/**

 *  Copyright Notice:

 *  Copyright 2021-2022 DMTF. All rights reserved.

 *  License: BSD 3-Clause License. For full text see link: https://github.com/DMTF/libspdm/blob/main/LICENSE.md

 **/

/** @file

 * Pseudorandom Number generator Wrapper Implementation.

 **/

#include "internal_crypt_lib.h"

#include "library/rnglib.h"

/**

 * Generates a random byte stream of the specified size.

 *

 * If output is NULL, then return false.

 * If this interface is not supported, then return false.

 *

 * @param[out]  output  Pointer to buffer to receive random value.

 * @param[in]   size    Size of random bytes to generate.

 *

 * @retval true   Random byte stream generated successfully.

 * @retval false  Generation of random byte stream failed.

 **/

bool libspdm_random_bytes(uint8_t *output, size_t size)

{

    bool ret;

    uint64_t temp_rand;

    size_t dst_size;

    ret = false;

    dst_size = size;

    while (size > 0) {

        /* Use rnglib to get random number*/

        ret = libspdm_get_random_number_64(&temp_rand);

        if (!ret) {

            return ret;

        }

        if (size >= sizeof(uint64_t)) {

            libspdm_copy_mem(output, dst_size, &temp_rand, sizeof(uint64_t));

            output += sizeof(uint64_t);

            size -= sizeof(uint64_t);

            dst_size -= sizeof(uint64_t);

        } else {

            libspdm_copy_mem(output, dst_size, &temp_rand, size);

            size = 0;

        }

    }

    return ret;

}

int libspdm_myrand(void *rng_state, unsigned char *output, size_t len)

{

    bool result = libspdm_random_bytes(output, len);

    /* The MbedTLS function f_rng, which myrand implements, is not

     * documented well. From looking at code: zero is considered success,

     * while non-zero return value is considered failure.*/

    return result ? 0 : -1;

}