SSL_CTX_SET_NUM_TICKETS(3ossl) OpenSSL SSL_CTX_SET_NUM_TICKETS(3ossl)
NAME
SSL_set_num_tickets, SSL_get_num_tickets, SSL_CTX_set_num_tickets,
SSL_CTX_get_num_tickets, SSL_new_session_ticket - control the number of
TLSv1.3 session tickets that are issued
SYNOPSIS
#include <openssl/ssl.h>
int SSL_set_num_tickets(SSL *s, size_t num_tickets);
size_t SSL_get_num_tickets(const SSL *s);
int SSL_CTX_set_num_tickets(SSL_CTX *ctx, size_t num_tickets);
size_t SSL_CTX_get_num_tickets(const SSL_CTX *ctx);
int SSL_new_session_ticket(SSL *s);
DESCRIPTION
SSL_CTX_set_num_tickets(3) and SSL_set_num_tickets() can be called for a
server application and set the number of TLSv1.3 session tickets that
will be sent to the client after a full handshake. Set the desired
value (which could be 0) in the num_tickets argument. Typically these
functions should be called before the start of the handshake.
The default number of tickets is 2. Following a resumption the number
of tickets issued will never be more than 1 regardless of the value set
via SSL_CTX_set_num_tickets(3). If num_tickets
is set to 0 then no tickets will be issued for either a normal
connection or a resumption.
Tickets are also issued on receipt of a post-handshake certificate from
the client following a request by the server using
SSL_verify_client_post_handshake(3). These new tickets will be
associated with the updated client identity (i.e. including their
certificate and verification status). The number of tickets issued will
normally be the same as was used for the initial handshake. If the
initial handshake was a full handshake then SSL_set_num_tickets() can
be called again prior to calling SSL_verify_client_post_handshake() to
update the number of tickets that will be sent.
To issue tickets after other events (such as application-layer
changes), SSL_new_session_ticket() is used by a server application to
request that a new ticket be sent when it is safe to do so. New
tickets are only allowed to be sent in this manner after the initial
handshake has completed, and only for TLS 1.3 connections. By default,
the ticket generation and transmission are delayed until the server is
starting a new write operation, so that it is bundled with other
application data being written and properly aligned to a record
boundary. If the connection was at a record boundary when
SSL_new_session_ticket() was called, the ticket can be sent immediately
(without waiting for the next application write) by calling
SSL_do_handshake(). SSL_new_session_ticket() can be called more than
once to request additional tickets be sent; all such requests are
queued and written together when it is safe to do so and triggered by
SSL_write() or SSL_do_handshake(). Note that a successful return from
SSL_new_session_ticket() indicates only that the request to send a
ticket was processed, not that the ticket itself was sent. To be
notified when the ticket itself is sent, a new-session callback can be
registered with SSL_CTX_sess_set_new_cb(3) that will be invoked as the
ticket or tickets are generated.
SSL_CTX_get_num_tickets() and SSL_get_num_tickets() return the number
of tickets set by a previous call to SSL_CTX_set_num_tickets(3) or
SSL_set_num_tickets(), or 2 if no such call has been made.
RETURN VALUES
SSL_CTX_set_num_tickets(3), SSL_set_num_tickets(), and
SSL_new_session_ticket() return 1 on success or 0 on failure.
SSL_CTX_get_num_tickets() and SSL_get_num_tickets() return the number
of tickets that have been previously set.
SEE ALSO
ssl(7)
HISTORY
SSL_new_session_ticket() was added in OpenSSL 3.0.0.
SSL_set_num_tickets(), SSL_get_num_tickets(),
SSL_CTX_set_num_tickets(3), and SSL_CTX_get_num_tickets() were added in
OpenSSL 1.1.1.
COPYRIGHT
Copyright 2018-2021 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
<https://www.openssl.org/source/license.html>.
3.3.2 2024-09-04 SSL_CTX_SET_NUM_TICKETS(3ossl)
openssl 3.3.2 - Generated Tue Sep 24 09:01:26 CDT 2024