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Diffstat (limited to 'static/openbsd/man3/SSL_CTX_set_session_cache_mode.3')
| -rw-r--r-- | static/openbsd/man3/SSL_CTX_set_session_cache_mode.3 | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/static/openbsd/man3/SSL_CTX_set_session_cache_mode.3 b/static/openbsd/man3/SSL_CTX_set_session_cache_mode.3 new file mode 100644 index 00000000..d19ff795 --- /dev/null +++ b/static/openbsd/man3/SSL_CTX_set_session_cache_mode.3 @@ -0,0 +1,199 @@ +.\" $OpenBSD: SSL_CTX_set_session_cache_mode.3,v 1.8 2025/06/08 22:52:00 schwarze Exp $ +.\" OpenSSL 67adf0a7 Dec 25 19:58:38 2016 +0100 +.\" +.\" This file was written by Lutz Jaenicke <jaenicke@openssl.org> and +.\" Geoff Thorpe <geoff@openssl.org>. +.\" Copyright (c) 2001, 2002 The OpenSSL Project. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in +.\" the documentation and/or other materials provided with the +.\" distribution. +.\" +.\" 3. All advertising materials mentioning features or use of this +.\" software must display the following acknowledgment: +.\" "This product includes software developed by the OpenSSL Project +.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" +.\" +.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to +.\" endorse or promote products derived from this software without +.\" prior written permission. For written permission, please contact +.\" openssl-core@openssl.org. +.\" +.\" 5. Products derived from this software may not be called "OpenSSL" +.\" nor may "OpenSSL" appear in their names without prior written +.\" permission of the OpenSSL Project. +.\" +.\" 6. Redistributions of any form whatsoever must retain the following +.\" acknowledgment: +.\" "This product includes software developed by the OpenSSL Project +.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY +.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR +.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED +.\" OF THE POSSIBILITY OF SUCH DAMAGE. +.\" +.Dd $Mdocdate: June 8 2025 $ +.Dt SSL_CTX_SET_SESSION_CACHE_MODE 3 +.Os +.Sh NAME +.Nm SSL_CTX_set_session_cache_mode , +.Nm SSL_CTX_get_session_cache_mode +.Nd enable/disable session caching +.Sh SYNOPSIS +.Lb libssl libcrypto +.In openssl/ssl.h +.Ft long +.Fn SSL_CTX_set_session_cache_mode "SSL_CTX ctx" "long mode" +.Ft long +.Fn SSL_CTX_get_session_cache_mode "SSL_CTX ctx" +.Sh DESCRIPTION +.Fn SSL_CTX_set_session_cache_mode +enables/disables session caching by setting the operational mode for +.Ar ctx +to +.Ar mode . +.Pp +.Fn SSL_CTX_get_session_cache_mode +returns the currently used cache mode. +.Pp +The OpenSSL library can store/retrieve SSL/TLS sessions for later reuse. +The sessions can be held in memory for each +.Fa ctx , +if more than one +.Vt SSL_CTX +object is being maintained, the sessions are unique for each +.Vt SSL_CTX +object. +.Pp +In order to reuse a session, a client must send the session's id to the server. +It can only send exactly one id. +The server then either agrees to reuse the session or it starts a full +handshake (to create a new session). +.Pp +A server will look up the session in its internal session storage. +If the session is not found in internal storage or lookups for the internal +storage have been deactivated +.Pq Dv SSL_SESS_CACHE_NO_INTERNAL_LOOKUP , +the server will try the external storage if available. +.Pp +Since a client may try to reuse a session intended for use in a different +context, the session id context must be set by the server (see +.Xr SSL_CTX_set_session_id_context 3 ) . +.Pp +The following session cache modes and modifiers are available: +.Bl -tag -width Ds +.It