1.\" $OpenBSD: SMIME_read_CMS.3,v 1.7 2021/12/14 14:30:50 schwarze Exp $ 2.\" full merge up to: OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100 3.\" 4.\" This file was written by Dr. Stephen Henson <steve@openssl.org>. 5.\" Copyright (c) 2008 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: December 14 2021 $ 52.Dt SMIME_READ_CMS 3 53.Os 54.Sh NAME 55.Nm SMIME_read_CMS 56.Nd extract CMS ContentInfo from an S/MIME message 57.Sh SYNOPSIS 58.In openssl/cms.h 59.Ft CMS_ContentInfo * 60.Fo SMIME_read_CMS 61.Fa "BIO *in" 62.Fa "BIO **bcont" 63.Fc 64.Sh DESCRIPTION 65.Fn SMIME_read_CMS 66parses a message in S/MIME format from 67.Fa in . 68.Pp 69If the message uses cleartext signing, the content is saved in a memory BIO 70which is written to 71.Pf * Fa bcont 72and which can then be passed to 73.Xr CMS_verify 3 74with the 75.Dv CMS_DETACHED 76flag set. 77Otherwise, 78.Pf * Fa bcont 79is set to 80.Dv NULL 81and the type of the returned structure can be determined using 82.Xr CMS_get0_type 3 . 83.Pp 84To support future functionality if 85.Fa bcont 86is not 87.Dv NULL , 88.Pf * Fa bcont 89should be initialized to 90.Dv NULL , 91for example: 92.Bd -literal -offset indent 93BIO *cont = NULL; 94CMS_ContentInfo *cms = SMIME_read_CMS(in, &cont); 95.Ed 96.Sh RETURN VALUES 97.Fn SMIME_read_CMS 98returns a valid 99.Vt CMS_ContentInfo 100structure or 101.Dv NULL 102if an error occurred. 103The error can be obtained from 104.Xr ERR_get_error 3 . 105.Sh SEE ALSO 106.Xr CMS_ContentInfo_new 3 , 107.Xr CMS_decrypt 3 , 108.Xr CMS_get0_type 3 , 109.Xr CMS_verify 3 , 110.Xr d2i_CMS_ContentInfo 3 , 111.Xr SMIME_read_ASN1 3 , 112.Xr SMIME_write_CMS 3 113.Sh HISTORY 114.Fn SMIME_read_CMS 115first appeared in OpenSSL 0.9.8h 116and has been available since 117.Ox 6.7 . 118.Sh BUGS 119The MIME parser used by 120.Fn SMIME_read_CMS 121is somewhat primitive. 122While it will handle most S/MIME messages, more complex compound formats 123may not work. 124.Pp 125The parser assumes that the 126.Vt CMS_ContentInfo 127structure is always base64 encoded and will not handle the case 128where it is in binary format or uses quoted printable format. 129.Pp 130The use of a memory BIO to hold the signed content limits the size of 131the message which can be processed due to memory restraints: a streaming 132single pass option should be available. 133