18 files changed, 1094 insertions, 0 deletions
diff --git a/mobile-kt/app/AndroidManifest.xml b/mobile-kt/app/AndroidManifest.xml
new file mode 100644
index 0000000..0c417b7
--- /dev/null
+++ b/mobile-kt/app/AndroidManifest.xml
@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<manifest
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    package="org.image-sync"
+    android:versionCode="1"
+    android:versionName="1.0.0"
+>
+    <uses-sdk
+        android:minSdkVersion="28"
+        android:targetSdkVersion="30"
+    />
+
+    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
+    <uses-permission android:name="android.permission.READ_SMS" />
+    <uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
+
+    <application
+        android:icon="@drawable/logo"
+        android:usesCleartextTraffic="true"
+    >
+        <!-- <service
+            android:name=".WifiListenerService"
+            android:foregroundServiceType="location"
+        ></service> -->
+
+        <activity
+            android:name=".MainActivity"
+            android:label="@string/app_label"
+            android:screenOrientation="portrait"
+        >
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+        <!-- <activity
+            android:name=".SettingsActivity"
+            android:label="@string/menu_settings"
+            android:parentActivityName=".MainActivity">
+
+            <meta-data
+                android:name="android.support.PARENT_ACTIVITY"
+                android:value=".MainActivity"
+            />
+        </activity> -->
+    </application>
+</manifest>
diff --git a/mobile-kt/app/BUILD b/mobile-kt/app/BUILD
new file mode 100644
index 0000000..c3e38c2
--- /dev/null
+++ b/mobile-kt/app/BUILD
@@ -0,0 +1,18 @@
+android_library(
+    name = "main",
+    manifest = "AndroidManifest.xml",
+    resource_files = glob(["res/**"]),
+)
+
+load("@rules_kotlin//kotlin:android.bzl", "kt_android_library")
+kt_android_library(
+    name = "main_kt",
+    srcs = glob(["src/*.kt"]),
+    deps = [":main"],
+)
+
+android_binary(
+    name = "image-sync",
+    manifest = "AndroidManifest.xml",
+    deps = [":main", ":main_kt"],
+)
diff --git a/mobile-kt/app/res/drawable/logo.png b/mobile-kt/app/res/drawable/logo.png
new file mode 100644
index 0000000..154b579
--- /dev/null
+++ b/mobile-kt/app/res/drawable/logo.png
diff --git a/mobile-kt/app/res/layout/main.xml b/mobile-kt/app/res/layout/main.xml
new file mode 100644
index 0000000..d3bbcf5
--- /dev/null
+++ b/mobile-kt/app/res/layout/main.xml
@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:paddingLeft="@dimen/activity_horizontal_margin"
+    android:paddingRight="@dimen/activity_horizontal_margin"
+    android:paddingTop="@dimen/activity_vertical_margin"
+    android:paddingBottom="@dimen/activity_vertical_margin"
+    android:orientation="vertical"
+    tools:context=".MainActivity"
+>
+
+    <TextureView
+        android:layout_width="fill_parent"
+        android:layout_height="wrap_content"
+        android:id="@+id/surface_view"
+    />
+
+    <Button
+        android:layout_width="fill_parent"
+        android:layout_height="fill_parent"
+        android:id="@+id/button_start"
+        android:layout_gravity="center"
+        android:onClick="onClickButtonStart"
+        android:text="@string/button_start"
+        android:background="#22B225"
+        android:textColor="@android:color/white"
+        android:textSize="96sp"
+    />
+    <Button
+        android:layout_width="fill_parent"
+        android:layout_height="fill_parent"
+        android:id="@+id/button_stop"
+        android:layout_gravity="center"
+        android:onClick="onClickButtonStop"
+        android:text="@string/button_stop"
+        android:background="#96060C"
+        android:textColor="@android:color/white"
+        android:textSize="96sp"
+    />
+</FrameLayout>
diff --git a/mobile-kt/app/res/menu/settings.xml b/mobile-kt/app/res/menu/settings.xml
new file mode 100644
index 0000000..3e3bcbb
--- /dev/null
+++ b/mobile-kt/app/res/menu/settings.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu
+    xmlns:android="http://schemas.android.com/apk/res/android"
+>
+    <item
+        android:id="@+id/menu_settings"
+        android:icon="@android:drawable/ic_menu_preferences"
+        android:title="@string/menu_settings"
+        android:showAsAction="always"
+    />
+</menu>
