Hi Daniel,
Thanks for your reply.
Used the following script for testing:
if (is_method("BYE")) {
xlog("CALLID: $ci\n");
xlog("CSEQ: $cs\n");
if (t_cancel_callid("$ci", "$cs", "0")) {
xlog("Transaction cancelled\n");
} else {
xlog("Failed to cancel transaction\n");
}
send_reply("200", "OK");
exit;
}
No cancel message was triggered.
Best Regards,
Lars
________________________________
From: Daniel-Constantin Mierla <[email protected]>
Sent: Friday, October 25, 2019 12:32 PM
To: Kamailio (SER) - Users Mailing List <[email protected]>; Lars
Olsson <[email protected]>
Subject: Re: [SR-Users] Rewrite BYE to Cancel
Hello,
actually sending BYE for an in-progress call setup (initial INVITE routed, but
200ok was not received yet) is valid from SIP RFC point of view. So it is not
really a broken implementation (or, not to put all my money in, it can be, but
not because of this kind of BYE).
Practically the BYE can be used to terminate a specific branch in a call setup.
Think about parallel forking, and many branches start sending back 183. The
caller UA can send BYE to some of the branches and let the others wait to
complete.
The CANCEL has to be used when all the branches should be terminated. If there
is a single branch, then the BYE terminates the call in progress, I am not sure
what the callee UA should reply to the INVITE.
On the other hand, in the very few cases when I saw UAs sending BYE for early
call setup, the other side was rejecting it, expecting the cancel.
I expect it should work with kamailio to send 200ok for such BYE and then use
t_cancel_callid():
https://www.kamailio.org/docs/modules/stable/modules/tmx.html#tmx.f.t_cancel_callid
The call-id and cseq values should be the same in the BYE request.
Try it and write back if works, I am quite curious about...
Cheers,
Daniel
On 25.10.19 12:17, Lars Olsson wrote:
Yes it is a BROKEN behavior from the remote system, unfortunately it can not be
changed.
Besides this issue, the remote system works as it should.
A custom b2bua can for sure resolve this, but perhaps not in a standard way.
Question is if it is possible to resolve with Kamailio or if I need to patch
SEMS to handle this.
Something like this:
if ("BYE" && dialog not confirmed)
reply back 200 OK
cancel other side of dialog
As Kamailio can terminate active dialog with sending bye in both directions, I
thought that it might be possible to resolve this as well. Hence asking for
ideas.
Best Regards,
Lars
________________________________
From: sr-users
<[email protected]><mailto:[email protected]>
on behalf of Steve Davies
<[email protected]><mailto:[email protected]>
Sent: Friday, October 25, 2019 11:25 AM
To: Kamailio (SER) - Users Mailing List
<[email protected]><mailto:[email protected]>
Subject: Re: [SR-Users] Rewrite BYE to Cancel
Hi,
I'm normally a bystander. But on this occasion I've got to comment - there are
broken SIP implementations, and there are BROKEN ones. Surely there is no hope
with this one? If they can't get this right just imagine how many more
problems it will have.
Steve
On Fri, 25 Oct 2019 at 11:19, Lars Olsson
<[email protected]<mailto:[email protected]>> wrote:
hi,
I have a Kamailio setup infront of a SIP system that do not handle cancellation
of a INVITE correctly.
The system sends out a BYE request instead of a Cancel request on non connected
dialogs.
I am trying to find a way to let Kamailio "translate" the BYE request to a
Cancel reqeust for the ongoing INVITE dialog.
Alternative if SEMS b2bua can do it, but currently it replies: "not
sip-relaying BYE in not connected dlg", and I have not found any obvious way to
rewrite it there.
Any thoughts. I can not change the behavior of the remote system.
Best Regards,
Lars
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--
Daniel-Constantin Mierla -- www.asipto.com<http://www.asipto.com>
www.twitter.com/miconda<http://www.twitter.com/miconda> --
www.linkedin.com/in/miconda<http://www.linkedin.com/in/miconda>
Kamailio Advanced Training, Oct 21-23, 2019, Berlin, Germany --
https://asipto.com/u/kat
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