[OpenSIPS-Users] Handling 488 on a leg B

[Bogdan-Andrei Iancu]

Hi Dmitry,

In order to push per-branch changes (changes which are specific only to 
a certainbranch and not to all of them), you need to use the branch 
route- see http://www.opensips.org/Documentation/Script-Routes-2-3#toc2

So, put the code for changing the body via rtpengine into a branch route.

Regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
   http://www.opensips-solutions.com
OpenSIPS Summit 2018
   http://www.opensips.org/events/Summit-2018Amsterdam

On 02/02/2018 12:53 PM, Dmitry wrote:
>
> Hi Bogdan,
>
> I change both of them. The first INVITE and the second (after 488).
>
> The first apply successfully, but the second (that in the 
> failure_route) does not.
>
> My script looks like this:
>
> route {
>
> …
>
> t_on_reply("ONREPLY”);
>
> if (isbflagset(NAT_BFLAG) && af!=INET6) {
>
> force_rport(); # add rport to first line Via:
>
> route(RTPENGINE_OFFER); # make offer
>
> }
>
> …
>
> t_relay();
>
> …
>
> }
>
> route[RTPENGINE_OFFER] {
>
> …
>
> $avp(rtp_profile) = "trust-address replace-origin 
> replace-session-connection ICE=remove DTLS=off RTP/SAVP";
>
>     if 
> (rtpengine_offer("$avp(rtp_profile)","$avp(rtp_socket)","$avp(rtp_body)")) 
> {
>
>   remove_body_part();
>
>   add_body_part("$avp(rtp_body)", "application/sdp"); # first changing 
> leg-B - successfully
>
> }
>
> …
>
> }
>
> onreply_route[ONREPLY] {
>
> …
>
> t_on_reply("RTPENGINE_ANSWER"); # positive
>
> t_on_failure("RTPENGINE_488");  # negative
>
> …
>
> }
>
> failure_route[RTPENGINE_488] {
>
> …
>
> if (t_check_status("488") ) {
>
> # try to change SDP in leg-B after 488 received - unsuccessfully
>
> # it returns: ERROR:rtpengine:rtpe_function_call: can't extract body 
> from the message.
>
> # from which message?
>
> if (rtpengine_offer("trust-address replace-origin 
> replace-session-connection ICE=remove DTLS=off 
> RTP/AVP","$avp(rtp_socket)","$avp(rtp_body)")) {
>
>     remove_body_part();
>
>   add_body_part("$avp(rtp_body)", "application/sdp");
>
> }
>
> #
>
> # just replace with re.subst
>
> $avp(rtp_body) = $(avp(rtp_body){re.subst,/SAVP/AVP/g});
>
> $avp(rtp_body) = $(avp(rtp_body){re.subst,/a=crypto.*//g});
>
> # if I use remove_body_part(), then add_body_part() is not adds 
> content. INVITE sends without body.
>
> remove_body_part();
>
> # if I don’t use remove_body_part(), then INVITE contains TWO sdp body 
> with RTP/SAVP and RTP/AVP
>
> add_body_part("$avp(rtp_body)", "application/sdp");
>
> #
>
>   xlog("rtp_body=$avp(rtp_body)\n");
>
>    # xlog for $avp(rtp_body) shows unchanged content (with RTP/SAVP)
>
> …
>
> t_relay();
>
> }
>
> …
>
> }
>
> *From:*Bogdan-Andrei Iancu [mailto:bogdan at opensips.org]
> *Sent:* Thursday, February 1, 2018 7:51 PM
> *To:* Dmitry <netaskd at gmail.com>; 'OpenSIPS users mailling list' 
> <users at lists.opensips.org>
> *Subject:* Re: [OpenSIPS-Users] Handling 488 on a leg B
>
> Hi Dmitry,
>
> In failure route you re-process the original request (INVITE) and not 
> the 488 reply - the reply is just the trigger.
> Do you change the INVITE SDP before the first attempt (which ends with 
> 488) ? Or you change it for the first time in the failure route ?
>
> Regards,
>
> Bogdan-Andrei Iancu
> OpenSIPS Founder and Developer
>    http://www.opensips-solutions.com
> OpenSIPS Summit 2018
>    http://www.opensips.org/events/Summit-2018Amsterdam
>
> On 02/01/2018 05:34 PM, Dmitry wrote:
>
>     Hello Bogdan,
>
>     Thank you for advice.
>
>     I catched 488 and can send INVITE from failure_route, but I can’t
>     modify body inside it.
>
>     The main goal is change SAVP profile to AVP when 488 received.
>
>     I tried to do it via rtpengine_offer function. It doesn’t work. I
>     guess, it try to read the body from response (488 in my case) but
>     not from request.
>
>     I tried to rewrite body via remove_body_part and add_body_part
>     functions, it also doesn’t work.
>
>     So, I don’t understand how exactly rewrite body in failure_route
>     before do t_relay().
>
>     In addition, I tried making a new branch (via append_branch
>     function and via branch_route). It just duplicate my re-INVITE
>     without changing the body.
>
>     Could you please drop a hint (example on few lines of code) how to
>     do it?
>
>     Thanks.
>
>     *From:*Bogdan-Andrei Iancu [mailto:bogdan at opensips.org]
>     *Sent:* Wednesday, January 31, 2018 6:55 PM
>     *To:* OpenSIPS users mailling list <users at lists.opensips.org>
>     <mailto:users at lists.opensips.org>; Dmitry <netaskd at gmail.com>
>     <mailto:netaskd at gmail.com>
>     *Subject:* Re: [OpenSIPS-Users] Handling 488 on a leg B
>
>     Hello Dmitry,
>
>     What you want to do is called (in SIP) serial forking. Use
>     failure_route{} to catch the 488 and to add a create a new branch
>     (with modified body) .
>
>     See: http://www.opensips.org/Documentation/Script-Routes-2-3#toc3
>
>     Regards,
>
>
>     Bogdan-Andrei Iancu
>
>       
>
>     OpenSIPS Founder and Developer
>
>        http://www.opensips-solutions.com
>
>     OpenSIPS Summit 2018
>
>        http://www.opensips.org/events/Summit-2018Amsterdam
>
>     On 01/30/2018 02:56 PM, Dmitry wrote:
>
>         Hello all,
>
>         Could you say how can I re-send INVITE with changed SDP to
>         B-leg after receive 488 from it?
>
>         Call flow:
>
>         -> A-leg INVITE
>
>         <- A-leg 100
>
>         -> B-leg INVITE
>
>         <- B-leg 100
>
>         <- B-leg 488 – I catch it, and want to send INVITE again with
>         properly SDP
>
>         -> B-leg ACK
>
>         <-A-leg 488
>
>         -> B-leg ACK
>
>         Thanks for any advice.
>
>         Cheers!
>
>
>
>
>
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>
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>
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>
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