/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project.
 */
/* ====================================================================
 * Copyright (c) 2011 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 */

#include <string.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/fips.h>
#include "crypto/fips.h"
#include <openssl/fips_rand.h>
#include "fips_locl.h"
#include "fips_rand_lcl.h"

/* Support framework for SP800-90 DRBGs */

int FIPS_drbg_init(DRBG_CTX *dctx, int type, unsigned int flags)
{
    int rv;
    memset(dctx, 0, sizeof(DRBG_CTX));
    dctx->status = DRBG_STATUS_UNINITIALISED;
    dctx->xflags = flags;
    dctx->type = type;

    dctx->iflags = 0;
    dctx->entropy_blocklen = 0;
    dctx->health_check_cnt = 0;
    dctx->health_check_interval = DRBG_HEALTH_INTERVAL;

    rv = fips_drbg_hash_init(dctx);

    if (rv == -2)
        rv = fips_drbg_ctr_init(dctx);
    if (rv == -2)
        rv = fips_drbg_hmac_init(dctx);

    if (rv <= 0) {
        if (rv == -2)
            FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_UNSUPPORTED_DRBG_TYPE);
        else
            FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_ERROR_INITIALISING_DRBG);
    }

    /* If not in test mode run selftests on DRBG of the same type */

    if (!(dctx->xflags & DRBG_FLAG_TEST)) {
        if (!FIPS_drbg_health_check(dctx)) {
            FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_SELFTEST_FAILURE);
            return 0;
        }
    }

    return rv;
}

DRBG_CTX *FIPS_drbg_new(int type, unsigned int flags)
{
    DRBG_CTX *dctx;
    dctx = OPENSSL_malloc(sizeof(DRBG_CTX));
    if (!dctx) {
        FIPSerr(FIPS_F_FIPS_DRBG_NEW, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    if (type == 0) {
        memset(dctx, 0, sizeof(DRBG_CTX));
        dctx->type = 0;
        dctx->status = DRBG_STATUS_UNINITIALISED;
        return dctx;
    }

    if (FIPS_drbg_init(dctx, type, flags) <= 0) {
        OPENSSL_free(dctx);
        return NULL;
    }

    return dctx;
}

void FIPS_drbg_free(DRBG_CTX *dctx)
{
    if (dctx->uninstantiate)
        dctx->uninstantiate(dctx);
    /* Don't free up default DRBG */
    if (dctx == FIPS_get_default_drbg()) {
        memset(dctx, 0, sizeof(DRBG_CTX));
        dctx->type = 0;
        dctx->status = DRBG_STATUS_UNINITIALISED;
    } else {
        OPENSSL_cleanse(&dctx->d, sizeof(dctx->d));
        OPENSSL_free(dctx);
    }
}

static size_t fips_get_entropy(DRBG_CTX *dctx, unsigned char **pout,
                               int entropy, size_t min_len, size_t max_len)
{
    unsigned char *tout, *p;
    size_t bl = dctx->entropy_blocklen, rv;
    if (!dctx->get_entropy)
        return 0;
    if (dctx->xflags & DRBG_FLAG_TEST || !bl)
        return dctx->get_entropy(dctx, pout, entropy, min_len, max_len);
    rv = dctx->get_entropy(dctx, &tout, entropy + bl,
                           min_len + bl, max_len + bl);
    if (tout == NULL)
        return 0;
    *pout = tout + bl;
    if (rv < (min_len + bl) || (rv % bl))
        return 0;
    /* Compare consecutive blocks for continuous PRNG test */
    for (p = tout; p < tout + rv - bl; p += bl) {
        if (!memcmp(p, p + bl, bl)) {
            FIPSerr(FIPS_F_FIPS_GET_ENTROPY, FIPS_R_ENTROPY_SOURCE_STUCK);
            return 0;
        }
    }
    rv -= bl;
    if (rv > max_len)
        return max_len;
    return rv;
}

static void fips_cleanup_entropy(DRBG_CTX *dctx,
                                 unsigned char *out, size_t olen)
{
    size_t bl;
    if (dctx->xflags & DRBG_FLAG_TEST)
        bl = 0;
    else
        bl = dctx->entropy_blocklen;
    /* Call cleanup with original arguments */
    dctx->cleanup_entropy(dctx, out - bl, olen + bl);
}

int FIPS_drbg_instantiate(DRBG_CTX *dctx,
                          const unsigned char *pers, size_t perslen)
{
    size_t entlen = 0, noncelen = 0;
    unsigned char *nonce = NULL, *entropy = NULL;

