- session-valid? sidprocedure
Returns #t if the session identified by sid is valid. Returns #f otherwise.
A session is valid if (all items should be satisfied):
- There is a session identifier equal to sid in the session table
- The session lifetime corresponding to the session identified by sid is greater than zero
- When match-ip-address? is not #f, the IP number corresponding to the session identified by sid matches the IP number of the client