OSSL_INDICATOR_set_callback, OSSL_INDICATOR_get_callback - specify a callback for FIPS indicators

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       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>.

3.5.0                                              2025-06-04                  OSSL_INDICATOR_SET_CALLBACK(3SSL)

OSSL_INDICATOR_set_callback() sets a user callback cb associated with a libctx that will be called when a
       non approved FIPS operation is detected.

       The user's callback may be triggered multiple times during an algorithm operation to indicate different
       approved mode checks have failed.

       Non approved operations may only occur if the user has deliberately chosen to do so (either by setting a
       global FIPS configuration option or via an option in an algorithm's operation context).

       The user's callback OSSL_INDICATOR_CALLBACKtype and desc contain the algorithm type and operation that
       is not approved.  params is not currently used.

       If the user callback returns 0, an error will occur in the caller. This can be used for testing purposes.

       A simple indicator callback to log non approved FIPS operations

        static int indicator_cb(const char *type, const char *desc,
                                const OSSL_PARAM params[])
        {
            if (type != NULL && desc != NULL)
                fprintf(stdout, "%s %s is not approved\n", type, desc);
       end:
            /* For Testing purposes you could return 0 here to cause an error */
            return 1;
        }

        OSSL_INDICATOR_set_callback(libctx, indicator_cb);

       The functions described here were added in OpenSSL 3.4.

       OSSL_INDICATOR_set_callback, OSSL_INDICATOR_get_callback - specify a callback for FIPS indicators

OSSL_INDICATOR_get_callback() returns the callback that has been set via OSSL_INDICATOR_set_callback()
       for the given library context libctx, or NULL if no callback is currently set.

openssl-core.h(7), OSSL_PROVIDER-FIPS(7) OSSL_LIB_CTX(3)

        #include <openssl/indicator.h>

       typedef int (OSSL_INDICATOR_CALLBACK)(const char *type, const char *desc,
                                             const OSSL_PARAM params[]);

        void OSSL_INDICATOR_set_callback(OSSL_LIB_CTX *libctx,
                                         OSSL_INDICATOR_CALLBACK *cb);
        void OSSL_INDICATOR_get_callback(OSSL_LIB_CTX *libctx,
                                         OSSL_INDICATOR_CALLBACK **cb);