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

=pod

=head1 NAME

OSSL_ENCODER_CTX,
OSSL_ENCODER_CTX_new,
OSSL_ENCODER_settable_ctx_params,
OSSL_ENCODER_CTX_set_params,
OSSL_ENCODER_CTX_free,
OSSL_ENCODER_CTX_set_selection,
OSSL_ENCODER_CTX_set_output_type,
OSSL_ENCODER_CTX_set_output_structure,
OSSL_ENCODER_CTX_add_encoder,
OSSL_ENCODER_CTX_add_extra,
OSSL_ENCODER_CTX_get_num_encoders,
OSSL_ENCODER_INSTANCE,
OSSL_ENCODER_INSTANCE_get_encoder,
OSSL_ENCODER_INSTANCE_get_encoder_ctx,
OSSL_ENCODER_INSTANCE_get_output_type,
OSSL_ENCODER_INSTANCE_get_output_structure,
OSSL_ENCODER_CONSTRUCT,
OSSL_ENCODER_CLEANUP,
OSSL_ENCODER_CTX_set_construct,
OSSL_ENCODER_CTX_set_construct_data,
OSSL_ENCODER_CTX_set_cleanup
- Encoder context routines

=head1 SYNOPSIS

 #include <openssl/encoder.h>

 typedef struct ossl_encoder_ctx_st OSSL_ENCODER_CTX;

 OSSL_ENCODER_CTX *OSSL_ENCODER_CTX_new();
 const OSSL_PARAM *OSSL_ENCODER_settable_ctx_params(OSSL_ENCODER *encoder);
 int OSSL_ENCODER_CTX_set_params(OSSL_ENCODER_CTX *ctx,
                                 const OSSL_PARAM params[]);
 void OSSL_ENCODER_CTX_free(OSSL_ENCODER_CTX *ctx);

 int OSSL_ENCODER_CTX_set_selection(OSSL_ENCODER_CTX *ctx, int selection);
 int OSSL_ENCODER_CTX_set_output_type(OSSL_ENCODER_CTX *ctx,
                                      const char *output_type);
 int OSSL_ENCODER_CTX_set_output_structure(OSSL_ENCODER_CTX *ctx,
                                           const char *output_structure);

 int OSSL_ENCODER_CTX_add_encoder(OSSL_ENCODER_CTX *ctx, OSSL_ENCODER *encoder);
 int OSSL_ENCODER_CTX_add_extra(OSSL_ENCODER_CTX *ctx,
                                OSSL_LIB_CTX *libctx, const char *propq);
 int OSSL_ENCODER_CTX_get_num_encoders(OSSL_ENCODER_CTX *ctx);

 typedef struct ossl_encoder_instance_st OSSL_ENCODER_INSTANCE;
 OSSL_ENCODER *
 OSSL_ENCODER_INSTANCE_get_encoder(OSSL_ENCODER_INSTANCE *encoder_inst);
 void *
 OSSL_ENCODER_INSTANCE_get_encoder_ctx(OSSL_ENCODER_INSTANCE *encoder_inst);
 const char *
 OSSL_ENCODER_INSTANCE_get_output_type(OSSL_ENCODER_INSTANCE *encoder_inst);
 const char *
 OSSL_ENCODER_INSTANCE_get_output_structure(OSSL_ENCODER_INSTANCE *encoder_inst);

 typedef const void *OSSL_ENCODER_CONSTRUCT(OSSL_ENCODER_INSTANCE *encoder_inst,
                                            void *construct_data);
 typedef void OSSL_ENCODER_CLEANUP(void *construct_data);

 int OSSL_ENCODER_CTX_set_construct(OSSL_ENCODER_CTX *ctx,
                                    OSSL_ENCODER_CONSTRUCT *construct);
 int OSSL_ENCODER_CTX_set_construct_data(OSSL_ENCODER_CTX *ctx,
                                         void *construct_data);
 int OSSL_ENCODER_CTX_set_cleanup(OSSL_ENCODER_CTX *ctx,
                                  OSSL_ENCODER_CLEANUP *cleanup);

=head1 DESCRIPTION

Encoding an input object to the desired encoding may be done with a chain of
encoder implementations, which means that the output from one encoder may be
the input for the next in the chain.  The B<OSSL_ENCODER_CTX> holds all the
data about these encoders.  This allows having generic format encoders such
as DER to PEM, as well as more specialized encoders like RSA to DER.