Dv SSL_SESS_CACHE_OFF +No session caching for client or server takes place. +.It Dv SSL_SESS_CACHE_CLIENT +Client sessions are added to the session cache. +As there is no reliable way for the OpenSSL library to know whether a session +should be reused or which session to choose (due to the abstract BIO layer the +SSL engine does not have details about the connection), +the application must select the session to be reused by using the +.Xr SSL_set_session 3 +function. +This option is not activated by default. +.It Dv SSL_SESS_CACHE_SERVER +Server sessions are added to the session cache. +When a client proposes a session to be reused, the server looks for the +corresponding session in (first) the internal session cache (unless +.Dv SSL_SESS_CACHE_NO_INTERNAL_LOOKUP +is set), then (second) in the external cache if available. +If the session is found, the server will try to reuse the session. +This is the default. +.It Dv SSL_SESS_CACHE_BOTH +Enable both +.Dv SSL_SESS_CACHE_CLIENT +and +.Dv SSL_SESS_CACHE_SERVER +at the same time. +.It Dv SSL_SESS_CACHE_NO_AUTO_CLEAR +Normally the session cache is checked for expired sessions every 255 +connections using the +.Xr SSL_CTX_flush_sessions 3 +function. +Since this may lead to a delay which cannot be controlled, +the automatic flushing may be disabled and +.Xr SSL_CTX_flush_sessions 3 +can be called explicitly by the application. +.It Dv SSL_SESS_CACHE_NO_INTERNAL_LOOKUP +By setting this flag, session-resume operations in an SSL/TLS server will not +automatically look up sessions in the internal cache, +even if sessions are automatically stored there. +If external session caching callbacks are in use, +this flag guarantees that all lookups are directed to the external cache. +As automatic lookup only applies for SSL/TLS servers, +the flag has no effect on clients. +.It Dv SSL_SESS_CACHE_NO_INTERNAL_STORE +Depending on the presence of +.Dv SSL_SESS_CACHE_CLIENT +and/or +.Dv SSL_SESS_CACHE_SERVER , +sessions negotiated in an SSL/TLS handshake may be cached for possible reuse. +Normally a new session is added to the internal cache as well as any external +session caching (callback) that is configured for the +.Vt SSL_CTX . +This flag will prevent sessions being stored in the internal cache +(though the application can add them manually using +.Xr SSL_CTX_add_session 3 ) . +Note: +in any SSL/TLS servers where external caching is configured, any successful +session lookups in the external cache (e.g., for session-resume requests) would +normally be copied into the local cache before processing continues \(en this +flag prevents these additions to the internal cache as well. +.It Dv SSL_SESS_CACHE_NO_INTERNAL +Enable both +.Dv SSL_SESS_CACHE_NO_INTERNAL_LOOKUP +and +.Dv SSL_SESS_CACHE_NO_INTERNAL_STORE +at the same time. +.El +.Pp +The default mode is +.Dv SSL_SESS_CACHE_SERVER . +.Sh RETURN VALUES +.Fn SSL_CTX_set_session_cache_mode +returns the previously set cache mode. +.Pp +.Fn SSL_CTX_get_session_cache_mode +returns the currently set cache mode. +.Sh SEE ALSO +.Xr ssl 3 , +.Xr SSL_CTX_add_session 3 , +.Xr SSL_CTX_ctrl 3 , +.Xr SSL_CTX_flush_sessions 3 , +.Xr SSL_CTX_sess_number 3 , +.Xr SSL_CTX_sess_set_cache_size 3 , +.Xr SSL_CTX_sess_set_get_cb 3 , +.Xr SSL_CTX_set_session_id_context 3 , +.Xr SSL_CTX_set_timeout 3 , +.Xr SSL_session_reused 3 , +.Xr SSL_set_session 3 +.Sh HISTORY +.Fn SSL_CTX_set_session_cache_mode +and +.Fn SSL_CTX_get_session_cache_mode +first appeared in SSLeay 0.6.1 and have been available since +.Ox 2.4 . +.Pp +.Dv SSL_SESS_CACHE_NO_INTERNAL_STORE +and +.Dv SSL_SESS_CACHE_NO_INTERNAL +were introduced in OpenSSL 0.9.6h. |