/* crypto/rand/md_rand.c */

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 * 

 * This library is free for commercial and non-commercial use as long as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 * 

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 * 

 * 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 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 acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from 

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 * 

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS 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 AUTHOR OR 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.

 * 

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */

/* ====================================================================

 * Copyright (c) 1998-2001 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

 *    openssl-core@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.

 * ====================================================================

 *

 * This product includes cryptographic software written by Eric Young

 * (eay@cryptsoft.com).  This product includes software written by Tim

 * Hudson (tjh@cryptsoft.com).

 *

 */

 /*

 © Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.

 */

#ifdef MD_RAND_DEBUG

# ifndef NDEBUG

#   define NDEBUG

# endif

#endif

#include <assert.h>

#include <stdio.h>

#include <string.h>

#include "e_os.h"

#include <openssl/rand.h>

#include "rand_lcl.h"

#include <openssl/crypto.h>

#include <openssl/err.h>

#if (defined(SYMBIAN) && (defined(__WINSCW__) || defined(__WINS__)))

#include "libcrypto_wsd_macros.h"

#include "libcrypto_wsd.h"

#endif

#ifdef BN_DEBUG

# define PREDICT

#endif

/* #define PREDICT	1 */

#define STATE_SIZE	1023

#ifndef EMULATOR

static int state_num=0,state_index=0;

static unsigned char state[STATE_SIZE+MD_DIGEST_LENGTH];

static unsigned char md[MD_DIGEST_LENGTH];

static long md_count[2]={0,0};

static double entropy=0;

static int initialized=0;

static unsigned int crypto_lock_rand = 0; /* may be set only when a thread

                                           * holds CRYPTO_LOCK_RAND

                                           * (to prevent double locking) */

/* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */

static unsigned long locking_thread = 0; /* valid iff crypto_lock_rand is set */

#else

GET_STATIC_VAR_FROM_TLS(state_num,md_rand,int)

#define state_num (*GET_WSD_VAR_NAME(state_num,md_rand, s)())

GET_STATIC_VAR_FROM_TLS(state_index,md_rand,int)

#define state_index (*GET_WSD_VAR_NAME(state_index,md_rand, s)())

GET_STATIC_ARRAY_FROM_TLS(state,md_rand,unsigned char)

#define state (GET_WSD_VAR_NAME(state,md_rand, s)())

GET_STATIC_ARRAY_FROM_TLS(md,md_rand,unsigned char)

#define md (GET_WSD_VAR_NAME(md,md_rand, s)())

GET_STATIC_ARRAY_FROM_TLS(md_count,md_rand,unsigned char)

#define md_count (GET_WSD_VAR_NAME(md_count,md_rand, s)())

GET_STATIC_VAR_FROM_TLS(entropy,md_rand,double)

#define entropy (*GET_WSD_VAR_NAME(entropy,md_rand, s)())

GET_STATIC_VAR_FROM_TLS(initialized,md_rand,int)

#define initialized (*GET_WSD_VAR_NAME(initialized,md_rand, s)())

GET_STATIC_VAR_FROM_TLS(crypto_lock_rand,md_rand,unsigned int)

#define crypto_lock_rand (*GET_WSD_VAR_NAME(crypto_lock_rand,md_rand, s)())

GET_STATIC_VAR_FROM_TLS(locking_thread,md_rand,unsigned long)

#define locking_thread  (*GET_WSD_VAR_NAME(locking_thread,md_rand, s)())

#endif

#ifdef PREDICT

int rand_predictable=0;

#endif

const char RAND_version[]="RAND" OPENSSL_VERSION_PTEXT;

static void ssleay_rand_cleanup(void);

static void ssleay_rand_seed(const void *buf, int num);

static void ssleay_rand_add(const void *buf, int num, double add_entropy);

static int ssleay_rand_bytes(unsigned char *buf, int num);

static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num);

static int ssleay_rand_status(void);

#ifndef EMULATOR

RAND_METHOD rand_ssleay_meth={

	ssleay_rand_seed,

	ssleay_rand_bytes,

	ssleay_rand_cleanup,

	ssleay_rand_add,

	ssleay_rand_pseudo_bytes,

	ssleay_rand_status

	}; 