The final output type must be given, and a chain of encoders must end with
an implementation that produces that output type.

At the beginning of the encoding process, a constructor provided by the
caller is called to ensure that there is an appropriate provider-side object
to start with.
The constructor is set with OSSL_ENCODER_CTX_set_construct().

B<OSSL_ENCODER_INSTANCE> is an opaque structure that contains data about the
encoder that is going to be used, and that may be useful for the
constructor.  There are some functions to extract data from this type,
described in L</Constructor> below.

=head2 Functions

OSSL_ENCODER_CTX_new() creates a B<OSSL_ENCODER_CTX>.

OSSL_ENCODER_settable_ctx_params() returns an L<OSSL_PARAM(3)>
array of parameter descriptors.

OSSL_ENCODER_CTX_set_params() attempts to set parameters specified
with an L<OSSL_PARAM(3)> array I<params>.  Parameters that the
implementation doesn't recognise should be ignored.

OSSL_ENCODER_CTX_free() frees the given context I<ctx>.

OSSL_ENCODER_CTX_add_encoder() populates the B<OSSL_ENCODER_CTX>
I<ctx> with a encoder, to be used to encode an input object.

OSSL_ENCODER_CTX_add_extra() finds encoders that further encodes output
from already added encoders, and adds them as well.  This is used to build
encoder chains.

OSSL_ENCODER_CTX_set_output_type() sets the ending output type.  This must
be specified, and determines if a complete encoder chain is available.

OSSL_ENCODER_CTX_set_output_structure() sets the desired output structure.
This may be used to determines what encoder implementations may be used.
Depending on the type of object being encoded, the output structure may
not be relevant.

OSSL_ENCODER_CTX_get_num_encoders() gets the number of encoders currently
added to the context I<ctx>.

OSSL_ENCODER_CTX_set_construct() sets the constructor I<construct>.

OSSL_ENCODER_CTX_set_construct_data() sets the constructor data that is
passed to the constructor every time it's called.

OSSL_ENCODER_CTX_set_cleanup() sets the constructor data I<cleanup>
function.  This is called by L<OSSL_ENCODER_CTX_free(3)>.

=head2 Constructor

A B<OSSL_ENCODER_CONSTRUCT> gets the following arguments:

=over 4

=item I<encoder_inst>

The B<OSSL_ENCODER_INSTANCE> for the encoder from which the constructor gets
its data.

=item I<construct_data>

The pointer that was set with OSSL_ENCODE_CTX_set_construct_data().

=back

The constructor is expected to return a valid (non-NULL) pointer to a
provider-native object that can be used as first input of an encoding chain,
or NULL to indicate that an error has occurred.

These utility functions may be used by a constructor:

OSSL_ENCODER_INSTANCE_get_encoder() can be used to get the encoder
implementation of the encoder instance I<encoder_inst>.

OSSL_ENCODER_INSTANCE_get_encoder_ctx() can be used to get the encoder
implementation's provider context of the encoder instance I<encoder_inst>.

OSSL_ENCODER_INSTANCE_get_output_type() can be used to get the output type
for the encoder implementation of the encoder instance I<encoder_inst>.
This will never be NULL.

OSSL_ENCODER_INSTANCE_get_output_structure() can be used to get the output
structure for the encoder implementation of the encoder instance
I<encoder_inst>.
This may be NULL.

=head1 RETURN VALUES

OSSL_ENCODER_CTX_new() returns a pointer to a B<OSSL_ENCODER_CTX>, or NULL
if the context structure couldn't be allocated.

OSSL_ENCODER_settable_ctx_params() returns an L<OSSL_PARAM(3)> array, or
NULL if none is available.

OSSL_ENCODER_CTX_set_params() returns 1 if all recognised parameters were
valid, or 0 if one of them was invalid or caused some other failure in the
implementation.

OSSL_ENCODER_CTX_add_encoder(), OSSL_ENCODER_CTX_add_extra(),
OSSL_ENCODER_CTX_set_construct(), OSSL_ENCODER_CTX_set_construct_data() and
OSSL_ENCODER_CTX_set_cleanup() return 1 on success, or 0 on failure.

OSSL_ENCODER_CTX_get_num_encoders() returns the current number of encoders.
It returns 0 if I<ctx> is NULL.

