1=pod 2 3=head1 NAME 4 5SSL_SESSION_new, 6SSL_SESSION_dup, 7SSL_SESSION_up_ref, 8SSL_SESSION_free - create, free and manage SSL_SESSION structures 9 10=head1 SYNOPSIS 11 12 #include <openssl/ssl.h> 13 14 SSL_SESSION *SSL_SESSION_new(void); 15 SSL_SESSION *SSL_SESSION_dup(const SSL_SESSION *src); 16 int SSL_SESSION_up_ref(SSL_SESSION *ses); 17 void SSL_SESSION_free(SSL_SESSION *session); 18 19=head1 DESCRIPTION 20 21SSL_SESSION_new() creates a new SSL_SESSION structure and returns a pointer to 22it. 23 24SSL_SESSION_dup() creates a new SSL_SESSION structure that is a copy of B<src>. 25The copy is not owned by any cache that B<src> may have been in. 26 27SSL_SESSION_up_ref() increments the reference count on the given SSL_SESSION 28structure. 29 30SSL_SESSION_free() decrements the reference count of B<session> and removes 31the B<SSL_SESSION> structure pointed to by B<session> and frees up the allocated 32memory, if the reference count has reached 0. 33If B<session> is NULL nothing is done. 34 35=head1 NOTES 36 37SSL_SESSION objects are allocated, when a TLS/SSL handshake operation 38is successfully completed. Depending on the settings, see 39L<SSL_CTX_set_session_cache_mode(3)>, 40the SSL_SESSION objects are internally referenced by the SSL_CTX and 41linked into its session cache. SSL objects may be using the SSL_SESSION object; 42as a session may be reused, several SSL objects may be using one SSL_SESSION 43object at the same time. It is therefore crucial to keep the reference 44count (usage information) correct and not delete a SSL_SESSION object 45that is still used, as this may lead to program failures due to 46dangling pointers. These failures may also appear delayed, e.g. 47when an SSL_SESSION object was completely freed as the reference count 48incorrectly became 0, but it is still referenced in the internal 49session cache and the cache list is processed during a 50L<SSL_CTX_flush_sessions(3)> operation. 51 52SSL_SESSION_free() must only be called for SSL_SESSION objects, for 53which the reference count was explicitly incremented (e.g. 54by calling SSL_get1_session(), see L<SSL_get_session(3)>) 55or when the SSL_SESSION object was generated outside a TLS handshake 56operation, e.g. by using L<d2i_SSL_SESSION(3)>. 57It must not be called on other SSL_SESSION objects, as this would cause 58incorrect reference counts and therefore program failures. 59 60=head1 RETURN VALUES 61 62SSL_SESSION_new returns a pointer to the newly allocated SSL_SESSION structure 63or NULL on error. 64 65SSL_SESSION_dup returns a pointer to the new copy or NULL on error. 66 67SSL_SESSION_up_ref returns 1 on success or 0 on error. 68 69=head1 SEE ALSO 70 71L<ssl(7)>, L<SSL_get_session(3)>, 72L<SSL_CTX_set_session_cache_mode(3)>, 73L<SSL_CTX_flush_sessions(3)>, 74L<d2i_SSL_SESSION(3)> 75 76=head1 HISTORY 77 78The SSL_SESSION_dup() function was added in OpenSSL 1.1.1. 79 80=head1 COPYRIGHT 81 82Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved. 83 84Licensed under the Apache License 2.0 (the "License"). You may not use 85this file except in compliance with the License. You can obtain a copy 86in the file LICENSE in the source distribution or at 87L<https://www.openssl.org/source/license.html>. 88 89=cut 90