Issue608

.gitignore

@@ -17,3 +17,4 @@ doc/api/
 .idea
 .DS_Store
 .directory
+/test/issues/issue602/venv/

example/mqtt_browser_client.dart

@@ -152,7 +152,7 @@ Future<int> main() async {
   /// Ok, we will now sleep a while, in this gap you will see ping request/response
   /// messages being exchanged by the keep alive mechanism.
   print('EXAMPLE::Sleeping....');
-  await MqttUtilities.asyncSleep(60);
+  await MqttUtilities.asyncSleep(20);
 
   /// Finally, unsubscribe and exit gracefully
   print('EXAMPLE::Unsubscribing');

lib/mqtt_client.dart

@@ -22,6 +22,8 @@ part 'src/mqtt_client_constants.dart';
 
 part 'src/mqtt_client_protocol.dart';
 
+part 'src/mqtt_client_environment.dart';
+
 part 'src/mqtt_client_events.dart';
 
 part 'src/exception/mqtt_client_client_identifier_exception.dart';

lib/src/mqtt_browser_client.dart

@@ -46,6 +46,8 @@ class MqttBrowserClient extends MqttClient {
     String? username,
     String? password,
   ]) async {
+    // A browser client
+    MqttClientEnvironment.isWebClient = true;
     instantiationCorrect = true;
     clientEventBus = events.EventBus();
     clientEventBus?.on<DisconnectOnNoPingResponse>().listen(

lib/src/mqtt_client_environment.dart

@@ -0,0 +1,14 @@
+/*
+ * Package : mqtt_client
+ * Author : S. Hamblett <[email protected]>
+ * Date   : 09/06/2025
+ * Copyright :  S.Hamblett
+ */
+
+part of '../mqtt_client.dart';
+
+/// Client Environment
+class MqttClientEnvironment {
+  /// Browser or server client
+  static bool isWebClient = false;
+}

lib/src/mqtt_server_client.dart

@@ -91,6 +91,8 @@ class MqttServerClient extends MqttClient {
     String? username,
     String? password,
   ]) async {
+    // A server client
+    MqttClientEnvironment.isWebClient = false;
     instantiationCorrect = true;
     clientEventBus = events.EventBus();
     clientEventBus?.on<DisconnectOnNoPingResponse>().listen(

lib/src/utility/mqtt_client_byte_buffer.dart

@@ -100,9 +100,18 @@ class MqttByteBuffer {
         'length $length, count $count, position $_position, buffer $buffer',
       );
     }
-    _position += count;
-    return typed.Uint8Buffer()
-      ..addAll(buffer!.getRange(_position - count, _position));
+    if (MqttClientEnvironment.isWebClient) {
+      final tmp = typed.Uint8Buffer();
+      tmp.addAll(buffer!.getRange(_position, _position + count));
+      _position += count;
+      final tmp2 = typed.Uint8Buffer();
+      tmp2.addAll(tmp);
+      return tmp2;
+    } else {
+      _position += count;
+      return typed.Uint8Buffer()
+        ..addAll(buffer!.getRange(_position - count, _position));
+    }
   }
 