diff --git a/mobile-kt/app/res/values-de/strings.xml b/mobile-kt/app/res/values-de/strings.xml
new file mode 100644
index 0000000..1b4ebc6
--- /dev/null
+++ b/mobile-kt/app/res/values-de/strings.xml
@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_label">
+        Pihole DNS Proxy
+    </string>
+
+    <string name="button_start">
+        Start
+    </string>
+    <string name="button_stop">
+        Stop
+    </string>
+
+    <!-- DNSProxyService -->
+    <string name="dns_proxy_service__notification__text" formatted="false">
+        %s wird verwendet
+    </string>
+    <string name="dns_proxy_service__notification__action__stop">
+        Stop
+    </string>
+
+    <!-- WifiListenerService -->
+    <string name="wifi_listener_service__notification__text">
+        Wartet auf Verbindungsänderungen
+    </string>
+    <string name="wifi_listener_service__notification__action__stop_listener">
+        Listener stoppen
+    </string>
+    <string name="wifi_listener_service__notification__action__start_proxy">
+        Proxy starten
+    </string>
+
+    <!-- Settings -->
+    <string name="menu_settings">
+        Einstellungen
+    </string>
+
+    <string name="settings__use_automatic_dns_server_discovery__title">
+        DNS Server / Pihole automatisch erkennen
+    </string>
+    <string name="settings__use_automatic_dns_server_discovery__summary">
+        Ob der automatische Erkennungsmechanismus verwendet werden soll, um den DNS Server zu setzen
+    </string>
+
+    <string name="settings__dns_server_address__title">
+        Pihole IP Adresse
+    </string>
+
+    <string name="settings__use_wifi_listener__title">
+        WiFi Listener verwenden
+    </string>
+    <string name="settings__use_wifi_listener__summary">
+        Deaktiviert den Proxy wenn die WiFi Verbindung verloren geht
+    </string>
+
+    <string name="settings__use_wifi_listener_for_activation__title">
+        WiFi Listener für Aktivierung verwenden
+    </string>
+    <string name="settings__use_wifi_listener_for_activation__summary">
+        Aktiviert den Proxy wenn mit bestimmtem WLAN verbunden wird. Braucht Standortdienste um zu funktionieren!
+    </string>
+
+    <string name="settings__wifi_listener_ssid__title">
+        WLAN SSID
+    </string>
+</resources>
diff --git a/mobile-kt/app/res/values-ja/strings.xml b/mobile-kt/app/res/values-ja/strings.xml
new file mode 100644
index 0000000..cdd2d3c
--- /dev/null
+++ b/mobile-kt/app/res/values-ja/strings.xml
@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_label">
+        Pihole DNS Proxy
+    </string>
+
+    <string name="button_start">
+        開始
+    </string>
+    <string name="button_stop">
+        止まる
+    </string>
+
+    <!-- DNSProxyService -->
+    <string name="dns_proxy_service__notification__text">
+        Running with %s
+    </string>
+    <string name="dns_proxy_service__notification__action__stop">
+        止まる
+    </string>
+
+    <!-- WifiListenerService -->
+    <string name="wifi_listener_service__notification__text">
+        Listening for WiFi connection change
+    </string>
+    <string name="wifi_listener_service__notification__action__stop_listener">
+        Stop Listener
+    </string>
+    <string name="wifi_listener_service__notification__action__start_proxy">
+        プロキシ開始
+    </string>
+
+    <!-- Settings -->
+    <string name="menu_settings">
+        設定
+    </string>
+
+    <string name="settings__use_automatic_dns_server_discovery__title">
+        Use automatic DNS Server / Pihole discovery
+    </string>
+    <string name="settings__use_automatic_dns_server_discovery__summary">
+        Whether to use the automatic discovery mechanism to set the DNS server
+    </string>
+
+    <string name="settings__dns_server_address__title">
+        Pihole IP アドレス
+    </string>
+
+    <string name="settings__use_wifi_listener__title">
+        Use WiFi listener
+    </string>
+    <string name="settings__use_wifi_listener__summary">
+        Automatically deactivates the proxy on WiFi disconnect
+    </string>
+
+    <string name="settings__use_wifi_listener_for_activation__title">
+        Use WiFi listener for activation
+    </string>
+    <string name="settings__use_wifi_listener_for_activation__summary">
+        Automatically activates the proxy on WiFi connect when connecting to specific WLAN. Needs location services to function!
