[thirdparty/openssl.git] / crypto / bn / bn_ctx.c

/* crypto/bn/bn_ctx.c */
/* Written by Ulf Moeller for the OpenSSL project. */
/* ====================================================================
 * Copyright (c) 1998-2004 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).
 *
 */

#if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
#ifndef NDEBUG
#define NDEBUG
#endif
#endif

#include <stdio.h>
#include <assert.h>

#include "cryptlib.h"
#include "bn_lcl.h"

/* TODO list
 *
 * 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
 * check they can be safely removed.
 *  - Check +1 and other ugliness in BN_from_montgomery()
 *
 * 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
 * appropriate 'block' size that will be honoured by bn_expand_internal() to
 * prevent piddly little reallocations. OTOH, profiling bignum expansions in
 * BN_CTX doesn't show this to be a big issue.
 */

/* How many bignums are in each "pool item"; */
#define BN_CTX_POOL_SIZE	16
/* The stack frame info is resizing, set a first-time expansion size; */
#define BN_CTX_START_FRAMES	32

/***********/
/* BN_POOL */
/***********/

/* A bundle of bignums that can be linked with other bundles */
typedef struct bignum_pool_item
	{
	/* The bignum values */
	BIGNUM vals[BN_CTX_POOL_SIZE];
	/* Linked-list admin */
	struct bignum_pool_item *prev, *next;
	} BN_POOL_ITEM;
/* A linked-list of bignums grouped in bundles */
typedef struct bignum_pool
	{
	/* Linked-list admin */
	BN_POOL_ITEM *head, *current, *tail;
	/* Stack depth and allocation size */
	unsigned used, size;
	} BN_POOL;
static void		BN_POOL_init(BN_POOL *);
static void		BN_POOL_finish(BN_POOL *);
#ifndef OPENSSL_NO_DEPRECATED
static void		BN_POOL_reset(BN_POOL *);
#endif
static BIGNUM *		BN_POOL_get(BN_POOL *);
static void		BN_POOL_release(BN_POOL *, unsigned int);

/************/
/* BN_STACK */
/************/

/* A wrapper to manage the "stack frames" */
typedef struct bignum_ctx_stack
	{
	/* Array of indexes into the bignum stack */
	unsigned int *indexes;
	/* Number of stack frames, and the size of the allocated array */
	unsigned int depth, size;
	} BN_STACK;
static void		BN_STACK_init(BN_STACK *);
static void		BN_STACK_finish(BN_STACK *);
#ifndef OPENSSL_NO_DEPRECATED
static void		BN_STACK_reset(BN_STACK *);
#endif
static int		BN_STACK_push(BN_STACK *, unsigned int);
static unsigned int	BN_STACK_pop(BN_STACK *);

/**********/
/* BN_CTX */
/**********/

/* The opaque BN_CTX type */
struct bignum_ctx
	{
	/* The bignum bundles */
	BN_POOL pool;
	/* The "stack frames", if you will */
	BN_STACK stack;
	/* The number of bignums currently assigned */
	unsigned int used;
	/* Depth of stack overflow */
	int err_stack;
	/* Block "gets" until an "end" (compatibility behaviour) */
	int too_many;
	};

/* Enable this to find BN_CTX bugs */
#ifdef BN_CTX_DEBUG
static const char *ctxdbg_cur = NULL;
static void ctxdbg(BN_CTX *ctx)
	{
	unsigned int bnidx = 0, fpidx = 0;
	BN_POOL_ITEM *item = ctx->pool.head;
	BN_STACK *stack = &ctx->stack;
	fprintf(stderr,"(%08x): ", (unsigned int)ctx);
	while(bnidx < ctx->used)
		{
		fprintf(stderr,"%02x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
		if(!(bnidx % BN_CTX_POOL_SIZE))
			item = item->next;
		}
	fprintf(stderr,"\n");
	bnidx = 0;
	fprintf(stderr,"          : ");
	while(fpidx < stack->depth)
		{
		while(bnidx++ < stack->indexes[fpidx])
			fprintf(stderr,"   ");
		fprintf(stderr,"^^ ");
		bnidx++;
		fpidx++;
		}
	fprintf(stderr,"\n");
	}
#define CTXDBG_ENTRY(str, ctx)	do { \
				ctxdbg_cur = (str); \
				fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
				ctxdbg(ctx); \
				} while(0)
#define CTXDBG_EXIT(ctx)	do { \
				fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
				ctxdbg(ctx); \
				} while(0)
#define CTXDBG_RET(ctx,ret)
#else
#define CTXDBG_ENTRY(str, ctx)
#define CTXDBG_EXIT(ctx)
#define CTXDBG_RET(ctx,ret)
#endif

