort(question.type().intValue());
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out.writeShort(question.dnsClass());
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}
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@Override
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public void encodeRecord(DnsRecord record, ByteBuf out) throws Exception {
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if (record instanceof DnsQuestion) {
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encodeQuestion((DnsQuestion) record, out);
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} else if (record instanceof DnsPtrRecord) {
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encodePtrRecord((DnsPtrRecord) record, out);
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} else if (record instanceof DnsOptEcsRecord) {
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encodeOptEcsRecord((DnsOptEcsRecord) record, out);
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} else if (record instanceof DnsOptPseudoRecord) {
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encodeOptPseudoRecord((DnsOptPseudoRecord) record, out);
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} else if (record instanceof DnsRawRecord) {
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encodeRawRecord((DnsRawRecord) record, out);
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} else {
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throw new UnsupportedMessageTypeException(StringUtil.simpleClassName(record));
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}
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}
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private void encodeRecord0(DnsRecord record, ByteBuf out) throws Exception {
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encodeName(record.name(), out);
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out.writeShort(record.type().intValue());
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out.writeShort(record.dnsClass());
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out.writeInt((int) record.timeToLive());
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}
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private void encodePtrRecord(DnsPtrRecord record, ByteBuf out) throws Exception {
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encodeRecord0(record, out);
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encodeName(record.hostname(), out);
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}
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private void encodeOptPseudoRecord(DnsOptPseudoRecord record, ByteBuf out) throws Exception {
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encodeRecord0(record, out);
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out.writeShort(0);
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}
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private void encodeOptEcsRecord(DnsOptEcsRecord record, ByteBuf out) throws Exception {
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encodeRecord0(record, out);
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int sourcePrefixLength = record.sourcePrefixLength();
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int scopePrefixLength = record.scopePrefixLength();
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int lowOrderBitsToPreserve = sourcePrefixLength & PREFIX_MASK;
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byte[] bytes = record.address();
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int addressBits = bytes.length << 3;
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if (addressBits < sourcePrefixLength || sourcePrefixLength < 0) {
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throw new IllegalArgumentException(sourcePrefixLength + ": " +
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sourcePrefixLength + " (expected: 0 >= " + addressBits + ')');
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}
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// See http://www.iana.org/assignments/address-family-numbers/address-family-numbers.xhtml
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final short addressNumber = (short) (bytes.length == 4 ?
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InternetProtocolFamily.IPv4.addressNumber() : InternetProtocolFamily.IPv6.addressNumber());
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int payloadLength = calculateEcsAddressLength(sourcePrefixLength, lowOrderBitsToPreserve);
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int fullPayloadLength = 2 + // OPTION-CODE
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2 + // OPTION-LENGTH
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2 + // FAMILY
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1 + // SOURCE PREFIX-LENGTH
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1 + // SCOPE PREFIX-LENGTH
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payloadLength; // ADDRESS...
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out.writeShort(fullPayloadLength);
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out.writeShort(8); // This is the defined type for ECS.
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out.writeShort(fullPayloadLength - 4); // Not include OPTION-CODE and OPTION-LENGTH
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out.writeShort(addressNumber);
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out.writeByte(sourcePrefixLength);
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out.writeByte(scopePrefixLength); // Must be 0 in queries.
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if (lowOrderBitsToPreserve > 0) {
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int bytesLength = payloadLength - 1;
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out.writeBytes(bytes, 0, bytesLength);
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// Pad the leftover of the last byte with zeros.
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out.writeByte(padWithZeros(bytes[bytesLength], lowOrderBitsToPreserve));
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} else {
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// The sourcePrefixLength align with Byte so just copy in the bytes directly.
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out.writeBytes(bytes, 0, payloadLength);
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}
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}
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// Package-Private for testing
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static int calculateEcsAddressLength(int sourcePrefixLength, int lowOrderBitsToPreserve) {
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return (sourcePrefixLength >>> 3) + (lowOrderBitsToPreserve != 0 ? 1 : 0);
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}
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private void encodeRawRecord(DnsRawRecord record, ByteBuf out) throws Exception {
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encodeRecord0(record, out);
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ByteBuf content = record.content();
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int contentLen = content.readableBytes();
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out.writeShort(contentLen);
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out.writeBytes(content, content.readerIndex(), contentLen);
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}
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protected void encodeName(String name, ByteBuf buf) throws Exception {
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DnsCodecUtil.encodeDomainName(name, buf);
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}
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private static byte padWithZeros(byte b, int lowOrderBitsToPreserve) {
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switch (lowOrderBitsToPreserve) {
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case 0:
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return 0;
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case 1:
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return (byte) (0x80 & b);
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case 2:
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return (byte) (0xC0 & b);
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case 3:
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return (byte) (0xE0 & b);
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case 4:
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return (byte) (0xF0 & b);
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case 5:
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return (byte) (0xF8 & b);
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case 6:
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return (byte) (0xFC & b);
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case 7:
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return (byte) (0xFE & b);
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case 8:
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return b;
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default:
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throw new IllegalArgumentException("lowOrderBitsToPreserve: " + lowOrderBitsToPreserve);
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}
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}
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}
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