NAME

       SMIME_read_PKCS7_ex, SMIME_read_PKCS7 - parse S/MIME message

SYNOPSIS

        #include <openssl/pkcs7.h>

        PKCS7 *SMIME_read_PKCS7_ex(BIO *bio, BIO **bcont, PKCS7 **p7);
        PKCS7 *SMIME_read_PKCS7(BIO *in, BIO **bcont);

DESCRIPTION

       SMIME_read_PKCS7() parses a message in S/MIME format.

       in is a BIO to read the message from.

       If cleartext signing is used then the content is saved in a memory bio which is written to
       *bcont, otherwise *bcont is set to NULL.

       The parsed PKCS#7 structure is returned or NULL if an error occurred.

       SMIME_read_PKCS7_ex() is similar to SMIME_read_PKCS7() but can optionally supply a
       previously created p7 PKCS#7 object. If p7 is NULL then it is identical to
       SMIME_read_PKCS7().  To create a p7 object use PKCS7_new_ex(3).

NOTES

       If *bcont is not NULL then the message is clear text signed. *bcont can then be passed to
       PKCS7_verify() with the PKCS7_DETACHED flag set.

       Otherwise the type of the returned structure can be determined using
       PKCS7_type_is_enveloped(), etc.

       To support future functionality if bcont is not NULL *bcont should be initialized to NULL.
       For example:

        BIO *cont = NULL;
        PKCS7 *p7;

        p7 = SMIME_read_PKCS7(in, &cont);

BUGS

       The MIME parser used by SMIME_read_PKCS7() is somewhat primitive.  While it will handle
       most S/MIME messages more complex compound formats may not work.

       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.

       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.

RETURN VALUES

       SMIME_read_PKCS7_ex() and SMIME_read_PKCS7() return a valid PKCS7 structure or NULL if an
       error occurred. The error can be obtained from ERR_get_error(3).

SEE ALSO

       ERR_get_error(3), SMIME_read_PKCS7(3), PKCS7_sign(3), PKCS7_verify(3), PKCS7_encrypt(3)
       PKCS7_decrypt(3)

HISTORY

       The function SMIME_read_PKCS7_ex() was added in OpenSSL 3.0.

COPYRIGHT

       Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.

       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>.