1/*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://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,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.net.dns;
18
19import static android.system.OsConstants.AI_ADDRCONFIG;
20
21import android.net.Network;
22import android.net.NetworkUtils;
23import android.system.GaiException;
24import android.system.OsConstants;
25import android.system.StructAddrinfo;
26
27import libcore.io.Libcore;
28
29import java.net.InetAddress;
30import java.net.UnknownHostException;
31
32
33/**
34 * DNS resolution utility class.
35 *
36 * @hide
37 */
38public class ResolvUtil {
39    // Non-portable DNS resolution flag.
40    private static final long NETID_USE_LOCAL_NAMESERVERS = 0x80000000L;
41
42    private ResolvUtil() {}
43
44    public static InetAddress[] blockingResolveAllLocally(Network network, String name)
45            throws UnknownHostException {
46        // Use AI_ADDRCONFIG by default
47        return blockingResolveAllLocally(network, name, AI_ADDRCONFIG);
48    }
49
50    public static InetAddress[] blockingResolveAllLocally(
51            Network network, String name, int aiFlags) throws UnknownHostException  {
52        final StructAddrinfo hints = new StructAddrinfo();
53        hints.ai_flags = aiFlags;
54        // Other hints identical to the default Inet6AddressImpl implementation
55        hints.ai_family = OsConstants.AF_UNSPEC;
56        hints.ai_socktype = OsConstants.SOCK_STREAM;
57
58        final Network networkForResolv = getNetworkWithUseLocalNameserversFlag(network);
59
60        try {
61            return Libcore.os.android_getaddrinfo(name, hints, (int) networkForResolv.netId);
62        } catch (GaiException gai) {
63            gai.rethrowAsUnknownHostException(name + ": TLS-bypass resolution failed");
64            return null;  // keep compiler quiet
65        }
66    }
67
68    public static Network getNetworkWithUseLocalNameserversFlag(Network network) {
69        final long netidForResolv = NETID_USE_LOCAL_NAMESERVERS | (long) network.netId;
70        return new Network((int) netidForResolv);
71    }
72
73    public static Network makeNetworkWithPrivateDnsBypass(Network network) {
74        return new Network(network) {
75            @Override
76            public InetAddress[] getAllByName(String host) throws UnknownHostException {
77                return blockingResolveAllLocally(network, host);
78            }
79        };
80    }
81}
82