[pjsip] Ticket 1185 and SDP in OPTIONS reply

Régis Montoya r3gis.3r at gmail.com
Thu Jun 28 17:20:59 EDT 2012


Hi,

As per ticket 1185 some parts of the code is disabled. As part of that, 
the OPTIONS reply doesn't include SDP body anymore.

I understand that the root cause is that no media transport are present 
at the point an incoming OPTIONS request arrives.
The problem is that it seems to break the incoming calls for some other 
sides. I've one report from user with an asterisk configured with SRTP 
incoming.
I don't know yet what the remote side is, but it maybe comes from their 
asterisk server. I guess there is some check to know first if client is 
able to use SRTP? Would it make sense? If so, I think that the app 
should 'try' to reply with a SDP body.

So I've one question :
Would it be acceptable to reply with a SDP with fake ip/port in OPTIONS 
reply (for example 0.0.0.0)? Is there any case where OPTIONS reply would 
be used for media ip/port?

I guess that if not a problem, it would be possible to generate a SDP 
with just codecs / crypto / known information. I don't know if it's 
possible in pjsip but I guess that at this point codec manager is 
already up and most things will go fine.

Also side note, while investigating the issue, I noticed that ticket 
1185 also remove something about SRTP optional mode (in 
pjsua_media.c:1980). I didn't get why this part of the code is disabled. 
After a very first look it seems nothing is missing at this point to 
have this part of code enabled. Did I miss something?

Best regards,
Régis



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