/* BEGIN_HEADER */
#include "mbedtls/hmac_drbg.h"
#include "string.h"

typedef struct {
    unsigned char *p;
    size_t len;
} entropy_ctx;

static int mbedtls_test_entropy_func(void *data, unsigned char *buf, size_t len)
{
    entropy_ctx *ctx = (entropy_ctx *) data;

    if (len > ctx->len) {
        return -1;
    }

    memcpy(buf, ctx->p, len);

    ctx->p += len;
    ctx->len -= len;

    return 0;
}
/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_HMAC_DRBG_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE */
void hmac_drbg_entropy_usage(int md_alg)
{
    unsigned char out[16];
    unsigned char buf[1024];
    const mbedtls_md_info_t *md_info;
    mbedtls_hmac_drbg_context ctx;
    entropy_ctx entropy;
    size_t i, reps = 10;
    size_t default_entropy_len;
    size_t expected_consumed_entropy = 0;

    mbedtls_hmac_drbg_init(&ctx);
    memset(buf, 0, sizeof(buf));
    memset(out, 0, sizeof(out));

    entropy.len = sizeof(buf);
    entropy.p = buf;

    md_info = mbedtls_md_info_from_type(md_alg);
    TEST_ASSERT(md_info != NULL);
    if (mbedtls_md_get_size(md_info) <= 20) {
        default_entropy_len = 16;
    } else if (mbedtls_md_get_size(md_info) <= 28) {
        default_entropy_len = 24;
    } else {
        default_entropy_len = 32;
    }

    /* Set reseed interval before seed */
    mbedtls_hmac_drbg_set_reseed_interval(&ctx, 2 * reps);

    /* Init must use entropy */
    TEST_ASSERT(mbedtls_hmac_drbg_seed(&ctx, md_info, mbedtls_test_entropy_func, &entropy,
                                       NULL, 0) == 0);
    /* default_entropy_len of entropy, plus half as much for the nonce */
    expected_consumed_entropy += default_entropy_len * 3 / 2;
    TEST_EQUAL(sizeof(buf)  - entropy.len, expected_consumed_entropy);

    /* By default, PR is off, and reseed interval was set to
     * 2 * reps so the next few calls should not use entropy */
    for (i = 0; i < reps; i++) {
        TEST_ASSERT(mbedtls_hmac_drbg_random(&ctx, out, sizeof(out) - 4) == 0);
        TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, out, sizeof(out) - 4,
                                                      buf, 16) == 0);
    }
    TEST_EQUAL(sizeof(buf)  - entropy.len, expected_consumed_entropy);

    /* While at it, make sure we didn't write past the requested length */
    TEST_ASSERT(out[sizeof(out) - 4] == 0);
    TEST_ASSERT(out[sizeof(out) - 3] == 0);
    TEST_ASSERT(out[sizeof(out) - 2] == 0);
    TEST_ASSERT(out[sizeof(out) - 1] == 0);

    /* There have been 2 * reps calls to random. The next call should reseed */
    TEST_ASSERT(mbedtls_hmac_drbg_random(&ctx, out, sizeof(out)) == 0);
    expected_consumed_entropy += default_entropy_len;
    TEST_EQUAL(sizeof(buf)  - entropy.len, expected_consumed_entropy);

    /* Set reseed interval after seed */
    mbedtls_hmac_drbg_set_reseed_interval(&ctx, 4 * reps + 1);

    /* The new few calls should not reseed */
    for (i = 0; i < (2 * reps); i++) {
        TEST_ASSERT(mbedtls_hmac_drbg_random(&ctx, out, sizeof(out)) == 0);
        TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, out, sizeof(out),
                                                      buf, 16) == 0);
    }
    TEST_EQUAL(sizeof(buf)  - entropy.len, expected_consumed_entropy);

