1package eu.siacs.conversations.utils;
 2
 3import android.annotation.TargetApi;
 4import android.content.Context;
 5import android.net.ConnectivityManager;
 6import android.net.LinkProperties;
 7import android.net.Network;
 8import android.net.NetworkInfo;
 9import android.net.RouteInfo;
10import android.os.Build;
11
12import java.net.Inet4Address;
13import java.net.InetAddress;
14import java.util.ArrayList;
15import java.util.List;
16import java.util.stream.Collectors;
17
18import org.minidns.dnsserverlookup.AbstractDnsServerLookupMechanism;
19import org.minidns.dnsserverlookup.AndroidUsingExec;
20
21public class AndroidUsingLinkProperties extends AbstractDnsServerLookupMechanism {
22
23    private final Context context;
24
25    AndroidUsingLinkProperties(Context context) {
26        super(AndroidUsingLinkProperties.class.getSimpleName(), AndroidUsingExec.PRIORITY - 1);
27        this.context = context;
28    }
29
30    @Override
31    public boolean isAvailable() {
32        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP;
33    }
34
35    @Override
36    @TargetApi(21)
37    public List<String> getDnsServerAddresses() {
38        final ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
39        final Network[] networks = connectivityManager == null ? null : connectivityManager.getAllNetworks();
40        if (networks == null) {
41            return new ArrayList<>();
42        }
43        final Network activeNetwork = getActiveNetwork(connectivityManager);
44        final List<String> servers = new ArrayList<>();
45        int offset = 0;
46        for(Network network : networks) {
47            LinkProperties linkProperties = connectivityManager.getLinkProperties(network);
48            if (linkProperties == null) {
49                continue;
50            }
51            final NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);
52            final boolean isActiveNetwork = network.equals(activeNetwork);
53            final boolean isVpn = networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_VPN;
54            if (isActiveNetwork) {
55                final List<String> tmp = getIPv4First(linkProperties.getDnsServers());
56                servers.addAll(0, tmp);
57                offset += tmp.size();
58            } else if (hasDefaultRoute(linkProperties) || isActiveNetwork || activeNetwork == null || isVpn) {
59				servers.addAll(offset, getIPv4First(linkProperties.getDnsServers()));
60            }
61        }
62        return servers.stream().distinct().collect(Collectors.toList());
63    }
64
65    @TargetApi(23)
66    private static Network getActiveNetwork(ConnectivityManager cm) {
67        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M ? cm.getActiveNetwork() : null;
68    }
69
70    private static List<String> getIPv4First(List<InetAddress> in) {
71        List<String> out = new ArrayList<>();
72        for(InetAddress address : in) {
73            if (address instanceof Inet4Address) {
74                out.add(0, address.getHostAddress());
75            } else {
76                out.add(address.getHostAddress());
77            }
78        }
79        return out;
80    }
81
82    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
83    private static boolean hasDefaultRoute(LinkProperties linkProperties) {
84        for(RouteInfo route: linkProperties.getRoutes()) {
85            if (route.isDefaultRoute()) {
86                return true;
87            }
88        }
89        return false;
90    }
91}