#if 0
    /* Put here so error script picks them up */
    FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE,
            FIPS_R_PERSONALISATION_STRING_TOO_LONG);
    FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_IN_ERROR_STATE);
    FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ALREADY_INSTANTIATED);
    FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ERROR_RETRIEVING_ENTROPY);
    FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ERROR_RETRIEVING_NONCE);
    FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_INSTANTIATE_ERROR);
    FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_DRBG_NOT_INITIALISED);
#endif

    int r = 0;

    if (perslen > dctx->max_pers) {
        r = FIPS_R_PERSONALISATION_STRING_TOO_LONG;
        goto end;
    }

    if (!dctx->instantiate) {
        r = FIPS_R_DRBG_NOT_INITIALISED;
        goto end;
    }

    if (dctx->status != DRBG_STATUS_UNINITIALISED) {
        if (dctx->status == DRBG_STATUS_ERROR)
            r = FIPS_R_IN_ERROR_STATE;
        else
            r = FIPS_R_ALREADY_INSTANTIATED;
        goto end;
    }

    dctx->status = DRBG_STATUS_ERROR;

    entlen = fips_get_entropy(dctx, &entropy, dctx->strength,
                              dctx->min_entropy, dctx->max_entropy);

    if (entlen < dctx->min_entropy || entlen > dctx->max_entropy) {
        r = FIPS_R_ERROR_RETRIEVING_ENTROPY;
        goto end;
    }

    if (dctx->max_nonce > 0 && dctx->get_nonce) {
        noncelen = dctx->get_nonce(dctx, &nonce,
                                   dctx->strength / 2,
                                   dctx->min_nonce, dctx->max_nonce);

        if (noncelen < dctx->min_nonce || noncelen > dctx->max_nonce) {
            r = FIPS_R_ERROR_RETRIEVING_NONCE;
            goto end;
        }

    }

    if (!dctx->instantiate(dctx,
                           entropy, entlen, nonce, noncelen, pers, perslen)) {
        r = FIPS_R_ERROR_INSTANTIATING_DRBG;
        goto end;
    }

    dctx->status = DRBG_STATUS_READY;
    if (!(dctx->iflags & DRBG_CUSTOM_RESEED))
        dctx->reseed_counter = 1;

 end:

    if (entropy && dctx->cleanup_entropy)
        fips_cleanup_entropy(dctx, entropy, entlen);

    if (nonce && dctx->cleanup_nonce)
        dctx->cleanup_nonce(dctx, nonce, noncelen);

    if (dctx->status == DRBG_STATUS_READY)
        return 1;

    if (r && !(dctx->iflags & DRBG_FLAG_NOERR))
        FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, r);

    return 0;

}

static int drbg_reseed(DRBG_CTX *dctx,
                       const unsigned char *adin, size_t adinlen, int hcheck)
{
    unsigned char *entropy = NULL;
    size_t entlen = 0;
    int r = 0;

#if 0
    FIPSerr(FIPS_F_DRBG_RESEED, FIPS_R_NOT_INSTANTIATED);
    FIPSerr(FIPS_F_DRBG_RESEED, FIPS_R_ADDITIONAL_INPUT_TOO_LONG);
#endif
    if (dctx->status != DRBG_STATUS_READY
        && dctx->status != DRBG_STATUS_RESEED) {
        if (dctx->status == DRBG_STATUS_ERROR)
            r = FIPS_R_IN_ERROR_STATE;
        else if (dctx->status == DRBG_STATUS_UNINITIALISED)
            r = FIPS_R_NOT_INSTANTIATED;
        goto end;
    }

    if (!adin)
        adinlen = 0;
    else if (adinlen > dctx->max_adin) {
        r = FIPS_R_ADDITIONAL_INPUT_TOO_LONG;
        goto end;
    }

    dctx->status = DRBG_STATUS_ERROR;
    /* Peform health check on all reseed operations if not a prediction
     * resistance request and not in test mode.
     */
    if (hcheck && !(dctx->xflags & DRBG_FLAG_TEST)) {
        if (!FIPS_drbg_health_check(dctx)) {
            r = FIPS_R_SELFTEST_FAILURE;
            goto end;
        }
    }

