Updated: 2021/Apr/14


SSL_SESSION_free(3)                 OpenSSL                SSL_SESSION_free(3)



NAME
       SSL_SESSION_new, SSL_SESSION_dup, SSL_SESSION_up_ref, SSL_SESSION_free
       - create, free and manage SSL_SESSION structures

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/ssl.h>

        SSL_SESSION *SSL_SESSION_new(void);
        SSL_SESSION *SSL_SESSION_dup(SSL_SESSION *src);
        int SSL_SESSION_up_ref(SSL_SESSION *ses);
        void SSL_SESSION_free(SSL_SESSION *session);

DESCRIPTION
       SSL_SESSION_new() creates a new SSL_SESSION structure and returns a
       pointer to it.

       SSL_SESSION_dup() copies the contents of the SSL_SESSION structure in
       src and returns a pointer to it.

       SSL_SESSION_up_ref() increments the reference count on the given
       SSL_SESSION structure.

       SSL_SESSION_free() decrements the reference count of session and
       removes the SSL_SESSION structure pointed to by session and frees up
       the allocated memory, if the reference count has reached 0.  If session
       is NULL nothing is done.

NOTES
       SSL_SESSION objects are allocated, when a TLS/SSL handshake operation
       is successfully completed. Depending on the settings, see
       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 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 SSL_get_session(3)) or when the SSL_SESSION
       object was generated outside a TLS handshake operation, e.g. by using
       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.

RETURN VALUES
       SSL_SESSION_new returns a pointer to the newly allocated SSL_SESSION
       structure or NULL on error.

       SSL_SESSION_up_ref returns 1 on success or 0 on error.

SEE ALSO
       ssl(7), SSL_get_session(3), SSL_CTX_set_session_cache_mode(3),
       SSL_CTX_flush_sessions(3), d2i_SSL_SESSION(3)

HISTORY
       The SSL_SESSION_dup() function was added in OpenSSL 1.1.1.

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
       <https://www.openssl.org/source/license.html>.



1.1.1i                            2019-03-12               SSL_SESSION_free(3)