package eu.siacs.conversations.utils; import android.annotation.TargetApi; import android.content.Context; import android.net.ConnectivityManager; import android.net.LinkProperties; import android.net.Network; import android.net.RouteInfo; import android.os.Build; import java.net.Inet4Address; import java.net.InetAddress; import java.util.ArrayList; import java.util.List; import de.measite.minidns.dnsserverlookup.AbstractDNSServerLookupMechanism; import de.measite.minidns.dnsserverlookup.AndroidUsingExec; public class AndroidUsingLinkProperties extends AbstractDNSServerLookupMechanism { private final Context context; protected AndroidUsingLinkProperties(Context context) { super(AndroidUsingLinkProperties.class.getSimpleName(), AndroidUsingExec.PRIORITY - 1); this.context = context; } @Override public boolean isAvailable() { return Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP; } @Override @TargetApi(21) public String[] getDnsServerAddresses() { ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); Network[] networks = connectivityManager == null ? null : connectivityManager.getAllNetworks(); if (networks == null) { return new String[0]; } List servers = new ArrayList<>(); for(Network network : networks) { LinkProperties linkProperties = connectivityManager.getLinkProperties(network); if (linkProperties != null) { if (hasDefaultRoute(linkProperties)) { servers.addAll(0, getIPv4First(linkProperties.getDnsServers())); } else { servers.addAll(getIPv4First(linkProperties.getDnsServers())); } } } return servers.toArray(new String[servers.size()]); } private static List getIPv4First(List in) { List out = new ArrayList<>(); for(InetAddress addr : in) { if (addr instanceof Inet4Address) { out.add(0, addr.toString()); } else { out.add(addr.toString()); } } return out; } @TargetApi(Build.VERSION_CODES.LOLLIPOP) private static boolean hasDefaultRoute(LinkProperties linkProperties) { for(RouteInfo route: linkProperties.getRoutes()) { if (route.isDefaultRoute()) { return true; } } return false; } }