8 Mar
2008
8 Mar
'08
2:39 a.m.
On Mar 06, 2008 at 17:45, Nuno Ribeiro <nribeiro82(a)gmail.com> wrote:
Hi all,
I'm facing a problem with "early CANCEL's" such the one described in
this
thread. The scenario is the following one:
A PSTN call to a SIP phone. When the PSTN decides to cancel the call only a
right after initiating, the PSTN will send the CANCEL message to the SER but
this is discarded and not forwarded to the correct path to the SIP Phone. So
what happens is that we have a ghost call.... The PSTN has already canceled
the call but the SIP phone continues to ring.
The code that I have in the SER script is really simple and the behavior to
a CANCEL is the same as to a INVITE:
if(subst_uri('/^sip:(\+[0-9]+)@
192.168.20.69.*user=phone$/sip:\1@xlab.com/i')){
record_route();
loose_route();
t_relay_to_udp("192.168.20.5", "5060");
break;
}
In the log file I see that:
RFC3261 transaction matching failed
t_lookup_request: no transaction found
e2e_cancel: e2e cancel proceeding
During this thread I saw that a CANCEL handling tm option was decided to be
created. Maybe this option can help me to solve the ghost call issue. How
can I change the default behavior ? this feature is available from which
SER release ?
The option is unmatched_cancel and is present for ser 2.1 (cvs head).
However what this does is select between dropping unmatched cancels,
forwarding them statelessly or statefully.
Older ser versions always forward the cancel statefully, which is what
you want in most cases (including yours).
It's strage that the cancel doesn't seem to match the invite transaction
in your case.
If you would send me some networks dumps with the invite and the cancel
I could tell you more.
Andrei
Any idea how I can solve this isse?
Thanks in advance.
Best Regards
On Thu, Mar 29, 2007 at 6:19 PM, Jiri Kuthan <jiri(a)iptel.org> wrote:
At 15:58 26/02/2007, Klaus Darilion wrote:
--
Nuno Ribeiro FYI: This is the pragmatic approach how openser
users handle the problem:
1. drop the CANCEL if there is no corresponding INVITE transaction. The
UAC must
retransmit the CANCEL and meanwhile there should be the INVITE
transaction. (since 1.0)
if ( is_method("CANCEL") && !t_check_trans() ) {
# CANCEL without matching INVITE transaction, ignore!
# May happen if the INVITE is slower than the CANCEL.
# Ignore the CANCEL, as the client will retransmit it, and maybe
# the INVITE transaction is already created for the next CANCEL
xlog("L_WARN","$ci CANCEL without matching transaction ...
ignore\n");
exit;
}
which does not appear really reboot-safe to me. What it can lead to that
ser reboot
affects pending calls in that cancels are never forwarded and ringing
phones will
never stop ringing -- not very pleasant indeed, is it.
-jiri
--
Jiri Kuthan http://iptel.org/~jiri/ <http://iptel.org/%7Ejiri/>
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