Re: [kitten] Permissible (and imp..) side-effects of GSS_Acquire_cred()

[Nico Williams <[e-mail]>]

On Thu, Mar 19, 2015 at 09:32:14AM -0400, Simo Sorce wrote:
> On Tue, 2015-03-10 at 19:18 -0500, Nico Williams wrote:
> > I can see three principles:
> > 
> > a) no side-effects outside caching,
> > b) idempotent side-effects only,
> > c) what principles?  anything goes.
> 
> I tend to agree with you in abstract, however given b) is the actual,
> and I would say expected in many cases, behavior, I do not't think we
> can retroactively mandate a), but b) should be good enough.

ISTR hearing someone (you?) say (a couple of weeks ago on a krbdev call)
that creating a default ccache with one of N > 1 principals' keytab
creds is sometimes surprising to users, and I can see why it would be!
This is a form of (b).  The problem here is setting the default
principal name when none had already been set -- a non-trivial side-effect.

I'm inclined to consider (b) a bug.  A low-priority bug perhaps, but a bug.

Implementations could do something else.  E.g., not cache (thus increasing
load on clients and KDCs), or cache in a "shadow default ccache", or
switch to DIR ccache.  Those are details.  The main thing is that (b) is
surprising.

Nico
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