DESCRIPTIONSSL_get_session() returns a pointer to the SSL_SESSION actually
used in ssl. The reference count of the SSL_SESSION is not incremented,
so that the pointer can become invalid by other operations.
SSL_get0_session() is the same as SSL_get_session().
SSL_get1_session() is the same as SSL_get_session(), but the
reference count of the SSL_SESSION is incremented by one.
NOTESThe ssl session contains all information required to re-establish
the connection without a new handshake.
SSL_get0_session() returns a pointer to the actual session.
As the reference counter is not incremented, the pointer is only
valid while the connection is in use. If SSL_clear(3) or SSL_free(3) is
called, the session may be removed completely (if considered bad),
and the pointer obtained will become invalid. Even if the session
is valid, it can be removed at any time due to timeout during SSL_CTX_flush_sessions(3) .
If the data is to be kept, SSL_get1_session() will increment
the reference count, so that the session will not be implicitly
removed by other operations but stays in memory. In order to remove
the session SSL_SESSION_free(3) must be explicitly called
once to decrement the reference count again.
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).
RETURN VALUESThe following return values can occur:
NULL There is no session available in ssl.
Pointer to an SSL The return value points to the data of an SSL session.
SEE ALSOssl(3) , SSL_free(3) , SSL_clear(3) , SSL_SESSION_free(3)
HP Open Source Security for OpenVMS Volume 2:... 
SSL Application Programming Interface (API) Reference
