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 org.minidns.dnsserverlookup.AbstractDnsServerLookupMechanism;
18import org.minidns.dnsserverlookup.AndroidUsingExec;
19
20public class AndroidUsingLinkProperties extends AbstractDnsServerLookupMechanism {
21
22    private final Context context;
23
24    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 List<String> getDnsServerAddresses() {
37        final ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
38        final Network[] networks = connectivityManager == null ? null : connectivityManager.getAllNetworks();
39        if (networks == null) {
40            return new ArrayList<>();
41        }
42        final Network activeNetwork = getActiveNetwork(connectivityManager);
43        final 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            final NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);
51            final boolean isActiveNetwork = network.equals(activeNetwork);
52            final boolean isVpn = networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_VPN;
53            if (isActiveNetwork && isVpn) {
54                final List<String> tmp = getIPv4First(linkProperties.getDnsServers());
55                servers.addAll(0, tmp);
56                vpnOffset += tmp.size();
57            } else if (hasDefaultRoute(linkProperties) || isActiveNetwork || activeNetwork == null || isVpn) {
58                servers.addAll(vpnOffset, getIPv4First(linkProperties.getDnsServers()));
59            }
60        }
61        return servers;
62    }
63
64    @TargetApi(23)
65    private static Network getActiveNetwork(ConnectivityManager cm) {
66        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M ? cm.getActiveNetwork() : null;
67    }
68
69    private static List<String> getIPv4First(List<InetAddress> in) {
70        List<String> out = new ArrayList<>();
71        for(InetAddress address : in) {
72            if (address instanceof Inet4Address) {
73                out.add(0, address.getHostAddress());
74            } else {
75                out.add(address.getHostAddress());
76            }
77        }
78        return out;
79    }
80
81    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
82    private static boolean hasDefaultRoute(LinkProperties linkProperties) {
83        for(RouteInfo route: linkProperties.getRoutes()) {
84            if (route.isDefaultRoute()) {
85                return true;
86            }
87        }
88        return false;
89    }
90}