/* This function is an evil legacy and should not be used. This implementation
 * is WYSIWYG, though I've done my best. */
#ifndef OPENSSL_NO_DEPRECATED
void BN_CTX_init(BN_CTX *ctx)
	{
	/* Assume the caller obtained the context via BN_CTX_new() and so is
	 * trying to reset it for use. Nothing else makes sense, least of all
	 * binary compatibility from a time when they could declare a static
	 * variable. */
	BN_POOL_reset(&ctx->pool);
	BN_STACK_reset(&ctx->stack);
	ctx->used = 0;
	ctx->err_stack = 0;
	ctx->too_many = 0;
	}
#endif

BN_CTX *BN_CTX_new(void)
	{
	BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
	if(!ret)
		{
		BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
		return NULL;
		}
	/* Initialise the structure */
	BN_POOL_init(&ret->pool);
	BN_STACK_init(&ret->stack);
	ret->used = 0;
	ret->err_stack = 0;
	ret->too_many = 0;
	return ret;
	}

void BN_CTX_free(BN_CTX *ctx)
	{
#ifdef BN_CTX_DEBUG
	BN_POOL_ITEM *pool = ctx->pool.head;
	fprintf(stderr,"BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
		ctx->stack.size, ctx->pool.size);
	fprintf(stderr,"dmaxs: ");
	while(pool) {
		unsigned loop = 0;
		while(loop < BN_CTX_POOL_SIZE)
			fprintf(stderr,"%02x ", pool->vals[loop++].dmax);
		pool = pool->next;
	}
	fprintf(stderr,"\n");
#endif
	BN_STACK_finish(&ctx->stack);
	BN_POOL_finish(&ctx->pool);
	OPENSSL_free(ctx);
	}

void BN_CTX_start(BN_CTX *ctx)
	{
	CTXDBG_ENTRY("BN_CTX_start", ctx);
	/* If we're already overflowing ... */
	if(ctx->err_stack || ctx->too_many)
		ctx->err_stack++;
	/* (Try to) get a new frame pointer */
	else if(!BN_STACK_push(&ctx->stack, ctx->used))
		{
		BNerr(BN_F_BN_CTX_START,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
		ctx->err_stack++;
		}
	CTXDBG_EXIT(ctx);
	}

void BN_CTX_end(BN_CTX *ctx)
	{
	CTXDBG_ENTRY("BN_CTX_end", ctx);
	if(ctx->err_stack)
		ctx->err_stack--;
	else
		{
		unsigned int fp = BN_STACK_pop(&ctx->stack);
		/* Does this stack frame have anything to release? */
		if(fp < ctx->used)
			BN_POOL_release(&ctx->pool, ctx->used - fp);
		ctx->used = fp;
		/* Unjam "too_many" in case "get" had failed */
		ctx->too_many = 0;
		}
	CTXDBG_EXIT(ctx);
	}

BIGNUM *BN_CTX_get(BN_CTX *ctx)
	{
	BIGNUM *ret;
	CTXDBG_ENTRY("BN_CTX_get", ctx);
	if(ctx->err_stack || ctx->too_many) return NULL;
	if((ret = BN_POOL_get(&ctx->pool)) == NULL)
		{
		/* Setting too_many prevents repeated "get" attempts from
		 * cluttering the error stack. */
		ctx->too_many = 1;
		BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
		return NULL;
		}
	/* OK, make sure the returned bignum is "zero" */
	BN_zero(ret);
	ctx->used++;
	CTXDBG_RET(ctx, ret);
	return ret;
	}

