Hi,
1. I set up a call between two UAs through a proxy:
UAC A ----> Proxy P1 -----> UAS B
2. P1 inserts a Record-Route header indicating that sequential requests
should be directed through it.
3. UAS B does not follow Record-Route properly and, upon hanging up,
sends a BYE directly to UAC A's Contact URI (remote target), not to P1.
Interestingly enough, this BYE includes the Route set constructed from
the intervening Record-Route headers, but the BYE is sent to UAC A's
Contact directly on the network and transport layer.
4. Clearly, UAS B behaving improperly, but in all known cases, over a
variety of UA implementations, UAC A accepts this BYE and the endpoints
end the dialog properly -- all unbeknownst to P1.
My reading of RFC 3261 doesn't give me clarity as to whether it is
proper for a UA to accept a sequential request that otherwise matches a
known dialog but which does not originate from an intermediate proxy
known by the UA to be in the route set for the dialog.
Assuming no properties of firewall or network preclude doing an end-run
around the proxy, is this legal?
Thanks!
-- Alex
--
Alex Balashov | Principal | Evariste Systems LLC
303 Perimeter Center North, Suite 300
Atlanta, GA 30346
United States
Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
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