Add event channel to handle state change

android/src/main/java/org/strongswan/android/logic/CharonVpnService.java

@@ -56,6 +56,9 @@
 import java.util.SortedSet;
 import java.util.UUID;
 
+import io.flutter.plugin.common.EventChannel;
+import io.xdea.fluttervpn.VPNStateHandler;
+
 
 public class CharonVpnService extends VpnService implements Runnable {
     private static final String NOTIFICATION_CHANNEL = "org.strongswan.android.CharonVpnService.VPN_STATE_NOTIFICATION";
@@ -110,12 +113,12 @@ public int onStartCommand(Intent intent, int flags, int startId) {
             Bundle bundle = intent.getExtras();
             VpnProfile profile = new VpnProfile();
             profile.setId(1);
-            profile.setUUID(UUID.fromString(bundle.getString("_uuid")));
-            profile.setName(bundle.getString("PROFILE_NAME"));
-            profile.setGateway(bundle.getString("PROFILE_NAME"));
-            profile.setVpnType(VpnType.fromIdentifier("ikev2-eap"));
+            profile.setUUID(UUID.randomUUID());
+            profile.setName(bundle.getString("address"));
+            profile.setGateway(bundle.getString("address"));
             profile.setUsername(bundle.getString("username"));
             profile.setPassword(bundle.getString("password"));
+            profile.setVpnType(VpnType.fromIdentifier("ikev2-eap"));
             profile.setSelectedAppsHandling(0);
             profile.setFlags(0);
             setNextProfile(profile);
@@ -226,6 +229,11 @@ public void run() {
     public void updateStatus(int status) {
         NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
         manager.notify(1, buildNotification());
+
+        // Update state through event channel.
+        EventChannel.EventSink sink = VPNStateHandler.Companion.getEventHandler();
+        if(sink != null)
+            sink.success(status);
     }
 
     /**

android/src/main/kotlin/io/xdea/fluttervpn/FlutterVpnPlugin.kt

@@ -1,10 +1,25 @@
+/**
+ * Copyright (C) 2018 Jason C.H
+ *
+ * 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, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
 package io.xdea.fluttervpn
 
 import android.app.Activity.RESULT_OK
 import android.content.Intent
 import android.net.VpnService
 import android.os.Bundle
 import android.support.v4.content.ContextCompat
+import io.flutter.plugin.common.EventChannel
 import io.flutter.plugin.common.MethodCall
 import io.flutter.plugin.common.MethodChannel
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler
@@ -22,16 +37,20 @@ class FlutterVpnPlugin(private val registrar: Registrar) : MethodCallHandler {
   companion object {
     @JvmStatic
     fun registerWith(registrar: Registrar) {
-      // Register method channel
+      // Register method channel.
       val channel = MethodChannel(registrar.messenger(), "flutter_vpn")
       channel.setMethodCallHandler(FlutterVpnPlugin(registrar))
+
+      // Register event channel to handle state change.
+      val eventChannel = EventChannel(registrar.messenger(), "flutter_vpn_states")
+      eventChannel.setStreamHandler(VPNStateHandler())
     }
 
     fun onPrepareResult(requestCode: Int, resultCode: Int, result: Result): Boolean {
       if (requestCode == 0 && resultCode == RESULT_OK)
         result.success(true)
       else
-        result.error("error", "Failed to prepare", false)
+        result.error("PrepareError", "Failed to prepare", false)
       return true
     }
   }
@@ -43,15 +62,15 @@ class FlutterVpnPlugin(private val registrar: Registrar) : MethodCallHandler {
         val intent = VpnService.prepare(registrar.activeContext())
         if (intent != null) {
           registrar.addActivityResultListener { req, res, _ -> onPrepareResult(req, res, result) }
-
           registrar.activity().startActivityForResult(intent, 0)
-
         }
       }
       "connect" -> {
         val intent = VpnService.prepare(registrar.activeContext())
-        if (intent != null)
-          result.error("error", "Not prepared", false)
+        if (intent != null) {
+          result.error("PrepareError", "Not prepared", false)
+          return
+        }
         val map = call.arguments as HashMap<String, String>
         val address = map["address"]
         val username = map["username"]
@@ -69,15 +88,12 @@ class FlutterVpnPlugin(private val registrar: Registrar) : MethodCallHandler {
 
   private fun connect(address: String?, username: String?, password: String?) {
     val profileInfo = Bundle()
-    profileInfo.putString("_uuid", "be869700-4ad4-4215-8453-619a1472b384")
+    profileInfo.putString("address", address)
     profileInfo.putString("username", username)
     profileInfo.putString("password", password)
-    profileInfo.putBoolean("REQUIRES_PASSWORD", true)
-    profileInfo.putString("PROFILE_NAME", address)
-    /* we assume we have the necessary permission */
-    val intent = Intent(registrar.activeContext(), CharonVpnService::class.java)
 
