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.\" ========================================================================
.\"
.IX Title "SMIME_READ_PKCS7 3ssl"
.TH SMIME_READ_PKCS7 3ssl 2024-10-23 3.4.0 OpenSSL
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
SMIME_read_PKCS7_ex, SMIME_read_PKCS7 \- parse S/MIME message
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/pkcs7.h>
\&
\& PKCS7 *SMIME_read_PKCS7_ex(BIO *bio, BIO **bcont, PKCS7 **p7);
\& PKCS7 *SMIME_read_PKCS7(BIO *in, BIO **bcont);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
\&\fBSMIME_read_PKCS7()\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 \fBNULL\fR.
.PP
The parsed PKCS#7 structure is returned or \fBNULL\fR if an
error occurred.
.PP
\&\fBSMIME_read_PKCS7_ex()\fR is similar to \fBSMIME_read_PKCS7()\fR but can optionally supply
a previously created \fIp7\fR PKCS#7 object. If \fIp7\fR is NULL then it is identical
to \fBSMIME_read_PKCS7()\fR.
To create a \fIp7\fR object use \fBPKCS7_new_ex\fR\|(3).
.SH NOTES
.IX Header "NOTES"
If \fB*bcont\fR is not \fBNULL\fR then the message is clear text
signed. \fB*bcont\fR can then be passed to \fBPKCS7_verify()\fR with
the \fBPKCS7_DETACHED\fR flag set.
.PP
Otherwise the type of the returned structure can be determined
using \fBPKCS7_type_is_enveloped()\fR, etc.
.PP
To support future functionality if \fBbcont\fR is not \fBNULL\fR
\&\fB*bcont\fR should be initialized to \fBNULL\fR. For example:
.PP
.Vb 2
\& BIO *cont = NULL;
\& PKCS7 *p7;
\&
\& p7 = SMIME_read_PKCS7(in, &cont);
.Ve
.SH BUGS
.IX Header "BUGS"
The MIME parser used by \fBSMIME_read_PKCS7()\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 PKCS7 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_PKCS7_ex()\fR and \fBSMIME_read_PKCS7()\fR return a valid \fBPKCS7\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),
\&\fBSMIME_read_PKCS7\fR\|(3), \fBPKCS7_sign\fR\|(3),
\&\fBPKCS7_verify\fR\|(3), \fBPKCS7_encrypt\fR\|(3)
\&\fBPKCS7_decrypt\fR\|(3)
.SH HISTORY
.IX Header "HISTORY"
The function \fBSMIME_read_PKCS7_ex()\fR was added in OpenSSL 3.0.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2002\-2020 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>.