On Mon, 2006-06-05 at 02:59 -0400, M. Rangnathan wrote: > RFC 3265 has a race condition where the NOTIFY can arrive at the > subscriber before the Response to the SUBSCRIBE arrives -- and has to be > allocated the same Dalog as the response to the subscribe. This results > in a race condition which is a headache for protocol implementors
This is less of a problem than it appears to be, because your assumptions are incorrect (as strange as that seems). The crucial item is that one SUBSCRIBE can get sent to two UASs, resulting in two SUBSCRIBE-dialogs, but the UAC will (usually, often) receive only one 200 response, with the to-tag of one of the SUBSCRIBE- dialogs. So in general your stack must distinguish the initial dialog created by your request (which has no to-tag) and the zero or more real dialogs created by responses/provisional responses/NOTIFYs (which have to-tags). Once you've implemented all that logic, having the NOTIFYs create real dialogs (if they match the call-id of a SUBSCRIBE that was sent) is not much work. Dale --- interop.pingtel.com -- the public SIP phone interoperability test server _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
