1 files changed, 90 insertions, 0 deletions
diff --git a/src/main/java/de/pixart/messenger/utils/AndroidUsingLinkProperties.java b/src/main/java/de/pixart/messenger/utils/AndroidUsingLinkProperties.java
new file mode 100644
index 000000000..f2f33dc1b
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/utils/AndroidUsingLinkProperties.java
@@ -0,0 +1,90 @@
+package de.pixart.messenger.utils;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.NetworkInfo;
+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;
+
+    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() {
+        final ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+        final Network[] networks = connectivityManager == null ? null : connectivityManager.getAllNetworks();
+        if (networks == null) {
+            return new String[0];
+        }
+        final Network activeNetwork = getActiveNetwork(connectivityManager);
+        final List<String> servers = new ArrayList<>();
+        int vpnOffset = 0;
+        for (Network network : networks) {
+            LinkProperties linkProperties = connectivityManager.getLinkProperties(network);
+            if (linkProperties == null) {
+                continue;
+            }
+            final NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);
+            final boolean isActiveNetwork = network.equals(activeNetwork);
+            final boolean isVpn = networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_VPN;
+            if (isActiveNetwork && isVpn) {
+                final List<String> tmp = getIPv4First(linkProperties.getDnsServers());
+                servers.addAll(0, tmp);
+                vpnOffset += tmp.size();
+            } else if (hasDefaultRoute(linkProperties) || isActiveNetwork || activeNetwork == null || isVpn) {
+                servers.addAll(vpnOffset, getIPv4First(linkProperties.getDnsServers()));
+            }
+        }
+        return servers.toArray(new String[0]);
+    }
+
+    @TargetApi(23)
+    private static Network getActiveNetwork(ConnectivityManager cm) {
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M ? cm.getActiveNetwork() : null;
+    }
+
+    private static List<String> getIPv4First(List<InetAddress> in) {
+        List<String> out = new ArrayList<>();
+        for (InetAddress address : in) {
+            if (address instanceof Inet4Address) {
+                out.add(0, address.getHostAddress());
+            } else {
+                out.add(address.getHostAddress());
+            }
+        }
+        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;
+    }
+}
+\ No newline at end of file