=pod =head1 NAME SSL_CTX_sess_set_new_cb, SSL_CTX_sess_set_remove_cb, SSL_CTX_sess_set_get_cb, SSL_CTX_sess_get_new_cb, SSL_CTX_sess_get_remove_cb, SSL_CTX_sess_get_get_cb - provide callback functions for server side external session caching =head1 SYNOPSIS #include void SSL_CTX_sess_set_new_cb(SSL_CTX *ctx, int (*new_session_cb)(SSL *, SSL_SESSION *)); void SSL_CTX_sess_set_remove_cb(SSL_CTX *ctx, void (*remove_session_cb)(SSL_CTX *ctx, SSL_SESSION *)); void SSL_CTX_sess_set_get_cb(SSL_CTX *ctx, SSL_SESSION (*get_session_cb)(SSL *, const unsigned char *, int, int *)); int (*SSL_CTX_sess_get_new_cb(SSL_CTX *ctx))(struct ssl_st *ssl, SSL_SESSION *sess); void (*SSL_CTX_sess_get_remove_cb(SSL_CTX *ctx))(struct ssl_ctx_st *ctx, SSL_SESSION *sess); SSL_SESSION *(*SSL_CTX_sess_get_get_cb(SSL_CTX *ctx))(struct ssl_st *ssl, const unsigned char *data, int len, int *copy); int (*new_session_cb)(struct ssl_st *ssl, SSL_SESSION *sess); void (*remove_session_cb)(struct ssl_ctx_st *ctx, SSL_SESSION *sess); SSL_SESSION *(*get_session_cb)(struct ssl_st *ssl, unsigned char *data, int len, int *copy); =head1 DESCRIPTION SSL_CTX_sess_set_new_cb() sets the callback function, which is automatically called whenever a new session was negotiated. SSL_CTX_sess_set_remove_cb() sets the callback function, which is automatically called whenever a session is removed by the SSL engine, because it is considered faulty or the session has become obsolete because of exceeding the timeout value. SSL_CTX_sess_set_get_cb() sets the callback function which is called, whenever a SSL/TLS client proposed to resume a session but the session could not be found in the internal session cache (see L). (SSL/TLS server only.) SSL_CTX_sess_get_new_cb(), SSL_CTX_sess_get_remove_cb(), and SSL_CTX_sess_get_get_cb() allow to retrieve the function pointers of the provided callback functions. If a callback function has not been set, the NULL pointer is returned. =head1 NOTES In order to allow external session caching, synchronization with the internal session cache is realized via callback functions. Inside these callback functions, session can be saved to disk or put into a database using the L interface. The new_session_cb() is called, whenever a new session has been negotiated and session caching is enabled (see L). The new_session_cb() is passed the B connection and the ssl session B. If the callback returns B<0>, the session will be immediately removed again. The remove_session_cb() is called, whenever the SSL engine removes a session from the internal cache. This happens when the session is removed because it is expired or when a connection was not shutdown cleanly. It also happens for all sessions in the internal session cache when L is called. The remove_session_cb() is passed the B and the ssl session B. It does not provide any feedback. The get_session_cb() is only called on SSL/TLS servers with the session id proposed by the client. The get_session_cb() is always called, also when session caching was disabled. The get_session_cb() is passed the B connection, the session id of length B at the memory location B. With the parameter B the callback can require the SSL engine to increment the reference count of the SSL_SESSION object, Normally the reference count is not incremented and therefore the session must not be explicitly freed with L. =head1 SEE ALSO L, L, L, L, L, L =head1 COPYRIGHT Copyright 2001-2016 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 L. =cut