SSL_CTX_SET_NUM_TICKETS(3ossl)

🎟️ SSL_CTX_SET_NUM_TICKETS 🎟️

okay bestie, welcome to the 3ossl manual page for the ticket-counting girlies 💅 this is an OpenSSL page, and it's all about controlling how many TLSv1.3 session tickets get issued — no cap, it's more interesting than it sounds.

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✨ NAME ✨

SSL_set_num_tickets, SSL_get_num_tickets, SSL_CTX_set_num_tickets, SSL_CTX_get_num_tickets, SSL_new_session_ticket — the whole friend group whose entire personality is controlling the number of TLSv1.3 session tickets that are issued 🎀

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🌸 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);

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🦋 DESCRIPTION 🦋

so. SSL_CTX_set_num_tickets() and SSL_set_num_tickets() are for server applications — like, server side only, bestie, don't come at them from the client side. They set how many TLSv1.3 session tickets get sent to the client after a full handshake. You put your desired value (and yes, it can literally be 0, that's valid) in the num_tickets argument. The vibe check here: these should typically be called before the start of the handshake. ⭐

The default number of tickets is 2. periodt. And listen — following a resumption, the number of tickets issued will never be more than 1, regardless of the value you set via SSL_set_num_tickets() or SSL_CTX_set_num_tickets(). That's just how it is, no negotiating. And if num_tickets is set to 0, then no tickets will be issued for either a normal connection or a resumption. zero tickets, iconic, very demure. 💀

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 get associated with the updated client identity — i.e. including their certificate and verification status, iykyk 🫶. The number of tickets issued will normally be the same as was used for the initial handshake. And if the initial handshake was a full handshake, then you can call SSL_set_num_tickets() again prior to calling SSL_verify_client_post_handshake() to update the number of tickets that will be sent. love a refresh moment ✨

Now — to issue tickets after other events (such as application-layer changes), a server application uses SSL_new_session_ticket() to request that a new ticket be sent when it's safe to do so. But there are rules, bestie: 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 gets bundled with other application data being written and properly aligned to a record boundary. cute, efficient, main character energy. 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() 🔥

And you can call SSL_new_session_ticket() more than once to request additional tickets be sent — all such requests are queued and written together when it's safe to do so, triggered by SSL_write() or SSL_do_handshake(). but here's the thing:

⚠️ 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. do not @ me, this is literally in the manpage.

To be notified when the ticket itself is sent, register a new-session callback with SSL_CTX_sess_set_new_cb(3) — it'll be invoked as the ticket or tickets are generated. notification slay 💖

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() or SSL_set_num_tickets() — or 2 if no such call has been made. the default really said "I live here now" 🎀

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👑 RETURN VALUES 👑

• SSL_CTX_set_num_tickets(), SSL_set_num_tickets(), and SSL_new_session_ticket() return 1 on success or 0 on failure. that's the whole spectrum, bestie.
• SSL_CTX_get_num_tickets() and SSL_get_num_tickets() return the number of tickets that have been previously set.

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🌈 SEE ALSO 🌈

• ssl(7)

go read it, it's giving required reading 💜

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🧚 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(), and SSL_CTX_get_num_tickets() were added in OpenSSL 1.1.1 🌸

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💅 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>.

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and that's the page, bestie 🫶 this was OpenSSL 3.5.0, dated 2026-09-25, filed under SSL_CTX_SET_NUM_TICKETS(3ossl) — go forth and issue exactly the number of tickets you meant to 💖✨🎀