Issue 8106: SSL session management (original) (raw)

Current SSL module doesn't manage SSL sessions, so any connection must do the full SSL handshake.

SSL/TLS support session restarting, when an old SSL context is used in a new connection, so you don't need to do the full SSL handshake.

This is a huge performance improvement.

I think SSL module should keep a small pool of sessions in core, to reuse. Better yet:

a) In SSL sockets, a method should be added to get the SSL context.

b) When creating a SSL socket, in client mode, a new optional parameter should be accepted, for a SSL context.

c) When creating a SSL socket, in server mode, we have two options: a) provide a dictionary or similar, with different contexts for possible clients connections or, better b) provide a callback the SSL module will call when getting an incoming connection, with a session ID as a parameter. The callback can provide a session SSL state or "None". This second approach allow for session management, like expiration or persistence to disk.

(the second option is equivalent to the first if the dict-like object includes this logic inside)

What do you think?.

Ok, I propose the following plan:

• add a new opaque type allowing to wrap a SSL_SESSION
• add a get_session() method to SSLSocket, returning the current session
• add an optional "session=..." parameter to SSLContext.wrap_socket, allowing to specify a session which we hope to reuse during the handshake

There is however, one complication (from OpenSSL man pages):

"""SSL_SESSION objects keep internal link information about the session cache list, when being inserted into one SSL_CTX object's session cache. One SSL_SESSION object, regardless of its reference count, must therefore only be used with one SSL_CTX object (and the SSL objects created from this SSL_CTX object)."""

So we would somehow also need to keep a pointer to the SSL context in our session object wrapper, and check that the session isn't reused with another context... (yuck)