Enhanced Auth Flow

VerneMQ supports enhanced authentication flows or SASL style authentication for MQTT 5.0 sessions. The enhanced authentication mechanism can be used for initial authentication when the client connects or to re-authenticate clients at a later point.

The on_auth_m5 hook allows the plugin to implement SASL style authentication flows by either accepting, rejecting (disconnecting the client) or continue the flow. The on_auth_m5 hook is specified in the Erlang behaviour on_auth_m5_hook in the vernemq_dev repo.