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.\"
.IX Title "SMIME_READ_CMS 3ssl"
.TH SMIME_READ_CMS 3ssl 2024-10-23 3.4.0 OpenSSL
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH NAME
SMIME_read_CMS_ex, SMIME_read_CMS \- parse S/MIME message
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/cms.h>
\&
\& CMS_ContentInfo *SMIME_read_CMS_ex(BIO *bio, int flags, BIO **bcont,
\&                                    CMS_ContentInfo **cms);
\& CMS_ContentInfo *SMIME_read_CMS(BIO *in, BIO **bcont);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
\&\fBSMIME_read_CMS()\fR parses a message in S/MIME format.
.PP
\&\fBin\fR is a BIO to read the message from.
.PP
If cleartext signing is used then the content is saved in a memory bio which is
written to \fB*bcont\fR, otherwise \fB*bcont\fR is set to NULL.
.PP
The parsed CMS_ContentInfo structure is returned or NULL if an
error occurred.
.PP
\&\fBSMIME_read_CMS_ex()\fR is similar to \fBSMIME_read_CMS()\fR but optionally a previously
created \fIcms\fR CMS_ContentInfo object can be supplied as well as some \fIflags\fR.
To create a \fIcms\fR object use \fBCMS_ContentInfo_new_ex\fR\|(3).
If the \fIflags\fR argument contains \fBCMS_BINARY\fR then the input is assumed to be
in binary format and is not translated to canonical form.
If in addition \fBSMIME_ASCIICRLF\fR is set then the binary input is assumed
to be followed by \fBCR\fR and \fBLF\fR characters, else only by an \fBLF\fR character.
If \fIflags\fR is 0 and \fIcms\fR is NULL then it is identical to \fBSMIME_read_CMS()\fR.
.SH NOTES
.IX Header "NOTES"
If \fB*bcont\fR is not NULL then the message is clear text signed. \fB*bcont\fR can
then be passed to \fBCMS_verify()\fR with the \fBCMS_DETACHED\fR flag set.
.PP
Otherwise the type of the returned structure can be determined
using \fBCMS_get0_type()\fR.
.PP
To support future functionality if \fBbcont\fR is not NULL \fB*bcont\fR should be
initialized to NULL. For example:
.PP
.Vb 2
\& BIO *cont = NULL;
\& CMS_ContentInfo *cms;
\&
\& cms = SMIME_read_CMS(in, &cont);
.Ve
.SH BUGS
.IX Header "BUGS"
The MIME parser used by \fBSMIME_read_CMS()\fR is somewhat primitive.  While it will
handle most S/MIME messages more complex compound formats may not work.
.PP
The parser assumes that the CMS_ContentInfo structure is always base64 encoded
and will not handle the case where it is in binary format or uses quoted
printable format.
.PP
The use of a memory BIO to hold the signed content limits the size of message
which can be processed due to memory restraints: a streaming single pass option
should be available.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBSMIME_read_CMS_ex()\fR and \fBSMIME_read_CMS()\fR return a valid \fBCMS_ContentInfo\fR
structure or \fBNULL\fR if an error occurred. The error can be obtained from
\&\fBERR_get_error\fR\|(3).
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBERR_get_error\fR\|(3),
\&\fBCMS_sign\fR\|(3),
\&\fBCMS_verify\fR\|(3),
\&\fBCMS_encrypt\fR\|(3),
\&\fBCMS_decrypt\fR\|(3)
.SH HISTORY
.IX Header "HISTORY"
The function \fBSMIME_read_CMS_ex()\fR was added in OpenSSL 3.0.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2008\-2021 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.