Getting SSL_SESSION remaining lifetime

[Benjamin Kaduk]

On Thu, Sep 16, 2021 at 04:11:49PM +0200, Hubert Kario wrote:
> On Thursday, 16 September 2021 04:41:44 CEST, Jaya Muthiah wrote:
> > 
> > I am trying to get the remaining lifetime of the ticket so that server
> > can decide to renew ticket or not
> 
> TLS 1.3 tickets are single use. If the ticket was used by a client, and
> you expect it to make a connection in the future, server needs to send a new
> one.

Single-use tickets are only a protocol requirement when 0-RTT data is used.
The OpenSSL implementation even allows the libssl-internal enforcement of
single-use to be disabled (see SSL_OP_NO_ANTI_REPLAY at
https://www.openssl.org/docs/manmaster/man3/SSL_CTX_set_options.html).
OpenSSL as a client also has some measures to encourate single-use tickets,
which I have a PR open to provide a knob to disable:
https://github.com/openssl/openssl/pull/16598 .

-Ben