+    </string>
+
+    <string name="settings__wifi_listener_ssid__title">
+        WLAN SSID
+    </string>
+</resources>
diff --git a/mobile-kt/app/res/values/dimens.xml b/mobile-kt/app/res/values/dimens.xml
new file mode 100644
index 0000000..fe991af
--- /dev/null
+++ b/mobile-kt/app/res/values/dimens.xml
@@ -0,0 +1,4 @@
+<resources>
+    <dimen name="activity_horizontal_margin">16dp</dimen>
+    <dimen name="activity_vertical_margin">16dp</dimen>
+</resources>
diff --git a/mobile-kt/app/res/values/strings.xml b/mobile-kt/app/res/values/strings.xml
new file mode 100644
index 0000000..3662cf5
--- /dev/null
+++ b/mobile-kt/app/res/values/strings.xml
@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_label">
+        Pihole DNS Proxy
+    </string>
+
+    <string name="button_start">
+        Start
+    </string>
+    <string name="button_stop">
+        Stop
+    </string>
+
+    <!-- DNSProxyService -->
+    <string name="dns_proxy_service__notification__text" formatted="false">
+        Running with %s
+    </string>
+    <string name="dns_proxy_service__notification__action__stop">
+        Stop
+    </string>
+
+    <!-- WifiListenerService -->
+    <string name="wifi_listener_service__notification__text">
+        Listening for WiFi connection change
+    </string>
+    <string name="wifi_listener_service__notification__action__stop_listener">
+        Stop Listener
+    </string>
+    <string name="wifi_listener_service__notification__action__start_proxy">
+        Start Proxy
+    </string>
+
+    <!-- Settings -->
+    <string name="menu_settings">
+        Settings
+    </string>
+
+    <string name="settings__use_automatic_dns_server_discovery__title">
+        Use automatic DNS Server / Pihole discovery
+    </string>
+    <string name="settings__use_automatic_dns_server_discovery__summary">
+        Whether to use the automatic discovery mechanism to set the DNS server
+    </string>
+
+    <string name="settings__dns_server_address__title">
+        Pihole IP address
+    </string>
+
+    <string name="settings__use_wifi_listener__title">
+        Use WiFi listener
+    </string>
+    <string name="settings__use_wifi_listener__summary">
+        Automatically deactivates the proxy on WiFi disconnect
+    </string>
+
+    <string name="settings__use_wifi_listener_for_activation__title">
+        Use WiFi listener for activation
+    </string>
+    <string name="settings__use_wifi_listener_for_activation__summary">
+        Automatically activates the proxy on WiFi connect when connecting to specific WLAN. Needs location services to function!
+    </string>
+
+    <string name="settings__wifi_listener_ssid__title">
+        WLAN SSID
+    </string>
+</resources>
diff --git a/mobile-kt/app/res/values/styles.xml b/mobile-kt/app/res/values/styles.xml
new file mode 100644
index 0000000..d5037d5
--- /dev/null
+++ b/mobile-kt/app/res/values/styles.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <style name="button_start__start" parent="@android:style/Widget.Button">
+        <item name="android:background">#96060C</item>
+        <item name="android:textColor">@android:color/white</item>
+    </style>
+    <style name="button_start__stop" parent="@android:style/Widget.Button">
+        <item name="android:background">#22B225</item>
+        <item name="android:textColor">@android:color/white</item>
+    </style>
+</resources>
diff --git a/mobile-kt/app/res/xml/settings.xml b/mobile-kt/app/res/xml/settings.xml
new file mode 100644
index 0000000..31cc8f0
--- /dev/null
+++ b/mobile-kt/app/res/xml/settings.xml
@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="utf-8"?>
+<PreferenceScreen
+    xmlns:android="http://schemas.android.com/apk/res/android"
+>
+    <SwitchPreference
+        android:key="use_automatic_dns_server_discovery"
+        android:defaultValue="true"
+        android:title="@string/settings__use_automatic_dns_server_discovery__title"
+        android:summary="@string/settings__use_automatic_dns_server_discovery__summary"
+    />
+
+    <EditTextPreference
+        android:key="dns_server_address"
+        android:title="@string/settings__dns_server_address__title"
+    />
+
+    <SwitchPreference
+        android:key="use_wifi_listener"
+        android:defaultValue="false"
+        android:title="@string/settings__use_wifi_listener__title"
+        android:summary="@string/settings__use_wifi_listener__summary"
+    />
+
+    <SwitchPreference
+        android:key="use_wifi_listener_for_activation"
+        android:dependency="use_wifi_listener"
+        android:defaultValue="false"
+        android:title="@string/settings__use_wifi_listener_for_activation__title"
+        android:summary="@string/settings__use_wifi_listener_for_activation__summary"
