[OpenSIPS-Users] stuck dialogs on proxy thru b2bua

[thrillerbee]

I've setup several OpenSIPS proxies (keeping track of dialogs,acc,etc.)
behind a OpenSIPS B2BUA (to implement topology hiding - nothing else).
I'm currently using version 1.6.3 on both the proxy & b2bua.  I updated the
b2bua modules from svn yesterday.

Certain dialogs "hang" because of how the B2BUA handles an inappropriate
response to an INVITE in a never-established (canceled) dialog coupled with
the proxy establishing a dialog after a CANCEL has been processed.

After the initial call attempt is canceled, the upstream carrier responds
with a 200 OK to the INVITE.  The B2BUA sends that back to the OpenSIPS
proxy.  The OpenSIPS proxy creates a dialog even though the INVITE has been
canceled.  Soon afterwards, a BYE is received from upstream but the B2BUA
does not send that back to the proxy.  As a result, the dialog hangs (until
the timeout is reached).  I've tried to show the call flow below:

proxy          b2bua         carrier

----- INV ----->
<---- 100 ------
                ------ INV ---->
                <----- 100 -----
                <----- 183 -----
<---- 183 ------
--- CANCEL ---->
<- 200(cancel)--
                --- CANCEL ---->
                <- 200(cancel)--
                <- 200(invite)--
<- 200(invite)--
                <- 200(invite)--
<- 200(invite)--
                <- 200(invite)--
<- 200(invite)--
                <- 200(invite)--
<- 200(invite)--
<- 200(invite)--
<- 200(invite)--
<- 200(invite)--
<- 200(invite)--
                <----- BYE -----
<- 200(invite)--
                <----- BYE -----
<- 200(invite)--

I'm hoping I'm doing something stupid in my implementation that could cause
this behavior.  Thanks for any help that might resolve this issue.
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