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

       BIO_new_CMS() was added to OpenSSL 1.0.0