Option `WithAutoReconnectDelay` fails to reconnect when unauthorized.

[jechtom]

Authorization failure breaks the managed client and it will never try to reconnect.

This happens if I use ManagedMqttClient with the feature AutoReconnectDelay (tuned on by default) together with client option WithoutThrowOnNonSuccessfulConnectResponse (expected to be turned on by default in the future).

Which component is your bug related to?

• Client (4.2.1.781, latest on 2023-08-06)
• ManagedClient (4.2.1.781, latest on 2023-08-06)

To Reproduce

Steps to reproduce the behavior:

1. Have any MQTT server that requires authentication.
2. Use (currently latest) MQTTnet.Extensions.ManagedClient 4.2.1.781.
3. Run this code:

            var mqttClientOptions = new ManagedMqttClientOptionsBuilder()
                //.WithAutoReconnectDelay(TimeSpan.FromSeconds(5)) <- no needed, turned on by default
                .WithClientOptions(b => b
                    .WithCredentials("aaaaaaaaaa invalid credentials")
                    .WithoutThrowOnNonSuccessfulConnectResponse() // will be enabled by default in the future versions
                    .WithConnectionUri("wss://address-of-you-mqtt-server")
                ).Build();

            var mqttClient = new MqttFactory().CreateManagedMqttClient();
            await mqttClient.StartAsync(mqttClientOptions).ConfigureAwait(false);
            await Task.Delay(Timeout.Infinite);

5. Run the code.
6. Client will contact the server only once and will not retry.

Expected behavior

The client should try to reconnect in regular intervals (5s by default).
Instead if will internally fail on error:

Not allowed to connect while connect/disconnect is pending.

Full code example with logging

Full code:

using MQTTnet.Extensions.ManagedClient;
using MQTTnet;
using System.Diagnostics;

namespace MqttReconnectTest
{
    internal class Program
    {
        static async Task Main(string[] args)
        {
            Stopwatch sw = Stopwatch.StartNew();

            Task Print(string text)
            {
                Console.WriteLine($"[{sw.Elapsed:s\\.fff}s] {text}");
                return Task.CompletedTask;
            }

            await Print("Starting.");

            var mqttClientOptions = new ManagedMqttClientOptionsBuilder()
                //.WithAutoReconnectDelay(TimeSpan.FromSeconds(5)) <- no e, turned on by default
                .WithClientOptions(b => b
                    .WithCredentials("aaaaaaaaaa invalid credentials")
                    .WithoutThrowOnNonSuccessfulConnectResponse() // will be enabled by default in the future versions
                    .WithConnectionUri("wss://localhost:6001/servicebus")
                ).Build();

            var mqttClient = new MqttFactory().CreateManagedMqttClient();

         
            mqttClient.ConnectedAsync += (t) => Print("ConnectedAsync.");
            mqttClient.ConnectingFailedAsync += (t) => Print($"ConnectingFailedAsync: {t.Exception}");
            mqttClient.ConnectionStateChangedAsync += (t) => Print("ConnectionStateChangedAsync.");
            mqttClient.DisconnectedAsync += (t) => Print("DisconnectedAsync.");

            await mqttClient.StartAsync(mqttClientOptions).ConfigureAwait(false);

            await Task.Delay(Timeout.Infinite);
        }
    }
}

Output:

[0.000s] Starting.
[0.209s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[5.217s] ConnectingFailedAsync: System.InvalidOperationException: Not allowed to connect while connect/disconnect is pending.
   at MQTTnet.Client.MqttClient.ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken)
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[10.230s] ConnectingFailedAsync: System.InvalidOperationException: Not allowed to connect while connect/disconnect is pending.
   at MQTTnet.Client.MqttClient.ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken)
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[15.241s] ConnectingFailedAsync: System.InvalidOperationException: Not allowed to connect while connect/disconnect is pending.
   at MQTTnet.Client.MqttClient.ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken)
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[20.243s] ConnectingFailedAsync: System.InvalidOperationException: Not allowed to connect while connect/disconnect is pending.
   at MQTTnet.Client.MqttClient.ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken)
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
..........

[jechtom]

Seems like a bug in MqttClient in the method ConnectAsync. Fixed it in the pull request.

After the fix, output is:

[0.000s] Starting.
[0.310s] DisconnectedAsync.
[0.382s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken) in /_/Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs:line 570
[5.429s] DisconnectedAsync.
[5.459s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken) in /_/Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs:line 570
[10.509s] DisconnectedAsync.
[10.542s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken) in /_/Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs:line 570
[15.593s] DisconnectedAsync.
[15.627s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken) in /_/Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs:line 570
..........

[jechtom]

Fixed in (merge) https://github.com/dotnet/MQTTnet/releases/tag/v4.3.0.858

[jwbrothers]

@jechtom I am still seeing this issue with 4.3.3.952. The odd thing is I do not see this log message at all with Warning level tracing enabled:

_logger.Warning("Connecting failed: {0}", connectResult.ResultCode);

Will need to debug through this more tomorrow, but when debugging last week prior to upgrading to the latest version of the library the connection status was 'Connecting'.

[jechtom]

@jwbrothers Tested again with example code using .NET 8.

Version 4.2.1.781 before the fix:

[0.000s] Starting.
[3.869s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[8.874s] ConnectingFailedAsync: System.InvalidOperationException: Not allowed to connect while connect/disconnect is pending.
   at MQTTnet.Client.MqttClient.ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken)
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[13.883s] ConnectingFailedAsync: System.InvalidOperationException: Not allowed to connect while connect/disconnect is pending.
   at MQTTnet.Client.MqttClient.ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken)
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[18.884s] ConnectingFailedAsync: System.InvalidOperationException: Not allowed to connect while connect/disconnect is pending.
   at MQTTnet.Client.MqttClient.ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken)
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
...

Version 4.3.3.952 after the fix:

[0.001s] Starting.
[0.231s] DisconnectedAsync.
[0.246s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[5.296s] DisconnectedAsync.
[5.296s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[10.333s] DisconnectedAsync.
[10.334s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
[15.373s] DisconnectedAsync.
[15.373s] ConnectingFailedAsync: MQTTnet.Exceptions.MqttCommunicationException: Client connected but server denied connection with reason 'NotAuthorized'.
   at MQTTnet.Extensions.ManagedClient.ManagedMqttClient.ReconnectIfRequiredAsync(CancellationToken cancellationToken)
...

Seems like the fix works. You can try to reproduce and create new ticket.