/************/
/* BN_STACK */
/************/

static void BN_STACK_init(BN_STACK *st)
	{
	st->indexes = NULL;
	st->depth = st->size = 0;
	}

static void BN_STACK_finish(BN_STACK *st)
	{
	if(st->size) OPENSSL_free(st->indexes);
	}

#ifndef OPENSSL_NO_DEPRECATED
static void BN_STACK_reset(BN_STACK *st)
	{
	st->depth = 0;
	}
#endif

static int BN_STACK_push(BN_STACK *st, unsigned int idx)
	{
	if(st->depth == st->size)
		/* Need to expand */
		{
		unsigned int newsize = (st->size ?
				(st->size * 3 / 2) : BN_CTX_START_FRAMES);
		unsigned int *newitems = OPENSSL_malloc(newsize *
						sizeof(unsigned int));
		if(!newitems) return 0;
		if(st->depth)
			memcpy(newitems, st->indexes, st->depth *
						sizeof(unsigned int));
		if(st->size) OPENSSL_free(st->indexes);
		st->indexes = newitems;
		st->size = newsize;
		}
	st->indexes[(st->depth)++] = idx;
	return 1;
	}

static unsigned int BN_STACK_pop(BN_STACK *st)
	{
	return st->indexes[--(st->depth)];
	}

/***********/
/* BN_POOL */
/***********/

static void BN_POOL_init(BN_POOL *p)
	{
	p->head = p->current = p->tail = NULL;
	p->used = p->size = 0;
	}

static void BN_POOL_finish(BN_POOL *p)
	{
	while(p->head)
		{
		unsigned int loop = 0;
		BIGNUM *bn = p->head->vals;
		while(loop++ < BN_CTX_POOL_SIZE)
			{
			if(bn->d) BN_clear_free(bn);
			bn++;
			}
		p->current = p->head->next;
		OPENSSL_free(p->head);
		p->head = p->current;
		}
	}

#ifndef OPENSSL_NO_DEPRECATED
static void BN_POOL_reset(BN_POOL *p)
	{
	BN_POOL_ITEM *item = p->head;
	while(item)
		{
		unsigned int loop = 0;
		BIGNUM *bn = item->vals;
		while(loop++ < BN_CTX_POOL_SIZE)
			{
			if(bn->d) BN_clear(bn);
			bn++;
			}
		item = item->next;
		}
	p->current = p->head;
	p->used = 0;
	}
#endif

static BIGNUM *BN_POOL_get(BN_POOL *p)
	{
	if(p->used == p->size)
		{
		BIGNUM *bn;
		unsigned int loop = 0;
		BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
		if(!item) return NULL;
		/* Initialise the structure */
		bn = item->vals;
		while(loop++ < BN_CTX_POOL_SIZE)
			BN_init(bn++);
		item->prev = p->tail;
		item->next = NULL;
		/* Link it in */
		if(!p->head)
			p->head = p->current = p->tail = item;
		else
			{
			p->tail->next = item;
			p->tail = item;
			p->current = item;
			}
		p->size += BN_CTX_POOL_SIZE;
		p->used++;
		/* Return the first bignum from the new pool */
		return item->vals;
		}
	if(!p->used)
		p->current = p->head;
	else if((p->used % BN_CTX_POOL_SIZE) == 0)
		p->current = p->current->next;
	return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
	}

