SSL_SESSION_free.pod revision 303975
1=pod 2 3=head1 NAME 4 5SSL_SESSION_free - free an allocated SSL_SESSION structure 6 7=head1 SYNOPSIS 8 9 #include <openssl/ssl.h> 10 11 void SSL_SESSION_free(SSL_SESSION *session); 12 13=head1 DESCRIPTION 14 15SSL_SESSION_free() decrements the reference count of B<session> and removes 16the B<SSL_SESSION> structure pointed to by B<session> and frees up the allocated 17memory, if the reference count has reached 0. 18 19=head1 NOTES 20 21SSL_SESSION objects are allocated, when a TLS/SSL handshake operation 22is successfully completed. Depending on the settings, see 23L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>, 24the SSL_SESSION objects are internally referenced by the SSL_CTX and 25linked into its session cache. SSL objects may be using the SSL_SESSION object; 26as a session may be reused, several SSL objects may be using one SSL_SESSION 27object at the same time. It is therefore crucial to keep the reference 28count (usage information) correct and not delete a SSL_SESSION object 29that is still used, as this may lead to program failures due to 30dangling pointers. These failures may also appear delayed, e.g. 31when an SSL_SESSION object was completely freed as the reference count 32incorrectly became 0, but it is still referenced in the internal 33session cache and the cache list is processed during a 34L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)> operation. 35 36SSL_SESSION_free() must only be called for SSL_SESSION objects, for 37which the reference count was explicitly incremented (e.g. 38by calling SSL_get1_session(), see L<SSL_get_session(3)|SSL_get_session(3)>) 39or when the SSL_SESSION object was generated outside a TLS handshake 40operation, e.g. by using L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>. 41It must not be called on other SSL_SESSION objects, as this would cause 42incorrect reference counts and therefore program failures. 43 44=head1 RETURN VALUES 45 46SSL_SESSION_free() does not provide diagnostic information. 47 48=head1 SEE ALSO 49 50L<ssl(3)|ssl(3)>, L<SSL_get_session(3)|SSL_get_session(3)>, 51L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>, 52L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)>, 53 L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)> 54 55=cut 56