[Users] ACK processing

[Bogdan-Andrei Iancu]

Hi Michael,

what to do with broken hop-by-hop ACKs ? :) just drop them, otherwise 
they will loop on the server.

t_newtran() basically creates a new transaction. If it's ACK and it 
matched to an INVITE transaction, it will be silently discarded (so 
function will never return to script). If ACk doesn't match, the 
function will return; so after t_newtran() you will have only unmatched 
ACKs filtered out.

so,

.....
if (is_method("ACK")) { #hop-by-hop ACKs are absorbed here
    t_newtran();
    # drop broken ACKs
    exit;
}
......


should be ok.

regards,
bogdan

Michael Ulitskiy wrote:

>Bogdan,
>
>Thanks a lot. Your replies are very useful.
>Just couple more questions raised by comments.
>What would I want to do with broken ACKs? I thought I'd just drop it.
>Also how would I distinguish them? I don't really understand how
>you use t_newtran(). Don't real ACKs still need to hit t_relay to
>finish transaction?
>I thought about something like the following, but so far couldn't find
>a way to determine if ACK is matching transaction or not:
>
>if (is_method("ACK")) { #hop-by-hop ACKs are absorbed here
>     if (in-transaction ACK) {
>        t_relay();
>     }
>     # lost ACKs are dropped
>     # .......
>     exit;
>}
>
>I've tried to t_lookup_request() to check if it's in transaction, but it didn't work.
>Could you please comment on it?
>Thanks,
>
>Michael
>
>On Tuesday 26 July 2005 06:55 am, you wrote:
>  
>
>>Hi Michael,
>>
>>that's ok. only two comments:
>>1) all ACKs are in-dialog: ACKs for negative replies are hop-by-hop and 
>>are the one absorbed by tm functions; the ACKs for 2xx replies are 
>>end-to-end and are Route driven.
>>2) since you may have hop-by-hop ACKs (no route) which doesn't match any 
>>transaction (broken or lost ACKs), if you want to deal with them 
>>separately, do like this:
>>   
>>
>>if (loose_route()) { #end-2-end ACKs are forwarded here
>>    #do something 
>>    t_relay();
>>    exit;
>>}
>>if (is_method("ACK")) { #hop-by-hop ACKs are absorbed here
>>    t_newtran();
>>    # deal with broken / lost ACKs
>>    # .......
>>    exit;
>>}
>>
>>
>>regards,
>>bogdan
>>    
>>