It's mostly a filler word. I've read through each use of it in the code
base and did minor rephrasings when "simply" carried some meaning. The
overwhelming majority of cases, removing it improved the text
significantly. Inspired by #20793.
Closes#20822
Described in detail in internal doc TLS-SESSIONS.md
Main points:
- use a new `ssl_peer_key` for cache lookups by connection filters
- recognize differences between TLSv1.3 and other tickets
* TLSv1.3 tickets are single-use, cache can hold several of them for a peer
* TLSv1.2 are reused, keep only a single one per peer
- differentiate between ticket BLOB to store (that could be persisted) and object instances
- use put/take/return pattern for cache access
- remember TLS version, ALPN protocol, time received and lifetime of ticket
- auto-expire tickets after their lifetime
Closes#15774
