[reSIProcate] overlapping NIT in INVITE usage

[Jason Fischl]

Hi folks,

As I work on the rewrite of the InviteSession some questions about 
overlapping transactions come up.

In the current implementation, it explicitly disallows overlapping INFO 
requests? The first INFO needs to finish before dum allows another one. 
It throws if you try to send an INFO while one is pending. Is this 
necessary? This behavior is not currently applied to REFER. What about BYE?

Consider the case where we have an established InviteSession 
(Connected). We receive a reINVITE from the peer. What happens if the 
peer sends us a second reINVITE before we respond? What happens if the 
peer sends us an INFO overlapping with the reINVITE? I'm assuming that 
the INFO overlapping the reINVITE is ok and the reINVITE overlapping the 
reINVITE is NOT ok and should be rejected with 4xx?

Jason