#else

GET_GLOBAL_VAR_FROM_TLS(rand_ssleay_meth,md_rand, RAND_METHOD)

#define rand_ssleay_meth (*GET_WSD_VAR_NAME(rand_ssleay_meth,md_rand, g)())

const RAND_METHOD temp_g_rand_ssleay_meth={

	ssleay_rand_seed,

	ssleay_rand_bytes,

	ssleay_rand_cleanup,

	ssleay_rand_add,

	ssleay_rand_pseudo_bytes,

	ssleay_rand_status

	}; 

#endif

EXPORT_C RAND_METHOD *RAND_SSLeay(void)

	{

	return(&rand_ssleay_meth);

	}

static void ssleay_rand_cleanup(void)

	{

	OPENSSL_cleanse(state,sizeof(state));

	state_num=0;

	state_index=0;

	OPENSSL_cleanse(md,MD_DIGEST_LENGTH);

	md_count[0]=0;

	md_count[1]=0;

	entropy=0;

	initialized=0;

	}

static void ssleay_rand_add(const void *buf, int num, double add)

	{

	int i,j,k,st_idx;

	long md_c[2];

	unsigned char local_md[MD_DIGEST_LENGTH];

	EVP_MD_CTX m;

	int do_not_lock;

	/*

	 * (Based on the rand(3) manpage)

	 *

	 * The input is chopped up into units of 20 bytes (or less for

	 * the last block).  Each of these blocks is run through the hash

	 * function as follows:  The data passed to the hash function

	 * is the current 'md', the same number of bytes from the 'state'

	 * (the location determined by in incremented looping index) as

	 * the current 'block', the new key data 'block', and 'count'

	 * (which is incremented after each use).

	 * The result of this is kept in 'md' and also xored into the

	 * 'state' at the same locations that were used as input into the

         * hash function.

	 */

	/* check if we already have the lock */

	if (crypto_lock_rand)

		{

		CRYPTO_r_lock(CRYPTO_LOCK_RAND2);

		do_not_lock = (locking_thread == CRYPTO_thread_id());

		CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);

		}

	else

		do_not_lock = 0;

	if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	st_idx=state_index;

	/* use our own copies of the counters so that even

	 * if a concurrent thread seeds with exactly the

	 * same data and uses the same subarray there's _some_

	 * difference */

	md_c[0] = md_count[0];

	md_c[1] = md_count[1];

	memcpy(local_md, md, sizeof md);

	/* state_index <= state_num <= STATE_SIZE */

	state_index += num;

	if (state_index >= STATE_SIZE)

		{

		state_index%=STATE_SIZE;

		state_num=STATE_SIZE;

		}

	else if (state_num < STATE_SIZE)	

		{

		if (state_index > state_num)

			state_num=state_index;

		}

	/* state_index <= state_num <= STATE_SIZE */

	/* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]

	 * are what we will use now, but other threads may use them

	 * as well */

	md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);

	if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	EVP_MD_CTX_init(&m);

	for (i=0; i<num; i+=MD_DIGEST_LENGTH)

		{

		j=(num-i);

		j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;

		MD_Init(&m);

		MD_Update(&m,local_md,MD_DIGEST_LENGTH);

		k=(st_idx+j)-STATE_SIZE;

		if (k > 0)

			{

			MD_Update(&m,&(state[st_idx]),j-k);

			MD_Update(&m,&(state[0]),k);

			}

		else

			MD_Update(&m,&(state[st_idx]),j);

		MD_Update(&m,buf,j);

		MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));

		MD_Final(&m,local_md);

		md_c[1]++;

		buf=(const char *)buf + j;

		for (k=0; k<j; k++)

			{

			/* Parallel threads may interfere with this,

			 * but always each byte of the new state is

			 * the XOR of some previous value of its

			 * and local_md (itermediate values may be lost).

