[TLS] Two Multi-CDN proposals

[Christopher Wood <[e-mail]>]

Hi folks,

Below are two PRs that seek to address the multi-CDN issue discussed
on this list and in meetings:

   1. https://github.com/tlswg/draft-ietf-tls-esni/pull/136
   2. https://github.com/tlswg/draft-ietf-tls-esni/pull/137

#136 implements the combined or stapled record approach discussed
several times, most recently in [1]. It includes these via an ESNIKeys
extension. #137 builds on this design with a mechanism that lets
clients detect and recover from A/AAAA and ESNI mismatch (if desired).
It is certainly more complex in several respects. A third variant,
which is not (yet) in PR form, is a simplification of #137 wherein
ESNIKeys addresses are only used as filters, instead of filters *or*
complete addresses.

We are asking for feedback on these PRs, as we would like to merge one
of them for the next draft version. As #136 is simpler and permits
extensibility, that is the current preference.

Thanks in advance for your feedback.

Best,
Chris (no hat, on behalf of the authors)

[1] https://mailarchive.ietf.org/arch/msg/tls/WXrPgaIsIPItDw3IQthmJk9VRlw