[SR-Users] Retransmission handling

[Alex Balashov]

On Thu, Oct 19, 2017 at 11:06:21AM +0300, Volkan Oransoy wrote:

> I wonder purpose of this block in default script. What I didn’t understand is the purpose of "t_check_trans()”. Accoording to documentation, this method returns a boolean. So why do we use it even we don’t check output?
> 
> 	# handle retransmissions
> 	if (!is_method("ACK")) {
> 		if(t_precheck_trans()) {
> 			t_check_trans();
> 			exit;
> 		}
> 		t_check_trans();
> 	}

Because t_check_trans() has certain behaviours simply in virtue of being
called:

https://kamailio.org/docs/modules/5.0.x/modules/tm.html#tm.f.t_check_trans

For example:

   "For ACKs to negative replies or for ACKs to local transactions it will
    terminate the script if the ACK belongs to a transaction"

-- Alex

-- 
Alex Balashov | Principal | Evariste Systems LLC

Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free) 
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/