OSSL_DECODER(3) - NetBSD Manual Pages

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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


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.  If the argument is
       NULL, nothing is done.

       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 2020-2024 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>.



3.0.15                            2024-09-03                   OSSL_DECODER(3)