Ticket #379 (closed enhancement: duplicate)
Implement merged request detection
|Reported by:||bennylp||Owned by:||bennylp|
|Backport to 1.x milestone:||Backported:|
Merged request is described in RFC 3261 Section 220.127.116.11:
18.104.22.168 Merged Requests If the request has no tag in the To header field, the UAS core MUST check the request against ongoing transactions. If the From tag, Call-ID, and CSeq exactly match those associated with an ongoing transaction, but the request does not match that transaction (based on the matching rules in Section 17.2.3), the UAS core SHOULD generate a 482 (Loop Detected) response and pass it to the server transaction. The same request has arrived at the UAS more than once, following different paths, most likely due to forking. The UAS processes the first such request received and responds with a 482 (Loop Detected) to the rest of them.
This feature is needed to cope with (Open)SER behavior in the scenario below.
- UAC sends INVITE
- UAS receives INVITE and sends 200 response
- This response doesn't reach UAC, so UAC keeps retransmitting INVITE
- At some point, it looks like the proxy kills the INVITE transaction, so upon receiving INVITE retransmission from UAC, it will forward the INVITE to UAS, with different branch.
- UAS, without merge request detection, will treat this INVITE as a new INVITE, thus it will create a new dialog.