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;
16
17import de.measite.minidns.dnsserverlookup.AbstractDNSServerLookupMechanism;
18import de.measite.minidns.dnsserverlookup.AndroidUsingExec;
19
20public class AndroidUsingLinkProperties extends AbstractDNSServerLookupMechanism {
21
22    private final Context context;
23
24    protected AndroidUsingLinkProperties(Context context) {
25        super(AndroidUsingLinkProperties.class.getSimpleName(), AndroidUsingExec.PRIORITY - 1);
26        this.context = context;
27    }
28
29    @Override
30    public boolean isAvailable() {
31        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP;
32    }
33
34    @Override
35    @TargetApi(21)
36    public String[] getDnsServerAddresses() {
37        ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
38        Network[] networks = connectivityManager == null ? null : connectivityManager.getAllNetworks();
39        if (networks == null) {
40            return new String[0];
41        }
42        final Network activeNetwork = getActiveNetwork(connectivityManager);
43        List<String> servers = new ArrayList<>();
44        int vpnOffset = 0;
45        for(Network network : networks) {
46            LinkProperties linkProperties = connectivityManager.getLinkProperties(network);
47            if (linkProperties == null) {
48                continue;
49            }
50            NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);
51            final boolean isActiveNetwork = network.equals(activeNetwork);
52            if (networkInfo != null && isActiveNetwork && networkInfo.getType() == ConnectivityManager.TYPE_VPN) {
53                final List<String> tmp = getIPv4First(linkProperties.getDnsServers());
54                servers.addAll(0, tmp);
55                vpnOffset += tmp.size();
56            } else if (hasDefaultRoute(linkProperties) || isActiveNetwork) {
57                servers.addAll(vpnOffset, getIPv4First(linkProperties.getDnsServers()));
58            } else {
59                servers.addAll(getIPv4First(linkProperties.getDnsServers()));
60            }
61        }
62        return servers.toArray(new String[servers.size()]);
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 addr : in) {
73            if (addr instanceof Inet4Address) {
74                out.add(0, addr.getHostAddress());
75            } else {
76                out.add(addr.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}