Authdata, preauth plugin headers

[Sam Hartman]

>>>>> "Greg" == Greg Hudson <ghudson at MIT.EDU> writes:

    Greg> On Thu, 2011-06-09 at 12:25 -0400, Greg Hudson wrote:
    >> 1. Use the new plugin framework.

    Greg> I've committed this to the trunk.  Anyone working on preauth
    Greg> plugins for 1.10 should feel free to contact me (via IRC or
    Greg> email) if they need help adjusting.

    >> 2. Provide a way to get and set the cookie.

    Greg> For current use cases, the only place you'd want to set a
    Greg> cookie is in get_edata.  So adding a cookie parameter there
    Greg> should be sufficient for now.

I think it's really important that the KDc handle hard parts of cookie
management itself:

* combining cookies from multiple mechanisms

* Doing the encryption

* managing expiration.

Supporting that reasonably is why I didn't make an interface in the
current mechanism.