Implemented DNS over TCP (very slow)

app/src/main/java/org/itxtech/daedalus/Daedalus.java

@@ -38,7 +38,8 @@ import java.util.List;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class Daedalus extends Application {
     private static final String SHORTCUT_ID_ACTIVATE = "shortcut_activate";

app/src/main/java/org/itxtech/daedalus/activity/DnsServerConfigActivity.java

@@ -21,7 +21,8 @@ import org.itxtech.daedalus.fragment.DnsServerConfigFragment;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class DnsServerConfigActivity extends AppCompatActivity {
     public static final String LAUNCH_ACTION_CUSTOM_DNS_SERVER_ID = "org.itxtech.daedalus.activity.DnsServerConfigActivity.LAUNCH_ACTION_CUSTOM_DNS_SERVER_ID";

app/src/main/java/org/itxtech/daedalus/activity/MainActivity.java

@@ -34,7 +34,8 @@ import org.itxtech.daedalus.fragment.*;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
     public static final String LAUNCH_ACTION = "org.itxtech.daedalus.activity.MainActivity.LAUNCH_ACTION";

app/src/main/java/org/itxtech/daedalus/fragment/AboutFragment.java

@@ -25,7 +25,8 @@ import java.util.Locale;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class AboutFragment extends Fragment {
     private WebView mWebView = null;

app/src/main/java/org/itxtech/daedalus/fragment/DnsServerConfigFragment.java

@@ -25,7 +25,8 @@ import org.itxtech.daedalus.util.DnsServer;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class DnsServerConfigFragment extends PreferenceFragment implements Toolbar.OnMenuItemClickListener {
     private Intent intent = null;

app/src/main/java/org/itxtech/daedalus/fragment/DnsServersFragment.java

@@ -24,7 +24,8 @@ import org.itxtech.daedalus.util.CustomDnsServer;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class DnsServersFragment extends Fragment {
     private DnsServersFragment.DnsServerAdapter adapter;

app/src/main/java/org/itxtech/daedalus/fragment/DnsTestFragment.java

@@ -37,7 +37,8 @@ import java.util.Set;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class DnsTestFragment extends Fragment {
     private static final String TAG = "DServerTest";

app/src/main/java/org/itxtech/daedalus/fragment/HostsFragment.java

@@ -30,7 +30,8 @@ import java.util.Date;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class HostsFragment extends Fragment {
 

app/src/main/java/org/itxtech/daedalus/fragment/MainFragment.java

@@ -26,7 +26,8 @@ import org.itxtech.daedalus.util.DnsServerHelper;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class MainFragment extends Fragment {
 

app/src/main/java/org/itxtech/daedalus/fragment/SettingsFragment.java

@@ -21,7 +21,8 @@ import org.itxtech.daedalus.util.DnsServerHelper;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class SettingsFragment extends PreferenceFragment {
     private View view = null;

app/src/main/java/org/itxtech/daedalus/provider/DnsProvider.java

@@ -11,7 +11,8 @@ import org.itxtech.daedalus.service.DaedalusVpnService;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public abstract class DnsProvider {
     ParcelFileDescriptor descriptor;

