1SSL_CTX_SET_NUM_TICKETS(3ossl) OpenSSL SSL_CTX_SET_NUM_TICKETS(3ossl)
2
6 SSL_set_num_tickets, SSL_get_num_tickets, SSL_CTX_set_num_tickets,
7 SSL_CTX_get_num_tickets, SSL_new_session_ticket - control the number of
8 TLSv1.3 session tickets that are issued
9
11 #include <openssl/ssl.h>
12 int SSL_set_num_tickets(SSL *s, size_t num_tickets);
14 size_t SSL_get_num_tickets(const SSL *s);
15 int SSL_CTX_set_num_tickets(SSL_CTX *ctx, size_t num_tickets);
16 size_t SSL_CTX_get_num_tickets(const SSL_CTX *ctx);
17 int SSL_new_session_ticket(SSL *s);
18
20 SSL_CTX_set_num_tickets() and SSL_set_num_tickets() can be called for a
21 server application and set the number of TLSv1.3 session tickets that
22 will be sent to the client after a full handshake. Set the desired
23 value (which could be 0) in the num_tickets argument. Typically these
24 functions should be called before the start of the handshake.
25 The default number of tickets is 2. Following a resumption the number
27 of tickets issued will never be more than 1 regardless of the value set
28 via SSL_set_num_tickets() or SSL_CTX_set_num_tickets(). If num_tickets
29 is set to 0 then no tickets will be issued for either a normal
30 connection or a resumption.
31 Tickets are also issued on receipt of a post-handshake certificate from
33 the client following a request by the server using
34 SSL_verify_client_post_handshake(3). These new tickets will be
35 associated with the updated client identity (i.e. including their
36 certificate and verification status). The number of tickets issued will
37 normally be the same as was used for the initial handshake. If the
38 initial handshake was a full handshake then SSL_set_num_tickets() can
39 be called again prior to calling SSL_verify_client_post_handshake() to
40 update the number of tickets that will be sent.
41 To issue tickets after other events (such as application-layer
43 changes), SSL_new_session_ticket() is used by a server application to
44 request that a new ticket be sent when it is safe to do so. New
45 tickets are only allowed to be sent in this manner after the initial
46 handshake has completed, and only for TLS 1.3 connections. By default,
47 the ticket generation and transmission are delayed until the server is
48 starting a new write operation, so that it is bundled with other
49 application data being written and properly aligned to a record
50 boundary. If the connection was at a record boundary when
51 SSL_new_session_ticket() was called, the ticket can be sent immediately
52 (without waiting for the next application write) by calling
53 SSL_do_handshake(). SSL_new_session_ticket() can be called more than
54 once to request additional tickets be sent; all such requests are
55 queued and written together when it is safe to do so and triggered by
56 SSL_write() or SSL_do_handshake(). Note that a successful return from
57 SSL_new_session_ticket() indicates only that the request to send a
58 ticket was processed, not that the ticket itself was sent. To be
59 notified when the ticket itself is sent, a new-session callback can be
60 registered with SSL_CTX_sess_set_new_cb(3) that will be invoked as the
61 ticket or tickets are generated.
62 SSL_CTX_get_num_tickets() and SSL_get_num_tickets() return the number
64 of tickets set by a previous call to SSL_CTX_set_num_tickets() or
65 SSL_set_num_tickets(), or 2 if no such call has been made.
66
68 SSL_CTX_set_num_tickets(), SSL_set_num_tickets(), and
69 SSL_new_session_ticket() return 1 on success or 0 on failure.
70 SSL_CTX_get_num_tickets() and SSL_get_num_tickets() return the number
72 of tickets that have been previously set.
73
75 ssl(7)
76
78 SSL_new_session_ticket() was added in OpenSSL 3.0.0.
79 SSL_set_num_tickets(), SSL_get_num_tickets(),
80 SSL_CTX_set_num_tickets(), and SSL_CTX_get_num_tickets() were added in
81 OpenSSL 1.1.1.
82
84 Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.
85 Licensed under the Apache License 2.0 (the "License"). You may not use
87 this file except in compliance with the License. You can obtain a copy
88 in the file LICENSE in the source distribution or at
89 <https://www.openssl.org/source/license.html>.
903.1.1 2023-08-31 SSL_CTX_SET_NUM_TICKETS(3ossl)