-    intent.putExtras(profileInfo)
+    val intent = Intent(registrar.activeContext(), CharonVpnService::class.java)
+            .putExtras(profileInfo)
     ContextCompat.startForegroundService(registrar.activeContext(), intent)
   }
 
@@ -92,6 +108,4 @@ class FlutterVpnPlugin(private val registrar: Registrar) : MethodCallHandler {
     intent.action = CharonVpnService.DISCONNECT_ACTION
     registrar.activeContext().startService(intent)
   }
-
-
 }

android/src/main/kotlin/io/xdea/fluttervpn/VPNStateHandler.kt

@@ -0,0 +1,46 @@
+/**
+ * Copyright (C) 2018 Jason C.H
+ *
+ * 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, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+package io.xdea.fluttervpn
+
+import io.flutter.plugin.common.EventChannel
+
+/*
+	STATE_CHILD_SA_UP = 1;
+	STATE_CHILD_SA_DOWN = 2;
+	STATE_AUTH_ERROR = 3;
+	STATE_PEER_AUTH_ERROR = 4;
+	STATE_LOOKUP_ERROR = 5;
+	STATE_UNREACHABLE_ERROR = 6;
+	STATE_CERTIFICATE_UNAVAILABLE = 7;
+	STATE_GENERIC_ERROR = 8;
+ */
+
+class VPNStateHandler : EventChannel.StreamHandler {
+
+  companion object {
+    /**
+     * The charon VPN service will update state through the sink if not `null`.
+     */
+    var eventHandler: EventChannel.EventSink? = null
+  }
+
+  override fun onListen(p0: Any?, sink: EventChannel.EventSink?) {
+    eventHandler = sink
+  }
+
+  override fun onCancel(p0: Any?) {
+    eventHandler = null
+  }
+}

example/lib/main.dart

@@ -27,9 +27,12 @@ class _MyAppState extends State<MyApp> {
   final _usernameController = TextEditingController();
   final _passwordController = TextEditingController();
 
+  var state = FlutterVpnState.down;
+
   @override
   void initState() {
     FlutterVpn.prepare();
+    FlutterVpn.onStateChanged.listen((s) => setState(() => state = s));
     super.initState();
   }
 
@@ -43,6 +46,7 @@ class _MyAppState extends State<MyApp> {
         body: ListView(
           padding: const EdgeInsets.all(15.0),
           children: <Widget>[
+            Text('Current State: $state'),
             TextFormField(
               controller: _addressController,
               decoration: InputDecoration(icon: Icon(Icons.map)),
@@ -53,6 +57,7 @@ class _MyAppState extends State<MyApp> {
             ),
             TextFormField(
               controller: _passwordController,
+              obscureText: true,
               decoration: InputDecoration(icon: Icon(Icons.lock_outline)),
             ),
             RaisedButton(

lib/flutter_vpn.dart

@@ -16,14 +16,52 @@ import 'dart:async';
 
 import 'package:flutter/services.dart';
 
+const _channel = const MethodChannel('flutter_vpn');
+const _eventChannel = const EventChannel('flutter_vpn_states');
+
+enum FlutterVpnState {
+  up,
+  down,
+  authError,
+  peerAuthError,
+  lookUpError,
+  unreachableError,
+  certificateUnavailable,
+  genericError
+}
+
 class FlutterVpn {
-  static const MethodChannel _channel = const MethodChannel('flutter_vpn');
+  /// Receive state change from charon VPN service.
+  ///
+  /// Can only be listened once.
+  /// If more than one, only the last subscription will receive events.
+  static Stream<FlutterVpnState> get onStateChanged =>
+      _eventChannel.receiveBroadcastStream().map((event) {
+        switch (event) {
+          case 1:
+            return FlutterVpnState.up;
+          case 2:
+            return FlutterVpnState.down;
+          case 3:
+            return FlutterVpnState.authError;
+          case 4:
+            return FlutterVpnState.peerAuthError;
+          case 5:
+            return FlutterVpnState.lookUpError;
+          case 6:
+            return FlutterVpnState.unreachableError;
+          case 7:
+            return FlutterVpnState.certificateUnavailable;
+          case 8:
+            return FlutterVpnState.genericError;
+        }
+      });
 
   /// Prepare for vpn connection.
   ///
   /// For first connection it will show a dialog to ask for permission.
   /// When your connection was interrupted by another VPN connection,
-  /// you should prepare again before reconnection.
+  /// you should prepare again before reconnect.
   static Future<bool> prepare() async {
     return await _channel.invokeMethod('prepare');
   }