SSL_CTX_SET_TIMEOUT(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💖 SSL_CTX_SET_TIMEOUT — the 3ossl era 💖

Okay bestie, welcome to the 3ossl manual page. This is literally the glow-up of SSL_CTX_set_timeout and SSL_CTX_get_timeout, and we're gonna get you comfy with session caching timeouts. No cap.

✨ NAME ✨

SSL_CTX_set_timeout, SSL_CTX_get_timeout — manipulate timeout values for session caching. That's the whole vibe. Periodt.

🌸 SYNOPSIS 🌸

#include <openssl/ssl.h>

long SSL_CTX_set_timeout(SSL_CTX *ctx, long t);
long SSL_CTX_get_timeout(SSL_CTX *ctx);

🦋 DESCRIPTION 🦋

So SSL_CTX_set_timeout() sets the timeout for newly created sessions for ctx to t. The timeout value t must be given in seconds. Lowkey important.

SSL_CTX_get_timeout() returns the currently set timeout value for ctx. It's giving "read the vibe" energy.

🎀 NOTES 🎀

Okay, deep breath, bestie, because this is where the lore lives.

Whenever a new session is created, it is assigned a maximum lifetime. This lifetime is specified by storing the creation time of the session and the timeout value valid at this time. If the actual time is later than creation time plus timeout, the session is not reused. So it's like a little expiration date, iykyk.

Due to this realization, all sessions behave according to the timeout value valid at the time of the session negotiation. Changes of the timeout value do not affect already established sessions. So don't come for already-negotiated sessions with a new timeout — they're not listening.

The expiration time of a single session can be modified using the SSL_SESSION_get_time(3) family of functions. Iconic.

Expired sessions are removed from the internal session cache whenever SSL_CTX_flush_sessions(3) is called, either directly by the application or automatically (see SSL_CTX_set_session_cache_mode(3)). So that's the cleanup crew.

The default value for session timeout is decided on a per protocol basis, see SSL_get_default_timeout(3). All currently supported protocols have the same default timeout value of 300 seconds. Three hundred seconds of main character energy.

This timeout value is used as the ticket lifetime hint for stateless session tickets. It is also used as the timeout value within the ticket itself. So it's doing double duty, slay.

For TLSv1.3, RFC8446 limits transmission of this value to 1 week (604800 seconds). That's the cap, no cap.

For TLSv1.2, tickets generated during an initial handshake use the value as specified. Tickets generated during a resumed handshake have a value of 0 for the ticket lifetime hint. So that's a little TLSv1.2 quirk, noted.

💅 RETURN VALUES 💅

SSL_CTX_set_timeout() returns the previously set timeout value. So you get the old one back — surprise, bestie.

SSL_CTX_get_timeout() returns the currently set timeout value. Simple as that.

🔥 SEE ALSO 🔥

Copyright 2001-2022 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.

And that's the tea, bestie. This was OpenSSL 3.5.0, dated 2026-09-25, and the page is SSL_CTX_SET_TIMEOUT(3ossl). Now go slay those session timeouts. 💖✨🎀🦋🌸💅🫶😭🔥👑🌈⭐💀🙈🍓🧚💜

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