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.netty5.resolver.dns;
17
18 import io.netty5.buffer.api.Buffer;
19 import io.netty5.handler.codec.dns.DnsRawRecord;
20 import io.netty5.handler.codec.dns.DnsRecord;
21
22 import java.net.IDN;
23 import java.net.InetAddress;
24 import java.net.UnknownHostException;
25
26 /**
27 * Decodes an {@link InetAddress} from an A or AAAA {@link DnsRawRecord}.
28 */
29 final class DnsAddressDecoder {
30
31 private static final int INADDRSZ4 = 4;
32 private static final int INADDRSZ6 = 16;
33
34 /**
35 * Decodes an {@link InetAddress} from an A or AAAA {@link DnsRawRecord}.
36 *
37 * @param record the {@link DnsRecord}, most likely a {@link DnsRawRecord}
38 * @param name the host name of the decoded address
39 * @param decodeIdn whether to convert {@code name} to a unicode host name
40 *
41 * @return the {@link InetAddress}, or {@code null} if {@code record} is not a {@link DnsRawRecord} or
42 * its content is malformed
43 */
44 static InetAddress decodeAddress(DnsRecord record, String name, boolean decodeIdn) {
45 if (!(record instanceof DnsRawRecord)) {
46 return null;
47 }
48 final Buffer content = ((DnsRawRecord) record).content();
49 final int contentLen = content.readableBytes();
50 if (contentLen != INADDRSZ4 && contentLen != INADDRSZ6) {
51 return null;
52 }
53
54 final byte[] addrBytes = new byte[contentLen];
55 content.copyInto(content.readerOffset(), addrBytes, 0, addrBytes.length);
56
57 try {
58 return InetAddress.getByAddress(decodeIdn ? IDN.toUnicode(name) : name, addrBytes);
59 } catch (UnknownHostException e) {
60 // Should never reach here.
61 throw new Error(e);
62 }
63 }
64
65 private DnsAddressDecoder() { }
66 }