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=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
and 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 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 and 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 OpenSSL license (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>.

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