[OpenSIPS-Users] CANCEL with a To tag.

[Brett Nemeroff]

I also agree with Alex.
I've tried to accommodate broken UAs in the past and I'll tell you, you're
just seeing a part of what's broken. If you allow for this, what else are
you going to find out down the road that isn't going to work.

As they say, it's the "Tip, of the iceburg"
-Brett




On Mon, May 11, 2009 at 6:40 AM, Alex Balashov <abalashov at evaristesys.com>wrote:

> It sounds like the CANCEL with the To-tag should have a Route header as
> well in order for it to be processed like any other sequential/in-dialog
> request -- that is to say, under loose_route().
>
> Or, the CANCEL is intended for OpenSIPS itself, in which case it should
> not have a To-tag.
>
> I would not try to accommodate this broken UA if I were you.  When
> breakage is so fundamental, this way lies madness.
>
> Chris Maciejewski wrote:
>
> > You can see a SIP flow before I added "CANCEL" to a lose routing
> > section of my Opensips config here:
> >
> > http://wima.co.uk/sip/2009-05-11_10-18-39-test-call_index.html
> >
> > Note: F23 is rejected by OpenSIPs as it got "tag" in a To: header.
> >
> > And after I added:
> >
> >   if (is_method("CANCEL"))
> >   {
> >     t_relay();
> >     exit;
> >   }
> >
> > to my lose routing logic, OpenSIPs generates CANCEL and sends it to
> > the next hop:
> >
> > http://wima.co.uk/sip/2009-05-11_10-46-46-test-call_index.html
> >
> >
> > 2009/5/11 Iñaki Baz Castillo <ibc at aliax.net>:
> >> 2009/5/11 Chris Maciejewski <chris at wima.co.uk>:
> >>> Hi,
> >>>
> >>> I would like to ask what would be the best way to handle CANCEL
> >>> request with a To tag. I know such a CANCEL request is not RFC
> >>> compatible
> >> CANCEL is hop-by-hop. This means that when OpenSIPS receives a CANCEL,
> >> it *doesn't* route it, but it generates a new one (this occurs when
> >> you do "t_relay()" for a CANCEL).
> >> It's impossible to add "To tag" to a CANCEL generated by OpenSIPS
> >> (expect if the CANCEL occurs for a re-INVITE being into an already
> >> established dialog, so arriving CANCEL has To tag and OpenSIPS routes
> >> it as any other in-dialog request).
> >>
> >>
> >>>  but unfortunately I came across some buggy UAs doing this.
> >> What do you mean with it? what does this UAS?
> >>
> >>
> >> --
> >> Iñaki Baz Castillo
> >> <ibc at aliax.net>
> >>
> >> _______________________________________________
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> >> Users at lists.opensips.org
> >> http://lists.opensips.org/cgi-bin/mailman/listinfo/users
> >>
> >
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>
> --
> Alex Balashov
> Evariste Systems
> Web     : http://www.evaristesys.com/
> Tel     : (+1) (678) 954-0670
> Direct  : (+1) (678) 954-0671
>
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