app/src/main/java/org/itxtech/daedalus/provider/TcpDnsProvider.java

@@ -0,0 +1,264 @@
+package org.itxtech.daedalus.provider;
+
+import android.annotation.TargetApi;
+import android.os.Build;
+import android.os.ParcelFileDescriptor;
+import android.system.ErrnoException;
+import android.system.Os;
+import android.system.OsConstants;
+import android.system.StructPollfd;
+import android.util.Log;
+import de.measite.minidns.DNSMessage;
+import org.itxtech.daedalus.service.DaedalusVpnService;
+import org.itxtech.daedalus.util.DnsServerHelper;
+import org.pcap4j.packet.*;
+
+import java.io.*;
+import java.net.*;
+import java.nio.channels.SocketChannel;
+import java.util.Iterator;
+import java.util.LinkedList;
+
+/**
+ * @author PeratX
+ */
+public class TcpDnsProvider extends UdpDnsProvider {
+
+    private static final String TAG = "TcpDnsProvider";
+
+    private final TcpDnsProvider.WospList dnsIn = new TcpDnsProvider.WospList();
+
+    public TcpDnsProvider(ParcelFileDescriptor descriptor, DaedalusVpnService service) {
+        super(descriptor, service);
+    }
+
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+    public void process() {
+        try {
+            Log.d(TAG, "Starting advanced DNS proxy.");
+            FileDescriptor[] pipes = Os.pipe();
+            mInterruptFd = pipes[0];
+            mBlockFd = pipes[1];
+            FileInputStream inputStream = new FileInputStream(descriptor.getFileDescriptor());
+            FileOutputStream outputStream = new FileOutputStream(descriptor.getFileDescriptor());
+
+            byte[] packet = new byte[32767];
+            while (running) {
+                StructPollfd deviceFd = new StructPollfd();
+                deviceFd.fd = inputStream.getFD();
+                deviceFd.events = (short) OsConstants.POLLIN;
+                StructPollfd blockFd = new StructPollfd();
+                blockFd.fd = mBlockFd;
+                blockFd.events = (short) (OsConstants.POLLHUP | OsConstants.POLLERR);
+
+                if (!deviceWrites.isEmpty())
+                    deviceFd.events |= (short) OsConstants.POLLOUT;
+
+                StructPollfd[] polls = new StructPollfd[2 + dnsIn.size()];
+                polls[0] = deviceFd;
+                polls[1] = blockFd;
+                {
+                    int i = -1;
+                    for (TcpDnsProvider.WaitingOnSocketPacket wosp : dnsIn) {
+                        i++;
+                        StructPollfd pollFd = polls[2 + i] = new StructPollfd();
+                        pollFd.fd = ParcelFileDescriptor.fromSocket(wosp.socket).getFileDescriptor();
+                        pollFd.events = (short) OsConstants.POLLIN;
+                    }
+                }
+
+                Log.d(TAG, "doOne: Polling " + polls.length + " file descriptors");
+                Os.poll(polls, -1);
+                if (blockFd.revents != 0) {
+                    Log.i(TAG, "Told to stop VPN");
+                    running = false;
+                    return;
+                }
+
+                // Need to do this before reading from the device, otherwise a new insertion there could
+                // invalidate one of the sockets we want to read from either due to size or time out
+                // constraints
+                {
+                    int i = -1;
+                    Iterator<TcpDnsProvider.WaitingOnSocketPacket> iter = dnsIn.iterator();
+                    while (iter.hasNext()) {
+                        i++;
+                        TcpDnsProvider.WaitingOnSocketPacket wosp = iter.next();
+                        if ((polls[i + 2].revents & OsConstants.POLLIN) != 0) {
+                            Log.d(TAG, "Read from TCP DNS socket" + wosp.socket);
+                            iter.remove();
+                            handleRawDnsResponse(wosp.packet, wosp.socket);
+                            wosp.socket.close();
+                        }
+                    }
+                }
+                if ((deviceFd.revents & OsConstants.POLLOUT) != 0) {
+                    Log.d(TAG, "Write to device");
+                    writeToDevice(outputStream);
+                }
+                if ((deviceFd.revents & OsConstants.POLLIN) != 0) {
+                    Log.d(TAG, "Read from device");
+                    readPacketFromDevice(inputStream, packet);
+                }
+
+                checkCache();
+
+                service.providerLoopCallback();
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    private byte[] processUdpPacket(DatagramPacket outPacket, IpPacket parsedPacket) {
+        if (parsedPacket == null) {
+            return new byte[0];
+        }
+        return outPacket.getData();
+    }
+
+    void forwardPacket(DatagramPacket outPacket, IpPacket parsedPacket) throws DaedalusVpnService.VpnNetworkException {
+        Socket dnsSocket;
+        try {
+            // Packets to be sent to the real DNS server will need to be protected from the VPN
+            dnsSocket = SocketChannel.open().socket();
+
+            Log.d(TAG, String.valueOf(service.protect(dnsSocket)));
+
+            SocketAddress address = new InetSocketAddress(outPacket.getAddress(), DnsServerHelper.getPortOrDefault(outPacket.getAddress(), outPacket.getPort()));
+            dnsSocket.connect(address, 5000);
+            dnsSocket.setSoTimeout(5000);
+            Log.d(TAG, "Sending");
