1.\" $OpenBSD: SSL_CTX_sess_set_cache_size.3,v 1.5 2019/06/12 09:36:30 schwarze Exp $ 2.\" OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100 3.\" 4.\" This file was written by Lutz Jaenicke <jaenicke@openssl.org>. 5.\" Copyright (c) 2001, 2002, 2014 The OpenSSL Project. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in 16.\" the documentation and/or other materials provided with the 17.\" distribution. 18.\" 19.\" 3. All advertising materials mentioning features or use of this 20.\" software must display the following acknowledgment: 21.\" "This product includes software developed by the OpenSSL Project 22.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 23.\" 24.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 25.\" endorse or promote products derived from this software without 26.\" prior written permission. For written permission, please contact 27.\" openssl-core@openssl.org. 28.\" 29.\" 5. Products derived from this software may not be called "OpenSSL" 30.\" nor may "OpenSSL" appear in their names without prior written 31.\" permission of the OpenSSL Project. 32.\" 33.\" 6. Redistributions of any form whatsoever must retain the following 34.\" acknowledgment: 35.\" "This product includes software developed by the OpenSSL Project 36.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 37.\" 38.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 39.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 40.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 41.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 42.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 43.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 44.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 45.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 46.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 47.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 48.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 49.\" OF THE POSSIBILITY OF SUCH DAMAGE. 50.\" 51.Dd $Mdocdate: June 12 2019 $ 52.Dt SSL_CTX_SESS_SET_CACHE_SIZE 3 53.Os 54.Sh NAME 55.Nm SSL_CTX_sess_set_cache_size , 56.Nm SSL_CTX_sess_get_cache_size 57.Nd manipulate session cache size 58.Sh SYNOPSIS 59.In openssl/ssl.h 60.Ft long 61.Fn SSL_CTX_sess_set_cache_size "SSL_CTX *ctx" "long t" 62.Ft long 63.Fn SSL_CTX_sess_get_cache_size "SSL_CTX *ctx" 64.Sh DESCRIPTION 65.Fn SSL_CTX_sess_set_cache_size 66sets the size of the internal session cache of context 67.Fa ctx 68to 69.Fa t . 70.Pp 71.Fn SSL_CTX_sess_get_cache_size 72returns the currently valid session cache size. 73.Pp 74The internal session cache size is 75.Dv SSL_SESSION_CACHE_MAX_SIZE_DEFAULT , 76currently 1024\(mu20, so that up to 20000 sessions can be held. 77This size can be modified using the 78.Fn SSL_CTX_sess_set_cache_size 79call. 80A special case is the size 0, which is used for unlimited size. 81.Pp 82If adding the session makes the cache exceed its size, then unused 83sessions are dropped from the end of the cache. 84Cache space may also be reclaimed by calling 85.Xr SSL_CTX_flush_sessions 3 86to remove expired sessions. 87.Pp 88If the size of the session cache is reduced and more sessions are already in 89the session cache, 90old session will be removed the next time a session shall be added. 91This removal is not synchronized with the expiration of sessions. 92.Sh RETURN VALUES 93.Fn SSL_CTX_sess_set_cache_size 94returns the previously valid size. 95.Pp 96.Fn SSL_CTX_sess_get_cache_size 97returns the currently valid size. 98.Sh SEE ALSO 99.Xr ssl 3 , 100.Xr SSL_CTX_ctrl 3 , 101.Xr SSL_CTX_flush_sessions 3 , 102.Xr SSL_CTX_sess_number 3 , 103.Xr SSL_CTX_set_session_cache_mode 3 104.Sh HISTORY 105.Fn SSL_CTX_sess_set_cache_size 106and 107.Fn SSL_CTX_sess_get_cache_size 108first appeared in SSLeay 0.9.0 and have been available since 109.Ox 2.4 . 110