path: root/lib/libssl/man/SSL_CTX_new.3

.\" $OpenBSD: SSL_CTX_new.3,v 1.6 2018/03/21 08:06:34 schwarze Exp $
.\" full merge up to: OpenSSL 21cd6e00 Oct 21 14:40:15 2015 +0100
.\" selective merge up to: OpenSSL eb43101f Dec 9 18:07:09 2016 +0100
.\"
.\" This file was written by Lutz Jaenicke <jaenicke@openssl.org>.
.\" Copyright (c) 2000, 2005, 2012, 2013, 2015, 2016 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: March 21 2018 $
.Dt SSL_CTX_NEW 3
.Os
.Sh NAME
.Nm SSL_CTX_new ,
.Nm SSL_CTX_up_ref ,
.Nm TLS_method ,
.Nm TLS_server_method ,
.Nm TLS_client_method ,
.Nm SSLv23_method ,
.Nm SSLv23_server_method ,
.Nm SSLv23_client_method ,
.Nm TLSv1_method ,
.Nm TLSv1_server_method ,
.Nm TLSv1_client_method ,
.Nm TLSv1_1_method ,
.Nm TLSv1_1_server_method ,
.Nm TLSv1_1_client_method ,
.Nm TLSv1_2_method ,
.Nm TLSv1_2_server_method ,
.Nm TLSv1_2_client_method ,
.Nm DTLSv1_method ,
.Nm DTLSv1_server_method ,
.Nm DTLSv1_client_method
.Nd create a new SSL_CTX object as framework for TLS/SSL enabled functions
.Sh SYNOPSIS
.In openssl/ssl.h
.Ft SSL_CTX *
.Fn SSL_CTX_new "const SSL_METHOD *method"
.Ft int
.Fn SSL_CTX_up_ref "SSL_CTX *ctx"
.Ft const SSL_METHOD *
.Fn TLS_method void
.Ft const SSL_METHOD *
.Fn TLS_server_method void
.Ft const SSL_METHOD *
.Fn TLS_client_method void
.Ft const SSL_METHOD *
.Fn SSLv23_method void
.Ft const SSL_METHOD *
.Fn SSLv23_server_method void
.Ft const SSL_METHOD *
.Fn SSLv23_client_method void
.Ft const SSL_METHOD *
.Fn TLSv1_method void
.Ft const SSL_METHOD *
.Fn TLSv1_server_method void
.Ft const SSL_METHOD *
.Fn TLSv1_client_method void
.Ft const SSL_METHOD *
.Fn TLSv1_1_method void
.Ft const SSL_METHOD *
.Fn TLSv1_1_server_method void
.Ft const SSL_METHOD *
.Fn TLSv1_1_client_method void
.Ft const SSL_METHOD *
.Fn TLSv1_2_method void
.Ft const SSL_METHOD *
.Fn TLSv1_2_server_method void
.Ft const SSL_METHOD *
.Fn TLSv1_2_client_method void
.Ft const SSL_METHOD *
.Fn DTLSv1_method void
.Ft const SSL_METHOD *
.Fn DTLSv1_server_method void
.Ft const SSL_METHOD *
.Fn DTLSv1_client_method void
.Sh DESCRIPTION
.Fn SSL_CTX_new
creates a new
.Vt SSL_CTX
object as framework to establish TLS/SSL or DTLS enabled connections.
It initializes the list of ciphers, the session cache setting, the
callbacks, the keys and certificates, and the options to its default
values.
.Pp
An
.Vt SSL_CTX
object is reference counted.
Creating a new
.Vt SSL_CTX
object sets its reference count to 1.
Calling
.Fn SSL_CTX_up_ref
on it increments the reference count by 1.
Calling
.Xr SSL_CTX_free 3
on it decrements the reference count by 1.
When the reference count drops to zero,
any memory or resources allocated to the
.Vt SSL_CTX
object are freed.
.Pp
The
.Vt SSL_CTX
object uses
.Fa method
as its connection method.
The methods exist in a generic type (for client and server use),
a server only type, and a client only type.
.Fa method
can be of the following types:
.Bl -tag -width Ds
.It Xo
.Fn TLS_method ,
.Fn TLS_server_method ,
.Fn TLS_client_method
.Xc
These are the general-purpose version-flexible SSL/TLS methods.
The actual protocol version used will be negotiated to the highest
version mutually supported by the client and the server.
The supported protocols are TLSv1, TLSv1.1 and TLSv1.2.
Applications should use these methods and avoid the version-specific
methods described below.
.It Xo
.Fn SSLv23_method ,
.Fn SSLv23_server_method ,
.Fn SSLv23_client_method
.Xc
Use of these functions is deprecated.
They have been replaced with the above
.Fn TLS_method ,
.Fn TLS_server_method ,
and
.Fn TLS_client_method ,
respectively.
New code should use those functions instead.
.It Xo
.Fn TLSv1_method ,
.Fn TLSv1_server_method ,
.Fn TLSv1_client_method
.Xc
A TLS/SSL connection established with these methods will only
understand the TLSv1 protocol.
.It Xo
.Fn TLSv1_1_method ,
.Fn TLSv1_1_server_method ,
.Fn TLSv1_1_client_method
.Xc
A TLS/SSL connection established with these methods will only
understand the TLSv1.1 protocol.
.It Xo
.Fn TLSv1_2_method ,
.Fn TLSv1_2_server_method ,
.Fn TLSv1_2_client_method
.Xc
A TLS/SSL connection established with these methods will only
understand the TLSv1.2 protocol.
.It Xo
.Fn DTLSv1_method ,
.Fn DTLSv1_server_method ,
.Fn DTLSv1_client_method
.Xc
These are the version-specific methods for DTLSv1.
.El
.Pp
The list of protocols available can also be limited using the
.Dv SSL_OP_NO_TLSv1 ,
.Dv SSL_OP_NO_TLSv1_1 ,
and
.Dv SSL_OP_NO_TLSv1_2
options of the
.Xr SSL_CTX_set_options 3
or
.Xr SSL_set_options 3
functions, but this approach is not recommended.
Clients should avoid creating "holes" in the set of protocols they support.
When disabling a protocol, make sure that you also disable either
all previous or all subsequent protocol versions.
In clients, when a protocol version is disabled without disabling
all previous protocol versions, the effect is to also disable all
subsequent protocol versions.
.Sh RETURN VALUES
.Fn SSL_CTX_new
returns a pointer to the newly allocated object or
.Dv NULL
on failure.
Check the error stack to find out the reason for failure.
.Pp
.Fn SSL_CTX_up_ref
returns 1 for success or 0 for failure.
.Sh SEE ALSO
.Xr ssl 3 ,
.Xr SSL_accept 3 ,
.Xr SSL_CTX_free 3 ,
.Xr SSL_CTX_set_min_proto_version 3 ,
.Xr SSL_CTX_set_options 3 ,
.Xr SSL_set_connect_state 3
.Sh HISTORY
.Fn SSL_CTX_new ,
.Fn SSLv23_method ,
.Fn SSLv23_server_method ,
and
.Fn SSLv23_client_method
appeared before SSLeay 0.8.
.Fn TLSv1_method ,
.Fn TLSv1_server_method ,
and
.Fn TLSv1_client_method
first appeared in SSLeay 0.9.0.
All these functions have been available since
.Ox 2.4 .