No subject

The fix from review 298 has exposed a new bug in chan_sip.

When we hang up an outgoing call, we first will dump all the outstanding
packets on the sip_pvt using __sip_pretend_ack. Then, if we can, we send
a CANCEL. The problem with this is that since destroyed all the
outstanding
packets on the dialog, we cannot match the incoming 487 response to our
INVITE. Because we cannot match the response, we do not send an ACK.

To correct this, instead of using __sip_pretend_ack, I have changed the
code
to loop through the list of packets and call __sip_semi_ack on each one
instead. This causes us to stop retransmitting the requests, but we still
have
them around in case we get responses for them.

When discussing this earlier today with Josh Colp, we both agreed that in
the
majority of cases, this would be enough of a fix. However, we also agreed
that
we should have a safety net in place in case we never receive a response
to
our initial INVITE. To handle this, I have modified __sip_autodestruct to
behave similar to the way it does in Asterisk 1.4. If there are
outstanding
packets on the sip_pvt, the needdestroy flag is not set, and the last
request
on the dialog was either a CANCEL or BYE, then we set the needdestroy flag
and
reschedule destruction for 10 seconds in the future. If, though, the
needdestroy flag is set, then we use __sip_pretend_ack to kill the
remaining
outstanding packets so that the monitor thread can destroy the sip_pvt.

I ran two separate tests. First, I placed a call from my Aastra phone to
my
Polycom phone. I hung up the Aastra before the Polycom answered. I
verified
through sip debug output that Asterisk properly ACKed the 487 received
from the
Polycom.

For my second test, I set up a SIPp UAS scenario so that it would send a
200 OK
in response to a CANCEL but would not send a 487 for the original INVITE.
I
verified that after about 40 seconds, Asterisk properly cleans up the
outgoing
sip_pvt for the call.

Review: https://reviewboard.asterisk.org/r/308 

Issue History 
Date Modified    Username       Field                    Change               
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2009-08-18 03:20 dant           Note Added: 0109201                          
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