Updated: 2022/Sep/29
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OSSL_DECODER(3) OpenSSL OSSL_DECODER(3)
NAME
OSSL_DECODER, OSSL_DECODER_fetch, OSSL_DECODER_up_ref,
OSSL_DECODER_free, OSSL_DECODER_get0_provider,
OSSL_DECODER_get0_properties, OSSL_DECODER_is_a,
OSSL_DECODER_get0_name, OSSL_DECODER_get0_description,
OSSL_DECODER_do_all_provided, OSSL_DECODER_names_do_all,
OSSL_DECODER_gettable_params, OSSL_DECODER_get_params - Decoder method
routines
LIBRARY
libcrypto, -lcrypto
SYNOPSIS
#include <openssl/decoder.h>
typedef struct ossl_decoder_st OSSL_DECODER;
OSSL_DECODER *OSSL_DECODER_fetch(OSSL_LIB_CTX *ctx, const char *name,
const char *properties);
int OSSL_DECODER_up_ref(OSSL_DECODER *decoder);
void OSSL_DECODER_free(OSSL_DECODER *decoder);
const OSSL_PROVIDER *OSSL_DECODER_get0_provider(const OSSL_DECODER *decoder);
const char *OSSL_DECODER_get0_properties(const OSSL_DECODER *decoder);
int OSSL_DECODER_is_a(const OSSL_DECODER *decoder, const char *name);
const char *OSSL_DECODER_get0_name(const OSSL_DECODER *decoder);
const char *OSSL_DECODER_get0_description(const OSSL_DECODER *decoder);
void OSSL_DECODER_do_all_provided(OSSL_LIB_CTX *libctx,
void (*fn)(OSSL_DECODER *decoder, void *arg),
void *arg);
int OSSL_DECODER_names_do_all(const OSSL_DECODER *decoder,
void (*fn)(const char *name, void *data),
void *data);
const OSSL_PARAM *OSSL_DECODER_gettable_params(OSSL_DECODER *decoder);
int OSSL_DECODER_get_params(OSSL_DECODER_CTX *ctx, const OSSL_PARAM params[]);
DESCRIPTION
OSSL_DECODER is a method for decoders, which know how to decode encoded
data into an object of some type that the rest of OpenSSL knows how to
handle.
OSSL_DECODER_fetch() looks for an algorithm within the provider that
has been loaded into the OSSL_LIB_CTX given by ctx, having the name
given by name and the properties given by properties. The name
determines what type of object the fetched decoder method is expected
to be able to decode, and the properties are used to determine the
expected output type. For known properties and the values they may
have, please have a look in "Names and properties" in
provider-encoder(7).
OSSL_DECODER_up_ref() increments the reference count for the given
decoder.
OSSL_DECODER_free() decrements the reference count for the given
decoder, and when the count reaches zero, frees it.
OSSL_DECODER_get0_provider() returns the provider of the given decoder.
OSSL_DECODER_get0_properties() returns the property definition
associated with the given decoder.
OSSL_DECODER_is_a() checks if decoder is an implementation of an
algorithm that's identifiable with name.
OSSL_DECODER_get0_name() returns the name used to fetch the given
decoder.
OSSL_DECODER_get0_description() returns a description of the decoder,
meant for display and human consumption. The description is at the
discretion of the decoder implementation.
OSSL_DECODER_names_do_all() traverses all names for the given decoder,
and calls fn with each name and data as arguments.
OSSL_DECODER_do_all_provided() traverses all decoder implementations by
all activated providers in the library context libctx, and for each of
the implementations, calls fn with the implementation method and arg as
arguments.
OSSL_DECODER_gettable_params() returns an OSSL_PARAM(3) array of
parameter descriptors.
OSSL_DECODER_get_params() attempts to get parameters specified with an
OSSL_PARAM(3) array params. Parameters that the implementation doesn't
recognise should be ignored.
RETURN VALUES
OSSL_DECODER_fetch() returns a pointer to an OSSL_DECODER object, or
NULL on error.
OSSL_DECODER_up_ref() returns 1 on success, or 0 on error.
OSSL_DECODER_free() doesn't return any value.
OSSL_DECODER_get0_provider() returns a pointer to a provider object, or
NULL on error.
OSSL_DECODER_get0_properties() returns a pointer to a property
definition string, or NULL on error.
OSSL_DECODER_is_a() returns 1 if decoder was identifiable, otherwise 0.
OSSL_DECODER_get0_name() returns the algorithm name from the provided
implementation for the given decoder. Note that the decoder may have
multiple synonyms associated with it. In this case the first name from
the algorithm definition is returned. Ownership of the returned string
is retained by the decoder object and should not be freed by the
caller.
OSSL_DECODER_get0_description() returns a pointer to a description, or
NULL if there isn't one.
OSSL_DECODER_names_do_all() returns 1 if the callback was called for
all names. A return value of 0 means that the callback was not called
for any names.
NOTES
OSSL_DECODER_fetch() may be called implicitly by other fetching
functions, using the same library context and properties. Any other
API that uses keys will typically do this.
EXAMPLES
To list all decoders in a provider to a bio_out:
static void collect_decoders(OSSL_DECODER *decoder, void *stack)
{
STACK_OF(OSSL_DECODER) *decoder_stack = stack;
sk_OSSL_DECODER_push(decoder_stack, decoder);
OSSL_DECODER_up_ref(decoder);
}
void print_name(const char *name, void *vdata)
{
BIO *bio = vdata;
BIO_printf(bio, "%s ", name);
}
STACK_OF(OSSL_DECODER) *decoders;
int i;
decoders = sk_OSSL_DECODER_new_null();
BIO_printf(bio_out, "DECODERs provided by %s:\n", provider);
OSSL_DECODER_do_all_provided(NULL, collect_decoders,
decoders);
for (i = 0; i < sk_OSSL_DECODER_num(decoders); i++) {
OSSL_DECODER *decoder = sk_OSSL_DECODER_value(decoders, i);
if (strcmp(OSSL_PROVIDER_get0_name(OSSL_DECODER_get0_provider(decoder)),
provider) != 0)
continue;
if (OSSL_DECODER_names_do_all(decoder, print_name, bio_out))
BIO_printf(bio_out, "\n");
}
sk_OSSL_DECODER_pop_free(decoders, OSSL_DECODER_free);
SEE ALSO
provider(7), OSSL_DECODER_CTX(3), OSSL_DECODER_from_bio(3),
OSSL_DECODER_CTX_new_for_pkey(3), OSSL_LIB_CTX(3)
HISTORY
The functions described here were added in OpenSSL 3.0.
COPYRIGHT
Copyright 2020-2023 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>.
3.0.12 2023-10-25 OSSL_DECODER(3)