static void BN_POOL_release(BN_POOL *p, unsigned int num)
	{
	unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
	p->used -= num;
	while(num--)
		{
		bn_check_top(p->current->vals + offset);
		if(!offset)
			{
			offset = BN_CTX_POOL_SIZE - 1;
			p->current = p->current->prev;
			}
		else
			offset--;
		}
	}
Commit	Line	Data
9b141126 UM	1	/* crypto/bn/bn_ctx.c */
	2	/* Written by Ulf Moeller for the OpenSSL project. */
	3	/* ====================================================================
5c98b2ca	4	* Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
9b141126 UM	5	*
	6	* Redistribution and use in source and binary forms, with or without
	7	* modification, are permitted provided that the following conditions
	8	* are met:
	9	*
	10	* 1. Redistributions of source code must retain the above copyright
	11	* notice, this list of conditions and the following disclaimer.
	12	*
	13	* 2. Redistributions in binary form must reproduce the above copyright
	14	* notice, this list of conditions and the following disclaimer in
	15	* the documentation and/or other materials provided with the
	16	* distribution.
	17	*
	18	* 3. All advertising materials mentioning features or use of this
	19	* software must display the following acknowledgment:
	20	* "This product includes software developed by the OpenSSL Project
	21	* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
	22	*
	23	* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
	24	* endorse or promote products derived from this software without
	25	* prior written permission. For written permission, please contact
	26	* openssl-core@openssl.org.
	27	*
	28	* 5. Products derived from this software may not be called "OpenSSL"
	29	* nor may "OpenSSL" appear in their names without prior written
	30	* permission of the OpenSSL Project.
	31	*
	32	* 6. Redistributions of any form whatsoever must retain the following
	33	* acknowledgment:
	34	* "This product includes software developed by the OpenSSL Project
	35	* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
	36	*
	37	* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
	38	* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	39	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	40	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
	41	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	42	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	43	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	44	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	45	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	46	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	47	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
	48	* OF THE POSSIBILITY OF SUCH DAMAGE.
	49	* ====================================================================
	50	*
	51	* This product includes cryptographic software written by Eric Young
	52	* (eay@cryptsoft.com). This product includes software written by Tim
	53	* Hudson (tjh@cryptsoft.com).
	54	*
	55	*/
	56
2ce90b9b GT	57	#if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
	58	#ifndef NDEBUG
	59	#define NDEBUG
	60	#endif
37e48b88 BM	61	#endif
37e48b88 BM	62
9b141126 UM	63	#include <stdio.h>
9b141126 UM	64	#include <assert.h>
c62b26fd	65
9b141126	66	#include "cryptlib.h"
