56 lines
2.1 KiB
Plaintext
56 lines
2.1 KiB
Plaintext
=pod
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=head1 NAME
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SSL_SESSION_free - free an allocated SSL_SESSION structure
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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void SSL_SESSION_free(SSL_SESSION *session);
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=head1 DESCRIPTION
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SSL_SESSION_free() decrements the reference count of B<session> and removes
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the B<SSL_SESSION> structure pointed to by B<session> and frees up the allocated
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memory, if the reference count has reached 0.
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=head1 NOTES
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SSL_SESSION objects are allocated, when a TLS/SSL handshake operation
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is successfully completed. Depending on the settings, see
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L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
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the SSL_SESSION objects are internally referenced by the SSL_CTX and
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linked into its session cache. SSL objects may be using the SSL_SESSION object;
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as a session may be reused, several SSL objects may be using one SSL_SESSION
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object at the same time. It is therefore crucial to keep the reference
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count (usage information) correct and not delete a SSL_SESSION object
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that is still used, as this may lead to program failures due to
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dangling pointers. These failures may also appear delayed, e.g.
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when an SSL_SESSION object was completely freed as the reference count
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incorrectly became 0, but it is still referenced in the internal
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session cache and the cache list is processed during a
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L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)> operation.
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SSL_SESSION_free() must only be called for SSL_SESSION objects, for
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which the reference count was explicitly incremented (e.g.
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by calling SSL_get1_session(), see L<SSL_get_session(3)|SSL_get_session(3)>)
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or when the SSL_SESSION object was generated outside a TLS handshake
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operation, e.g. by using L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>.
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It must not be called on other SSL_SESSION objects, as this would cause
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incorrect reference counts and therefore program failures.
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=head1 RETURN VALUES
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SSL_SESSION_free() does not provide diagnostic information.
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=head1 SEE ALSO
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L<ssl(3)|ssl(3)>, L<SSL_get_session(3)|SSL_get_session(3)>,
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L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
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L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)>,
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L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>
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=cut
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