Fix settings not persisted

mobile/src/main/java/be/mygod/vpnhotspot/App.kt

@@ -15,6 +15,7 @@ import android.widget.Toast
 class App : Application() {
     companion object {
         const val ACTION_CLEAN_ROUTINGS = "be.mygod.vpnhotspot.CLEAN_ROUTINGS"
+        private const val KEY_DNS = "service.dns"
 
         @SuppressLint("StaticFieldLeak")
         lateinit var app: App
@@ -27,6 +28,8 @@ class App : Application() {
             deviceContext = createDeviceProtectedStorageContext()
             deviceContext.moveSharedPreferencesFrom(this, PreferenceManager.getDefaultSharedPreferencesName(this))
         } else deviceContext = this
+        // workaround for support lib PreferenceDataStore bug
+        dns = dns
         ServiceNotification.updateNotificationChannels()
     }
 
@@ -40,5 +43,9 @@ class App : Application() {
     val pref: SharedPreferences by lazy { PreferenceManager.getDefaultSharedPreferences(deviceContext) }
     val connectivity by lazy { getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager }
 
+    var dns: String
+        get() = pref.getString(KEY_DNS, "8.8.8.8")
+        set(value) = pref.edit().putString(KEY_DNS, value).apply()
+
     fun toast(@StringRes resId: Int) = handler.post { Toast.makeText(this, resId, Toast.LENGTH_SHORT).show() }
 }

mobile/src/main/java/be/mygod/vpnhotspot/SettingsPreferenceFragment.kt

@@ -10,6 +10,7 @@ import android.support.v4.content.ContextCompat
 import android.support.v4.content.FileProvider
 import android.support.v4.content.LocalBroadcastManager
 import android.widget.Toast
+import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.net.Routing
 import com.takisoft.fix.support.v7.preference.PreferenceFragmentCompatDividers
 import java.io.File
@@ -24,6 +25,7 @@ class SettingsPreferenceFragment : PreferenceFragmentCompatDividers() {
     }
 
     override fun onCreatePreferencesFix(savedInstanceState: Bundle?, rootKey: String?) {
+        preferenceManager.preferenceDataStore = SharedPreferenceDataStore(app.pref)
         addPreferencesFromResource(R.xml.pref_settings)
         findPreference("service.clean").setOnPreferenceClickListener {
             if (Routing.clean() == null) {

mobile/src/main/java/be/mygod/vpnhotspot/SharedPreferenceDataStore.kt

@@ -0,0 +1,20 @@
+package be.mygod.vpnhotspot
+
+import android.content.SharedPreferences
+import android.support.v7.preference.PreferenceDataStore
+
+class SharedPreferenceDataStore(private val pref: SharedPreferences) : PreferenceDataStore() {
+    override fun getBoolean(key: String?, defValue: Boolean) = pref.getBoolean(key, defValue)
+    override fun getFloat(key: String?, defValue: Float) = pref.getFloat(key, defValue)
+    override fun getInt(key: String?, defValue: Int) = pref.getInt(key, defValue)
+    override fun getLong(key: String?, defValue: Long) = pref.getLong(key, defValue)
+    override fun getString(key: String?, defValue: String?): String? = pref.getString(key, defValue)
+    override fun getStringSet(key: String?, defValue: MutableSet<String>?): MutableSet<String>? =
+            pref.getStringSet(key, defValue)
+    override fun putBoolean(key: String?, value: Boolean) = pref.edit().putBoolean(key, value).apply()
+    override fun putFloat(key: String?, value: Float) = pref.edit().putFloat(key, value).apply()
+    override fun putInt(key: String?, value: Int) = pref.edit().putInt(key, value).apply()
+    override fun putLong(key: String?, value: Long) = pref.edit().putLong(key, value).apply()
+    override fun putString(key: String?, value: String?) = pref.edit().putString(key, value).apply()
+    override fun putStringSet(key: String?, value: MutableSet<String>?) = pref.edit().putStringSet(key, value).apply()
+}

mobile/src/main/java/be/mygod/vpnhotspot/net/Routing.kt

@@ -101,8 +101,7 @@ class Routing(val upstream: String?, val downstream: String, ownerAddress: InetA
 
     fun dnsRedirect(dnses: List<InetAddress>): Routing {
         val hostAddress = hostAddress.hostAddress
-        val dns = dnses.firstOrNull { it is Inet4Address }?.hostAddress
+        val dns = dnses.firstOrNull { it is Inet4Address }?.hostAddress ?: app.dns
-                ?: app.pref.getString("service.dns", "8.8.8.8")
         debugLog("Routing", "Using $dns from ($dnses)")
         startScript.add("$IPTABLES -t nat -A PREROUTING -i $downstream -p tcp -d $hostAddress --dport 53 -j DNAT --to-destination $dns")
         startScript.add("$IPTABLES -t nat -A PREROUTING -i $downstream -p udp -d $hostAddress --dport 53 -j DNAT --to-destination $dns")