    /* Now enable PR, so the next few calls should all reseed */
    mbedtls_hmac_drbg_set_prediction_resistance(&ctx, MBEDTLS_HMAC_DRBG_PR_ON);
    TEST_ASSERT(mbedtls_hmac_drbg_random(&ctx, out, sizeof(out)) == 0);
    expected_consumed_entropy += default_entropy_len;
    TEST_EQUAL(sizeof(buf)  - entropy.len, expected_consumed_entropy);

    /* Finally, check setting entropy_len */
    mbedtls_hmac_drbg_set_entropy_len(&ctx, 42);
    TEST_ASSERT(mbedtls_hmac_drbg_random(&ctx, out, sizeof(out)) == 0);
    expected_consumed_entropy += 42;
    TEST_EQUAL(sizeof(buf)  - entropy.len, expected_consumed_entropy);

    mbedtls_hmac_drbg_set_entropy_len(&ctx, 13);
    TEST_ASSERT(mbedtls_hmac_drbg_random(&ctx, out, sizeof(out)) == 0);
    expected_consumed_entropy += 13;
    TEST_EQUAL(sizeof(buf)  - entropy.len, expected_consumed_entropy);

exit:
    mbedtls_hmac_drbg_free(&ctx);
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_FS_IO */
void hmac_drbg_seed_file(int md_alg, char *path, int ret)
{
    const mbedtls_md_info_t *md_info;
    mbedtls_hmac_drbg_context ctx;

    mbedtls_hmac_drbg_init(&ctx);

    md_info = mbedtls_md_info_from_type(md_alg);
    TEST_ASSERT(md_info != NULL);

    TEST_ASSERT(mbedtls_hmac_drbg_seed(&ctx, md_info,
                                       mbedtls_test_rnd_std_rand, NULL,
                                       NULL, 0) == 0);

    TEST_ASSERT(mbedtls_hmac_drbg_write_seed_file(&ctx, path) == ret);
    TEST_ASSERT(mbedtls_hmac_drbg_update_seed_file(&ctx, path) == ret);

exit:
    mbedtls_hmac_drbg_free(&ctx);
}
/* END_CASE */

/* BEGIN_CASE */
void hmac_drbg_buf(int md_alg)
{
    unsigned char out[16];
    unsigned char buf[100];
    const mbedtls_md_info_t *md_info;
    mbedtls_hmac_drbg_context ctx;
    size_t i;

    mbedtls_hmac_drbg_init(&ctx);
    memset(buf, 0, sizeof(buf));
    memset(out, 0, sizeof(out));

    md_info = mbedtls_md_info_from_type(md_alg);
    TEST_ASSERT(md_info != NULL);
    TEST_ASSERT(mbedtls_hmac_drbg_seed_buf(&ctx, md_info, buf, sizeof(buf)) == 0);

    /* Make sure it never tries to reseed (would segfault otherwise) */
    mbedtls_hmac_drbg_set_reseed_interval(&ctx, 3);
    mbedtls_hmac_drbg_set_prediction_resistance(&ctx, MBEDTLS_HMAC_DRBG_PR_ON);

    for (i = 0; i < 30; i++) {
        TEST_ASSERT(mbedtls_hmac_drbg_random(&ctx, out, sizeof(out)) == 0);
    }

exit:
    mbedtls_hmac_drbg_free(&ctx);
}
/* END_CASE */

/* BEGIN_CASE */
void hmac_drbg_no_reseed(int md_alg, data_t *entropy,
                         data_t *custom, data_t *add1,
                         data_t *add2, data_t *output)
{
    unsigned char data[1024];
    unsigned char my_output[512];
    entropy_ctx p_entropy;
    const mbedtls_md_info_t *md_info;
    mbedtls_hmac_drbg_context ctx;

    mbedtls_hmac_drbg_init(&ctx);

    p_entropy.p = entropy->x;
    p_entropy.len = entropy->len;

    md_info = mbedtls_md_info_from_type(md_alg);
    TEST_ASSERT(md_info != NULL);

