SSL_CTX_SESS_SET_GET_... BSD Library Functions Manual SSL_CTX_SESS_SET_GET_...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);
DESCRIPTIONSSL_CTX_sess_set_new_cb() sets the callback function which is automati‐
cally called whenever a new session was negotiated.
SSL_CTX_sess_set_remove_cb() sets the callback function which is automat‐
ically 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 proposes to resume a session but the session
cannot 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() 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 saved to disk or put into a database
using the d2i_SSL_SESSION(3) interface.
The new_session_cb() function 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 ses‐
sion from the internal cache. This happens when the session is removed
because it is expired or when a connection was not shut down cleanly. It
also happens for all sessions in the internal session cache when
SSL_CTX_free(3) is called. The remove_session_cb() function is passed
the ctx and the ssl session sess. It does not provide any feedback.
The get_session_cb() function is only called on SSL/TLS servers with the
session id proposed by the client. The get_session_cb() function 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 ALSOd2i_SSL_SESSION(3), ssl(3), SSL_CTX_flush_sessions(3), SSL_CTX_free(3),
SSL_CTX_set_session_cache_mode(3), SSL_SESSION_free(3)BSD April 18, 2024 BSD
