[SR-Users] potential PRACK related topos bug

Daniel-Constantin Mierla miconda at gmail.com
Thu Apr 22 17:23:12 CEST 2021


On 22.04.21 16:06, Juha Heinanen wrote:
> Daniel-Constantin Mierla writes:
>> Hmm ... the issue seems to be related to missing record-route list for
>> callee side in the transaction record.
>> I do not have a test bedwhere I can reproduce during the next days,
>> would it be possible for you to use topos with db backend (mysql)
>> instead of redis and send again the logs with debug=3? That should
>> provide details of the db queries and indicate if the record-route
>> values are stored/retrieved to/from database.
> Daniel,
> We did more tests, this time using topos mysql instead of redis.  With
> exactly same config, PRACK to 183 is now forwarded correctly:
> A->P1->P2->P1-B.  We then switched back to redis and P1 responded with
> 404 as before when it received the PRACK.  So looks like there is some
> issue with redis.
OK, I will check topos_redis and see if something is missing there on
this case.
> But, there is another problem that showed up with mysql topos.
> When A receives 200 OK to PRACK, it sends another PRACK with the same
> "CSeq: 2 PRACK" header, to which P1 responds with 200 OK without
> forwarding the PRACK.  So looks like it thinks there is something with
> the 200 OK that A does not like .  The same happens three more times.
> At the third time P1 forwards the PRACK to P2, which forwards is back to
> P1 starting a loop that finally gets terminated with "483 Too many
> hops".
> Syslog of P1 shows these kind of error messages during PRACK processing:
> Apr 22 12:49:49 edge /usr/bin/edge-proxy[402]: ERROR: {2 2 PRACK FQzhCOkpzqUJGaXntnCyKw} topos [topos_mod.c:416]: tps_prepare_msg(): mandatory headers missing - via1: (nil) callid: 0x7f0b1b67c5b0
Can you send me a pcap and debug logs for such case taken on P1? I will
try to check what is missing/wrong there.
> Lesson: do not try to use any dialog based stuff in a SIP proxy.

This has nothing to do with the dialog, the fact here is that topos was
not designed for spirals, as I said in one of the previous emails. I am
trying to fix the missing parts to make it work, if you can provide


Daniel-Constantin Mierla -- www.asipto.com
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