c62b26fd	67	#include "bn_lcl.h"
9b141126	68
5c98b2ca GT	69	/* TODO list
	70	*
	71	* 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
	72	* check they can be safely removed.
5c98b2ca	73	* - Check +1 and other ugliness in BN_from_montgomery()
5c98b2ca GT	74	*
	75	* 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
	76	* appropriate 'block' size that will be honoured by bn_expand_internal() to
	77	* prevent piddly little reallocations. OTOH, profiling bignum expansions in
	78	* BN_CTX doesn't show this to be a big issue.
	79	*/
	80
	81	/* How many bignums are in each "pool item"; */
	82	#define BN_CTX_POOL_SIZE 16
	83	/* The stack frame info is resizing, set a first-time expansion size; */
	84	#define BN_CTX_START_FRAMES 32
	85
	86	/***********/
	87	/* BN_POOL */
	88	/***********/
	89
	90	/* A bundle of bignums that can be linked with other bundles */
	91	typedef struct bignum_pool_item
	92	{
	93	/* The bignum values */
	94	BIGNUM vals[BN_CTX_POOL_SIZE];
	95	/* Linked-list admin */
	96	struct bignum_pool_item prev, next;
	97	} BN_POOL_ITEM;
	98	/* A linked-list of bignums grouped in bundles */
	99	typedef struct bignum_pool
	100	{
	101	/* Linked-list admin */
	102	BN_POOL_ITEM head, current, *tail;
	103	/* Stack depth and allocation size */
	104	unsigned used, size;
	105	} BN_POOL;
	106	static void BN_POOL_init(BN_POOL *);
	107	static void BN_POOL_finish(BN_POOL *);
	108	#ifndef OPENSSL_NO_DEPRECATED
	109	static void BN_POOL_reset(BN_POOL *);
	110	#endif
	111	static BIGNUM * BN_POOL_get(BN_POOL *);
	112	static void BN_POOL_release(BN_POOL *, unsigned int);
	113
	114	/************/
	115	/* BN_STACK */
	116	/************/
	117
	118	/* A wrapper to manage the "stack frames" */
	119	typedef struct bignum_ctx_stack
	120	{
	121	/* Array of indexes into the bignum stack */
	122	unsigned int *indexes;
	123	/* Number of stack frames, and the size of the allocated array */
	124	unsigned int depth, size;
	125	} BN_STACK;
	126	static void BN_STACK_init(BN_STACK *);
	127	static void BN_STACK_finish(BN_STACK *);
	128	#ifndef OPENSSL_NO_DEPRECATED
	129	static void BN_STACK_reset(BN_STACK *);
	130	#endif
	131	static int BN_STACK_push(BN_STACK *, unsigned int);
	132	static unsigned int BN_STACK_pop(BN_STACK *);
	133
	134	/**********/
	135	/* BN_CTX */
	136	/**********/
	137
138	/* The opaque BN_CTX type */
2ce90b9b	139	struct bignum_ctx
9b141126	140	{
5c98b2ca GT	141	/* The bignum bundles */
	142	BN_POOL pool;
	143	/* The "stack frames", if you will */
	144	BN_STACK stack;
	145	/* The number of bignums currently assigned */
	146	unsigned int used;
	147	/* Depth of stack overflow */
	148	int err_stack;
	149	/* Block "gets" until an "end" (compatibility behaviour) */
2ce90b9b GT	150	int too_many;
2ce90b9b GT	151	};
9b141126	152
5c98b2ca GT	153	/* Enable this to find BN_CTX bugs */
	154	#ifdef BN_CTX_DEBUG
	155	static const char *ctxdbg_cur = NULL;
	156	static void ctxdbg(BN_CTX *ctx)
	157	{
	158	unsigned int bnidx = 0, fpidx = 0;
	159	BN_POOL_ITEM *item = ctx->pool.head;
	160	BN_STACK *stack = &ctx->stack;
863d2b19	161	fprintf(stderr,"(%08x): ", (unsigned int)ctx);
5c98b2ca GT	162	while(bnidx < ctx->used)
5c98b2ca GT	163	{
863d2b19	164	fprintf(stderr,"%02x ", item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
