1.\" $OpenBSD: d2i_SSL_SESSION.3,v 1.7 2019/06/08 15:25:43 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, 2005, 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 8 2019 $ 52.Dt D2I_SSL_SESSION 3 53.Os 54.Sh NAME 55.Nm d2i_SSL_SESSION , 56.Nm i2d_SSL_SESSION 57.Nd convert SSL_SESSION object from/to ASN1 representation 58.Sh SYNOPSIS 59.In openssl/ssl.h 60.Ft SSL_SESSION * 61.Fn d2i_SSL_SESSION "SSL_SESSION **a" "const unsigned char **pp" "long length" 62.Ft int 63.Fn i2d_SSL_SESSION "SSL_SESSION *in" "unsigned char **pp" 64.Sh DESCRIPTION 65.Fn d2i_SSL_SESSION 66transforms the external ASN1 representation of an SSL/TLS session, 67stored as binary data at location 68.Fa pp 69with length 70.Fa length , 71into 72an 73.Vt SSL_SESSION 74object. 75.Pp 76.Fn i2d_SSL_SESSION 77transforms the 78.Vt SSL_SESSION 79object 80.Fa in 81into the ASN1 representation and stores it into the memory location pointed to 82by 83.Fa pp . 84The length of the resulting ASN1 representation is returned. 85If 86.Fa pp 87is the 88.Dv NULL 89pointer, only the length is calculated and returned. 90.Pp 91The 92.Vt SSL_SESSION 93object is built from several 94.Xr malloc 3 Ns 95-ed parts; it can therefore not be moved, copied or stored directly. 96In order to store session data on disk or into a database, 97it must be transformed into a binary ASN1 representation. 98.Pp 99When using 100.Fn d2i_SSL_SESSION , 101the 102.Vt SSL_SESSION 103object is automatically allocated. 104The reference count is 1, so that the session must be explicitly removed using 105.Xr SSL_SESSION_free 3 , 106unless the 107.Vt SSL_SESSION 108object is completely taken over, when being called inside the 109.Fn get_session_cb , 110see 111.Xr SSL_CTX_sess_set_get_cb 3 . 112.Pp 113.Vt SSL_SESSION 114objects keep internal link information about the session cache list when being 115inserted into one 116.Vt SSL_CTX 117object's session cache. 118One 119.Vt SSL_SESSION 120object, regardless of its reference count, must therefore only be used with one 121.Vt SSL_CTX 122object (and the 123.Vt SSL 124objects created from this 125.Vt SSL_CTX 126object). 127.Pp 128When using 129.Fn i2d_SSL_SESSION , 130the memory location pointed to by 131.Fa pp 132must be large enough to hold the binary representation of the session. 133There is no known limit on the size of the created ASN1 representation, 134so call 135.Fn i2d_SSL_SESSION 136first with 137.Fa pp Ns = Ns Dv NULL 138to obtain the encoded size, before allocating the required amount of memory and 139calling 140.Fn i2d_SSL_SESSION 141again. 142Note that this will advance the value contained in 143.Fa *pp 144so it is necessary to save a copy of the original allocation. 145For example: 146.Bd -literal -offset indent 147char *p, *pp; 148int elen, len; 149 150elen = i2d_SSL_SESSION(sess, NULL); 151p = pp = malloc(elen); 152if (p != NULL) { 153 len = i2d_SSL_SESSION(sess, &pp); 154 assert(elen == len); 155 assert(p + len == pp); 156} 157.Ed 158.Sh RETURN VALUES 159.Fn d2i_SSL_SESSION 160returns a pointer to the newly allocated 161.Vt SSL_SESSION 162object. 163In case of failure a 164.Dv NULL 165pointer is returned and the error message can be retrieved from the error 166stack. 167.Pp 168.Fn i2d_SSL_SESSION 169returns the size of the ASN1 representation in bytes. 170When the session is not valid, 0 is returned and no operation is performed. 171.Sh SEE ALSO 172.Xr d2i_X509 3 , 173.Xr ssl 3 , 174.Xr SSL_CTX_sess_set_get_cb 3 , 175.Xr SSL_SESSION_free 3 176.Sh HISTORY 177.Fn d2i_SSL_SESSION 178and 179.Fn i2d_SSL_SESSION 180first appeared in SSLeay 0.5.2 and have been available since 181.Ox 2.4 . 182