=pod

=head1 NAME

CMS_get0_type, CMS_set1_eContentType, CMS_get0_eContentType, CMS_get0_content - get and set CMS content types and content

=head1 SYNOPSIS

 #include <openssl/cms.h>

 const ASN1_OBJECT *CMS_get0_type(const CMS_ContentInfo *cms);
 int CMS_set1_eContentType(CMS_ContentInfo *cms, const ASN1_OBJECT *oid);
 const ASN1_OBJECT *CMS_get0_eContentType(CMS_ContentInfo *cms);
 ASN1_OCTET_STRING **CMS_get0_content(CMS_ContentInfo *cms);

=head1 DESCRIPTION

CMS_get0_type() returns the content type of a CMS_ContentInfo structure as
an ASN1_OBJECT pointer. An application can then decide how to process the
CMS_ContentInfo structure based on this value.

CMS_set1_eContentType() sets the embedded content type of a CMS_ContentInfo
structure. It should be called with CMS functions (such as L<CMS_sign>, L<CMS_encrypt>)
with the B<CMS_PARTIAL>
flag and B<before> the structure is finalised, otherwise the results are
undefined.

ASN1_OBJECT *CMS_get0_eContentType() returns a pointer to the embedded
content type.

CMS_get0_content() returns a pointer to the B<ASN1_OCTET_STRING> pointer
containing the embedded content.

=head1 NOTES

As the B<0> implies CMS_get0_type(), CMS_get0_eContentType() and
CMS_get0_content() return internal pointers which should B<not> be freed up.
CMS_set1_eContentType() copies the supplied OID and it B<should> be freed up
after use.

The B<ASN1_OBJECT> values returned can be converted to an integer B<NID> value
using OBJ_obj2nid(). For the currently supported content types the following
values are returned:

 NID_pkcs7_data
 NID_pkcs7_signed
 NID_pkcs7_digest
 NID_id_smime_ct_compressedData:
 NID_pkcs7_encrypted
 NID_pkcs7_enveloped

The return value of CMS_get0_content() is a pointer to the B<ASN1_OCTET_STRING>
content pointer. That means that for example:

 ASN1_OCTET_STRING **pconf = CMS_get0_content(cms);

B<*pconf> could be NULL if there is no embedded content. Applications can
access, modify or create the embedded content in a B<CMS_ContentInfo> structure
using this function. Applications usually will not need to modify the
embedded content as it is normally set by higher level functions.

=head1 RETURN VALUES

CMS_get0_type() and CMS_get0_eContentType() return an ASN1_OBJECT structure.

CMS_set1_eContentType() returns 1 for success or 0 if an error occurred.  The
error can be obtained from ERR_get_error(3).

=head1 SEE ALSO

L<ERR_get_error(3)>

=head1 COPYRIGHT

Copyright 2008-2016 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
L<https://www.openssl.org/source/license.html>.

=cut
