1.\" $OpenBSD: SSL_CTX_flush_sessions.3,v 1.5 2018/03/27 17:35:50 schwarze Exp $ 2.\" OpenSSL SSL_CTX_flush_sessions.pod 1722496f Jun 8 15:18:38 2017 -0400 3.\" 4.\" This file was written by Lutz Jaenicke <jaenicke@openssl.org>. 5.\" Copyright (c) 2001 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: March 27 2018 $ 52.Dt SSL_CTX_FLUSH_SESSIONS 3 53.Os 54.Sh NAME 55.Nm SSL_CTX_flush_sessions 56.Nd remove expired sessions 57.Sh SYNOPSIS 58.In openssl/ssl.h 59.Ft void 60.Fn SSL_CTX_flush_sessions "SSL_CTX *ctx" "long tm" 61.Sh DESCRIPTION 62.Fn SSL_CTX_flush_sessions 63causes a run through the session cache of 64.Fa ctx 65to remove sessions expired at time 66.Fa tm . 67.Pp 68If enabled, the internal session cache will collect all sessions established 69up to the specified maximum number (see 70.Xr SSL_CTX_sess_set_cache_size 3 ) . 71As sessions will not be reused once they are expired, they should be 72removed from the cache to save resources. 73This can either be done automatically whenever 255 new sessions were 74established (see 75.Xr SSL_CTX_set_session_cache_mode 3 ) 76or manually by calling 77.Fn SSL_CTX_flush_sessions . 78.Pp 79The parameter 80.Fa tm 81specifies the time which should be used for the 82expiration test, in most cases the actual time given by 83.Fn time 0 84will be used. 85.Pp 86.Fn SSL_CTX_flush_sessions 87will only check sessions stored in the internal cache. 88When a session is found and removed, the 89.Va remove_session_cb 90is however called to synchronize with the external cache (see 91.Xr SSL_CTX_sess_set_get_cb 3 ) . 92.Sh SEE ALSO 93.Xr ssl 3 , 94.Xr SSL_CTX_sess_set_get_cb 3 , 95.Xr SSL_CTX_set_session_cache_mode 3 , 96.Xr SSL_CTX_set_timeout 3 97.Sh HISTORY 98.Fn SSL_CTX_flush_sessions 99first appeared in SSLeay 0.8.0 and has been available since 100.Ox 2.4 . 101