[Anima] GRASP as a secure session layer

[Brian E Carpenter <[e-mail]>]

Hi,

While thinking about what we need in an ANIMA ecosystem, and about how
we might marry ANIMA with more traditional techniques like NETCONF/YANG
(as indicated in RFC8368), I remembered one suggestion that I think came
from Toerless: is there a way for an ASA to use a secure "clear channel"
across the ACP? But of course if we do that, many of the features of
GRASP would be lost (discovery, session management).

So here's a possible solution. Allow an ASA to use GRASP discovery etc.
to set up a secure session with another ASA, but then instead of using
GRASP negotiation or synchronization messages, simply take over the session
and use simple send/receive primitives for whatever it wants.

No sooner thought than done. I added one optional parameter to
grasp.req_negotiate() to indicate this mode, and two new functions
grasp.send() and grasp.recv(), and GRASP became a secure session layer.
The code is really too new for me to commit to GitHub, but it's a very
convincing proof of concept.
 
Regards
   Brian Carpenter