/*

 * Copyright (C) 2017 Red Hat

 * Copyright (C) 1995-2017 Free Software Foundation, Inc.

 * This file is part of the GNU C Library.

 * Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.

 *

 * This file is part of GnuTLS.

 *

 * Libgcrypt is free software; you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as

 * published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * Libgcrypt is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this program.  If not, see <https://www.gnu.org/licenses/>.

 */

#include "config.h"

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include <sys/types.h>

#include "drbg-aes.h"

#include "fips.h"

#include "gnutls_int.h"

#include "errors.h"

#include <stdlib.h>

#include "rnd-common.h"

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION

struct r48_rand_data {

  unsigned short int __x[3]; /* Current state.  */

  unsigned short int __old_x[3]; /* Old state.  */

  unsigned short int __c; /* Additive const. in congruential formula.  */

  unsigned short int __init; /* Flag for initializing.  */

  __extension__ unsigned long long int __a; /* Factor in congruential

                 formula.  */

};

#ifdef __clang__

__attribute__((no_sanitize("integer")))

#endif

static int

__r48_rand_iterate(unsigned short int xsubi[3], struct r48_rand_data *buffer)

{

  uint64_t X;

  uint64_t result;

  /* Initialize buffer, if not yet done.  */

  if (unlikely(!buffer->__init)) {

    buffer->__a = 0x5deece66dull;

    buffer->__c = 0xb;

    buffer->__init = 1;

  }

  /* Do the real work.  We choose a data type which contains at least

     48 bits.  Because we compute the modulus it does not care how

     many bits really are computed.  */

  X = (uint64_t)xsubi[2] << 32 | (uint32_t)xsubi[1] << 16 | xsubi[0];

  result = X * buffer->__a + buffer->__c;

  xsubi[0] = result & 0xffff;

  xsubi[1] = (result >> 16) & 0xffff;

  xsubi[2] = (result >> 32) & 0xffff;

  return 0;

}

#ifdef __clang__

__attribute__((no_sanitize("integer")))

#elif defined __GNUC__

__attribute__((no_sanitize("shift-base")))

#endif

static int

r48_r(unsigned short int xsubi[3], struct r48_rand_data *buffer,

      long int *result)

{

  /* Compute next state.  */

  if (__r48_rand_iterate(xsubi, buffer) < 0)

    return -1;

  /* Store the result.  */

  *result = (int32_t)((xsubi[2] << 16) | xsubi[1]);

  return 0;

}

static int r48(struct r48_rand_data *buffer, long int *result)

{

  return r48_r(buffer->__x, buffer, result);

}

/* This is a dummy random generator intended to be reproducible

 * for use in fuzzying targets.

 */

static int _rngfuzz_init(void **_ctx)

{

  *_ctx = calloc(1, sizeof(struct r48_rand_data));

  return 0;

}

static int _rngfuzz_rnd(void *_ctx, int level, void *buffer, size_t length)

{

  struct r48_rand_data *ctx = _ctx;

  uint8_t *p = buffer;

  long r;

  unsigned i;

  memset(ctx, 0, sizeof(*ctx));

  for (i = 0; i < length; i++) {

    r48(ctx, &r);

    p[i] = r;

  }

  return 0;

}

static void _rngfuzz_deinit(void *_ctx)

{

  struct r48_rand_data *ctx = _ctx;

  free(ctx);

}

static void _rngfuzz_refresh(void *_ctx)

{

  /* this is predictable RNG. Don't refresh */

  return;

}

gnutls_crypto_rnd_st _gnutls_fuzz_rnd_ops = {

  .init = _rngfuzz_init,

  .deinit = _rngfuzz_deinit,

  .rnd = _rngfuzz_rnd,

  .rnd_refresh = _rngfuzz_refresh,

  .self_test = NULL,

};

#endif /* FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */