[sr-dev] git:andrei/cancel_reason: tm: Reason header copy for received CANCELs

[Iñaki Baz Castillo]

El Martes, 2 de Marzo de 2010, Andrei Pelinescu-Onciul escribió:
> tm: Reason header copy for received CANCELs
> 
> When canceling branches due to a received CANCEL, use the Reason
> headers in the received CANCEL (all the Reason headers from the
> received CANCEL will be copied in the generated CANCELs, see
> RFC3326 for more details).



Hi Andrei, great addition. However there could be a minor security issue:

Perhaps it wouldn't be safe to propagate any Reason header coming in a CANCEL 
from any sender (imagine you receive a malicius call at 5 o'clock in the night 
and the hacker added "Reason" header to the CANCEL so you don't find that call 
in the missed calls list of the phone).

- This local policy could be implemented as follows:

a) Enabling a flag in t_relay() that only makes sense for CANCEL rather than 
INVITE, so:

  if (is_method("CANCEL")) {
    if ($si == MY_APPLICATION_SERVER_IP)
      # Allow propagating "Reason" header.
      t_relay(0x12);
    else
      t_relay();
  }

or using an explicit flag:

  if (is_method("CANCEL")) {
    if ($si == MY_APPLICATION_SERVER_IP)
      setflag(FLAG_ALLOW_CANCEL_REASON);
    t_relay();
  }



Opinions? Thanks a lot.


-- 
Iñaki Baz Castillo <ibc at aliax.net>