1/*
 2 * Copyright 2015-2016 the original author or authors
 3 *
 4 * This software is licensed under the Apache License, Version 2.0,
 5 * the GNU Lesser General Public License version 2 or later ("LGPL")
 6 * and the WTFPL.
 7 * You may choose either license to govern your use of this software only
 8 * upon the condition that you accept all of the terms of either
 9 * the Apache License 2.0, the LGPL 2.1+ or the WTFPL.
10 */
11package eu.siacs.conversations.utils;
12
13
14import java.io.IOException;
15import java.io.InputStream;
16import java.io.InputStreamReader;
17import java.io.LineNumberReader;
18import java.net.InetAddress;
19import java.util.HashSet;
20import java.util.logging.Level;
21
22import java.util.ArrayList;
23import java.util.List;
24
25import org.minidns.dnsserverlookup.AbstractDnsServerLookupMechanism;
26import org.minidns.dnsserverlookup.AndroidUsingReflection;
27import org.minidns.dnsserverlookup.DnsServerLookupMechanism;
28import org.minidns.util.PlatformDetection;
29
30/**
31 * Try to retrieve the list of DNS server by executing getprop.
32 */
33public class AndroidUsingExecLowPriority extends AbstractDnsServerLookupMechanism {
34
35	public static final DnsServerLookupMechanism INSTANCE = new AndroidUsingExecLowPriority();
36	public static final int PRIORITY = AndroidUsingReflection.PRIORITY + 1;
37
38	private AndroidUsingExecLowPriority() {
39		super(AndroidUsingExecLowPriority.class.getSimpleName(), PRIORITY);
40	}
41
42	@Override
43	public List<String> getDnsServerAddresses() {
44		try {
45			Process process = Runtime.getRuntime().exec("getprop");
46			InputStream inputStream = process.getInputStream();
47			LineNumberReader lnr = new LineNumberReader(
48					new InputStreamReader(inputStream));
49			String line;
50			HashSet<String> server = new HashSet<>(6);
51			while ((line = lnr.readLine()) != null) {
52				int split = line.indexOf("]: [");
53				if (split == -1) {
54					continue;
55				}
56				String property = line.substring(1, split);
57				String value = line.substring(split + 4, line.length() - 1);
58
59				if (value.isEmpty()) {
60					continue;
61				}
62
63				if (property.endsWith(".dns") || property.endsWith(".dns1") ||
64						property.endsWith(".dns2") || property.endsWith(".dns3") ||
65						property.endsWith(".dns4")) {
66
67					// normalize the address
68
69					InetAddress ip = InetAddress.getByName(value);
70
71					if (ip == null) continue;
72
73					value = ip.getHostAddress();
74
75					if (value == null) continue;
76					if (value.length() == 0) continue;
77
78					server.add(value);
79				}
80			}
81			if (server.size() > 0) {
82				return new ArrayList<>(server);
83			}
84		} catch (IOException e) {
85			LOGGER.log(Level.WARNING, "Exception in findDNSByExec", e);
86		}
87		return null;
88	}
89
90	@Override
91	public boolean isAvailable() {
92		return PlatformDetection.isAndroid();
93	}
94
95}