+    />
+
+    <EditTextPreference
+        android:key="wifi_listener_ssid"
+        android:dependency="use_wifi_listener_for_activation"
+        android:title="@string/settings__wifi_listener_ssid__title"
+    />
+
+    <!-- SELECT_FROM_KNOWN_SSIDS -->
+    <!-- <MultiSelectListPreference -->
+    <!--     android:id="@+id/known_ssids" -->
+    <!--     android:key="known_ssids" -->
+    <!--     android:entries="" -->
+    <!--     android:entryValues="" -->
+    <!-- /> -->
+</PreferenceScreen>
diff --git a/mobile-kt/app/src/DNSProxyConnection.java b/mobile-kt/app/src/DNSProxyConnection.java
new file mode 100644
index 0000000..420b5fc
--- /dev/null
+++ b/mobile-kt/app/src/DNSProxyConnection.java
@@ -0,0 +1,43 @@
+package org.pihole.dnsproxy;
+
+import android.os.ParcelFileDescriptor;
+
+import android.util.Log;
+
+public class DNSProxyConnection {
+
+    public static String THREAD_NAME = "org.pihole.dnsproxy.service.dnsproxy.thread";
+
+    private DNSProxyService service;
+    private Thread thread;
+    private ParcelFileDescriptor networkInterface;
+
+    public DNSProxyConnection(DNSProxyService service) {
+        this.service = service;
+    }
+
+    /**
+     * Setup and start the connection
+     */
+    public void start() {
+        DNSProxyRunner runner = new DNSProxyRunner(this.service);
+        runner.setOnEstablishListener(tunInterface -> {
+            this.networkInterface = tunInterface;
+        });
+
+        this.thread = new Thread(runner, DNSProxyConnection.THREAD_NAME);
+        this.thread.start();
+    }
+
+    /**
+     * Stop and close the connection
+     */
+    public void stop() {
+        try {
+            this.thread.interrupt();
+            this.networkInterface.close();
+        } catch (Exception exception) {
+            Log.e(DNSProxyService.LOG_TAG, "Closing VPN interface", exception);
+        }
+    }
+}
diff --git a/mobile-kt/app/src/DNSProxyRunner.java b/mobile-kt/app/src/DNSProxyRunner.java
new file mode 100644
index 0000000..dd0e3e5
--- /dev/null
+++ b/mobile-kt/app/src/DNSProxyRunner.java
@@ -0,0 +1,43 @@
+package org.pihole.dnsproxy;
+
+import android.net.VpnService;
+
+import android.os.ParcelFileDescriptor;
+
+import android.util.Log;
+
+public class DNSProxyRunner implements Runnable {
+
+    public interface OnEstablishListener {
+        void onEstablish(ParcelFileDescriptor networkInterface);
+    }
+    private OnEstablishListener onEstablishListener;
+
+    private DNSProxyService service;
+
+    DNSProxyRunner(DNSProxyService service) {
+        this.service = service;
+    }
+
+    @Override
+    public void run() {
+        try {
+            VpnService.Builder builder = this.service.newBuilder()
+                .setSession("Pihole DNS Proxy")
+                .addAddress("10.111.222.1", 24)
+                .addDnsServer(DNSProxyService.PIHOLE_ADDRESS)
+                .setBlocking(true);
+
+            this.onEstablishListener.onEstablish(builder.establish());
+        } catch (Exception exception) {
+            Log.e(DNSProxyService.LOG_TAG, "Failed to establish VPN connection", exception);
+        }
+    }
+
+    /**
+     * Callback when proxy connection is established
+     */
+    public void setOnEstablishListener(OnEstablishListener listener) {
+        this.onEstablishListener = listener;
+    }
+}
diff --git a/mobile-kt/app/src/DNSProxyService.java b/mobile-kt/app/src/DNSProxyService.java
new file mode 100644
index 0000000..10e127b
--- /dev/null
+++ b/mobile-kt/app/src/DNSProxyService.java
@@ -0,0 +1,171 @@
+package org.pihole.dnsproxy;
+
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.app.Service;
+import android.content.SharedPreferences;
+
+import android.content.Context;
+import android.content.Intent;
+
+import android.net.DhcpInfo;
+import android.net.VpnService;
+import android.net.wifi.WifiManager;
+
+import android.preference.PreferenceManager;
+
+import android.util.Log;
+
+import java.net.InetAddress;
+
+public class DNSProxyService extends VpnService {
+
+    public static String LOG_TAG = "org.pihole.dnsproxy.log";
+    public static String NOTIFICATION_NOTIFY = "org.pihole.dnsproxy.service.dnsproxy.notification.NOTIFY";
+    public static String NOTIFICATION_CHANNEL_ID = "org.pihole.dnsproxy.service.dnsproxy.NOTIFICATION";
+    public static String ACTION_START = "org.pihole.dnsproxy.service.dnsproxy.START";
+    public static String ACTION_STOP = "org.pihole.dnsproxy.service.dnsproxy.STOP";
+
+    public static String PIHOLE_ADDRESS = "";
+
+    private static DNSProxyConnection connection;
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId)    {
+        if (intent.getAction().equals(DNSProxyService.ACTION_START)) {
+            this.connect();
+
+            return Service.START_STICKY;