OSSL_ENCODER_INSTANCE_get_encoder() returns an B<OSSL_ENCODER> pointer on
success, or NULL on failure.

OSSL_ENCODER_INSTANCE_get_encoder_ctx() returns a provider context pointer on
success, or NULL on failure.

OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the
input type, if relevant.  NULL is a valid returned value.

OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the
output type.

OSSL_ENCODER_INSTANCE_get_output_structure() returns a string with the name
of the output structure.

=head1 SEE ALSO

L<provider(7)>, L<OSSL_ENCODER(3)>

=head1 HISTORY

The functions described here were added in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2019-2022 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
L<https://www.openssl.org/source/license.html>.

=cut
Commit	Line	Data
ece9304c RL	1	=pod
	2
	3	=head1 NAME
	4
	5	OSSL_ENCODER_CTX,
	6	OSSL_ENCODER_CTX_new,
ece9304c RL	7	OSSL_ENCODER_settable_ctx_params,
ece9304c RL	8	OSSL_ENCODER_CTX_set_params,
b8975c68	9	OSSL_ENCODER_CTX_free,
b8975c68	10	OSSL_ENCODER_CTX_set_selection,
8a98a507 RL	11	OSSL_ENCODER_CTX_set_output_type,
8a98a507 RL	12	OSSL_ENCODER_CTX_set_output_structure,
b8975c68 RL	13	OSSL_ENCODER_CTX_add_encoder,
	14	OSSL_ENCODER_CTX_add_extra,
	15	OSSL_ENCODER_CTX_get_num_encoders,
	16	OSSL_ENCODER_INSTANCE,
	17	OSSL_ENCODER_INSTANCE_get_encoder,
	18	OSSL_ENCODER_INSTANCE_get_encoder_ctx,
b8975c68	19	OSSL_ENCODER_INSTANCE_get_output_type,
8a98a507	20	OSSL_ENCODER_INSTANCE_get_output_structure,
b8975c68 RL	21	OSSL_ENCODER_CONSTRUCT,
	22	OSSL_ENCODER_CLEANUP,
	23	OSSL_ENCODER_CTX_set_construct,
	24	OSSL_ENCODER_CTX_set_construct_data,
	25	OSSL_ENCODER_CTX_set_cleanup
ece9304c RL	26	- Encoder context routines
	27
	28	=head1 SYNOPSIS
	29
	30	#include <openssl/encoder.h>
	31
	32	typedef struct ossl_encoder_ctx_st OSSL_ENCODER_CTX;
	33
b8975c68	34	OSSL_ENCODER_CTX *OSSL_ENCODER_CTX_new();
ece9304c RL	35	const OSSL_PARAM OSSL_ENCODER_settable_ctx_params(OSSL_ENCODER encoder);
	36	int OSSL_ENCODER_CTX_set_params(OSSL_ENCODER_CTX *ctx,
	37	const OSSL_PARAM params[]);
	38	void OSSL_ENCODER_CTX_free(OSSL_ENCODER_CTX *ctx);
	39
8a98a507	40	int OSSL_ENCODER_CTX_set_selection(OSSL_ENCODER_CTX *ctx, int selection);
b8975c68 RL	41	int OSSL_ENCODER_CTX_set_output_type(OSSL_ENCODER_CTX *ctx,
b8975c68 RL	42	const char *output_type);
8a98a507 RL	43	int OSSL_ENCODER_CTX_set_output_structure(OSSL_ENCODER_CTX *ctx,
8a98a507 RL	44	const char *output_structure);
b8975c68 RL	45
	46	int OSSL_ENCODER_CTX_add_encoder(OSSL_ENCODER_CTX ctx, OSSL_ENCODER encoder);
	47	int OSSL_ENCODER_CTX_add_extra(OSSL_ENCODER_CTX *ctx,
b4250010	48	OSSL_LIB_CTX libctx, const char propq);
b8975c68 RL	49	int OSSL_ENCODER_CTX_get_num_encoders(OSSL_ENCODER_CTX *ctx);
	50
	51	typedef struct ossl_encoder_instance_st OSSL_ENCODER_INSTANCE;
	52	OSSL_ENCODER *
	53	OSSL_ENCODER_INSTANCE_get_encoder(OSSL_ENCODER_INSTANCE *encoder_inst);
	54	void *
	55	OSSL_ENCODER_INSTANCE_get_encoder_ctx(OSSL_ENCODER_INSTANCE *encoder_inst);
	56	const char *
b8975c68	57	OSSL_ENCODER_INSTANCE_get_output_type(OSSL_ENCODER_INSTANCE *encoder_inst);
8a98a507 RL	58	const char *
8a98a507 RL	59	OSSL_ENCODER_INSTANCE_get_output_structure(OSSL_ENCODER_INSTANCE *encoder_inst);
b8975c68 RL	60
	61	typedef const void OSSL_ENCODER_CONSTRUCT(OSSL_ENCODER_INSTANCE encoder_inst,
	62	void *construct_data);
	63	typedef void OSSL_ENCODER_CLEANUP(void *construct_data);
	64
