Socket error on client <unknown>

[Abenstex]

Hello everyone,

I've been struggling a lot to get mqtt up and running with Flutter. I've been using it with Golang and Javascript for a while, but currently I'm at a loss in Flutter. My code is the following:

_mqttClient = MqttBrowserClient(config.getConfigValue("mqttAddress")!, "AnansiUI");

    _mqttClient.port = config.getConfigValue("mqttPort")!;
    _mqttClient.logging(on: true);

    _mqttClient.keepAlivePeriod = 60;

    _mqttClient.keepAlivePeriod =
        config.getConfigValue("mqttKeepAliveSeconds")!;

    _mqttClient.onConnected = _onConnected;

    final connMess = MqttConnectMessage()
        .withClientIdentifier('AnansiUI')
        .keepAliveFor(60) // Must agree with the keep alive set above or not set
        .startClean() // Non persistent session for testing
        .withWillQos(MqttQos.atLeastOnce);
    print('EXAMPLE::Mosquitto client connecting....');
    _mqttClient.connectionMessage = connMess;

    try {
      await _mqttClient.connect();

    } on Exception catch (e) {
      print('EXAMPLE::client exception - $e');
      _mqttClient.disconnect();
    }

However I keep seeing this error message in the mosquitto log file: Socket error on client <unknown>, disconnecting. My mosquitto config is as follows:

pid_file /var/run/mosquitto.pid

persistence true
persistence_location /var/lib/mosquitto/

#log_type error
#log_type warning
log_type all
log_dest file /var/log/mosquitto/mosquitto.log

include_dir /etc/mosquitto/conf.d
allow_anonymous true
port 1883
listener 9001
protocol websockets

The debug output:

EXAMPLE::Mosquitto client connecting....
1-2021-11-15 12:29:26.826 -- MqttClient::connect - keep alive is enabled with a value of 120 seconds
1-2021-11-15 12:29:26.827 -- MqttConnectionKeepAlive:: Initialised with a keep alive value of 120 seconds
1-2021-11-15 12:29:26.827 -- MqttConnectionKeepAlive:: Disconnect on no ping response is disabled
1-2021-11-15 12:29:26.828 -- MqttConnectionHandlerBase::connect - server ws://192.168.2.43, port 9001
1-2021-11-15 12:29:26.828 -- SynchronousMqttBrowserConnectionHandler::internalConnect entered
1-2021-11-15 12:29:26.828 -- SynchronousMqttBrowserConnectionHandler::internalConnect - initiating connection try 0, auto reconnect in progress false
1-2021-11-15 12:29:26.829 -- SynchronousMqttBrowserConnectionHandler::internalConnect - calling connect
1-2021-11-15 12:29:26.830 -- MqttBrowserWsConnection::connect - entered
1-2021-11-15 12:29:26.830 -- MqttBrowserWsConnection::connect -  WS URL is ws://192.168.2.43:9001
1-2021-11-15 12:29:26.834 -- MqttBrowserWsConnection::connect - connection is waiting
1-2021-11-15 12:29:27.186 -- MqttBrowserWsConnection::connect - websocket has erred
1-2021-11-15 12:29:27.187 -- SynchronousMqttBrowserConnectionHandler::internalConnect - connection complete
1-2021-11-15 12:29:27.187 -- SynchronousMqttBrowserConnectionHandler::internalConnect sending connect message
1-2021-11-15 12:29:27.187 -- MqttConnectionHandlerBase::sendMessage - MQTTMessage of type MqttMessageType.connect
Header: MessageType = MqttMessageType.connect, Duplicate = false, Retain = false, Qos = MqttQos.atMostOnce, Size = 0
Connect Variable Header: ProtocolName=MQIsdp, ProtocolVersion=3, ConnectFlags=Connect Flags: Reserved1=false, CleanStart=true, WillFlag=false, WillQos=MqttQos.atLeastOnce, WillRetain=false, PasswordFlag=false, UserNameFlag=false, KeepAlive=120
MqttConnectPayload - client identifier is : AnansiUI

