YEs, 200 OK is accepted on top of any previous negative reply...that's the RFC :)

Regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
  https://www.opensips-solutions.com
  https://www.siphub.com

On 6/28/23 4:38 PM, Alexander Kogan wrote:

BTW, we have the line in log when 200 has been received for timed out branch:

/usr/sbin/opensips[9653]: DBG:tm:reply_received: org. status uas=180, *uac[1]=408* local=0 is_invite=1)

Of course, it's a fake reply generated on timeout. Does it mean that if OpenSIPS receives a real final reply >=300 and after that it will receive 200, it will pass 200 to the caller?

Best regards,
Alexander Kogan,
Director of R&D
5g Future
http://5gfuture.com


On 28.06.2023 15:01, Alexander Kogan wrote:
Well, it would have worked if I didn't need loops....

Best regards,
Alexander Kogan,
Director of R&D
5g Future
http://5gfuture.com


On 28.06.2023 14:06, Bogdan-Andrei Iancu wrote:
True, multiple 200 OK replies will mess up the dialog module, as the module is not able to separately keep track of the calls deriving from the same original dialog... You may have good chances to get it work almost correctly if using the sip only dialog matching (in dialog module), as the to-tag will make the difference between the two calls resulted from the original dialog.

Regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
https://www.opensips-solutions.com
https://www.siphub.com

On 6/28/23 11:05 AM, Alexander Kogan wrote:
Agreed, it's really ugly. But on practice it means that the caller has two confirmed dialogs with the same did, but opensips has only one. And when caller sends BYE for one of its dialogs it ruins the dialog on OpenSIPS.... So it seems much better to make an ugly solution...

Best regards,
Alexander Kogan,
Director of R&D
5g Future
http://5gfuture.com


On 28.06.2023 11:52, Bogdan-Andrei Iancu wrote:
Hi Alexander.

The problem here is not related to the ability or inability of OpenSIPS to drop the late 200 OK - the problem is you MUST not drop it, as you will break the signaling. Again, a callee party sending a 200 OK expects an ACK and nothing else. If you drop (on OpenSIPS level) the late 200 OK, the vendor 1 will remain inconsistent - it will keep retransmitting the 200 OK as it expected the ACK for it.

Of course, there is the ugly approach of "playing dead", dropping every single late 200 OK from Vendor 1, forcing it to generate a BYE (eventually) and close the call. But this is something really ugly.

Regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
https://www.opensips-solutions.com
https://www.siphub.com

On 6/28/23 10:13 AM, Alexander Kogan wrote:
Hi,

I got the point. Nevertheless, isn't it a good idea to have a way to discard messages of branches that have already been timed out instead of reanimating them? E.g. t_check() could return -2 in reply_received(), or drop() action could be allowed for 200...

Best regards,
Alexander Kogan,
Director of R&D
5g Future
http://5gfuture.com


On 28.06.2023 10:37, Bogdan-Andrei Iancu wrote:
Hi Alexander,

According to RFC3261, there is noting a proxy should/must do about a received 200 OK rather than sending further to the caller (even if the 200 OK is received on an old branch). Basically, if for whatever reasons you end up getting 200 OK from several branches of the same transaction, you need to forward them all to caller - why? as in SIP, once a 200 OK was fired by a callee device, there is no signaling /mechanism available to "cancel"/"reject"/"discard" that it. The only way to handle "unwanted" 200 OK is to accept it, ack it  and then send a BYE for it. Now, as a proxy does not have the necessary "logic" to decide which 200 OK to keep and which to BYE, there is nothing to be done than "moving" this decision to the caller - so pass all the 200 OK to caller and let it decide which to keep or not.

Regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
https://www.opensips-solutions.com
https://www.siphub.com

On 6/27/23 5:59 PM, Alexander Kogan wrote:
Hello,

I've got such a call flow:

Client      OpenSIPS
|--INVITE-->|
|<--100-----| Vendor1
|           |--INVITE-->|
|           |--INVITE-->|
|           |--INVITE-->|
|           |           |           Vendor2
| |--INVITE------------- >|
| |<--100-----------------|
| |<--180-----------------|
|<--180-----|                       |
|           |<--200-----------------|
|<--200-----|                       |
|           |                       |
|           |<--200-----|           |
|<--200-----|        |
|           |           |           |

The first branch was timed out and we switched up to the next one. A bit later we received 200 OK from the first one. The question is - how to avoid passing 200 to the first leg? drop() doesn't work for final responses. I also can't use t_cancel_branches() because it works in onreply_route only which is not called in case of timeout....





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