+        } else {
+            this.disconnect();
+
+            return Service.START_NOT_STICKY;
+        }
+    }
+
+    @Override
+    public void onDestroy() {
+        this.disconnect();
+
+        super.onDestroy();
+    }
+
+    /**
+     * Builder has to be created by service
+     */
+    public VpnService.Builder newBuilder() {
+        return new VpnService.Builder();
+    }
+
+    /**
+     * Whether the proxy is setup running
+     */
+    public static boolean isRunning()
+    {
+        return DNSProxyService.connection != null;
+    }
+
+    /**
+     * Start this service
+     */
+    public static void start(Context context) {
+        context.startService((new Intent(context, DNSProxyService.class)).setAction(DNSProxyService.ACTION_START));
+    }
+
+    /**
+     * Stop this service
+     */
+    public static void stop(Context context) {
+        context.startService((new Intent(context, DNSProxyService.class)).setAction(DNSProxyService.ACTION_STOP));
+    }
+
+    /**
+     * Setup connection
+     */
+    private void connect() {
+        this.setPiholeAddress();
+
+        DNSProxyService.connection = new DNSProxyConnection(this);
+        DNSProxyService.connection.start();
+
+        this.startForeground();
+
+        // send notification when started
+        Intent notification = new Intent(DNSProxyService.NOTIFICATION_NOTIFY);
+        sendBroadcast(notification);
+    }
+
+    /**
+     * Disconnect from connection
+     */
+    private void disconnect() {
+        DNSProxyService.connection.stop();
+        DNSProxyService.connection = null;
+
+        stopForeground(true);
+
+        // send notification when stopped
+        Intent notification = new Intent(DNSProxyService.NOTIFICATION_NOTIFY);
+        sendBroadcast(notification);
+    }
+
+    /**
+     * Get and set IP address of Pihole DNS server
+     */
+    private void setPiholeAddress() {
+        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
+        if (!sharedPreferences.getBoolean("use_automatic_dns_server_discovery", true)) {
+            DNSProxyService.PIHOLE_ADDRESS = sharedPreferences.getString("dns_server_address", "");
+            return;
+        }
+
+        WifiManager manager = (WifiManager) getSystemService(WIFI_SERVICE);
+        DhcpInfo info = manager.getDhcpInfo();
+
+        byte[] addressBytes = {
+            (byte) (0xff & info.dns1),
+            (byte) (0xff & (info.dns1 >> 8)),
+            (byte) (0xff & (info.dns1 >> 16)),
+            (byte) (0xff & (info.dns1 >> 24)),
+        };
+
+        try {
+            DNSProxyService.PIHOLE_ADDRESS = InetAddress.getByAddress(addressBytes).toString().replaceAll("/", "");
+        } catch (Exception e) {
+            DNSProxyService.PIHOLE_ADDRESS = "";
+        }
+    }
+
+    /**
+     * Start the Foreground notification process
+     */
+    private void startForeground() {
+        NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
+
+        NotificationChannel channel = new NotificationChannel(
+            DNSProxyService.NOTIFICATION_CHANNEL_ID,
+            DNSProxyService.NOTIFICATION_CHANNEL_ID,
+            NotificationManager.IMPORTANCE_DEFAULT
+        );
+        manager.createNotificationChannel(channel);
+
+        Notification notification = new Notification.Builder(this, DNSProxyService.NOTIFICATION_CHANNEL_ID)
+            .setSmallIcon(R.drawable.logo)
+            .setContentTitle(getString(R.string.app_label))
+            .setContentText(String.format(getString(R.string.dns_proxy_service__notification__text), DNSProxyService.PIHOLE_ADDRESS))
+            .setContentIntent(PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), Intent.FLAG_ACTIVITY_NEW_TASK))
+            .addAction(
+                R.drawable.logo,
+                getString(R.string.dns_proxy_service__notification__action__stop),
+                PendingIntent.getService(this, 0,
+                    (new Intent(this, DNSProxyService.class)).setAction(DNSProxyService.ACTION_STOP),
+                    PendingIntent.FLAG_IMMUTABLE
+                )
+            )
+            .build();
+
+        startForeground(1, notification);
+    }
+}
diff --git a/mobile-kt/app/src/MainActivity.kt b/mobile-kt/app/src/MainActivity.kt
new file mode 100644
index 0000000..8d42f6a
--- /dev/null
+++ b/mobile-kt/app/src/MainActivity.kt
@@ -0,0 +1,35 @@
+package org.pihole.dnsproxy;
+
+import android.os.Bundle
+import android.widget.TextView
+import androidx.appcompat.app.AppCompatActivity
+import kotlinx.coroutines.*
+
+class MainActivity : AppCompatActivity() {
+
+    public override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+
+        findViewById<TextView>(R.id.tv_label).text = "Hello Bazel, from Kotlin!"
