java/com/tailscale/ipn: set hostname to nickname if available

Fixes tailscale/tailscale#482

Signed-off-by: nirev <guilherme@nirev.org>

android/src/main/java/com/tailscale/ipn/App.java

@@ -13,6 +13,7 @@ import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.SharedPreferences;
 import android.content.BroadcastReceiver;
+import android.provider.Settings;
 import android.net.ConnectivityManager;
 import android.view.View;
 import android.os.Build;
@@ -83,6 +84,13 @@ public class App extends Application {
 	}
 
 	String getHostname() {
+		String userConfiguredDeviceName = getUserConfiguredDeviceName();
+		if (!isEmpty(userConfiguredDeviceName)) return userConfiguredDeviceName;
+
+		return getModelName();
+	}
+
+	private String getModelName() {
 		String manu = Build.MANUFACTURER;
 		String model = Build.MODEL;
 		// Strip manufacturer from model.
@@ -94,6 +102,23 @@ public class App extends Application {
 		return manu + " " + model;
 	}
 
+	// get user defined nickname from Settings
+	// returns null if not available
+	private String getUserConfiguredDeviceName() {
+		String nameFromSystemBluetooth = Settings.System.getString(getContentResolver(), "bluetooth_name");
+		String nameFromSecureBluetooth = Settings.Secure.getString(getContentResolver(), "bluetooth_name");
+		String nameFromSystemDevice = Settings.Secure.getString(getContentResolver(), "device_name");
+
+		if (!isEmpty(nameFromSystemBluetooth)) return nameFromSystemBluetooth;
+		if (!isEmpty(nameFromSecureBluetooth)) return nameFromSecureBluetooth;
+		if (!isEmpty(nameFromSystemDevice)) return nameFromSystemDevice;
+		return null;
+	}
+
+	private static boolean isEmpty(String str) {
+		return str == null || str.length() == 0;
+	}
+
 	// Tracklifecycle adds a Peer fragment for tracking the Activity
 	// lifecycle.
 	static void trackLifecycle(View view) {