Hi,
I am trying to use dlg_req_within() for a 3pcc-style call setup, to set up media via a
reinvite:
1. Store original SDP offer from caller in $dlg_var()s;
2. Later, after e2e ACK is processed for initial INVITE transaction, send reinvite to
callee using dlg_req_within(). I call rtpengine_offer() and feed it the original SDP offer
(via read_sdp_pv modparam), and take the RTPEngine-transformed SDP and feed that to
dlg_req_within():
dlg_req_within("callee", "INVITE", "application/sdp",
"$var(sdp_from_rtpengine)");
3. I have found that event_route[tm:local-response] does not allow me to capture the 200
OK / SDP answer to this reinvite; it is internally absorbed.
However, it is possible to arm an onreply_route in event_route[tm:local-request], to
receive the 200 OK:
event_route[tm:local-request] {
if(method == "INVITE" && has_body("application/sdp"))
t_on_reply("REINVITE_REPLY");
}
4. My intent is for this reinvite reply handler to set off a reinvite to the caller side:
onreply_route[REINVITE_REPLY] {
if(method == "INVITE" && has_body("application/sdp")
&& t_check_status("200")) {
...
$var(rtpengine_use_this_sdp) = $rb;
rtpengine_answer("...");
dlg_req_within("caller", "INVITE",
"application/sdp", "$var(sdp_from_rtpengine)");
}
This ensures proper relay symmetry. Otherwise, the caller will continue to send RTP to the
previous upstream endpoint of the call, prior to any reinvite.
However, dlg_req_within() doesn't work in this later context, even though the
documentation says it can be used from ANY_ROUTE. Kamailio doesn't complain, there is
no error. It just doesn't initiate a reinvite to the caller.
I considered the possibility that this may be because the calling scope is that of a
pending reinvite transaction to the callee, but there is no obvious way to defer that into
the future. If I send it to an async task worker, the transaction scope required for
dlg_req_within() to know which dialog it's operating on will be lost.
Any ideas appreciated, and thank you in advance!
-- Alex
--
Alex Balashov
Principal Consultant
Evariste Systems LLC
Web:
https://evaristesys.com
Tel: +1-706-510-6800