BIO_new_CMS - CMS streaming filter BIO
BIO *BIO_new_CMS(BIO *out, CMS_ContentInfo *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
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
must be called to finalise the structure.
flag must be included in the corresponding flags
parameter of the cms
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()
is reached. If no additional data needs to be written
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
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
buffering BIO will prevent this.
There is currently no corresponding inverse BIO: i.e. one which can decode a CMS
structure on the fly.
returns a BIO chain when successful or NULL if an error
occurred. The error can be obtained from ERR_get_error(3)
was added to OpenSSL 1.0.0