+            DataOutputStream dos = new DataOutputStream(dnsSocket.getOutputStream());
+            byte[] packet = processUdpPacket(outPacket, parsedPacket);
+            dos.writeShort(packet.length);
+            dos.write(packet);
+            dos.flush();
+
+            if (parsedPacket != null) {
+                dnsIn.add(new TcpDnsProvider.WaitingOnSocketPacket(dnsSocket, parsedPacket));
+            } else {
+                dnsSocket.close();
+            }
+        } catch (IOException e) {
+            if (e.getCause() instanceof ErrnoException) {
+                ErrnoException errnoExc = (ErrnoException) e.getCause();
+                if ((errnoExc.errno == OsConstants.ENETUNREACH) || (errnoExc.errno == OsConstants.EPERM)) {
+                    throw new DaedalusVpnService.VpnNetworkException("Cannot send message:", e);
+                }
+            }
+            Log.w(TAG, "handleDnsRequest: Could not send packet to upstream", e);
+        }
+    }
+
+    private void handleRawDnsResponse(IpPacket parsedPacket, Socket dnsSocket) throws IOException, IllegalRawDataException {
+        if (!dnsSocket.isClosed()) {
+            DataInputStream stream = new DataInputStream(dnsSocket.getInputStream());
+            int length = stream.readUnsignedShort();
+            Log.d(TAG, "Reading length: " + String.valueOf(length));
+            byte[] data = new byte[length];
+            stream.read(data);
+            dnsSocket.close();
+            handleDnsResponse(parsedPacket, data);
+        }
+    }
+
+
+    /**
+     * Handles a responsePayload from an upstream DNS server
+     *
+     * @param requestPacket   The original request packet
+     * @param responsePayload The payload of the response
+     */
+    private void handleDnsResponse(IpPacket requestPacket, byte[] responsePayload) throws IllegalRawDataException, IOException {
+        DNSMessage message = new DNSMessage(responsePayload);
+        Log.d(TAG, message.toString());
+
+        UdpPacket udpOutPacket = (UdpPacket) requestPacket.getPayload();
+        UdpPacket.Builder payLoadBuilder = new UdpPacket.Builder(udpOutPacket)
+                .srcPort(udpOutPacket.getHeader().getDstPort())
+                .dstPort(udpOutPacket.getHeader().getSrcPort())
+                .srcAddr(requestPacket.getHeader().getDstAddr())
+                .dstAddr(requestPacket.getHeader().getSrcAddr())
+                .correctChecksumAtBuild(true)
+                .correctLengthAtBuild(true)
+                .payloadBuilder(
+                        new UnknownPacket.Builder()
+                                .rawData(responsePayload)
+                );
+
+
+        IpPacket ipOutPacket;
+        if (requestPacket instanceof IpV4Packet) {
+            ipOutPacket = new IpV4Packet.Builder((IpV4Packet) requestPacket)
+                    .srcAddr((Inet4Address) requestPacket.getHeader().getDstAddr())
+                    .dstAddr((Inet4Address) requestPacket.getHeader().getSrcAddr())
+                    .correctChecksumAtBuild(true)
+                    .correctLengthAtBuild(true)
+                    .payloadBuilder(payLoadBuilder)
+                    .build();
+
+        } else {
+            ipOutPacket = new IpV6Packet.Builder((IpV6Packet) requestPacket)
+                    .srcAddr((Inet6Address) requestPacket.getHeader().getDstAddr())
+                    .dstAddr((Inet6Address) requestPacket.getHeader().getSrcAddr())
+                    .correctLengthAtBuild(true)
+                    .payloadBuilder(payLoadBuilder)
+                    .build();
+        }
+
+        queueDeviceWrite(ipOutPacket);
+    }
+
+    /**
+     * Helper class holding a socket, the packet we are waiting the answer for, and a time
+     */
+    private static class WaitingOnSocketPacket {
+        final Socket socket;
+        final IpPacket packet;
+        private final long time;
+
+        WaitingOnSocketPacket(Socket socket, IpPacket packet) {
+            this.socket = socket;
+            this.packet = packet;
+            this.time = System.currentTimeMillis();
+        }
+
+        long ageSeconds() {
+            return (System.currentTimeMillis() - time) / 1000;
+        }
+    }
+
+    /**
+     * Queue of WaitingOnSocketPacket, bound on time and space.
+     */
+    private static class WospList implements Iterable<TcpDnsProvider.WaitingOnSocketPacket> {
+        private final LinkedList<TcpDnsProvider.WaitingOnSocketPacket> list = new LinkedList<>();
+
+        void add(TcpDnsProvider.WaitingOnSocketPacket wosp) {
+            try {
+                if (list.size() > 1024) {
+                    Log.d(TAG, "Dropping socket due to space constraints: " + list.element().socket);
+                    list.element().socket.close();
+                    list.remove();
+                }
+                while (!list.isEmpty() && list.element().ageSeconds() > 10) {
+                    Log.d(TAG, "Timeout on socket " + list.element().socket);
+                    list.element().socket.close();
+                    list.remove();
+                }
+                list.add(wosp);
+            } catch (Exception ignored) {
+            }
+        }
+
+        public Iterator<TcpDnsProvider.WaitingOnSocketPacket> iterator() {
+            return list.iterator();
+        }
+
+        int size() {
+            return list.size();
+        }
+
+    }
+}

