Protocol Version 132 (MQTT 3.1.1 Bridge) Support

[mac866]

Hi,

I currently use MQTTnet as a endpoint for various MQTT clients.
For this reason, I would like to thank you for your great work!

I need to integrate a new "BlackBox-Hardware client", but it connects with protocol version 132 [MQTT 3.1.1 Bridge] which results in:

MQTTnet.Exceptions.MqttProtocolViolationException: Protocol level '132' not supported.
   at MQTTnet.Formatter.MqttPacketFormatterAdapter.ParseProtocolVersion(ReceivedMqttPacket receivedMqttPacket)
   at MQTTnet.Formatter.MqttPacketFormatterAdapter.DetectProtocolVersion(ReceivedMqttPacket receivedMqttPacket)
   at MQTTnet.Adapter.MqttChannelAdapter.ReceivePacketAsync(CancellationToken cancellationToken)
   at MQTTnet.Server.Internal.MqttClientSessionsManager.ReceiveConnectPacket(IMqttChannelAdapter channelAdapter, CancellationToken cancellationToken)
   at MQTTnet.Server.Internal.MqttClientSessionsManager.HandleClientConnectionAsync(IMqttChannelAdapter channelAdapter, CancellationToken cancellationToken)

I cannot change the configuration of this client, but I could reproduce the same behaviour via the Mosquitto Broker in bridge mode.

Are there ways to connect with version 132 without making changes to the client?

THX

[chkr1011]

Do you have a link for me with the full protocol specification or more details? Currently there is no way to make a connection but I can add support for this when you provide more details about this feature.

[MD-V]

Hello @chkr1011 according to https://github.com/eclipse/mosquitto/blob/3cbe805e71ac41a2a20cc9b2ea6b3b619f49554a/lib/send_connect.c#L153 the protocol level property will additionally contain 0x80 if try_private is set to true (https://mosquitto.org/man/mosquitto-conf-5.html) on the bridge side. Maybe this issue is related to: #1166

[mac866]

Hello @chkr1011,
I have not found a spec, but there is a VerneMQ commit that solved it for them:
vernemq/vernemq@70b5691
THX

[chkr1011]

Please try this version from the myget feed: https://www.myget.org/feed/mqttnet/package/nuget/MQTTnet/4.0.0.180

It allows sending the flag in the client and the server will now "ignore" it so that a connection can be established.

[mac866]

Hi @chkr1011,
4.0.0.180 works like a charm - thanks a lot!!!

[SeppPenner]

Nice, so we can close this issue? :)

[mac866]

Yes - THX!