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 de.measite.minidns.dnsserverlookup.AbstractDNSServerLookupMechanism;
23import de.measite.minidns.dnsserverlookup.AndroidUsingReflection;
24import de.measite.minidns.dnsserverlookup.DNSServerLookupMechanism;
25import de.measite.minidns.util.PlatformDetection;
26
27/**
28 * Try to retrieve the list of DNS server by executing getprop.
29 */
30public class AndroidUsingExecLowPriority extends AbstractDNSServerLookupMechanism {
31
32	public static final DNSServerLookupMechanism INSTANCE = new AndroidUsingExecLowPriority();
33	public static final int PRIORITY = AndroidUsingReflection.PRIORITY + 1;
34
35	private AndroidUsingExecLowPriority() {
36		super(AndroidUsingExecLowPriority.class.getSimpleName(), PRIORITY);
37	}
38
39	@Override
40	public String[] getDnsServerAddresses() {
41		try {
42			Process process = Runtime.getRuntime().exec("getprop");
43			InputStream inputStream = process.getInputStream();
44			LineNumberReader lnr = new LineNumberReader(
45					new InputStreamReader(inputStream));
46			String line;
47			HashSet<String> server = new HashSet<>(6);
48			while ((line = lnr.readLine()) != null) {
49				int split = line.indexOf("]: [");
50				if (split == -1) {
51					continue;
52				}
53				String property = line.substring(1, split);
54				String value = line.substring(split + 4, line.length() - 1);
55
56				if (value.isEmpty()) {
57					continue;
58				}
59
60				if (property.endsWith(".dns") || property.endsWith(".dns1") ||
61						property.endsWith(".dns2") || property.endsWith(".dns3") ||
62						property.endsWith(".dns4")) {
63
64					// normalize the address
65
66					InetAddress ip = InetAddress.getByName(value);
67
68					if (ip == null) continue;
69
70					value = ip.getHostAddress();
71
72					if (value == null) continue;
73					if (value.length() == 0) continue;
74
75					server.add(value);
76				}
77			}
78			if (server.size() > 0) {
79				return server.toArray(new String[server.size()]);
80			}
81		} catch (IOException e) {
82			LOGGER.log(Level.WARNING, "Exception in findDNSByExec", e);
83		}
84		return null;
85	}
86
87	@Override
88	public boolean isAvailable() {
89		return PlatformDetection.isAndroid();
90	}
91
92}