[SR-Users] Very strange reinvite behaviour
Alex Balashov
abalashov at evaristesys.com
Tue Aug 14 19:19:54 CEST 2018
One curiosity is that the reinvite does not appear to have the Via from
the UAC that sent the initial invite. But certainly that would not cause
this behaviour?
On Tue, Aug 14, 2018 at 12:52:50PM -0400, Alex Balashov wrote:
> Another aspect of this mystery:
>
> Here is the route set in the reinvite:
>
> Route: <sip:1.1.1.1:5061;transport=tls;r2=on;lr=on;ftag=gK00253981;vsf=AAAAACERAR0RHQYQJVJ3GAUdAx0EAAQfATEw;dlgcor=4411.f183;proxy_media=yes>
> Route: <sip:1.1.1.1;r2=on;lr=on;ftag=gK00253981;vsf=AAAAACERAR0RHQYQJVJ3GAUdAx0EAAQfATEw;dlgcor=4411.f183;proxy_media=yes>
> Route: <sip:Restricted at 3.3.3.3:5060;lr>
>
> The expectation would be that Kamailio would strip off its two Routes
> and then relay this request to 3.3.3.3:5060, even if the RURI says to
> relay the request to itself.
>
> But that's not what actually happens. Kamailio clearly forwards the
> request to itself, as per the RURI, because the next log message we see
> is:
>
> [R-MAIN:...] Re-INVITE received from 1.1.1.1:5060 to RURI sip:Restricted at 3.3.3.3:5060;lr
>
> Um, what?
>
> Here is the full logged reinvite, for reference:
>
> ---
>
> INVITE sip:1.1.1.1:5061 SIP/2.0
> CSeq: 2 INVITE
> To: <sip:stricted at 3.3.3.3>;tag=gK00253981
> From: <sip:+17023880118 at 1.1.1.1>;tag=8812465_1533349860
> Call-ID: 992000768_14572846 at 3.3.3.3
> Via: SIP/2.0/TLS 4.4.4.4:5061;rport;branch=z9hG4bK845565_1533349860
> Route: <sip:1.1.1.1:5061;transport=tls;r2=on;lr=on;ftag=gK00253981;vsf=AAAAACERAR0RHQYQJVJ3GAUdAx0EAAQfATEw;dlgcor=4411.f183;proxy_media=yes>
> Route: <sip:1.1.1.1;r2=on;lr=on;ftag=gK00253981;vsf=AAAAACERAR0RHQYQJVJ3GAUdAx0EAAQfATEw;dlgcor=4411.f183;proxy_media=yes>
> Route: <sip:Restricted at 3.3.3.3:5060;lr>
> User-Agent: ClownCar WhoKnows
> Max-Forwards: 32
> ASupportedCodec: 0 8
> Contact: <sip:MyTrunk at 4.4.4.4:5061;transport=tls>
> Supported: em,timer,replaces,path,resource-priority
> Allow: REGISTER,OPTIONS,INVITE,ACK,CANCEL,BYE,NOTIFY,PRACK,REFER,INFO,SUBSCRIBE,UPDATE
> Content-Type: application/sdp
> Content-Length: 303
>
> v=0
> o=ClownCar 1534262664 1534262665 IN IP4 4.4.4.4
> s=SIP Call
> c=IN IP4 4.4.4.4
> t=0 0
> m=image 50104 udptl t38
> a=T38FaxVersion:0
> a=T38FaxMaxBuffer:1024
> a=T38FaxMaxDatagram:238
> a=T38FaxRateManagement:transferredTCF
> a=T38FaxUdpEC:t38UDPRedundancy
> a=T38MaxBitRate:14400
> a=sendrecv
>
> -- Alex
>
> On Tue, Aug 14, 2018 at 12:44:21PM -0400, Alex Balashov wrote:
>
> > Hi,
> >
> > We have a scenario like this:
> >
> > ITSP -----> Kamailio -----> Endpoint
> > (UDP) (TLS)
> >
> > So, TLS is only being used on the last hop, and the upstream interaction
> > with the ITSP is plain-old UDP.
> >
> > Kamailio has the following listeners:
> >
> > listen=udp:1.1.1.1:5060
> > listen=udp:1.1.1.2:5060
> > listen=tcp:10.0.0.1:5060
> > listen=tls:1.1.1.1:5061
> >
> > At some point, 'Endpoint' sends a reinvite which has the following RURI:
> >
> > INVITE sip:1.1.1.1:5061 SIP/2.0
> >
> > This is clearly improper, and caused a loop that led to the rtpengine
> > SDP loop issue I previously reported in another thread.
> >
> > So, in an effort to stop this, I added the following:
> >
> > if(has_totag()) {
> > if(loose_route()) {
> > ...
> >
> > if(is_method("INVITE")) {
> > xlog("L_INFO", "[R-MAIN:$ci] Re-INVITE received from $si:$sp to RURI $ru\n");
> > xlog("L_INFO", "[R-MAIN:$ci] Reinvite body: $mb\n");
> >
> > if(!is_method("ACK") && uri == myself) {
> > sl_send_reply("400", "Bad Request");
> > exit;
> > }
> > }
> > }
> >
> > But it doesn't work. It appears that the '400 Bad Request' rejection
> > never happens, presumably because the this domain doesn't match
> > 'myself'.
> >
> > Another perplexing mystery: the log message containing the reinvite's
> > '$ru' does not show a RURI of 'sip:1.1.1.1:5061', but rather the remote
> > target in the initial inbound INVITE, which we also logged:
> >
> > Contact: "Anonymous" <sip:Restricted at 3.3.3.3:5060>
> >
> > The log message says:
> >
> > [R-MAIN:...] Re-INVITE received from 4.4.4.4:5060 to RURI sip:Restricted at 3.3.3.3:5060;lr.
> >
> > Note a subtle detail here: the ';lr' parameter is present, which is an
> > attribute of the Record-Route inserted by the sending ITSP (3.3.3.3).
> > It's at the bottom of the Route set, of course, below Kamailio's two RRs
> > (inserted for the ingress UDP interface and the egress TLS interface):
> >
> > Route: <sip:Restricted at 3.3.3.3:5060;lr>
> >
> > This leads to two questions whose causes seem to be related:
> >
> > 1. Why does Kamailio think the request URI of this re-invite is
> > something other than what $mb reveals it to be?
> >
> > 2. Is that, presumably, why it does not match 'myself'?
> >
> > 3. Why would Kamailio think it is actually set to the far-end
> > Record-Route URI?
> >
> > This is version: kamailio 4.4.5 (x86_64/linux) d48094.
> >
> > Thanks,
> >
> > -- Alex
> >
> > --
> > Alex Balashov | Principal | Evariste Systems LLC
> >
> > Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
> > Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
> >
> > _______________________________________________
> > Kamailio (SER) - Users Mailing List
> > sr-users at lists.kamailio.org
> > https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>
> --
> Alex Balashov | Principal | Evariste Systems LLC
>
> Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
> Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
>
> _______________________________________________
> Kamailio (SER) - Users Mailing List
> sr-users at lists.kamailio.org
> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
--
Alex Balashov | Principal | Evariste Systems LLC
Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
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