[thirdparty/openssl.git] / doc / man3 / SSL_SESSION_free.pod

=pod

=head1 NAME

SSL_SESSION_free - free an allocated SSL_SESSION structure

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 void SSL_SESSION_free(SSL_SESSION *session);

=head1 DESCRIPTION

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 reference count has reached 0.
If B<session> is NULL nothing is done.

=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)>,
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)> 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)>)
or when the SSL_SESSION object was generated outside a TLS handshake
operation, e.g. by using L<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(7)>, L<SSL_get_session(3)>,
L<SSL_CTX_set_session_cache_mode(3)>,
L<SSL_CTX_flush_sessions(3)>,
L<d2i_SSL_SESSION(3)>

=head1 COPYRIGHT

Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.

=cut
Commit	Line	Data
	1	=pod
	2
	3	=head1 NAME
	4
	5	SSL_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
	15	SSL_SESSION_free() decrements the reference count of B<session> and removes
	16	the B<SSL_SESSION> structure pointed to by B<session> and frees up the allocated
	17	memory, if the reference count has reached 0.
	18	If B<session> is NULL nothing is done.
	19
	20	=head1 NOTES
	21
	22	SSL_SESSION objects are allocated, when a TLS/SSL handshake operation
	23	is successfully completed. Depending on the settings, see
	24	L<SSL_CTX_set_session_cache_mode(3)>,
	25	the SSL_SESSION objects are internally referenced by the SSL_CTX and
	26	linked into its session cache. SSL objects may be using the SSL_SESSION object;
	27	as a session may be reused, several SSL objects may be using one SSL_SESSION
	28	object at the same time. It is therefore crucial to keep the reference
	29	count (usage information) correct and not delete a SSL_SESSION object
	30	that is still used, as this may lead to program failures due to
	31	dangling pointers. These failures may also appear delayed, e.g.
	32	when an SSL_SESSION object was completely freed as the reference count
	33	incorrectly became 0, but it is still referenced in the internal
	34	session cache and the cache list is processed during a
	35	L<SSL_CTX_flush_sessions(3)> operation.
	36
	37	SSL_SESSION_free() must only be called for SSL_SESSION objects, for
	38	which the reference count was explicitly incremented (e.g.
	39	by calling SSL_get1_session(), see L<SSL_get_session(3)>)
	40	or when the SSL_SESSION object was generated outside a TLS handshake
	41	operation, e.g. by using L<d2i_SSL_SESSION(3)>.
	42	It must not be called on other SSL_SESSION objects, as this would cause
	43	incorrect reference counts and therefore program failures.
	44
	45	=head1 RETURN VALUES
	46
	47	SSL_SESSION_free() does not provide diagnostic information.
	48
	49	=head1 SEE ALSO
	50
	51	L<ssl(7)>, L<SSL_get_session(3)>,
	52	L<SSL_CTX_set_session_cache_mode(3)>,
	53	L<SSL_CTX_flush_sessions(3)>,
	54	L<d2i_SSL_SESSION(3)>
	55
	56	=head1 COPYRIGHT
	57
	58	Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
	59
	60	Licensed under the OpenSSL license (the "License"). You may not use
	61	this file except in compliance with the License. You can obtain a copy
	62	in the file LICENSE in the source distribution or at
	63	L<https://www.openssl.org/source/license.html>.
	64
	65	=cut