/xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
0.9.7e/doc/ssl
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SSL_CTX_sess_set_get_cb27/Mar/2003 (0.9SSL_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
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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_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),
SSL_CTX_free(3)
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