[SR-Users] Dialog module's keep-alive feature uses wrong CSeq?

[Dmitri Savolainen]

hi

Indeed dialog  OPTIONS are send with wrong CSeq and there is no way to fix
it without patching source.

In docs for dialog module  "If keep alive is enabled for a dialog, the
module will send SIP OPTIONS requests with CSeq lower or equal than last
request within dialog"

Usually Kamailio is used before some media server (asterisk, freeswitch...):
endpoint1 - kamailio ----leg1----   media_server ---leg2---- kamailio -
endpoint2

So if it is your case and you want to check if dialog alive, you may ping
media server instead of pinging remote endpoints:
for leg1: dlg_set_property("ka-dst");
for leg2: dlg_set_property("ka-src");

Of course your media server should support this not inaccurate CSeq
handling. I successfully use it with freeswitch for example (with some
minimal freeswitch tuning)






2018-04-12 23:34 GMT+03:00 Oded Arbel <odeda at cloudonix.io>:

> Hi all.
>
> I'm trying to use the dialog module's keep alive feature (ka_interval()
> and dlg_set_property()), and the documentation (under dlg_set_property)
> says this:
>
> If keep alive is enabled for a dialog, the module will send SIP OPTIONS
> requests with CSeq lower or equal than last request within dialog
>
> This is seems really weird to me, but the problem is worse than that -
> when setting dlg_set_property("ka-src"), the OPTIONS messages sent to the
> caller always have CSeq set to "0", regardless of what CSeq the UA sent on
> its invite.
>
> The problem is that while some UAs respond to these purposefully broken
> messages with some kind of a 5xx reply (for example, Linphone funnily sends
> "500 Internal Server Error"), several UAs don't respond at all. Worse than
> that - some of the UAs that send back 5xx replies to OPTIONS with a
> non-zero but invalid CSeq will completely ignore the OPTIONS keep-alive
> message that is sent to the caller with a CSeq 0 - for example, PJSIP
> responds with "503 Invalid CSeq" to a "ka-dst" OPTIONS message but will
> ignore a "ka-src" OPTIONS message with CSeq 0.
>
> My questions:
> 1. Why are keep-alive messages sent with a wrong CSeq?
> 2. If we're keeping the "wrong CSeq" approach, can we at least not send
> CSeq "0"?
> 3. Is there a way to change any of the above behaviors with a
> configuration (i.e. without patching the sources)?
>
> Thanks in advance
>
> --
> Oded Arbel
> odeda at cloudonix.io
>
>
>
> _______________________________________________
> Kamailio (SER) - Users Mailing List
> sr-users at lists.kamailio.org
> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>
>


-- 
Savolainen Dmitri
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.kamailio.org/pipermail/sr-users/attachments/20180416/917e265f/attachment.html>