app/src/main/java/org/itxtech/daedalus/provider/UdpDnsProvider.java

@@ -37,15 +37,16 @@ import java.util.Queue;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class UdpDnsProvider extends DnsProvider {
     private static final String TAG = "UdpDnsProvider";
 
     private final WospList dnsIn = new WospList();
-    private FileDescriptor mBlockFd = null;
+    FileDescriptor mBlockFd = null;
-    private FileDescriptor mInterruptFd = null;
+    FileDescriptor mInterruptFd = null;
-    private final Queue<byte[]> deviceWrites = new LinkedList<>();
+    final Queue<byte[]> deviceWrites = new LinkedList<>();
 
     /**
      * Number of iterations since we last cleared the pcap4j cache
@@ -73,7 +74,7 @@ public class UdpDnsProvider extends DnsProvider {
         }
     }
 
-    private void queueDeviceWrite(IpPacket ipOutPacket) {
+    void queueDeviceWrite(IpPacket ipOutPacket) {
         dnsQueryTimes++;
         Log.i(TAG, "QT " + dnsQueryTimes);
         deviceWrites.add(ipOutPacket.getRawData());
@@ -132,7 +133,7 @@ public class UdpDnsProvider extends DnsProvider {
                         i++;
                         WaitingOnSocketPacket wosp = iter.next();
                         if ((polls[i + 2].revents & OsConstants.POLLIN) != 0) {
-                            Log.d(TAG, "Read from DNS socket" + wosp.socket);
+                            Log.d(TAG, "Read from UDP DNS socket" + wosp.socket);
                             iter.remove();
                             handleRawDnsResponse(wosp.packet, wosp.socket);
                             wosp.socket.close();
@@ -148,6 +149,15 @@ public class UdpDnsProvider extends DnsProvider {
                     readPacketFromDevice(inputStream, packet);
                 }
 
+                checkCache();
+                service.providerLoopCallback();
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    void checkCache() {
         // pcap4j has some sort of properties cache in the packet factory. This cache leaks, so
         // we need to clean it up.
         if (++pcap4jFactoryClearCacheCounter % 1024 == 0) {
@@ -164,15 +174,9 @@ public class UdpDnsProvider extends DnsProvider {
                 Log.e(TAG, "Cannot get declared loader field", e);
             }
         }
-                service.providerLoopCallback();
-            }
-        } catch (Exception e) {
-            e.printStackTrace();
-        }
     }
 
-
+    void writeToDevice(FileOutputStream outFd) throws DaedalusVpnService.VpnNetworkException {
-    private void writeToDevice(FileOutputStream outFd) throws DaedalusVpnService.VpnNetworkException {
         try {
             outFd.write(deviceWrites.poll());
         } catch (IOException e) {
@@ -181,7 +185,7 @@ public class UdpDnsProvider extends DnsProvider {
         }
     }
 
-    private void readPacketFromDevice(FileInputStream inputStream, byte[] packet) throws DaedalusVpnService.VpnNetworkException, SocketException {
+    void readPacketFromDevice(FileInputStream inputStream, byte[] packet) throws DaedalusVpnService.VpnNetworkException, SocketException {
         // Read the outgoing packet from the input stream.
         int length;
 
@@ -203,7 +207,7 @@ public class UdpDnsProvider extends DnsProvider {
         handleDnsRequest(readPacket);
     }
 
