SSL_CTX_sess_set_get_cb(3)

     SSL_CTX_sess_set_get_cb0.9.6h (2002-07-SSL_CTX_sess_set_get_cb(3)

     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

     SYNOPSIS
           #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
          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
          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

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     SSL_CTX_sess_set_get_cb0.9.6h (2002-07-SSL_CTX_sess_set_get_cb(3)

          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 if
          the session is removed because it is expired or when a
          connection was not shutdown cleanly. 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_session_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
          ssl(3), d2i_SSL_SESSION(3),
          SSL_CTX_set_session_cache_mode(3),
          SSL_CTX_flush_sessions(3), SSL_SESSION_free(3)

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