[TLS] TLS 1.3 ServerConfiguration

[Ilari Liusvaara <[e-mail]>]

This came up while writing serializers/deserializers for various TLS
1.2 and 1.3 stuff... Didn't see issues/pull requests for any of
these...

1) ServerConfiguration has field early_data_type, which is of type
EarlyDataType. I don't see definition of that type anywhere. I
guess it was missed when that type was removed?

2) If ServerConfiguration contains an unknown extension, how should
the client behave? Ignore the unknown extension, ignore the entiere
ServerConfiguration or send a fatal alert?

3) Could the group and server_key fields be combined into a single
field of type KeyShareEntry? The layout would be identical, and
one could clearly reuse KeyShareEntry parsing (especially
considering some groups have 2-byte interrior length fields
as opposed to 1-byte).


BTW: The new TLS 1.3 extensions don't have even test values
assigned. The values I put in were:
- early_data: 13000 (0x32C8)
- pre_shared_key: 13001 (0x32C9)
- key_share: 13002 (0x32CA)
- cookie: 13003 (0x32CB)


-Ilari