I agree that we need to have list discussion on this.
Whether this goes into this release is something we can hold off
until the end of the discussion to decide.
The problem that we have is that if we, as a TU, do not want to send
any response to the request, we
currently have no way to do so without permanently leaking the memory
for that TransactionState. It's
cleanup is entirely dependent upon the TU saying "Here's a response".
Or have I missed something?
What Byron is proposing is adding an interface that says "We're not
going to respond to that" that has
the same side-effects on transaction state that sending a response
has (we need the transaction to go
into a retransmission-draining-state the same as it would if we
replied, not just instantly go away). From
my poking at it so far, this seems to be the best approach available
to us.
Byron - to make this concrete, what are the cases where repro doesn't
respond to a request that's passed up?
RjS
On Aug 8, 2006, at 1:49 PM, Jason Fischl wrote:
When a new request is received by the stack, a new
TransactionState
is created, and the request is handed off to the TU. This
TransactionState will wait indefinitely for the TU to get back to it.
So the TU is expected to respond to EVERY request sent to it by the
stack (which, incidentally, repro doesn't do). But, in the cases
where the message is so malformed that the TU is unable to form a
response, the TU has no way (that I can see) of letting the stack
know to clean up the TransactionState.
What I think we need to do is create a function in
SipStack that
takes a transaction id and a bool indicating whether this is a NIT,
and schedules the deletion of the corresponding TransactionState. We
shouldn't just delete the transaction immediately, because we would
end up treating any retransmissions as new requests. This function
will create a TimerH for invite transactions, or a TimerJ for non-
invite transactions, as if the TU had sent a failure response (Timer
G does not need to be added, since there is no "real" response to
retransmit), which will prompt deletion of the TransactionState after
it has had a chance to absorb retransmissions.
In the case of an INVITE in a proxy, it should be the TU's
responsibility to terminate the transaction if no 1xx or final
response has been received for more than Timer C.
In the case of a NIT, it should also be the TU's responsibility to
send a final response. I don't believe this job should be done by the
transaction layer.
Any comments? Should we push for this to make it in the
release?
This feels to me like a risky thing to try and get into this release.
Can we have some additional discussion on it before proceeding with
any implementation?
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