[reSIProcate] prack sent in response to provisional even if prack support is disabled

[Justin Matthews]

Hi,

Prack support is not enabled (did not enable it in the master profile), but
the following scenario causes resip/dum to send a prack to a 183:

DUM (UAC)						UAS
1) INVITE ->(does not contain Supported: 100rel)
2) 183 (contains Supported: 100rel) <-
3) PRACK (RAck: 0 0 UNKNOWN)->
.

The UAS fails on the PRACK.  Is resip/dum behaving correctly?  How would
this behavior be changed to not send the PRACK?  InviteSession::isReliable
only checks the profile if the message is a request to determine if prack is
supported.  This probably assumes that if a response contains the Supported:
100rel, then the Supported: 100rel must have been sent in the initial
INVITE?

Thanks,

-Justin

1) 
INVITE sip:13101234567 at 192.168.2.41:5060 SIP/2.0
Via: SIP/2.0/UDP
192.168.2.31:5060;branch=z9hG4bK-d8754z-c93595140268b620-1---d8754z-;rport
Max-Forwards: 70
Contact: <sip:6 at 192.168.2.31:5060>
To: <sip:13101234567 at 192.168.2.41:5060>
From: "0309"<sip:6 at 192.168.2.31>;tag=1c0b8f57
Call-ID: 00075027-b9dd0026-14e75433-73d133a6 at 192.168.2.6-2
CSeq: 1 INVITE
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, INFO, NOTIFY, REGISTER

2)
SIP/2.0 183 Ringing
Via: SIP/2.0/UDP
192.168.2.31:5060;branch=z9hG4bK-d8754z-c93595140268b620-1---d8754z-;rport
From: "0309"<sip:6 at 192.168.2.31>;tag=1c0b8f57
To: <sip:13101234567 at 192.168.2.41:5060>;tag=6608SIPpTag0171
Call-ID: 00075027-b9dd0026-14e75433-73d133a6 at 192.168.2.6-2
CSeq: 1 INVITE
Supported: 100rel
Contact: <sip:192.168.2.41:5060;transport=UDP>

3)
PRACK sip:192.168.2.41:5060;transport=UDP SIP/2.0
Via: SIP/2.0/UDP
192.168.2.31:5060;branch=z9hG4bK-d8754z-d74a3f6e45648638-1---d8754z-;rport
Max-Forwards: 70
Contact: <sip:6 at 192.168.2.31:5060>
To: <sip:13101234567 at 192.168.2.41:5060>;tag=6608SIPpTag0171
From: "0309"<sip:6 at 192.168.2.31>;tag=1c0b8f57
Call-ID: 00075027-b9dd0026-14e75433-73d133a6 at 192.168.2.6-2
CSeq: 2 PRACK
RAck: 0 0 UNKNOWN
Content-Length: 0