			 * Alway using locking could hurt performance more

			 * than necessary given that conflicts occur only

			 * when the total seeding is longer than the random

			 * state. */

			state[st_idx++]^=local_md[k];

			if (st_idx >= STATE_SIZE)

				st_idx=0;

			}

		}

	EVP_MD_CTX_cleanup(&m);

	if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	/* Don't just copy back local_md into md -- this could mean that

	 * other thread's seeding remains without effect (except for

	 * the incremented counter).  By XORing it we keep at least as

	 * much entropy as fits into md. */

	for (k = 0; k < (int)sizeof(md); k++)

		{

		md[k] ^= local_md[k];

		}

	if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */

	    entropy += add;

	if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

#if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)

	assert(md_c[1] == md_count[1]);

#endif

	}

static void ssleay_rand_seed(const void *buf, int num)

	{

	ssleay_rand_add(buf, num, (double)num);

	}

#ifdef EMULATOR

GET_STATIC_VAR_FROM_TLS(stirred_pool,md_rand,volatile int)

#define stirred_pool (*GET_WSD_VAR_NAME(stirred_pool,md_rand, s)())

#endif

static int ssleay_rand_bytes(unsigned char *buf, int num)

	{

#ifndef EMULATOR	

	static volatile int stirred_pool = 0;

#endif	

	int i,j,k,st_num,st_idx;

	int num_ceil;

	int ok;

	long md_c[2];

	unsigned char local_md[MD_DIGEST_LENGTH];

	EVP_MD_CTX m;

#ifndef GETPID_IS_MEANINGLESS

	pid_t curr_pid = getpid();

#endif

	int do_stir_pool = 0;

#ifdef PREDICT

	if (rand_predictable)

		{

		static unsigned char val=0;

		for (i=0; i<num; i++)

			buf[i]=val++;

		return(1);

		}

#endif

	if (num <= 0)

		return 1;

	EVP_MD_CTX_init(&m);

	/* round upwards to multiple of MD_DIGEST_LENGTH/2 */

	num_ceil = (1 + (num-1)/(MD_DIGEST_LENGTH/2)) * (MD_DIGEST_LENGTH/2);

	/*

	 * (Based on the rand(3) manpage:)

	 *

	 * For each group of 10 bytes (or less), we do the following:

	 *

	 * Input into the hash function the local 'md' (which is initialized from

	 * the global 'md' before any bytes are generated), the bytes that are to

	 * be overwritten by the random bytes, and bytes from the 'state'

	 * (incrementing looping index). From this digest output (which is kept

	 * in 'md'), the top (up to) 10 bytes are returned to the caller and the

	 * bottom 10 bytes are xored into the 'state'.

	 * 

	 * Finally, after we have finished 'num' random bytes for the

	 * caller, 'count' (which is incremented) and the local and global 'md'

	 * are fed into the hash function and the results are kept in the

	 * global 'md'.

	 */

	CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	/* prevent ssleay_rand_bytes() from trying to obtain the lock again */

	CRYPTO_w_lock(CRYPTO_LOCK_RAND2);

	locking_thread = CRYPTO_thread_id();

	CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);

	crypto_lock_rand = 1;

	if (!initialized)

		{

		RAND_poll();

		initialized = 1;

		}

	if (!stirred_pool)

		do_stir_pool = 1;

	ok = (entropy >= ENTROPY_NEEDED);

	if (!ok)

		{

		/* If the PRNG state is not yet unpredictable, then seeing

		 * the PRNG output may help attackers to determine the new

		 * state; thus we have to decrease the entropy estimate.

		 * Once we've had enough initial seeding we don't bother to

		 * adjust the entropy count, though, because we're not ambitious

		 * to provide *information-theoretic* randomness.

		 *

		 * NOTE: This approach fails if the program forks before

		 * we have enough entropy. Entropy should be collected

		 * in a separate input pool and be transferred to the

		 * output pool only when the entropy limit has been reached.

		 */

		entropy -= num;

		if (entropy < 0)

			entropy = 0;

		}

	if (do_stir_pool)

		{

		/* In the output function only half of 'md' remains secret,

		 * so we better make sure that the required entropy gets

		 * 'evenly distributed' through 'state', our randomness pool.

		 * The input function (ssleay_rand_add) chains all of 'md',

		 * which makes it more suitable for this purpose.

