mirror of
https://github.com/openssl/openssl.git
synced 2024-12-15 06:01:37 +08:00
33388b44b6
Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/11616)
124 lines
5.7 KiB
Plaintext
124 lines
5.7 KiB
Plaintext
=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 <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 *,
|
|
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);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
SSL_CTX_sess_set_new_cb() sets the callback function that is
|
|
called whenever a new session was negotiated.
|
|
|
|
SSL_CTX_sess_set_remove_cb() sets the callback function that is
|
|
called whenever a session is removed by the SSL engine. For example,
|
|
this can occur because a session is considered faulty or has become obsolete
|
|
because of exceeding the timeout value.
|
|
|
|
SSL_CTX_sess_set_get_cb() sets the callback function that is called
|
|
whenever a TLS client proposed to resume a session but the session
|
|
could not be found in the internal session cache (see
|
|
L<SSL_CTX_set_session_cache_mode(3)>).
|
|
(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 set by the
|
|
corresponding set 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<d2i_SSL_SESSION(3)> interface.
|
|
|
|
The new_session_cb() is called whenever a new session has been negotiated and
|
|
session caching is enabled (see L<SSL_CTX_set_session_cache_mode(3)>). The
|
|
new_session_cb() is passed the B<ssl> connection and the nascent
|
|
ssl session B<sess>.
|
|
Since sessions are reference-counted objects, the reference count on the
|
|
session is incremented before the callback, on behalf of the application. If
|
|
the callback returns B<0>, the session will be immediately removed from the
|
|
internal cache and the reference count released. If the callback returns B<1>,
|
|
the application retains the reference (for an entry in the
|
|
application-maintained "external session cache"), and is responsible for
|
|
calling SSL_SESSION_free() when the session reference is no longer in use.
|
|
|
|
Note that in TLSv1.3, sessions are established after the main
|
|
handshake has completed. The server decides when to send the client the session
|
|
information and this may occur some time after the end of the handshake (or not
|
|
at all). This means that applications should expect the new_session_cb()
|
|
function to be invoked during the handshake (for <= TLSv1.2) or after the
|
|
handshake (for TLSv1.3). It is also possible in TLSv1.3 for multiple sessions to
|
|
be established with a single connection. In these case the new_session_cb()
|
|
function will be invoked multiple times.
|
|
|
|
In TLSv1.3 it is recommended that each SSL_SESSION object is only used for
|
|
resumption once. One way of enforcing that is for applications to call
|
|
L<SSL_CTX_remove_session(3)> after a session has been used.
|
|
|
|
The remove_session_cb() is called whenever the SSL engine removes a session
|
|
from the internal cache. This can happen 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<SSL_CTX_free(3)> is called. The remove_session_cb() is passed
|
|
the B<ctx> and the ssl session B<sess>. It does not provide any feedback.
|
|
|
|
The get_session_cb() is only called on SSL/TLS servers, and is given
|
|
the session id
|
|
proposed by the client. The get_session_cb() is always called, even when
|
|
session caching was disabled. The get_session_cb() is passed the
|
|
B<ssl> connection and the session id of length B<length> at the memory location
|
|
B<data>. By setting the parameter B<copy> to B<1>, the callback can require the
|
|
SSL engine to increment the reference count of the SSL_SESSION object;
|
|
setting B<copy> to B<0> causes the reference count to remain unchanged.
|
|
If the get_session_cb() does not write to B<copy>, the reference count
|
|
is incremented and the session must be explicitly freed with
|
|
L<SSL_SESSION_free(3)>.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
SSL_CTX_sess_get_new_cb(), SSL_CTX_sess_get_remove_cb() and SSL_CTX_sess_get_get_cb()
|
|
return different callback function pointers respectively.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ssl(7)>, L<d2i_SSL_SESSION(3)>,
|
|
L<SSL_CTX_set_session_cache_mode(3)>,
|
|
L<SSL_CTX_flush_sessions(3)>,
|
|
L<SSL_SESSION_free(3)>,
|
|
L<SSL_CTX_free(3)>
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
Licensed under the Apache License 2.0 (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<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|