	65	int OSSL_ENCODER_CTX_set_construct(OSSL_ENCODER_CTX *ctx,
	66	OSSL_ENCODER_CONSTRUCT *construct);
	67	int OSSL_ENCODER_CTX_set_construct_data(OSSL_ENCODER_CTX *ctx,
	68	void *construct_data);
	69	int OSSL_ENCODER_CTX_set_cleanup(OSSL_ENCODER_CTX *ctx,
	70	OSSL_ENCODER_CLEANUP *cleanup);
	71
ece9304c RL	72	=head1 DESCRIPTION
ece9304c RL	73
b8975c68 RL	74	Encoding an input object to the desired encoding may be done with a chain of
	75	encoder implementations, which means that the output from one encoder may be
	76	the input for the next in the chain. The B<OSSL_ENCODER_CTX> holds all the
	77	data about these encoders. This allows having generic format encoders such
	78	as DER to PEM, as well as more specialized encoders like RSA to DER.
ece9304c	79
b8975c68 RL	80	The final output type must be given, and a chain of encoders must end with
b8975c68 RL	81	an implementation that produces that output type.
ece9304c	82
e304aa87	83	At the beginning of the encoding process, a constructor provided by the
b8975c68 RL	84	caller is called to ensure that there is an appropriate provider-side object
	85	to start with.
	86	The constructor is set with OSSL_ENCODER_CTX_set_construct().
ece9304c	87
b8975c68 RL	88	B<OSSL_ENCODER_INSTANCE> is an opaque structure that contains data about the
	89	encoder that is going to be used, and that may be useful for the
	90	constructor. There are some functions to extract data from this type,
	91	described in L</Constructor> below.
ece9304c	92
b8975c68	93	=head2 Functions
ece9304c	94
b8975c68	95	OSSL_ENCODER_CTX_new() creates a B<OSSL_ENCODER_CTX>.
ece9304c RL	96
	97	OSSL_ENCODER_settable_ctx_params() returns an L<OSSL_PARAM(3)>
	98	array of parameter descriptors.
	99
	100	OSSL_ENCODER_CTX_set_params() attempts to set parameters specified
	101	with an L<OSSL_PARAM(3)> array I<params>. Parameters that the
	102	implementation doesn't recognise should be ignored.
	103
	104	OSSL_ENCODER_CTX_free() frees the given context I<ctx>.
	105
b8975c68 RL	106	OSSL_ENCODER_CTX_add_encoder() populates the B<OSSL_ENCODER_CTX>
	107	I<ctx> with a encoder, to be used to encode an input object.
	108
	109	OSSL_ENCODER_CTX_add_extra() finds encoders that further encodes output
	110	from already added encoders, and adds them as well. This is used to build
	111	encoder chains.
	112
	113	OSSL_ENCODER_CTX_set_output_type() sets the ending output type. This must
	114	be specified, and determines if a complete encoder chain is available.
	115
8a98a507 RL	116	OSSL_ENCODER_CTX_set_output_structure() sets the desired output structure.
	117	This may be used to determines what encoder implementations may be used.
	118	Depending on the type of object being encoded, the output structure may
	119	not be relevant.
	120
	121	OSSL_ENCODER_CTX_get_num_encoders() gets the number of encoders currently
	122	added to the context I<ctx>.
b8975c68 RL	123
	124	OSSL_ENCODER_CTX_set_construct() sets the constructor I<construct>.
	125
	126	OSSL_ENCODER_CTX_set_construct_data() sets the constructor data that is
	127	passed to the constructor every time it's called.
	128
	129	OSSL_ENCODER_CTX_set_cleanup() sets the constructor data I<cleanup>
	130	function. This is called by L<OSSL_ENCODER_CTX_free(3)>.
	131
	132	=head2 Constructor
	133
	134	A B<OSSL_ENCODER_CONSTRUCT> gets the following arguments:
	135
	136	=over 4
	137
	138	=item I<encoder_inst>
	139
	140	The B<OSSL_ENCODER_INSTANCE> for the encoder from which the constructor gets
