[SR-Users] Double Record-Route to subscriber with multiple locations on different SIP transports

[Andrey Utkin]

Hi!
We found that we need double Record-Route when we call from one SIP
transport to another (let's say, TCP -> TLS), because without
|transport=" hint in Record-Route, mobile Linphone app sends messages
(INVITE reply, ACK, BYE) via UDP, even if configured for another
transport.

record_route_advertised_address() is told to add double RR if needed,
automatically, so we use it.

But the subscriber (the receiver of call) can have multiple registered
locations, let's say, one connected via TCP, and another via TLS. So
we need to handle each call branch added by lookup(). But adding
record_route_advertised_address() ONLY to branch_route attached by
t_on_branch() doesn't execute if there's only one location. Having
record_route_advertised_address() just in routing script after
lookup() seems wrong because it seems unable to edit it for other
branches (I don't remember if I have tested this and have proven a
failure, or this is just my speculation). So we have added it in both
places - right under lookup(), and in branch_route. But in this case
we have an error logged:

ERROR: rr [rr_mod.c:337]: w_record_route_advertised_address(): Double
attempt to record-route

Could anyone explain what would be the most correct solution?
What is intended behaviour of branch_route? Is it omitted from
execution on "primary" branch of call? Is there any parameter which
could help?

Thanks in advance.

-- 
Andrey Utkin