[thirdparty/openssl.git] / doc / man3 / BIO_new_CMS.pod

=pod

=head1 NAME

BIO_new_CMS - CMS streaming filter BIO

=head1 SYNOPSIS

 #include <openssl/cms.h>

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

=head1 DESCRIPTION

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

=head1 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 B<CMS_STREAM> flag must be included in the corresponding B<flags>
parameter of the B<cms> creation function.

If an application wishes to write additional data to B<out> BIOs should be
removed from the chain using BIO_pop() and freed with BIO_free() until B<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.

=head1 BUGS

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

=head1 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).

=head1 SEE ALSO

L<ERR_get_error(3)>, L<CMS_sign(3)>,
L<CMS_encrypt(3)>

=head1 HISTORY

BIO_new_CMS() was added to OpenSSL 1.0.0

=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>.

=cut
Commit	Line	Data
287df2fe DSH	1	=pod
	2
	3	=head1 NAME
	4
1bc74519	5	BIO_new_CMS - CMS streaming filter BIO
287df2fe DSH	6
	7	=head1 SYNOPSIS
	8
	9	#include <openssl/cms.h>
	10
	11	BIO BIO_new_CMS(BIO out, CMS_ContentInfo *cms);
	12
	13	=head1 DESCRIPTION
	14
	15	BIO_new_CMS() returns a streaming filter BIO chain based on B<cms>. The output
38d3a738 DSH	16	of the filter is written to B<out>. Any data written to the chain is
38d3a738 DSH	17	automatically translated to a BER format CMS structure of the appropriate type.
287df2fe DSH	18
	19	=head1 NOTES
	20
38d3a738 DSH	21	The chain returned by this function behaves like a standard filter BIO. It
38d3a738 DSH	22	supports non blocking I/O. Content is processed and streamed on the fly and not
287df2fe	23	all held in memory at once: so it is possible to encode very large structures.
38d3a738	24	After all content has been written through the chain BIO_flush() must be called
287df2fe DSH	25	to finalise the structure.
	26
	27	The B<CMS_STREAM> flag must be included in the corresponding B<flags>
	28	parameter of the B<cms> creation function.
	29
38d3a738 DSH	30	If an application wishes to write additional data to B<out> BIOs should be
	31	removed from the chain using BIO_pop() and freed with BIO_free() until B<out>
	32	is reached. If no additional data needs to be written BIO_free_all() can be
	33	called to free up the whole chain.
287df2fe	34
38d3a738	35	Any content written through the filter is used verbatim: no canonical
287df2fe DSH	36	translation is performed.
287df2fe DSH	37
38d3a738 DSH	38	It is possible to chain multiple BIOs to, for example, create a triple wrapped
38d3a738 DSH	39	signed, enveloped, signed structure. In this case it is the applications
287df2fe DSH	40	responsibility to set the inner content type of any outer CMS_ContentInfo
	41	structures.
	42
	43	Large numbers of small writes through the chain should be avoided as this will
	44	produce an output consisting of lots of OCTET STRING structures. Prepending
	45	a BIO_f_buffer() buffering BIO will prevent this.
	46
	47	=head1 BUGS
	48
	49	There is currently no corresponding inverse BIO: i.e. one which can decode
	50	a CMS structure on the fly.
	51
	52	=head1 RETURN VALUES
	53
	54	BIO_new_CMS() returns a BIO chain when successful or NULL if an error
	55	occurred. The error can be obtained from ERR_get_error(3).
	56
	57	=head1 SEE ALSO
	58
9b86974e RS	59	L<ERR_get_error(3)>, L<CMS_sign(3)>,
9b86974e RS	60	L<CMS_encrypt(3)>
287df2fe DSH	61
	62	=head1 HISTORY
	63
fb552ac6	64	BIO_new_CMS() was added to OpenSSL 1.0.0
287df2fe	65
e2f92610 RS	66	=head1 COPYRIGHT
	67
	68	Copyright 2008-2016 The OpenSSL Project Authors. All Rights Reserved.
	69
	70	Licensed under the OpenSSL license (the "License"). You may not use
	71	this file except in compliance with the License. You can obtain a copy
	72	in the file LICENSE in the source distribution or at
	73	L<https://www.openssl.org/source/license.html>.
	74
	75	=cut