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.\" $OpenBSD: SSL_clear.3,v 1.2 2016/12/01 22:45:28 schwarze Exp $
.\" OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
.\"
.\" This file was written by Lutz Jaenicke <jaenicke@openssl.org>.
.\" Copyright (c) 2000, 2001, 2002, 2011, 2015 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: December 1 2016 $
.Dt SSL_CLEAR 3
.Os
.Sh NAME
.Nm SSL_clear
.Nd reset SSL object to allow another connection
.Sh SYNOPSIS
.In openssl/ssl.h
.Ft int
.Fn SSL_clear "SSL *ssl"
.Sh DESCRIPTION
Reset
.Fa ssl
to allow another connection.
All settings (method, ciphers, BIOs) are kept.
.Pp
.Fn SSL_clear
is used to prepare an
.Vt SSL
object for a new connection.
While all settings are kept,
a side effect is the handling of the current SSL session.
If a session is still
.Em open ,
it is considered bad and will be removed from the session cache,
as required by RFC2246.
A session is considered open if
.Xr SSL_shutdown 3
was not called for the connection or at least
.Xr SSL_set_shutdown 3
was used to
set the
.Dv SSL_SENT_SHUTDOWN
state.
.Pp
If a session was closed cleanly,
the session object will be kept and all settings corresponding.
This explicitly means that for example the special method used during the
session will be kept for the next handshake.
So if the session was a TLSv1 session, a
.Vt SSL
client object will use a TLSv1 client method for the next handshake and a
.Vt SSL
server object will use a TLSv1 server method, even if
.Fn TLS_*_method Ns s
were chosen on startup.
This might lead to connection failures (see
.Xr SSL_new 3 )
for a description of the method's properties.
.Sh RETURN VALUES
The following return values can occur:
.Bl -tag -width Ds
.It 0
The
.Fn SSL_clear
operation could not be performed.
Check the error stack to find out the reason.
.It 1
The
.Fn SSL_clear
operation was successful.
.El
.Sh SEE ALSO
.Xr ssl 3 ,
.Xr SSL_CTX_set_client_cert_cb 3 ,
.Xr SSL_CTX_set_options 3 ,
.Xr SSL_free 3 ,
.Xr SSL_new 3 ,
.Xr SSL_set_shutdown 3 ,
.Xr SSL_shutdown 3
.Sh CAVEATS
.Fn SSL_clear
resets the
.Vt SSL
object to allow for another connection.
The reset operation however keeps several settings of the last sessions
(some of these settings were made automatically during the last handshake).
It only makes sense for a new connection with the exact same peer that shares
these settings,
and may fail if that peer changes its settings between connections.
Use the sequence
.Xr SSL_get_session 3 ;
.Xr SSL_new 3 ;
.Xr SSL_set_session 3 ;
.Xr SSL_free 3
instead to avoid such failures (or simply
.Xr SSL_free 3 ;
.Xr SSL_new 3
if session reuse is not desired).
|
