On 19 Oct 2017, at 20:22, Daniel-Constantin Mierla <miconda@gmail.com> wrote:

On 19.10.17 17:41, Alex Balashov wrote:

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"

Just to highlight, the other section in the docs is also relevant,
respectively stopping the config execution if it was a retransmission
after sending back the last response.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio Advanced Training, Nov 13-15, 2017, in Berlin - www.asipto.com
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