    /* Test the simplified buffer-based variant */
    memcpy(data, entropy->x, p_entropy.len);
    memcpy(data + p_entropy.len, custom->x, custom->len);
    TEST_ASSERT(mbedtls_hmac_drbg_seed_buf(&ctx, md_info,
                                           data, p_entropy.len + custom->len) == 0);
    TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, my_output, output->len,
                                                  add1->x, add1->len) == 0);
    TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, my_output, output->len,
                                                  add2->x, add2->len) == 0);

    /* Reset context for second run */
    mbedtls_hmac_drbg_free(&ctx);

    TEST_ASSERT(memcmp(my_output, output->x, output->len) == 0);

    /* And now the normal entropy-based variant */
    TEST_ASSERT(mbedtls_hmac_drbg_seed(&ctx, md_info, mbedtls_test_entropy_func, &p_entropy,
                                       custom->x, custom->len) == 0);
    TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, my_output, output->len,
                                                  add1->x, add1->len) == 0);
    TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, my_output, output->len,
                                                  add2->x, add2->len) == 0);
    TEST_ASSERT(memcmp(my_output, output->x, output->len) == 0);

exit:
    mbedtls_hmac_drbg_free(&ctx);
}
/* END_CASE */

/* BEGIN_CASE */
void hmac_drbg_nopr(int md_alg, data_t *entropy, data_t *custom,
                    data_t *add1, data_t *add2, data_t *add3,
                    data_t *output)
{
    unsigned char my_output[512];
    entropy_ctx p_entropy;
    const mbedtls_md_info_t *md_info;
    mbedtls_hmac_drbg_context ctx;

    mbedtls_hmac_drbg_init(&ctx);

    p_entropy.p = entropy->x;
    p_entropy.len = entropy->len;

    md_info = mbedtls_md_info_from_type(md_alg);
    TEST_ASSERT(md_info != NULL);

    TEST_ASSERT(mbedtls_hmac_drbg_seed(&ctx, md_info, mbedtls_test_entropy_func, &p_entropy,
                                       custom->x, custom->len) == 0);
    TEST_ASSERT(mbedtls_hmac_drbg_reseed(&ctx, add1->x, add1->len) == 0);
    TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, my_output, output->len,
                                                  add2->x, add2->len) == 0);
    TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, my_output, output->len,
                                                  add3->x, add3->len) == 0);

    TEST_ASSERT(memcmp(my_output, output->x, output->len) == 0);

exit:
    mbedtls_hmac_drbg_free(&ctx);
}
/* END_CASE */

/* BEGIN_CASE */
void hmac_drbg_pr(int md_alg, data_t *entropy, data_t *custom,
                  data_t *add1, data_t *add2, data_t *output)
{
    unsigned char my_output[512];
    entropy_ctx p_entropy;
    const mbedtls_md_info_t *md_info;
    mbedtls_hmac_drbg_context ctx;

    mbedtls_hmac_drbg_init(&ctx);

    p_entropy.p = entropy->x;
    p_entropy.len = entropy->len;

    md_info = mbedtls_md_info_from_type(md_alg);
    TEST_ASSERT(md_info != NULL);

    TEST_ASSERT(mbedtls_hmac_drbg_seed(&ctx, md_info, mbedtls_test_entropy_func, &p_entropy,
                                       custom->x, custom->len) == 0);
    mbedtls_hmac_drbg_set_prediction_resistance(&ctx, MBEDTLS_HMAC_DRBG_PR_ON);
    TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, my_output, output->len,
                                                  add1->x, add1->len) == 0);
    TEST_ASSERT(mbedtls_hmac_drbg_random_with_add(&ctx, my_output, output->len,
                                                  add2->x, add2->len) == 0);

    TEST_ASSERT(memcmp(my_output, output->x, output->len) == 0);

exit:
    mbedtls_hmac_drbg_free(&ctx);
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
void hmac_drbg_selftest()
{
    TEST_ASSERT(mbedtls_hmac_drbg_self_test(1) == 0);
}
/* END_CASE */