		 */

		int n = STATE_SIZE; /* so that the complete pool gets accessed */

		while (n > 0)

			{

#if MD_DIGEST_LENGTH > 20

# error "Please adjust DUMMY_SEED."

#endif

#define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */

			/* Note that the seed does not matter, it's just that

			 * ssleay_rand_add expects to have something to hash. */

			ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);

			n -= MD_DIGEST_LENGTH;

			}

		if (ok)

			stirred_pool = 1;

		}

	st_idx=state_index;

	st_num=state_num;

	md_c[0] = md_count[0];

	md_c[1] = md_count[1];

	memcpy(local_md, md, sizeof md);

	state_index+=num_ceil;

	if (state_index > state_num)

		state_index %= state_num;

	/* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]

	 * are now ours (but other threads may use them too) */

	md_count[0] += 1;

	/* before unlocking, we must clear 'crypto_lock_rand' */

	crypto_lock_rand = 0;

	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	while (num > 0)

		{

		/* num_ceil -= MD_DIGEST_LENGTH/2 */

		j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;

		num-=j;

		MD_Init(&m);

#ifndef GETPID_IS_MEANINGLESS

		if (curr_pid) /* just in the first iteration to save time */

			{

			MD_Update(&m,(unsigned char*)&curr_pid,sizeof curr_pid);

			curr_pid = 0;

			}

#endif

		MD_Update(&m,local_md,MD_DIGEST_LENGTH);

		MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));

#ifndef PURIFY

		MD_Update(&m,buf,j); /* purify complains */

#endif

		k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;

		if (k > 0)

			{

			MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2-k);

			MD_Update(&m,&(state[0]),k);

			}

		else

			MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2);

		MD_Final(&m,local_md);

		for (i=0; i<MD_DIGEST_LENGTH/2; i++)

			{

			state[st_idx++]^=local_md[i]; /* may compete with other threads */

			if (st_idx >= st_num)

				st_idx=0;

			if (i < j)

				*(buf++)=local_md[i+MD_DIGEST_LENGTH/2];

			}

		}

	MD_Init(&m);

	MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));

	MD_Update(&m,local_md,MD_DIGEST_LENGTH);

	CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	MD_Update(&m,md,MD_DIGEST_LENGTH);

	MD_Final(&m,md);

	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	EVP_MD_CTX_cleanup(&m);

	if (ok)

		return(1);

	else

		{

		RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);

		ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "

			"http://www.openssl.org/support/faq.html");

		return(0);

		}

	}

/* pseudo-random bytes that are guaranteed to be unique but not

   unpredictable */

static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num) 

	{

	int ret;

	unsigned long err;

	ret = RAND_bytes(buf, num);

	if (ret == 0)

		{

		err = ERR_peek_error();

		if (ERR_GET_LIB(err) == ERR_LIB_RAND &&

		    ERR_GET_REASON(err) == RAND_R_PRNG_NOT_SEEDED)

			ERR_clear_error();

		}

	return (ret);

	}

static int ssleay_rand_status(void)

	{

	int ret;

	int do_not_lock;

	/* check if we already have the lock

	 * (could happen if a RAND_poll() implementation calls RAND_status()) */

	if (crypto_lock_rand)

		{

		CRYPTO_r_lock(CRYPTO_LOCK_RAND2);

		do_not_lock = (locking_thread == CRYPTO_thread_id());

		CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);

		}

	else

		do_not_lock = 0;

	if (!do_not_lock)

		{

		CRYPTO_w_lock(CRYPTO_LOCK_RAND);

		/* prevent ssleay_rand_bytes() from trying to obtain the lock again */

		CRYPTO_w_lock(CRYPTO_LOCK_RAND2);

		locking_thread = CRYPTO_thread_id();

		CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);

		crypto_lock_rand = 1;

		}

	if (!initialized)

		{

		RAND_poll();

		initialized = 1;

		}

	ret = entropy >= ENTROPY_NEEDED;

	if (!do_not_lock)

		{

		/* before unlocking, we must clear 'crypto_lock_rand' */

		crypto_lock_rand = 0;

		CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

		}

	return ret;

	}