1 /*
2 * Copyright 2018 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.resolver.dns;
17
18 import java.net.IDN;
19 import java.net.InetAddress;
20 import java.net.UnknownHostException;
21
22 import io.netty.buffer.ByteBuf;
23 import io.netty.buffer.ByteBufHolder;
24 import io.netty.handler.codec.dns.DnsRawRecord;
25 import io.netty.handler.codec.dns.DnsRecord;
26
27 /**
28 * Decodes an {@link InetAddress} from an A or AAAA {@link DnsRawRecord}.
29 */
30 final class DnsAddressDecoder {
31
32 private static final int INADDRSZ4 = 4;
33 private static final int INADDRSZ6 = 16;
34
35 /**
36 * Decodes an {@link InetAddress} from an A or AAAA {@link DnsRawRecord}.
37 *
38 * @param record the {@link DnsRecord}, most likely a {@link DnsRawRecord}
39 * @param name the host name of the decoded address
40 * @param decodeIdn whether to convert {@code name} to a unicode host name
41 *
42 * @return the {@link InetAddress}, or {@code null} if {@code record} is not a {@link DnsRawRecord} or
43 * its content is malformed
44 */
45 static InetAddress decodeAddress(DnsRecord record, String name, boolean decodeIdn) {
46 if (!(record instanceof DnsRawRecord)) {
47 return null;
48 }
49 final ByteBuf content = ((ByteBufHolder) record).content();
50 final int contentLen = content.readableBytes();
51 if (contentLen != INADDRSZ4 && contentLen != INADDRSZ6) {
52 return null;
53 }
54
55 final byte[] addrBytes = new byte[contentLen];
56 content.getBytes(content.readerIndex(), addrBytes);
57
58 try {
59 return InetAddress.getByAddress(decodeIdn ? IDN.toUnicode(name) : name, addrBytes);
60 } catch (UnknownHostException e) {
61 // Should never reach here.
62 throw new Error(e);
63 }
64 }
65
66 private DnsAddressDecoder() { }
67 }