    entlen = fips_get_entropy(dctx, &entropy, dctx->strength,
                              dctx->min_entropy, dctx->max_entropy);

    if (entlen < dctx->min_entropy || entlen > dctx->max_entropy) {
        r = FIPS_R_ERROR_RETRIEVING_ENTROPY;
        goto end;
    }

    if (!dctx->reseed(dctx, entropy, entlen, adin, adinlen))
        goto end;

    dctx->status = DRBG_STATUS_READY;
    if (!(dctx->iflags & DRBG_CUSTOM_RESEED))
        dctx->reseed_counter = 1;
 end:

    if (entropy && dctx->cleanup_entropy)
        fips_cleanup_entropy(dctx, entropy, entlen);

    if (dctx->status == DRBG_STATUS_READY)
        return 1;

    if (r && !(dctx->iflags & DRBG_FLAG_NOERR))
        FIPSerr(FIPS_F_DRBG_RESEED, r);

    return 0;
}

int FIPS_drbg_reseed(DRBG_CTX *dctx,
                     const unsigned char *adin, size_t adinlen)
{
    int len = (int)adinlen;

    if (len < 0 || (size_t)len != adinlen) {
        FIPSerr(FIPS_F_DRBG_RESEED, FIPS_R_ADDITIONAL_INPUT_TOO_LONG);
        return 0;
    }
    RAND_seed(adin, len);
    return 1;
}

int FIPS_drbg_reseed_internal(DRBG_CTX *dctx,
                     const unsigned char *adin, size_t adinlen)
{
    return drbg_reseed(dctx, adin, adinlen, 1);
}

static int fips_drbg_check(DRBG_CTX *dctx)
{
    if (dctx->xflags & DRBG_FLAG_TEST)
        return 1;
    dctx->health_check_cnt++;
    if (dctx->health_check_cnt >= dctx->health_check_interval) {
        if (!FIPS_drbg_health_check(dctx)) {
            FIPSerr(FIPS_F_FIPS_DRBG_CHECK, FIPS_R_SELFTEST_FAILURE);
            return 0;
        }
    }
    return 1;
}

int FIPS_drbg_generate(DRBG_CTX *dctx, unsigned char *out, size_t outlen,
                       int prediction_resistance,
                       const unsigned char *adin, size_t adinlen)
{
    int len = (int)outlen;

    if (len < 0 || (size_t)len != outlen) {
        FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, FIPS_R_REQUEST_TOO_LARGE_FOR_DRBG);
        return 0;
    }
    return RAND_bytes(out, len);
}

int FIPS_drbg_generate_internal(DRBG_CTX *dctx, unsigned char *out, size_t outlen,
                       int prediction_resistance,
                       const unsigned char *adin, size_t adinlen)
{
    int r = 0;

    if (FIPS_selftest_failed()) {
        FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, FIPS_R_SELFTEST_FAILED);
        return 0;
    }

    if (!fips_drbg_check(dctx))
        return 0;

    if (dctx->status != DRBG_STATUS_READY
        && dctx->status != DRBG_STATUS_RESEED) {
        if (dctx->status == DRBG_STATUS_ERROR)
            r = FIPS_R_IN_ERROR_STATE;
        else if (dctx->status == DRBG_STATUS_UNINITIALISED)
            r = FIPS_R_NOT_INSTANTIATED;
        goto end;
    }

    if (outlen > dctx->max_request) {
        r = FIPS_R_REQUEST_TOO_LARGE_FOR_DRBG;
        return 0;
    }

    if (adinlen > dctx->max_adin) {
        r = FIPS_R_ADDITIONAL_INPUT_TOO_LONG;
        goto end;
    }

    if (dctx->iflags & DRBG_CUSTOM_RESEED)
        dctx->generate(dctx, NULL, outlen, NULL, 0);
    else if (dctx->reseed_counter >= dctx->reseed_interval)
        dctx->status = DRBG_STATUS_RESEED;

    if (dctx->status == DRBG_STATUS_RESEED || prediction_resistance) {
        /* If prediction resistance request don't do health check */
        int hcheck = prediction_resistance ? 0 : 1;