5c98b2ca GT	165	if(!(bnidx % BN_CTX_POOL_SIZE))
	166	item = item->next;
	167	}
863d2b19	168	fprintf(stderr,"\n");
5c98b2ca	169	bnidx = 0;
863d2b19	170	fprintf(stderr," : ");
5c98b2ca GT	171	while(fpidx < stack->depth)
	172	{
	173	while(bnidx++ < stack->indexes[fpidx])
863d2b19 RL	174	fprintf(stderr," ");
863d2b19 RL	175	fprintf(stderr,"^^ ");
5c98b2ca GT	176	bnidx++;
	177	fpidx++;
	178	}
863d2b19	179	fprintf(stderr,"\n");
5c98b2ca GT	180	}
	181	#define CTXDBG_ENTRY(str, ctx) do { \
	182	ctxdbg_cur = (str); \
863d2b19	183	fprintf(stderr,"Starting %s\n", ctxdbg_cur); \
5c98b2ca GT	184	ctxdbg(ctx); \
	185	} while(0)
	186	#define CTXDBG_EXIT(ctx) do { \
863d2b19	187	fprintf(stderr,"Ending %s\n", ctxdbg_cur); \
5c98b2ca GT	188	ctxdbg(ctx); \
	189	} while(0)
	190	#define CTXDBG_RET(ctx,ret)
2ce90b9b	191	#else
5c98b2ca GT	192	#define CTXDBG_ENTRY(str, ctx)
	193	#define CTXDBG_EXIT(ctx)
	194	#define CTXDBG_RET(ctx,ret)
2ce90b9b	195	#endif
5c98b2ca GT	196
	197	/* This function is an evil legacy and should not be used. This implementation
	198	* is WYSIWYG, though I've done my best. */
	199	#ifndef OPENSSL_NO_DEPRECATED
	200	void BN_CTX_init(BN_CTX *ctx)
9b141126	201	{
5c98b2ca GT	202	/* Assume the caller obtained the context via BN_CTX_new() and so is
	203	* trying to reset it for use. Nothing else makes sense, least of all
	204	* binary compatibility from a time when they could declare a static
	205	* variable. */
	206	BN_POOL_reset(&ctx->pool);
	207	BN_STACK_reset(&ctx->stack);
	208	ctx->used = 0;
	209	ctx->err_stack = 0;
eb5a6a55	210	ctx->too_many = 0;
9b141126	211	}
5c98b2ca	212	#endif
9b141126	213
2ce90b9b GT	214	BN_CTX *BN_CTX_new(void)
2ce90b9b GT	215	{
5c98b2ca GT	216	BN_CTX *ret = OPENSSL_malloc(sizeof(BN_CTX));
5c98b2ca GT	217	if(!ret)
2ce90b9b GT	218	{
2ce90b9b GT	219	BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
5c98b2ca	220	return NULL;
2ce90b9b	221	}
5c98b2ca GT	222	/* Initialise the structure */
	223	BN_POOL_init(&ret->pool);
	224	BN_STACK_init(&ret->stack);
	225	ret->used = 0;
	226	ret->err_stack = 0;
	227	ret->too_many = 0;
	228	return ret;
2ce90b9b GT	229	}
2ce90b9b GT	230
9b141126 UM	231	void BN_CTX_free(BN_CTX *ctx)
9b141126 UM	232	{
5c98b2ca GT	233	#ifdef BN_CTX_DEBUG
5c98b2ca GT	234	BN_POOL_ITEM *pool = ctx->pool.head;
863d2b19	235	fprintf(stderr,"BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
5c98b2ca	236	ctx->stack.size, ctx->pool.size);
863d2b19	237	fprintf(stderr,"dmaxs: ");
5c98b2ca GT	238	while(pool) {
	239	unsigned loop = 0;
	240	while(loop < BN_CTX_POOL_SIZE)
863d2b19	241	fprintf(stderr,"%02x ", pool->vals[loop++].dmax);
5c98b2ca	242	pool = pool->next;
d870740c	243	}
863d2b19	244	fprintf(stderr,"\n");
5c98b2ca GT	245	#endif
	246	BN_STACK_finish(&ctx->stack);
	247	BN_POOL_finish(&ctx->pool);
	248	OPENSSL_free(ctx);
9b141126 UM	249	}
	250
	251	void BN_CTX_start(BN_CTX *ctx)
	252	{
5c98b2ca GT	253	CTXDBG_ENTRY("BN_CTX_start", ctx);
	254	/* If we're already overflowing ... */
	255	if(ctx->err_stack \|\| ctx->too_many)
	256	ctx->err_stack++;
	257	/* (Try to) get a new frame pointer */
	258	else if(!BN_STACK_push(&ctx->stack, ctx->used))
	259	{
aa4ce731	260	BNerr(BN_F_BN_CTX_START,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
5c98b2ca GT	261	ctx->err_stack++;
	262	}
	263	CTXDBG_EXIT(ctx);
