Re: [PATCH 1/4] tls: Allow ServerHello extensions when resuming session

Hi Andrew,

On 11/9/22 11:47, Andrew Zaborowski wrote:
> While, as the spec notes, most extensions are not used during the
> resumption of a cached session (are offered in the ClientHello but are
> ignored and not be included in the ServerHello), this not a rule so allow
> each extension to decide whether to skip adding itself to the ServerHello.
> 
> Specifically those extensions should rather be ignored by the server
> when it is parsing the ClientHello but at that point we don't yet know
> whether we'll allow the session to be resumed so instead the ServerHello
> writer callbacks decide whether to reply or not.  As an example RFC 4492
> Section 4 says: "In the case of session resumption, the server simply
> ignores the Supported Elliptic Curves Extension and the Supported Point
> Formats Extension appearing in the current ClientHello message.  These
> extensions only play a role during handshakes negotiating a new session."
> ---
>   ell/tls-extensions.c |  9 +++++++++
>   ell/tls.c            | 31 ++++++++++---------------------
>   2 files changed, 19 insertions(+), 21 deletions(-)
> 

All applied, thanks.

Regards,
-Denis