[mosquitto-dev] How to determine status of network loop

[Tony Klein <tklein@xxxxxxxxxxx>]

I am a client using libmosquitto to connect to a broker over TLS.

I am having difficulty determining the status of the network thread,
or alternately the status of my connection attempt.

I call mosquitto_loop_start()
then mosquitto_connect()
then wait for  on_connect() callback to get driven.

Perhaps the broker name does not resolve,
or perhaps the connection is refused (broker not running),
or perhaps the server or client certificates don't validate properly,
or perhaps any number of misadventures occur.

Sometimes the connection will eventually succeed,
but sometimes it does not.

How can my client determine what to do next?

In some cases its appropriate to simply wait, because the network thread 
is working,
(For example, suppose the broker is not running: mosquitto_connect() 
returns a "connection refused" error,  I can essentially ignore ...
start the broker and the connection completes as if by magic. Amazing.)

in other cases its hopeless because the network thread has exited and 
the waiting would be forever.
(For example if either server or client certificates fail to validate 
properly.  Bummer. No error return on connect(), no callback, no clue.)

How do I know the difference?

What technique can I use to determine if the network thread is running,
or to resolve faults that may have occurred?

Regards,
Tony
St. Paul, Minnesota, USA