	141	its data.
	142
	143	=item I<construct_data>
	144
	145	The pointer that was set with OSSL_ENCODE_CTX_set_construct_data().
	146
	147	=back
	148
	149	The constructor is expected to return a valid (non-NULL) pointer to a
	150	provider-native object that can be used as first input of an encoding chain,
e304aa87	151	or NULL to indicate that an error has occurred.
b8975c68 RL	152
	153	These utility functions may be used by a constructor:
	154
8a98a507 RL	155	OSSL_ENCODER_INSTANCE_get_encoder() can be used to get the encoder
	156	implementation of the encoder instance I<encoder_inst>.
	157
	158	OSSL_ENCODER_INSTANCE_get_encoder_ctx() can be used to get the encoder
	159	implementation's provider context of the encoder instance I<encoder_inst>.
b8975c68	160
8a98a507 RL	161	OSSL_ENCODER_INSTANCE_get_output_type() can be used to get the output type
	162	for the encoder implementation of the encoder instance I<encoder_inst>.
	163	This will never be NULL.
	164
	165	OSSL_ENCODER_INSTANCE_get_output_structure() can be used to get the output
	166	structure for the encoder implementation of the encoder instance
	167	I<encoder_inst>.
	168	This may be NULL.
b8975c68	169
ece9304c RL	170	=head1 RETURN VALUES
ece9304c RL	171
b8975c68 RL	172	OSSL_ENCODER_CTX_new() returns a pointer to a B<OSSL_ENCODER_CTX>, or NULL
b8975c68 RL	173	if the context structure couldn't be allocated.
ece9304c	174
b8975c68 RL	175	OSSL_ENCODER_settable_ctx_params() returns an L<OSSL_PARAM(3)> array, or
b8975c68 RL	176	NULL if none is available.
ece9304c	177
b8975c68 RL	178	OSSL_ENCODER_CTX_set_params() returns 1 if all recognised parameters were
	179	valid, or 0 if one of them was invalid or caused some other failure in the
	180	implementation.
	181
8a98a507 RL	182	OSSL_ENCODER_CTX_add_encoder(), OSSL_ENCODER_CTX_add_extra(),
	183	OSSL_ENCODER_CTX_set_construct(), OSSL_ENCODER_CTX_set_construct_data() and
	184	OSSL_ENCODER_CTX_set_cleanup() return 1 on success, or 0 on failure.
b8975c68	185
8a98a507 RL	186	OSSL_ENCODER_CTX_get_num_encoders() returns the current number of encoders.
8a98a507 RL	187	It returns 0 if I<ctx> is NULL.
b8975c68	188
8a98a507	189	OSSL_ENCODER_INSTANCE_get_encoder() returns an B<OSSL_ENCODER> pointer on
b8975c68 RL	190	success, or NULL on failure.
b8975c68 RL	191
8a98a507	192	OSSL_ENCODER_INSTANCE_get_encoder_ctx() returns a provider context pointer on
b8975c68 RL	193	success, or NULL on failure.
b8975c68 RL	194
8a98a507	195	OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the
b8975c68	196	input type, if relevant. NULL is a valid returned value.
ece9304c	197
8a98a507	198	OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the
b8975c68	199	output type.
ece9304c	200
8a98a507 RL	201	OSSL_ENCODER_INSTANCE_get_output_structure() returns a string with the name
	202	of the output structure.
	203
ece9304c RL	204	=head1 SEE ALSO
	205
	206	L<provider(7)>, L<OSSL_ENCODER(3)>
	207
	208	=head1 HISTORY
	209
	210	The functions described here were added in OpenSSL 3.0.
	211
	212	=head1 COPYRIGHT
	213
fecb3aae	214	Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
ece9304c RL	215
	216	Licensed under the Apache License 2.0 (the "License"). You may not use
	217	this file except in compliance with the License. You can obtain a copy
	218	in the file LICENSE in the source distribution or at
	219	L<https://www.openssl.org/source/license.html>.
	220
	221	=cut