[OpenSIPS-Users] Problem proxying a SIP connection with t_relay and rtpproxy

[Bogdan-Andrei Iancu]

Hi Thomas,

Your handling of sequential requests is broken, see here for a correct 
sample:

https://github.com/OpenSIPS/opensips/blob/master/etc/opensips.cfg#L109

Regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
   https://www.opensips-solutions.com
OpenSIPS Summit 27-30 Sept 2022, Athens
   https://www.opensips.org/events/Summit-2022Athens/

On 9/30/22 11:07 AM, Thomas Pircher via Users wrote:
> Thomas Pircher wrote:
>> The problem I am seeing is when I initiate a connection from the sipp
>> client then I see RTP flowing only in one direction (sipp client to sipp
>> server). I believe this is due to a missing ACK from OpenSIPS to the
>> sipp server following the 200 OK.
>
> Hi,
>
> I no longer think the rtpproxy is part of the problem. I believe this is
> purely an issue with my t_relay configuration.
>
> I did some more tests, and I think the issue is that the ACK from the
> sipp client at 10.30.8.203 is discarded by OpenSIPS, and therefore the
> OpenSIPS does not send the ACK to the sipp server on the internal
> interface.
>
> This would also explain the "404 Not here" response to the BYE at the
> end of the connection:
>
>>  ┌───────────┐ ┌─────────────────┐ 
>> ┌─────────────────┐                    ┌───────────┐
>>  │sipp client│                    │OpenSIPS external│ │OpenSIPS 
>> internal│                    │sipp server│
>>  │10.30.8.203│                    │10.30.8.201      │ 
>> │10.30.9.10       │                    │10.30.90.11│
>>  └─────┬─────┘                    └────────┬────────┘ 
>> └────────┬────────┘                    └─────┬─────┘
>>        │        INVITE SDP (g711A) │                            │ │
>> │──────────────────────────────────>│ 
>> │                                   │
>>        │ │                            │ │
>>        │       100 Giving it a try │                            │ │
>> │<──────────────────────────────────│ 
>> │                                   │
>>        │ │                            │ │
>>        │ │                            │        INVITE SDP (g711A) │
>>        │ │ │──────────────────────────────────>│
>>        │ │                            │ │
>>        │ │                            │           180 Ringing │
>>        │ │ │<──────────────────────────────────│
>>        │ │                            │ │
>>        │           180 Ringing │                            │ │
>> │<──────────────────────────────────│ 
>> │                                   │
>>        │ │                            │ │
>>        │ │                            │200 OK SDP (g711A 
>> telephone-event) │
>>        │ │ │<──────────────────────────────────│
>>        │ │                            │ │
>>        │200 OK SDP (g711A telephone-event) 
>> │                            │ │
>> │<──────────────────────────────────│ 
>> │                                   │
>>        │ │                            │ │
>>        │               ACK │                            │ │
>> │──────────────────────────────────>│ 
>> │                                   │
>>        │ │                            │ │
>>        │ │                            │200 OK SDP (g711A 
>> telephone-event) │
>>        │ │ │<──────────────────────────────────│
>>        │ │                            │ │
>>        │200 OK SDP (g711A telephone-event) 
>> │                            │ │
>> │<──────────────────────────────────│ 
>> │                                   │
>>        │ │                            │ │
>>        │               ACK │                            │ │
>> │──────────────────────────────────>│ 
>> │                                   │
>>        │ │                            │ │
>>        │ │                            │200 OK SDP (g711A 
>> telephone-event) │
>>        │ │ │<──────────────────────────────────│
>>        │ │                            │ │
>>        │200 OK SDP (g711A telephone-event) 
>> │                            │ │
>> │<──────────────────────────────────│ 
>> │                                   │
>>        │ │                            │ │
>>        │               ACK │                            │ │
>> │──────────────────────────────────>│ 
>> │                                   │
>>        │ │                            │ │
>>        │ │                            │200 OK SDP (g711A 
>> telephone-event) │
>>        │ │ │<──────────────────────────────────│
>>        │ │                            │ │
>>        │200 OK SDP (g711A telephone-event) 
>> │                            │ │
>> │<──────────────────────────────────│ 
>> │                                   │
>>        │ │                            │ │
>>        │               ACK │                            │ │
>> │──────────────────────────────────>│ 
>> │                                   │
>>        │ │                            │ │
>>        │ │                            │200 OK SDP (g711A 
>> telephone-event) │
>>        │ │ │<──────────────────────────────────│
>>        │ │                            │ │
>>        │               BYE │                            │ │
>> │──────────────────────────────────>│ 
>> │                                   │
>>        │ │                            │ │
>>        │           404 Not here │                            │ │
>> │<──────────────────────────────────│ 
>> │                                   │
>>        │ │                            │ │
>>        │               BYE │                            │ │
>> │──────────────────────────────────>│ 
>> │                                   │
>>        │ │                            │ │
>>        │           404 Not here │                            │ │
>> │<──────────────────────────────────│ 
>> │                                   │
>>  ┌─────┴─────┐                    ┌────────┴────────┐ 
>> ┌────────┴────────┐                    ┌─────┴─────┐
>>  │sipp client│                    │OpenSIPS external│ │OpenSIPS 
>> internal│                    │sipp server│
>>  │10.30.8.203│                    │10.30.8.201      │ 
>> │10.30.9.10       │                    │10.30.90.11│
>>  └───────────┘                    └─────────────────┘ 
>> └─────────────────┘                    └───────────┘
>
>
> In my understanding the ACK from the sipp client should be handled by
> the t_relay() code in the global route:
>
>> route {
>>     if (!mf_process_maxfd_header(10) {
>>         send_reply(483, "Too many hops");
>>         exit;
>>     }
>>
>>     if (has_totag()) {
>>         if (is_method("ACK") && t_check_trans()) {
>>         t_relay();
>>         exit;
>>     }
>> ...
>
> However, the t_check_trans() function seems to return False for the ACK
> from the sipp client. Is my understanding wrong? Or is there a mistake
> in my usage in t_relay(, "udp:10.30.90.11:5060")?
>
> Any help is greatly appreciated.
>
> Thanks,
> Thomas
>
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