SSL_SESSION_free(3)

SSL_SESSION_free(3) | OpenSSL | SSL_SESSION_free(3)

# NAME

SSL_SESSION_free - free an allocated SSL_SESSION structure

# LIBRARY

libcrypto, -lcrypto

# SYNOPSIS

#include <openssl/ssl.h>
void SSL_SESSION_free(SSL_SESSION *session);

# DESCRIPTION

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.

# 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_free() does not provide diagnostic information.

# SEE ALSO

ssl(3), SSL_get_session(3), SSL_CTX_set_session_cache_mode(3), SSL_CTX_flush_sessions(3),
d2i_SSL_SESSION(3)

2009-07-19 | 1.0.1u