[TLS] SNI with early data

[Matt Caswell <[e-mail]>]

I note in draft-21 the following text:

   When clients use a PSK obtained externally to send early data, then
   the following additional information MUST be provisioned to both
   parties:

   -  The TLS version number for use with this PSK

   -  The cipher suite for use with this PSK

   -  The Application-Layer Protocol Negotiation (ALPN) protocol
      [RFC7301], if any is to be used

   -  The Server Name Indication (SNI), if any is to be used

Later it says this:

   In order to accept early data, the server MUST have accepted a PSK
   cipher suite and selected the first key offered in the client's
   "pre_shared_key" extension.  In addition, it MUST verify that the
   following values are consistent with those negotiated in the
   connection during which the ticket was established.

   -  The TLS version number and cipher suite.

   -  The selected ALPN [RFC7301] protocol, if any.


The language about "during which the ticket was established" seems to
suggest that the following checks do not apply to an external PSK -
which I don't think is intended. Additionally there does not seem to
be a requirement on the server to check that the SNI is consistent.
So, there is a mandatory requirement for an external PSK to specify
the SNI, but no requirement on the server to check that it is actually
correct. Is this discrepancy intentional?

Matt