+
+        `kotlin_13_test`("test")
+
+        launchCoroutine()
+    }
+
+    private fun kotlin_13_test(x: String?) {
+        if (!x.isNullOrEmpty()) {
+            println("length of '$x' is ${x.length}") // Yay, smartcasted to not-null!
+        }
+    }
+
+    private fun launchCoroutine() {
+        GlobalScope.launch(context = Dispatchers.Default) {
+            delay(1000)
+            withContext(context = Dispatchers.Main) {
+                findViewById<TextView>(R.id.tv_label).text = "Hello Bazel, from Kotlin And Coroutine!"
+            }
+        }
+    }
+}
diff --git a/mobile-kt/app/src/SettingsActivity.java b/mobile-kt/app/src/SettingsActivity.java
new file mode 100644
index 0000000..0b3c7f2
--- /dev/null
+++ b/mobile-kt/app/src/SettingsActivity.java
@@ -0,0 +1,132 @@
+package org.pihole.dnsproxy;
+
+import android.content.SharedPreferences;
+import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
+
+import android.os.Bundle;
+
+import android.preference.PreferenceActivity;
+import android.preference.PreferenceFragment;
+
+import android.util.Log;
+
+public class SettingsActivity extends PreferenceActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        getFragmentManager().beginTransaction().replace(android.R.id.content, new SettingsFragment()).commit();
+    }
+
+    public static class SettingsFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener {
+
+        @Override
+        public void onCreate(Bundle savedInstanceState) {
+            super.onCreate(savedInstanceState);
+
+            addPreferencesFromResource(R.xml.settings);
+        }
+
+        @Override
+        public void onResume() {
+            super.onResume();
+
+            getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
+
+            DNSServerAddress.toggleEnabled(this);
+            DNSServerAddress.displayValue(this);
+            WifiListener.SSID.displayValue(this);
+        }
+
+        @Override
+        public void onPause() {
+            super.onPause();
+
+            getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
+        }
+
+        @Override
+        public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
+            if (key.equals("use_automatic_dns_server_discovery")) {
+                DNSServerAddress.toggleEnabled(this);
+            }
+
+            else if (key.equals("dns_server_address")) {
+                DNSServerAddress.displayValue(this);
+            }
+
+            else if (key.equals("use_wifi_listener")) {
+                WifiListener.toggle(this);
+            }
+
+            else if (key.equals("use_wifi_listener_for_activation")) {
+                if (sharedPreferences.getBoolean("use_wifi_listener_for_activation", false)) {
+                    WifiListener.Activation.enable(this);
+                }
+            }
+
+            else if (key.equals("wifi_listener_ssid")) {
+                WifiListener.SSID.displayValue(this);
+            }
+        }
+
+        static class DNSServerAddress {
+            public static void toggleEnabled(PreferenceFragment context) {
+                context.findPreference("dns_server_address").setEnabled(
+                    !context.getPreferenceScreen().getSharedPreferences().getBoolean("use_automatic_dns_server_discovery", true)
+                );
+            }
+
+            public static void displayValue(PreferenceFragment context) {
+                context.findPreference("dns_server_address").setSummary(
+                    context.getPreferenceScreen().getSharedPreferences().getString("dns_server_address", "")
+                );
+            }
+        }
+
+        static class WifiListener {
+            public static void toggle(PreferenceFragment context) {
+                SharedPreferences sharedPreferences = context.getPreferenceScreen().getSharedPreferences();
+
+                if (sharedPreferences.getBoolean("use_wifi_listener", false)) {
+                    WifiListenerService.start(context.getActivity());
+                } else {
+                    disable(context);
+                }
+            }
+
+            public static void disable(PreferenceFragment context) {
+                SharedPreferences sharedPreferences = context.getPreferenceScreen().getSharedPreferences();
+
+                WifiListenerService.disable(context.getActivity());
+            }
+
+            static class Activation {
+                public static void enable(PreferenceFragment context) {
+                    SharedPreferences sharedPreferences = context.getPreferenceScreen().getSharedPreferences();
+
+                    WifiListenerService.OnActivationListener.askLocationIfNeeded(context.getActivity());
+
+                    if (sharedPreferences.getString("wifi_listener_ssid", "").equals("")) {
+                        String ssid = WifiListenerService.getWifiSSID(context.getActivity());
+
+                        if (!ssid.equals("unknown ssid")) {
+                            SharedPreferences.Editor sharedPreferencesEditor = sharedPreferences.edit();
+                            sharedPreferencesEditor.putString("wifi_listener_ssid", ssid);
