NAME

       BIO_new_CMS - CMS streaming filter BIO

SYNOPSIS

        #include <openssl/cms.h>

        BIO *BIO_new_CMS(BIO *out, CMS_ContentInfo *cms);

DESCRIPTION

       BIO_new_CMS() returns a streaming filter BIO chain based on cms. The output of the filter
       is written to out. Any data written to the chain is automatically translated to a BER
       format CMS structure of the appropriate type.

NOTES

       The chain returned by this function behaves like a standard filter BIO. It supports non
       blocking I/O. Content is processed and streamed on the fly and not all held in memory at
       once: so it is possible to encode very large structures.  After all content has been
       written through the chain BIO_flush() must be called to finalise the structure.

       The CMS_STREAM flag must be included in the corresponding flags parameter of the cms
       creation function.

       If an application wishes to write additional data to out BIOs should be removed from the
       chain using BIO_pop() and freed with BIO_free() until out is reached. If no additional
       data needs to be written BIO_free_all() can be called to free up the whole chain.

       Any content written through the filter is used verbatim: no canonical translation is
       performed.

       It is possible to chain multiple BIOs to, for example, create a triple wrapped signed,
       enveloped, signed structure. In this case it is the applications responsibility to set the
       inner content type of any outer CMS_ContentInfo structures.

       Large numbers of small writes through the chain should be avoided as this will produce an
       output consisting of lots of OCTET STRING structures. Prepending a BIO_f_buffer()
       buffering BIO will prevent this.

BUGS

       There is currently no corresponding inverse BIO: i.e. one which can decode a CMS structure
       on the fly.

RETURN VALUES

       BIO_new_CMS() returns a BIO chain when successful or NULL if an error occurred. The error
       can be obtained from ERR_get_error(3).

SEE ALSO

       ERR_get_error(3), CMS_sign(3), CMS_encrypt(3)

HISTORY

       The BIO_new_CMS() function was added in OpenSSL 1.0.0.

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 <https://www.openssl.org/source/license.html>.