1-2021-11-15 12:29:27.192 -- SynchronousMqttBrowserConnectionHandler::internalConnect - pre sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-15 12:29:32.211 -- SynchronousMqttBrowserConnectionHandler::internalConnect - post sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-15 12:29:32.212 -- SynchronousMqttBrowserConnectionHandler::internalConnect - initiating connection try 1, auto reconnect in progress false
1-2021-11-15 12:29:32.212 -- SynchronousMqttBrowserConnectionHandler::internalConnect - calling connect
1-2021-11-15 12:29:32.212 -- MqttBrowserWsConnection::connect - entered
1-2021-11-15 12:29:32.213 -- MqttBrowserWsConnection::connect -  WS URL is ws://192.168.2.43:9001
1-2021-11-15 12:29:32.213 -- MqttBrowserWsConnection::connect - connection is waiting
1-2021-11-15 12:29:32.370 -- MqttBrowserWsConnection::connect - websocket has erred
1-2021-11-15 12:29:32.370 -- SynchronousMqttBrowserConnectionHandler::internalConnect - connection complete
1-2021-11-15 12:29:32.371 -- SynchronousMqttBrowserConnectionHandler::internalConnect sending connect message
1-2021-11-15 12:29:32.371 -- MqttConnectionHandlerBase::sendMessage - MQTTMessage of type MqttMessageType.connect
Header: MessageType = MqttMessageType.connect, Duplicate = false, Retain = false, Qos = MqttQos.atMostOnce, Size = 22
Connect Variable Header: ProtocolName=MQIsdp, ProtocolVersion=3, ConnectFlags=Connect Flags: Reserved1=false, CleanStart=true, WillFlag=false, WillQos=MqttQos.atLeastOnce, WillRetain=false, PasswordFlag=false, UserNameFlag=false, KeepAlive=120
MqttConnectPayload - client identifier is : AnansiUI

1-2021-11-15 12:29:32.373 -- SynchronousMqttBrowserConnectionHandler::internalConnect - pre sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-15 12:29:37.391 -- SynchronousMqttBrowserConnectionHandler::internalConnect - post sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-15 12:29:37.391 -- SynchronousMqttBrowserConnectionHandler::internalConnect - initiating connection try 2, auto reconnect in progress false
1-2021-11-15 12:29:37.392 -- SynchronousMqttBrowserConnectionHandler::internalConnect - calling connect
1-2021-11-15 12:29:37.392 -- MqttBrowserWsConnection::connect - entered
1-2021-11-15 12:29:37.392 -- MqttBrowserWsConnection::connect -  WS URL is ws://192.168.2.43:9001
1-2021-11-15 12:29:37.394 -- MqttBrowserWsConnection::connect - connection is waiting
1-2021-11-15 12:29:37.597 -- MqttBrowserWsConnection::connect - websocket has erred
1-2021-11-15 12:29:37.597 -- SynchronousMqttBrowserConnectionHandler::internalConnect - connection complete
1-2021-11-15 12:29:37.597 -- SynchronousMqttBrowserConnectionHandler::internalConnect sending connect message
1-2021-11-15 12:29:37.597 -- MqttConnectionHandlerBase::sendMessage - MQTTMessage of type MqttMessageType.connect
Header: MessageType = MqttMessageType.connect, Duplicate = false, Retain = false, Qos = MqttQos.atMostOnce, Size = 22
Connect Variable Header: ProtocolName=MQIsdp, ProtocolVersion=3, ConnectFlags=Connect Flags: Reserved1=false, CleanStart=true, WillFlag=false, WillQos=MqttQos.atLeastOnce, WillRetain=false, PasswordFlag=false, UserNameFlag=false, KeepAlive=120
MqttConnectPayload - client identifier is : AnansiUI

1-2021-11-15 12:29:37.598 -- SynchronousMqttBrowserConnectionHandler::internalConnect - pre sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-15 12:29:42.624 -- SynchronousMqttBrowserConnectionHandler::internalConnect - post sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-15 12:29:42.625 -- SynchronousMqttBrowserConnectionHandler::internalConnect failed
EXAMPLE::client exception - mqtt-client::NoConnectionException: The maximum allowed connection attempts ({3}) were exceeded. The broker is not responding to the connection request message (Missing Connection Acknowledgement?
1-2021-11-15 12:29:42.626 -- MqttConnectionHandlerBase::disconnect - entered
1-2021-11-15 12:29:42.626 -- MqttConnectionHandlerBase::_performConnectionDisconnect entered
1-2021-11-15 12:29:42.626 -- MqttConnectionKeepAlive::stop - stopping keep alive

What am I missing? Why is it client unknown even though I specified a client id?

