[OpenSIPS-Users] B2B bye method handling

[Ross]

Grabbing it now, I'll send it directly/off-list.


R.

On 09/02/16 04:37 PM, Alex Balashov wrote:
> Ross,
>
> Could you provide a libpcap-formatted capture of this scenario, either
> on-list or privately?
>
> -- Alex
>
> On 02/09/2016 04:35 PM, Ross wrote:
>
>> (I'm new to opensips, so bare with me if I'm off track).
>>
>> I setup a very simple configuration using b2bua for a quick top hiding
>> setup/proxy, and it works correctly, except for handling BYE messages
>> coming from the upstream connection. Note, db_mode is set to 0 for both
>> b2b_logic + entities.
>>
>> setup: source client (aka invite initiator) -> os/b2b -> upstream
>>
>> Quick Issue description:
>>
>> Call sessions is established, and works fine, and when the client
>> disconnects (initiates the bye message), the call disconnects cleanly
>> with all parties as expected. (this is good/normal)
>>
>> But when the server side disconnects first (sends the initial bye
>> message), opensips improperly handles the bye message by believing it to
>> be from the client side. Therefore doesn't properly send the
>> corresponding responses to the remote parties.
>>
>> In more detail:
>>
>> Delving into the code, and looking at some packet sniffs/debugs, I've
>> come to the idea that the b2b code (notably starting dlg.c:706) doesn't
>> take into account that the new BYE message will have the To/From Fields
>> reversed when from the server as it's not technically a response.
>> Because of this, the b2b_parse_key on 708 fails as it's only looking at
>> the "to" field tag for it's index key.
>>
>> Then the request falls through and is then incorrectly parsed as a
>> client sourced packet, as that lookup uses a different index key
>> (callid), which is correct for the session.
>>
>> I've tested this using metaswitch and asterisk in both the client and
>> server positions and they both return the same data (to/from), but would
>> like anyone else's thoughts on this.  Apologies, while I can read code,
>> I'm not a proper programmer to make a real patch.
>>
>> Thanks,
>>    Ross.
>>
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>
>