NAME    [Toc]    [Back]

       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

SYNOPSIS    [Toc]    [Back]

        #include <openssl/ssl.h>

        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  *, 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,  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);

DESCRIPTION    [Toc]    [Back]

       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 SSL_CTX_set_session_cache_mode(3)).
       (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.

NOTES    [Toc]    [Back]

       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
       d2i_SSL_SESSION(3) interface.

       The new_session_cb() is called, whenever a new session has
       been negotiated and session caching is enabled (see
       SSL_CTX_set_session_cache_mode(3)).  The new_session_cb()
       is passed the ssl connection and the ssl session sess. If
       the callback returns 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
       SSL_CTX_free(3) is called. The remove_session_cb() is
       passed the ctx and the ssl session sess. 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_ses-
       sion_cb() is always called, also when session caching was
       disabled. The get_session_cb() is passed the ssl connection,
 the session id of length length at the memory location
 data. With the parameter copy 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 SSL_SESSION_free(3).

SEE ALSO    [Toc]    [Back]

       ssl(3), d2i_SSL_SESSION(3),
       SSL_CTX_set_session_cache_mode(3),
       SSL_CTX_flush_sessions(3), SSL_SESSION_free(3),
       SSL_CTX_free(3)


OpenBSD 3.6                 2003-05-11                          2