/*

 * Copyright (C) 2008-2012 Free Software Foundation, Inc.

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS 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.

 *

 * This library 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 <http://www.gnu.org/licenses/>

 *

 */

/* This file handles all the internal functions that cope with random data.

 */

#include "gnutls_int.h"

#include "errors.h"

#include <random.h>

#include "locks.h"

#include <fips.h>

#ifdef HAVE_THREADS_H

# include <threads.h>

#elif defined(__GNUC__)

# define _Thread_local __thread

#else

# error Unsupported platform

#endif

#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)

extern gnutls_crypto_rnd_st _gnutls_fuzz_rnd_ops;

#endif

/* Per thread context of random generator, and a flag to indicate initialization */

static _Thread_local void *gnutls_rnd_ctx;

static _Thread_local unsigned rnd_initialized = 0;

struct rnd_ctx_list_st {

	void *ctx;

	struct rnd_ctx_list_st *next;

};

/* A global list of all allocated contexts - to be

 * used during deinitialization. */

GNUTLS_STATIC_MUTEX(gnutls_rnd_ctx_list_mutex);

static struct rnd_ctx_list_st *head = NULL;

static int append(void *ctx)

{

	struct rnd_ctx_list_st *e = gnutls_malloc(sizeof(*e));

	if (e == NULL)

		return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

	e->ctx = ctx;

	e->next = head;

	head = e;

	return 0;

}

inline static int _gnutls_rnd_init(void)

{

	if (unlikely(!rnd_initialized)) {

		int ret;

		if (_gnutls_rnd_ops.init == NULL) {

			rnd_initialized = 1;

			return 0;

		}

		if (_gnutls_rnd_ops.init(&gnutls_rnd_ctx) < 0) {

			gnutls_assert();

			return GNUTLS_E_RANDOM_FAILED;

		}

		GNUTLS_STATIC_MUTEX_LOCK(gnutls_rnd_ctx_list_mutex);

		ret = append(gnutls_rnd_ctx);

		GNUTLS_STATIC_MUTEX_UNLOCK(gnutls_rnd_ctx_list_mutex);

		if (ret < 0) {

			gnutls_assert();

			_gnutls_rnd_ops.deinit(gnutls_rnd_ctx);

			return ret;

		}

		rnd_initialized = 1;

	}

	return 0;

}

int _gnutls_rnd_preinit(void)

{

	int ret;

#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)

# warning Insecure PRNG is enabled

	ret = gnutls_crypto_rnd_register(100, &_gnutls_fuzz_rnd_ops);

	if (ret < 0)

		return ret;

#elif defined(ENABLE_FIPS140)

	/* The FIPS140 random generator is only enabled when we are compiled

	 * with FIPS support, _and_ the system requires FIPS140.

	 */

	if (_gnutls_fips_mode_enabled() == 1) {

		ret = gnutls_crypto_rnd_register(100, &_gnutls_fips_rnd_ops);

		if (ret < 0)

			return ret;

	}

#endif

	ret = _rnd_system_entropy_init();

	if (ret < 0) {

		gnutls_assert();

		return GNUTLS_E_RANDOM_FAILED;

	}

	return 0;

}

void _gnutls_rnd_deinit(void)

{

	if (_gnutls_rnd_ops.deinit != NULL) {

		struct rnd_ctx_list_st *e = head, *next;

		while(e != NULL) {

			next = e->next;

			_gnutls_rnd_ops.deinit(e->ctx);

			gnutls_free(e);

			e = next;

		}

		head = NULL;

	}

	rnd_initialized = 0;

	_rnd_system_entropy_deinit();

	return;

}

/**

 * gnutls_rnd:

 * @level: a security level

 * @data: place to store random bytes

 * @len: The requested size

 *

 * This function will generate random data and store it to output

 * buffer. The value of @level should be one of %GNUTLS_RND_NONCE,

 * %GNUTLS_RND_RANDOM and %GNUTLS_RND_KEY. See the manual and

 * %gnutls_rnd_level_t for detailed information.

 *

 * This function is thread-safe and also fork-safe.

 *

 * Returns: Zero on success, or a negative error code on error.

 *

 * Since: 2.12.0

 **/

int gnutls_rnd(gnutls_rnd_level_t level, void *data, size_t len)

{

	int ret;

	FAIL_IF_LIB_ERROR;

	if (unlikely((ret=_gnutls_rnd_init()) < 0))

		return gnutls_assert_val(ret);

	if (likely(len > 0)) {

		return _gnutls_rnd_ops.rnd(gnutls_rnd_ctx, level, data,

					   len);

	}

	return 0;

}

/**

 * gnutls_rnd_refresh:

 *

 * This function refreshes the random generator state.

 * That is the current precise time, CPU usage, and

 * other values are input into its state.

 *

 * On a slower rate input from /dev/urandom is mixed too.

 *

 * Since: 3.1.7

 **/

void gnutls_rnd_refresh(void)

{

	if (rnd_initialized && _gnutls_rnd_ops.rnd_refresh)

		_gnutls_rnd_ops.rnd_refresh(gnutls_rnd_ctx);

}