NAME

       SMIME_read_ASN1_ex, SMIME_read_ASN1 - parse S/MIME message

SYNOPSIS

        #include <openssl/asn1.h>

        ASN1_VALUE *SMIME_read_ASN1_ex(BIO *in, int flags, BIO **bcont,
                                       const ASN1_ITEM *it, ASN1_VALUE **x,
                                       OSSL_LIB_CTX *libctx, const char *propq);
        ASN1_VALUE *SMIME_read_ASN1(BIO *in, BIO **bcont, const ASN1_ITEM *it);

DESCRIPTION

       SMIME_read_ASN1_ex() parses a message in S/MIME format.

       in is a BIO to read the message from.  If the flags argument contains CMS_BINARY then the
       input is assumed to be in binary format and is not translated to canonical form.  If in
       addition SMIME_ASCIICRLF is set then the binary input is assumed to be followed by CR and
       LF characters, else only by an LF character.  x can be used to optionally supply a
       previously created it ASN1_VALUE object (such as CMS_ContentInfo or PKCS7), it can be set
       to NULL. Valid values that can be used by ASN.1 structure it are ASN1_ITEM_rptr(PKCS7) or
       ASN1_ITEM_rptr(CMS_ContentInfo). Any algorithm fetches that occur during the operation
       will use the OSSL_LIB_CTX supplied in the libctx parameter, and use the property query
       string propq See "ALGORITHM FETCHING" in crypto(7) for further details about algorithm
       fetching.

       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 ASN1_VALUE structure is returned or NULL if an error occurred.

       SMIME_read_ASN1() is similar to SMIME_read_ASN1_ex() but sets the value of x to NULL and
       the value of flags to 0.

NOTES

       The higher level functions SMIME_read_CMS_ex(3) and SMIME_read_PKCS7_ex(3) should be used
       instead of SMIME_read_ASN1_ex().

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

BUGS

       The MIME parser used by SMIME_read_ASN1_ex() is somewhat primitive. While it will handle
       most S/MIME messages more complex compound formats may not work.

       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_ASN1_ex() and SMIME_read_ASN1() return a valid ASN1_VALUE 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_CMS_ex(3), SMIME_read_PKCS7_ex(3), SMIME_write_ASN1(3),
       SMIME_write_ASN1_ex(3)

HISTORY

       The function SMIME_read_ASN1_ex() was added in OpenSSL 3.0.

COPYRIGHT

       Copyright 2020-2021 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>.