-    private void forwardPacket(DatagramPacket outPacket, IpPacket parsedPacket) throws DaedalusVpnService.VpnNetworkException {
+    void forwardPacket(DatagramPacket outPacket, IpPacket parsedPacket) throws DaedalusVpnService.VpnNetworkException {
         DatagramSocket dnsSocket;
         try {
             // Packets to be sent to the real DNS server will need to be protected from the VPN

app/src/main/java/org/itxtech/daedalus/receiver/BootBroadcastReceiver.java

@@ -17,7 +17,8 @@ import org.itxtech.daedalus.util.DnsServerHelper;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class BootBroadcastReceiver extends BroadcastReceiver {
     @Override

app/src/main/java/org/itxtech/daedalus/receiver/StatusBarBroadcastReceiver.java

@@ -17,7 +17,8 @@ import java.lang.reflect.Method;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class StatusBarBroadcastReceiver extends BroadcastReceiver {
     public static String STATUS_BAR_BTN_DEACTIVATE_CLICK_ACTION = "org.itxtech.daedalus.receiver.StatusBarBroadcastReceiver.STATUS_BAR_BTN_DEACTIVATE_CLICK_ACTION";

app/src/main/java/org/itxtech/daedalus/service/DaedalusVpnService.java

@@ -16,6 +16,7 @@ import org.itxtech.daedalus.Daedalus;
 import org.itxtech.daedalus.R;
 import org.itxtech.daedalus.activity.MainActivity;
 import org.itxtech.daedalus.provider.DnsProvider;
+import org.itxtech.daedalus.provider.TcpDnsProvider;
 import org.itxtech.daedalus.provider.UdpDnsProvider;
 import org.itxtech.daedalus.receiver.StatusBarBroadcastReceiver;
 import org.itxtech.daedalus.util.DnsServerHelper;
@@ -31,7 +32,8 @@ import java.net.Inet4Address;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class DaedalusVpnService extends VpnService implements Runnable {
     public static final String ACTION_ACTIVATE = "org.itxtech.daedalus.service.DaedalusVpnService.ACTION_ACTIVATE";
@@ -191,7 +193,11 @@ public class DaedalusVpnService extends VpnService implements Runnable {
             ParcelFileDescriptor descriptor = builder.establish();
 
             if (advanced) {
+                if (Daedalus.getPrefs().getBoolean("settings_dns_over_tcp", false)) {
+                    provider = new TcpDnsProvider(descriptor, this);
+                } else {
                     provider = new UdpDnsProvider(descriptor, this);
+                }
                 provider.start();
                 provider.process();
             } else {

app/src/main/java/org/itxtech/daedalus/util/Configurations.java

@@ -18,7 +18,8 @@ import java.util.ArrayList;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class Configurations {
     private static final int CUSTOM_DNS_ID_START = 32;

app/src/main/java/org/itxtech/daedalus/util/CustomDnsServer.java

@@ -10,7 +10,8 @@ import org.itxtech.daedalus.Daedalus;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class CustomDnsServer {
     private String name;

app/src/main/java/org/itxtech/daedalus/util/DnsServer.java

@@ -10,7 +10,8 @@ import android.content.Context;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class DnsServer {
     public static int DNS_SERVER_DEFAULT_PORT = 53;

app/src/main/java/org/itxtech/daedalus/util/DnsServerHelper.java

@@ -15,7 +15,8 @@ import java.util.HashMap;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class DnsServerHelper {
     private static HashMap<String, Integer> portCache = null;

app/src/main/java/org/itxtech/daedalus/util/HostsProvider.java

@@ -12,7 +12,8 @@ import java.util.ArrayList;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class HostsProvider {
     private String name;

app/src/main/java/org/itxtech/daedalus/util/HostsResolver.java

@@ -16,7 +16,8 @@ import java.util.HashMap;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class HostsResolver implements Runnable {
     private static final String TAG = "DHostsResolver";

app/src/main/java/org/itxtech/daedalus/view/ClearAutoCompleteTextView.java

@@ -20,7 +20,8 @@ import org.itxtech.daedalus.R;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class ClearAutoCompleteTextView extends AutoCompleteTextView implements View.OnTouchListener, View.OnFocusChangeListener, TextWatcher {
 

app/src/main/java/org/itxtech/daedalus/view/ClickPreference.java

@@ -1,6 +1,8 @@
 package org.itxtech.daedalus.view;
 
+import android.annotation.TargetApi;
 import android.content.Context;
+import android.os.Build;
 import android.preference.ListPreference;
 import android.util.AttributeSet;
 
@@ -12,10 +14,12 @@ import android.util.AttributeSet;
  * <p>
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
  */
 public class ClickPreference extends ListPreference {
 
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
     public ClickPreference(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
     }