7 May
2021
7 May
'21
12:17 p.m.
Hello,
I saw there are some topics on this already and carefully walked through
all of them, but can't solve following issue.
For a reason I do need that in Record-Route header sent to endpoint
would present FQDN. If it matters, it's UDP/WSS conversion done on Kamailio.
So, scheme is quite simple
Enpoint A ->UDP-> Kamailio ->WSS-> Endpoint B (NAT)
Main issue here, that if in Record-Route headers it's FQDN, but not IP
addresses, on a new transactions with a dialog (ACK on 200, PRACK, BYE),
Kamailio*loose_route()* function resolves address of destination not
current dialog, but actual R-URI (or itself, if R-URI is something from
WebRTC world) that is not correct due to NAT.
If in RR headers IP addresses are present - all is working as expected.
As an example (RR with FQDN)
B answers 200
SIP/2.0 200 OK
Record-Route:
<sip:KAMAILIO_FQDN:8089;transport=ws;r2=on;lr=on;ftag=0a3e31a6-96ad-42d0-9310-81b35cedbd3d;nat=wss>
Record-Route:
<sip:KAMAILIO_FQDN;r2=on;lr=on;ftag=0a3e31a6-96ad-42d0-9310-81b35cedbd3d;nat=wss>
Via: SIP/2.0/UDP <A_IP_ADDRESS>:5060;received=A IP
ADDRESS;rport=5060;branch=z9hG4bKPj67fb6d86-97d7-4231-995b-e54b0f62881e
To: <sip:88290@<KAMAILIO_FQDN>>;tag=hvra7mj3q0
From:
<sip:+XXXX7688881@<KAMAILIO_FQDN>>;tag=0a3e31a6-96ad-42d0-9310-81b35cedbd3d
Call-ID: 46f44741-d155-4dd5-8fd8-78e540fc1acb
CSeq: 18326 INVITE
Contact: <sip:88290@toleivu2gdbh.invalid;transport=wss>
Allow: ACK,CANCEL,INVITE,MESSAGE,BYE,OPTIONS,INFO,NOTIFY,REFER
Supported: outbound
Content-Type: application/sdp
Content-Length: 817
ACK looks like
ACK sip:88290@toleivu2gdbh.invalid;transport=wss SIP/2.0
Via: SIP/2.0/UDP
A_IP_ADDRESS:5060;rport;branch=z9hG4bKPj8d05548a-91ef-4332-8617-32f8eeebf8f2
From: <sip:88881@A_IP_ADDRESS>;tag=0a3e31a6-96ad-42d0-9310-81b35cedbd3d
To: <sip:88290@KAMAILIO_FQDN>;tag=hvra7mj3q0
Call-ID: 46f44741-d155-4dd5-8fd8-78e540fc1acb
CSeq: 18326 ACK
Route: <sip:FQDN;lr;r2=on;ftag=0a3e31a6-96ad-42d0-9310-81b35cedbd3d;nat=wss>
Route:
<sip:FQDN:8089;transport=ws;lr;r2=on;ftag=0a3e31a6-96ad-42d0-9310-81b35cedbd3d;nat=wss>
Max-Forwards: 70
User-Agent: Asterisk PBX 13.33.0
Content-Length: 0
And Kamailio on *loose_route()* loops ACK to itself. (with result of
function == 1)
In a case if in Record-Route/Route headers just IP address of Kamailio
present, all works as expected, but it's not really behavior I want to
achieve.
I've tried to play with *record_route_preset("...")* specifying only WSS
part (as suggested in https://skalatan.de/de/blog/kamailio-sbc-teams)
with FQDN, but no luck.
Also wanted to try approach using record_route_preset() function in
branch route, but it was working only with first branch, not affecting
others (but I assume having different RR headers across branches is not
a good idea)
--
Regards,
Igor