|
@@ -16,12 +16,40 @@ SSL_SESSION_free() decrements the reference count of B<session> and removes
|
|
|
the B<SSL_SESSION> structure pointed to by B<session> and frees up the allocated
|
|
|
memory, if the the reference count has reached 0.
|
|
|
|
|
|
+=head1 NOTES
|
|
|
+
|
|
|
+SSL_SESSION objects are allocated, when a TLS/SSL handshake operation
|
|
|
+is successfully completed. Depending on the settings, see
|
|
|
+L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
|
|
|
+the SSL_SESSION objects are internally referenced by the SSL_CTX and
|
|
|
+linked into its session cache. SSL objects may be using the SSL_SESSION object;
|
|
|
+as a session may be reused, several SSL objects may be using one SSL_SESSION
|
|
|
+object at the same time. It is therefore crucial to keep the reference
|
|
|
+count (usage information) correct and not delete a SSL_SESSION object
|
|
|
+that is still used, as this may lead to program failures due to
|
|
|
+dangling pointers. These failures may also appear delayed, e.g.
|
|
|
+when an SSL_SESSION object was completely freed as the reference count
|
|
|
+incorrectly became 0, but it is still referenced in the internal
|
|
|
+session cache and the cache list is processed during a
|
|
|
+L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)> operation.
|
|
|
+
|
|
|
+SSL_SESSION_free() must only be called for SSL_SESSION objects, for
|
|
|
+which the reference count was explicitly incremented (e.g.
|
|
|
+by calling SSL_get1_session(), see L<SSL_get_session(3)|SSL_get_session(3)>)
|
|
|
+or when the SSL_SESSION object was generated outside a TLS handshake
|
|
|
+operation, e.g. by using L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>.
|
|
|
+It must not be called on other SSL_SESSION objects, as this would cause
|
|
|
+incorrect reference counts and therefore program failures.
|
|
|
+
|
|
|
=head1 RETURN VALUES
|
|
|
|
|
|
SSL_SESSION_free() does not provide diagnostic information.
|
|
|
|
|
|
=head1 SEE ALSO
|
|
|
|
|
|
-L<ssl(3)|ssl(3)>, L<SSL_get_session(3)|SSL_get_session(3)>
|
|
|
+L<ssl(3)|ssl(3)>, L<SSL_get_session(3)|SSL_get_session(3)>,
|
|
|
+L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
|
|
|
+L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)>,
|
|
|
+ L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>
|
|
|
|
|
|
=cut
|