+                            sharedPreferencesEditor.commit();
+                        }
+                    }
+                }
+            }
+
+            static class SSID {
+                public static void displayValue(PreferenceFragment context) {
+                    context.findPreference("wifi_listener_ssid").setSummary(
+                        context.getPreferenceScreen().getSharedPreferences().getString("wifi_listener_ssid", "")
+                    );
+                }
+            }
+        }
+    }
+}
diff --git a/mobile-kt/app/src/WifiListenerReceiver.java b/mobile-kt/app/src/WifiListenerReceiver.java
new file mode 100644
index 0000000..5e05654
--- /dev/null
+++ b/mobile-kt/app/src/WifiListenerReceiver.java
@@ -0,0 +1,50 @@
+package org.pihole.dnsproxy;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SharedPreferences;
+
+import android.net.NetworkInfo;
+import android.net.wifi.WifiManager;
+
+import android.os.Handler;
+
+import android.preference.PreferenceManager;
+
+import android.util.Log;
+
+public class WifiListenerReceiver extends BroadcastReceiver
+{
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        NetworkInfo networkInfo = (NetworkInfo) intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
+        Intent dnsProxyService = new Intent(context, DNSProxyService.class);
+
+        // start
+        if (networkInfo.getState().equals(NetworkInfo.State.CONNECTED)) {
+            SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
+
+            if (!sharedPreferences.getBoolean("use_wifi_listener_for_activation", false)) {
+                return;
+            }
+
+            // wait a few moments for wifi to be fully there
+            (new Handler()).postDelayed(new Runnable() {
+                @Override
+                public void run() {
+                    String ssid = WifiListenerService.getWifiSSID(context);
+
+                    if (ssid.equals(sharedPreferences.getString("wifi_listener_ssid", ""))) {
+                        DNSProxyService.start(context);
+                    }
+                }
+            }, 1000);
+        }
+
+        // stop
+        else if (networkInfo.getState().equals(NetworkInfo.State.DISCONNECTED) && DNSProxyService.isRunning()) {
+            DNSProxyService.stop(context);
+        }
+    }
+}
diff --git a/mobile-kt/app/src/WifiListenerService.java b/mobile-kt/app/src/WifiListenerService.java
new file mode 100644
index 0000000..0920677
--- /dev/null
+++ b/mobile-kt/app/src/WifiListenerService.java
@@ -0,0 +1,236 @@
+package org.pihole.dnsproxy;
+
+import android.app.Activity;
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.app.Service;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.SharedPreferences;
+
+import android.location.LocationManager;
+
+import android.net.wifi.WifiInfo;
+import android.net.wifi.WifiManager;
+
+import android.os.IBinder;
+
+import android.preference.PreferenceManager;
+
+import android.util.Log;
+
+public class WifiListenerService extends Service
+{
+
+    public static String NOTIFICATION_CHANNEL_ID = "org.pihole.dnsproxy.service.wifiListener.NOTIFICATION";
+    public static String ACTION_START = "org.pihole.dnsproxy.service.wifiListener.START";
+    public static String ACTION_STOP = "org.pihole.dnsproxy.service.wifiListener.STOP";
+    public static String ACTION_STOP_SET_PREFERENCE = "org.pihole.dnsproxy.service.wifiListener.STOP_SET_PREFERENCE";
+
+    private BroadcastReceiver receiver = new WifiListenerReceiver();
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        // start the service
+        if (intent.getAction().equals(WifiListenerService.ACTION_START)) {
+            this.listen();
+
+            return Service.START_STICKY;
+        }
+
+        // stop the service
+        else if (intent.getAction().equals(WifiListenerService.ACTION_STOP)) {
+            try {
+                this.deafen();
+            } catch (Exception exception) {}
+
+            return Service.START_NOT_STICKY;
+        }
+
+        // stop and disable
+        else if (intent.getAction().equals(WifiListenerService.ACTION_STOP_SET_PREFERENCE)) {
+            WifiListenerService.disable(this);
+
+            return Service.START_NOT_STICKY;
+        }
+
+        return Service.START_NOT_STICKY;
+    }
+
+    @Override
+    public void onDestroy() {
+        this.deafen();
+
+        super.onDestroy();
+    }
+
+    @Override
+    public IBinder onBind(Intent intent) { return null; }
+
+    /**
+     * Start the service
+     */
+    public static void start(Context context) {
+        context.startService((new Intent(context, WifiListenerService.class)).setAction(WifiListenerService.ACTION_START));
+    }
+
+    /**
+     * Stop the service
+     */
+    public static void stop(Context context) {
+        context.startService((new Intent(context, WifiListenerService.class)).setAction(WifiListenerService.ACTION_STOP));
+    }
+
+    /**
+     * Start/Stop based on setting
+     */
+    public static void toggle(Context context) {
+        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
+
