Add mqtt_connect and mqtt_disconnect hooks to mod_mqtt_session

[dilshan-bhasha]

I'm not a good erlang developer, but I have developed some custom modules for my ejabberd service. When developing a module, we need to track MQTT device connections. some times device connects but disconnects for some reason. but we cannot isolate the devices that frequently connection/disconnection happening.

Currently, ejabberd's MQTT implementation lacks event hooks for connection and disconnection events (it may be for performance optimization). Unlike XMPP which provides sm_register_connection_hook and sm_remove_connection_hook, MQTT has no equivalent mechanism for external modules to react to client lifecycle events.

This limitation prevents:

• Real-time user/device tracking and analytics
• Integration with external monitoring systems
• Custom authentication/authorization workflows post-connection
• IoT device provisioning workflows