[TLS] TLS 1.3 and OCSP stapling

[Ilari Liusvaara <[e-mail]>]

When looking at stuff some more, I noticed that extension
status_request_v2, which is used by OCSP stapling and is not deprecated
[1].

Now, that extension uses additional handshake message type
(certificate_status), which is specified to go between Certificate
and SKE. Now, TLS 1.3 does not have SKE, and closest equivalent is
server CertificateVerify. But OTOH, Cerficate/CertificateVerify/
Finished are supposed to form a block? Where it is supposed to go?

Then there are other supported extensions that add messages.
Specifically the following messages:

- certificate_url: This can replace client certificate, whic is
  straightforward (if causing security issues by its sheer nature).
- supplemental_data: There's ladder diagrams placing this just
  before Certificate. Where should this go in TLS 1.3 (there are
  undeprecated extensions that would use it)?


[1] Unlike status_request, which is listed as deprecated. Was
that intentional or mistake (if intentional, cert_type would also be a
good to deprecate as superceded).


-Ilari