        if (!drbg_reseed(dctx, adin, adinlen, hcheck)) {
            r = FIPS_R_RESEED_ERROR;
            goto end;
        }
        adin = NULL;
        adinlen = 0;
    }

    if (!dctx->generate(dctx, out, outlen, adin, adinlen)) {
        r = FIPS_R_GENERATE_ERROR;
        dctx->status = DRBG_STATUS_ERROR;
        goto end;
    }
    if (!(dctx->iflags & DRBG_CUSTOM_RESEED)) {
        if (dctx->reseed_counter >= dctx->reseed_interval)
            dctx->status = DRBG_STATUS_RESEED;
        else
            dctx->reseed_counter++;
    }

 end:
    if (r) {
        if (!(dctx->iflags & DRBG_FLAG_NOERR))
            FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, r);
        return 0;
    }

    return 1;
}

int FIPS_drbg_uninstantiate(DRBG_CTX *dctx)
{
    int rv;
    if (!dctx->uninstantiate)
        rv = 1;
    else
        rv = dctx->uninstantiate(dctx);
    /* Although we'd like to cleanse here we can't because we have to
     * test the uninstantiate really zeroes the data.
     */
    memset(&dctx->d, 0, sizeof(dctx->d));
    dctx->status = DRBG_STATUS_UNINITIALISED;
    /* If method has problems uninstantiating, return error */
    return rv;
}

int FIPS_drbg_set_callbacks(DRBG_CTX *dctx,
                            size_t (*get_entropy) (DRBG_CTX *ctx,
                                                   unsigned char **pout,
                                                   int entropy,
                                                   size_t min_len,
                                                   size_t max_len),
                            void (*cleanup_entropy) (DRBG_CTX *ctx,
                                                     unsigned char *out,
                                                     size_t olen),
                            size_t entropy_blocklen,
                            size_t (*get_nonce) (DRBG_CTX *ctx,
                                                 unsigned char **pout,
                                                 int entropy, size_t min_len,
                                                 size_t max_len),
                            void (*cleanup_nonce) (DRBG_CTX *ctx,
                                                   unsigned char *out,
                                                   size_t olen))
{
    if (dctx->status != DRBG_STATUS_UNINITIALISED)
        return 0;
    dctx->entropy_blocklen = entropy_blocklen;
    dctx->get_entropy = get_entropy;
    dctx->cleanup_entropy = cleanup_entropy;
    dctx->get_nonce = get_nonce;
    dctx->cleanup_nonce = cleanup_nonce;
    return 1;
}

int FIPS_drbg_set_rand_callbacks(DRBG_CTX *dctx,
                                 size_t (*get_adin) (DRBG_CTX *ctx,
                                                     unsigned char **pout),
                                 void (*cleanup_adin) (DRBG_CTX *ctx,
                                                       unsigned char *out,
                                                       size_t olen),
                                 int (*rand_seed_cb) (DRBG_CTX *ctx,
                                                      const void *buf,
                                                      int num),
                                 int (*rand_add_cb) (DRBG_CTX *ctx,
                                                     const void *buf, int num,
                                                     double entropy))
{
    if (dctx->status != DRBG_STATUS_UNINITIALISED)
        return 0;
    dctx->get_adin = get_adin;
    dctx->cleanup_adin = cleanup_adin;
    dctx->rand_seed_cb = rand_seed_cb;
    dctx->rand_add_cb = rand_add_cb;
    return 1;
}

void *FIPS_drbg_get_app_data(DRBG_CTX *dctx)
{
    return dctx->app_data;
}

void FIPS_drbg_set_app_data(DRBG_CTX *dctx, void *app_data)
{
    dctx->app_data = app_data;
}

size_t FIPS_drbg_get_blocklength(DRBG_CTX *dctx)
{
    return dctx->blocklength;
}

int FIPS_drbg_get_strength(DRBG_CTX *dctx)
{
    return dctx->strength;
}

void FIPS_drbg_set_check_interval(DRBG_CTX *dctx, int interval)
{
    dctx->health_check_interval = interval;
}

void FIPS_drbg_set_reseed_interval(DRBG_CTX *dctx, int interval)
{
    dctx->reseed_interval = interval;
}

void FIPS_drbg_stick(int onoff)
{
    /* Just backwards compatibility API call with no effect. */
}