SSL_SESSION_free.pod 2.1 KB

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  1. =pod
  2. =head1 NAME
  3. SSL_SESSION_free - free an allocated SSL_SESSION structure
  4. =head1 SYNOPSIS
  5. #include <openssl/ssl.h>
  6. void SSL_SESSION_free(SSL_SESSION *session);
  7. =head1 DESCRIPTION
  8. SSL_SESSION_free() decrements the reference count of B<session> and removes
  9. the B<SSL_SESSION> structure pointed to by B<session> and frees up the allocated
  10. memory, if the reference count has reached 0.
  11. =head1 NOTES
  12. SSL_SESSION objects are allocated, when a TLS/SSL handshake operation
  13. is successfully completed. Depending on the settings, see
  14. L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
  15. the SSL_SESSION objects are internally referenced by the SSL_CTX and
  16. linked into its session cache. SSL objects may be using the SSL_SESSION object;
  17. as a session may be reused, several SSL objects may be using one SSL_SESSION
  18. object at the same time. It is therefore crucial to keep the reference
  19. count (usage information) correct and not delete a SSL_SESSION object
  20. that is still used, as this may lead to program failures due to
  21. dangling pointers. These failures may also appear delayed, e.g.
  22. when an SSL_SESSION object was completely freed as the reference count
  23. incorrectly became 0, but it is still referenced in the internal
  24. session cache and the cache list is processed during a
  25. L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)> operation.
  26. SSL_SESSION_free() must only be called for SSL_SESSION objects, for
  27. which the reference count was explicitly incremented (e.g.
  28. by calling SSL_get1_session(), see L<SSL_get_session(3)|SSL_get_session(3)>)
  29. or when the SSL_SESSION object was generated outside a TLS handshake
  30. operation, e.g. by using L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>.
  31. It must not be called on other SSL_SESSION objects, as this would cause
  32. incorrect reference counts and therefore program failures.
  33. =head1 RETURN VALUES
  34. SSL_SESSION_free() does not provide diagnostic information.
  35. =head1 SEE ALSO
  36. L<ssl(3)|ssl(3)>, L<SSL_get_session(3)|SSL_get_session(3)>,
  37. L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
  38. L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)>,
  39. L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>
  40. =cut