Operating system name and version: OpenWrt 19.07.7
Version of smsd: 3.1.21
Smsd installed from: package repository
Name and model of a modem / phone: Quectel EC200
Interface: USB

I have an OpenWRT router with smstools3 installed in a remote area, I configured a forward scripts with eventhandler so I can receive the SMS text via email.
I want to add network connectivity check to eventhandler function in case the router loses internet and the SMS couldn't be sent through email.
So I find the run_eventhandler() func in smsd.c, I want to add a network connectivity check(while loop) in this function, it will sleep until passing the network connectivity check, but I am not sure if this will cause any problem, will this works?

Any help will be appreciated.

Hello!

What about an ping command with result to your sms response? For example ping www.nasa.gov
and send to you the result in an sms!

Regards
Rui

Not so clear what you want to achive, may please provide some details.
To check internet you may can use nagios plugin check_smtp:https://www.monitoring-plugins.org/doc/man/check_smtp.html
This checks the availability of SMTP relay.
You could use either eventhandler script or regular_run but I would avoid looping because it may block smsd process.

regards

Mike