   /// Reads a sequence of bytes from the current

test/issues/issue608.dart

@@ -0,0 +1,118 @@
+import 'dart:async';
+
+import 'package:mqtt_client/mqtt_browser_client.dart';
+import 'package:mqtt_client/mqtt_client.dart';
+
+class MqttParams {
+  final url = 'ws://test.mosquitto.org';
+  final port = 8080;
+  final keepAlivePeriod = 60;
+  final username = null;
+  final password = null;
+}
+
+class MqttWebInitializer {
+  late MqttBrowserClient _client;
+
+  void initClient({
+    required MqttParams params,
+    String willTopic = 'willTopic',
+    String willMessage = 'will message',
+  }) {
+    _client = MqttBrowserClient(params.url, '');
+    final clientId = 'Geppo-Web}';
+    _client.logging(on: false);
+    _client.port = params.port;
+    _client.setProtocolV311();
+    _client.websocketProtocols = MqttClientConstants.protocolsSingleDefault;
+    // Keep alive period (in secondi) a 0 = disabilitato
+    if (params.keepAlivePeriod > 0) {
+      _client.keepAlivePeriod = params.keepAlivePeriod;
+    }
+    _client.onDisconnected = onDisconnected;
+    _client.onConnected = onConnected;
+    _client.onSubscribed = onSubscribed;
+    _client.onUnsubscribed = onUnsubscribed;
+
+    final MqttConnectMessage connectMessage = MqttConnectMessage();
+    if (params.username != null && params.password != null) {
+      connectMessage.authenticateAs(params.username!, params.password!);
+    }
+    connectMessage
+        .withClientIdentifier(clientId)
+        .withWillTopic(willTopic)
+        .withWillMessage(willMessage)
+        .withWillQos(MqttQos.atLeastOnce)
+        .startClean();
+
+    connectMessage.withWillQos(MqttQos.exactlyOnce);
+    print('EXECUTING - MQTT CONNECT...');
+    _client.connectionMessage = connectMessage;
+  }
+
+  MqttClient get client => _client;
+
+  Future<MqttClientConnectionStatus?> connect([
+    String? username,
+    String? password,
+  ]) async {
+    MqttClientConnectionStatus? status;
+    try {
+      print('EXECUTING - MQTT CONNECTING...');
+
+      if (username == null && password == null) {
+        status = await _client.connect(username, password);
+      } else {
+        status = await _client.connect();
+      }
+    } catch (e) {
+      print('EXCEPTION - MQTT CONNECT: $e');
+    }
+    return status;
+  }
+
+  void disconnect() {
+    print('EXECUTING - MQTT DISCONNECTING...');
+    _client.disconnect();
+  }
+
+  void onConnected() {
+    print('EXECUTING - MQTT CONNECTED');
+  }
+
+  void onDisconnected() {
+    print('EXECUTING - MQTT DISCONNECTED');
+  }
+
+  void onSubscribed(String topic) {
+    print('EXECUTING - MQTT SUBSCRIBED TO TOPIC: $topic');
+  }
+
+  void onUnsubscribed(String? topic) {
+    print('EXECUTING - MQTT UNSUBSCRIBED FROM TOPIC: $topic');
+  }
+
+  void subscribe(String topic, {MqttQos qos = MqttQos.exactlyOnce}) {
+    print('EXECUTING - MQTT SUBSCRIBING TO TOPIC: $topic');
+    _client.subscribe(topic, qos);
+  }
+
+  void unsubscribe(String topic) {
+    print('EXECUTING - MQTT UNSUBSCRIBED FROM TOPIC: $topic');
+    _client.unsubscribe(topic);
+  }
+}
+
+void main() async {
+  final browser = MqttWebInitializer();
+  browser.initClient(params: MqttParams());
+  print('EXECUTING - Connecting');
+  await browser.connect();
+  print('EXECUTING - Waiting before subscription');
+  await Future.delayed(Duration(seconds: 5));
+  browser.subscribe('my/dashboard/topic/chatList/#', qos: MqttQos.exactlyOnce);
+  print('EXECUTING - Subscribed - waiting for disconnect');
+  await Future.delayed(Duration(seconds: 10));
+  browser.unsubscribe('my/dashboard/topic/chatList/#');
+  browser.disconnect();
+}

test/manual/mqtt_client_mosquitto_ws_browser_test_manual.dart

@@ -45,12 +45,14 @@ void main() {
           .withWillQos(MqttQos.atLeastOnce);
       client.connectionMessage = connMess;
       var ok = true;
+      expect(MqttClientEnvironment.isWebClient, isFalse);
       try {
         await client.connect();
         var connectionOK = false;
         if (client.connectionStatus!.state == MqttConnectionState.connected) {
           print('Browser client connected locally');
           connectionOK = true;
+          expect(MqttClientEnvironment.isWebClient, isTrue);
         } else {
           print(
             'Browser client connection failed - disconnecting, status is ${client.connectionStatus}',

test/manual/mqtt_client_mosquitto_wss_browser_test_manual.dart

@@ -48,9 +48,11 @@ void main() {
       try {
         await client.connect();
         var connectionOK = false;
+        expect(MqttClientEnvironment.isWebClient, isFalse);
         if (client.connectionStatus!.state == MqttConnectionState.connected) {
           print('Browser client connected locally');
           connectionOK = true;
+          expect(MqttClientEnvironment.isWebClient, isTrue);
         } else {
           print(
             'Browser client connection failed - disconnecting, status is ${client.connectionStatus}',

test/mqtt_client_connection_unsecure_test.dart

@@ -365,11 +365,13 @@ void main() {
             socketTimeout: null,
           );
           ch.onConnected = connectCb;
+          expect(MqttClientEnvironment.isWebClient, isFalse);
           final status = await ch.connect(
             mockBrokerAddress,
             mockBrokerPort,
             MqttConnectMessage().withClientIdentifier(testClientId),
           );
+          expect(MqttClientEnvironment.isWebClient, isFalse);
           expect(ch.connectionStatus.state, MqttConnectionState.connected);
           expect(
             ch.connectionStatus.returnCode,