14 Aug
2017
14 Aug
'17
8:30 a.m.
2016-03-18 Daniel-Constantin Mierla <miconda(a)gmail.com> wrote:
My guess that the sbc_5 is so poor implemented that it
takes the Via
from last request, which is CANCEL, but CANCEL is a hop-by-hop request
in this case. If my guess is confirmed, the implementation of sbc_5 is
really far away from RFC3261, something that I haven't probably seen
since 2002/3.
To test, you can try to use forward() for CANCEL instead of t_relay().
But you need to know where to send it -- same address as for INVITE --
you can hardcode some values in config for sake of simplicity to test. A
proper workaround can be built using htable module to store where the
invite was sent, using call-id as a key.
Hi Grant, Daniel
I accidentally found this 2016 thread and wanted to share my different solution.
I ran into similar issue: 487 reply from SIP phone UA came with
insufficient Via headers after CANCEL.
In fact situation looked exactly like described above:
Via stack for reply to INVITE seem to be taken incorrectly from CANCEL.
I did not observe any errors from Kamailio, but Asterisk chan_sip
(original INVITE sender) spits:
---
parse_via: received request without a Via header
handle_incoming: Dropping this SIP message with Call-ID 'abc', it's
incomplete
---
My quick solution was to reply locally with t_reply() when
branch with missing second via was winning:
---
...usrloc lookup()...
+t_on_branch_failure("TOUSER");
t_on_failure("FAILURE_TOUSER");
route(RELAY);
+event_route[tm:branch-failure:TOUSER]
+{
+ # Save branch ruid if broken Via detected
+ # If this branch wins, Via will be "fixed" with local reply
+ if ( $T_rpl($sel(via[2])) == $null ) $avp(secondviamissing) = $T(ruid);
+}
+
failure_route[FAILURE_TOUSER]
{
+ if ( $avp(secondviamissing) != $null && $avp(secondviamissing) == $T(ruid) )
+ {
+ # Some UAs (VP530P 23.70.74.5) seem to copy Via stack from CANCEL
+ # Lets "add" missing Via by creating internal reply
+ append_to_reply("X-log: viafix\r\n");
+ t_reply("$T(reply_code)", "$T_reply_reason");
+ exit;
+ }
}
---
That seems to do the trick, at least in simple non-branching case.
What do you think?
(other than using single $avp(secondviamissing) for whole transaction...)
--
Mikko