+        if (sharedPreferences.getBoolean("use_wifi_listener", false)) {
+            WifiListenerService.start(context);
+        } else {
+            WifiListenerService.stop(context);
+        }
+    }
+
+    /**
+     * Stop Wifi Listener and disable completely
+     */
+    public static void disable(Context context) {
+        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
+        SharedPreferences.Editor sharedPreferencesEditor = sharedPreferences.edit();
+
+        WifiListenerService.stop(context);
+        sharedPreferencesEditor.putBoolean("use_wifi_listener", false);
+        sharedPreferencesEditor.commit();
+
+        WifiListenerService.OnActivationListener.disable(context);
+    }
+
+    /**
+     * Get current Wifi SSID
+     */
+    public static String getWifiSSID(Context context) {
+        WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
+        WifiInfo wifiInfo = wifiManager.getConnectionInfo();
+        String ssid = wifiInfo.getSSID();
+
+        // remove quotes around ssid
+        ssid = ssid.substring(1, ssid.length() - 1);
+
+        return ssid;
+    }
+
+    /**
+     * Setup listener
+     */
+    private void listen() {
+        registerReceiver(this.receiver, new IntentFilter(WifiManager.NETWORK_STATE_CHANGED_ACTION));
+
+        this.startForeground();
+    }
+
+    /**
+     * Stop listening
+     */
+    private void deafen() {
+        unregisterReceiver(this.receiver);
+
+        stopForeground(true);
+    }
+
+    /**
+     * Start the Foreground notification process
+     */
+    private void startForeground() {
+        NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
+
+        NotificationChannel channel = new NotificationChannel(
+            WifiListenerService.NOTIFICATION_CHANNEL_ID,
+            WifiListenerService.NOTIFICATION_CHANNEL_ID,
+            NotificationManager.IMPORTANCE_DEFAULT
+        );
+        manager.createNotificationChannel(channel);
+
+        Notification notification = new Notification.Builder(this, WifiListenerService.NOTIFICATION_CHANNEL_ID)
+            .setSmallIcon(R.drawable.logo)
+            .setContentTitle(getString(R.string.app_label) + " - WiFi Listener")
+            .setContentText(getString(R.string.wifi_listener_service__notification__text))
+            .setContentIntent(PendingIntent.getActivity(this, 0, new Intent(this, SettingsActivity.class), Intent.FLAG_ACTIVITY_NEW_TASK))
+            .addAction(
+                R.drawable.logo,
+                getString(R.string.wifi_listener_service__notification__action__stop_listener),
+                PendingIntent.getService(this, 0,
+                    (new Intent(this, WifiListenerService.class)).setAction(WifiListenerService.ACTION_STOP_SET_PREFERENCE),
+                    PendingIntent.FLAG_IMMUTABLE
+                )
+            )
+            .addAction(
+                R.drawable.logo,
+                getString(R.string.wifi_listener_service__notification__action__start_proxy),
+                PendingIntent.getService(this, 0,
+                    (new Intent(this, DNSProxyService.class)).setAction(DNSProxyService.ACTION_START),
+                    PendingIntent.FLAG_IMMUTABLE
+                )
+            )
+            .build();
+
+        startForeground(2, notification);
+    }
+
+    /**
+     * SubClass to enable auto-activation
+     */
+    public static class OnActivationListener {
+
+        /**
+         * Disable auto-activation
+         */
+        public static void disable(Context context) {
+            SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
+            SharedPreferences.Editor sharedPreferencesEditor = sharedPreferences.edit();
+            LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
+
+            sharedPreferencesEditor.putBoolean("use_wifi_listener_for_activation", false);
+            sharedPreferencesEditor.commit();
+
+            if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
+                context.startActivity((new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS)).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK));
+            }
+        }
+
+        /**
+         * Check if location services are needed
+         */
+        public static boolean checkLocationNeeded(Context context) {
+            SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
+
+            if (!sharedPreferences.getBoolean("use_wifi_listener_for_activation", false)) {
+                return false;
+            }
+
+            LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
+
+            return !locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
+        }
+
+        /**
+         * Ask User to enable location services if they are needed
+         */
+        public static void askLocationIfNeeded(Activity context) {
+            if (checkLocationNeeded(context)) {
+                context.requestPermissions(new String[]{
+                    android.Manifest.permission.ACCESS_FINE_LOCATION,
+                }, 3765);
+
+                context.startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
+            }
+        }
+    }
+}