[Abenstex]

BTW, I am getting the same debug output when I use 'ws://test.mosquitto.org' and port 8080 or 8081. So I don't think it has anything to do with my internal mosquitto setup especially because I can connect using other applications. I am using version 9.6.1 by the way.

[shamblett]

Run the at the mqtt_browser_client.dart example from the examples directory, this is known to work, see what that gives.

[Abenstex]

I ran the browser client example, but still got the same output:

1-2021-11-16 10:50:29.782 -- SynchronousMqttBrowserConnectionHandler::internalConnect - pre sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-16 10:50:34.809 -- SynchronousMqttBrowserConnectionHandler::internalConnect - post sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-16 10:50:34.809 -- SynchronousMqttBrowserConnectionHandler::internalConnect - initiating connection try 2, auto reconnect in progress false
1-2021-11-16 10:50:34.809 -- SynchronousMqttBrowserConnectionHandler::internalConnect - calling connect
1-2021-11-16 10:50:34.810 -- MqttBrowserWsConnection::connect - entered
1-2021-11-16 10:50:34.810 -- MqttBrowserWsConnection::connect -  WS URL is ws://test.mosquitto.org:8080
1-2021-11-16 10:50:34.810 -- MqttBrowserWsConnection::connect - connection is waiting
1-2021-11-16 10:50:34.885 -- MqttBrowserWsConnection::connect - websocket has erred
1-2021-11-16 10:50:34.885 -- SynchronousMqttBrowserConnectionHandler::internalConnect - connection complete
1-2021-11-16 10:50:34.885 -- SynchronousMqttBrowserConnectionHandler::internalConnect sending connect message
1-2021-11-16 10:50:34.885 -- MqttConnectionHandlerBase::sendMessage - MQTTMessage of type MqttMessageType.connect
Header: MessageType = MqttMessageType.connect, Duplicate = false, Retain = false, Qos = MqttQos.atMostOnce, Size = 63
Connect Variable Header: ProtocolName=MQIsdp, ProtocolVersion=3, ConnectFlags=Connect Flags: Reserved1=false, CleanStart=true, WillFlag=true, WillQos=MqttQos.atLeastOnce, WillRetain=false, PasswordFlag=false, UserNameFlag=false, KeepAlive=20
MqttConnectPayload - client identifier is : Mqtt_MyClientUniqueId

1-2021-11-16 10:50:34.886 -- SynchronousMqttBrowserConnectionHandler::internalConnect - pre sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-16 10:50:39.891 -- SynchronousMqttBrowserConnectionHandler::internalConnect - post sleep, state = Connection status is connecting with return code of noneSpecified and a disconnection origin of none
1-2021-11-16 10:50:39.892 -- SynchronousMqttBrowserConnectionHandler::internalConnect failed
EXAMPLE::client exception - mqtt-client::NoConnectionException: The maximum allowed connection attempts ({3}) were exceeded. The broker is not responding to the connection request message (Missing Connection Acknowledgement?
1-2021-11-16 10:50:39.895 -- MqttConnectionHandlerBase::disconnect - entered
1-2021-11-16 10:50:39.896 -- MqttConnectionHandlerBase::_performConnectionDisconnect entered
1-2021-11-16 10:50:39.897 -- MqttConnectionKeepAlive::stop - stopping keep alive
EXAMPLE::OnDisconnected client callback - Client disconnection
EXAMPLE::OnDisconnected callback is solicited, this is correct
EXAMPLE::ERROR Mosquitto client connection failed - disconnecting, status is Connection status is disconnected with return code of noneSpecified and a disconnection origin of solicited
EXAMPLE::OnDisconnected client callback - Client disconnection
EXAMPLE::OnDisconnected callback is solicited, this is correct

I thought that maybe the problem could have something with the browser setting, so I set the security level to "insecure" allowing all kind of connections, but that didn't solve the problem unfortunately.

[shamblett]

Try this -

client.websocketProtocols = MqttClientConstants.protocolsSingleDefault;

i.e manually set the WS headers the client sends to mosquito. If this works I'll update the example, I'm sure mosquito didn't need this at one time, other brokers do though.

[Abenstex]

Thank you! That solved the problem

[shamblett]

Browser client example updated, package re released at version 9.6.2.