9b141126 UM	264	}
9b141126 UM	265
5c98b2ca GT	266	void BN_CTX_end(BN_CTX *ctx)
	267	{
	268	CTXDBG_ENTRY("BN_CTX_end", ctx);
	269	if(ctx->err_stack)
	270	ctx->err_stack--;
	271	else
	272	{
	273	unsigned int fp = BN_STACK_pop(&ctx->stack);
	274	/* Does this stack frame have anything to release? */
	275	if(fp < ctx->used)
	276	BN_POOL_release(&ctx->pool, ctx->used - fp);
	277	ctx->used = fp;
	278	/* Unjam "too_many" in case "get" had failed */
	279	ctx->too_many = 0;
	280	}
	281	CTXDBG_EXIT(ctx);
	282	}
7f7b8d68	283
9b141126 UM	284	BIGNUM BN_CTX_get(BN_CTX ctx)
9b141126 UM	285	{
9e051bac	286	BIGNUM *ret;
5c98b2ca GT	287	CTXDBG_ENTRY("BN_CTX_get", ctx);
	288	if(ctx->err_stack \|\| ctx->too_many) return NULL;
	289	if((ret = BN_POOL_get(&ctx->pool)) == NULL)
9b141126	290	{
5c98b2ca GT	291	/* Setting too_many prevents repeated "get" attempts from
	292	* cluttering the error stack. */
	293	ctx->too_many = 1;
	294	BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
9b141126 UM	295	return NULL;
9b141126 UM	296	}
5c98b2ca	297	/* OK, make sure the returned bignum is "zero" */
9e051bac	298	BN_zero(ret);
5c98b2ca GT	299	ctx->used++;
5c98b2ca GT	300	CTXDBG_RET(ctx, ret);
9e051bac	301	return ret;
9b141126 UM	302	}
9b141126 UM	303
5c98b2ca GT	304	/************/
	305	/* BN_STACK */
	306	/************/
	307
	308	static void BN_STACK_init(BN_STACK *st)
	309	{
	310	st->indexes = NULL;
	311	st->depth = st->size = 0;
	312	}
	313
	314	static void BN_STACK_finish(BN_STACK *st)
9b141126	315	{
5c98b2ca GT	316	if(st->size) OPENSSL_free(st->indexes);
5c98b2ca GT	317	}
37e48b88	318
5c98b2ca GT	319	#ifndef OPENSSL_NO_DEPRECATED
	320	static void BN_STACK_reset(BN_STACK *st)
	321	{
	322	st->depth = 0;
	323	}
	324	#endif
	325
	326	static int BN_STACK_push(BN_STACK *st, unsigned int idx)
	327	{
	328	if(st->depth == st->size)
	329	/* Need to expand */
	330	{
	331	unsigned int newsize = (st->size ?
	332	(st->size * 3 / 2) : BN_CTX_START_FRAMES);
	333	unsigned int newitems = OPENSSL_malloc(newsize
	334	sizeof(unsigned int));
	335	if(!newitems) return 0;
	336	if(st->depth)
	337	memcpy(newitems, st->indexes, st->depth *
	338	sizeof(unsigned int));
	339	if(st->size) OPENSSL_free(st->indexes);
	340	st->indexes = newitems;
	341	st->size = newsize;
	342	}
	343	st->indexes[(st->depth)++] = idx;
	344	return 1;
	345	}
	346
	347	static unsigned int BN_STACK_pop(BN_STACK *st)
	348	{
	349	return st->indexes[--(st->depth)];
	350	}
	351
	352	/***********/
	353	/* BN_POOL */
	354	/***********/
	355
	356	static void BN_POOL_init(BN_POOL *p)
	357	{
	358	p->head = p->current = p->tail = NULL;
	359	p->used = p->size = 0;
	360	}
	361
	362	static void BN_POOL_finish(BN_POOL *p)
	363	{
	364	while(p->head)
	365	{
	366	unsigned int loop = 0;
	367	BIGNUM *bn = p->head->vals;
	368	while(loop++ < BN_CTX_POOL_SIZE)
	369	{
	370	if(bn->d) BN_clear_free(bn);
	371	bn++;
	372	}
	373	p->current = p->head->next;
	374	OPENSSL_free(p->head);
	375	p->head = p->current;
	376	}
	377	}
	378
	379	#ifndef OPENSSL_NO_DEPRECATED
	380	static void BN_POOL_reset(BN_POOL *p)
	381	{
	382	BN_POOL_ITEM *item = p->head;
383	while(item)
384	{
385	unsigned int loop = 0;
386	BIGNUM *bn = item->vals;
387	while(loop++ < BN_CTX_POOL_SIZE)
388	{
389	if(bn->d) BN_clear(bn);
390	bn++;
391	}
392	item = item->next;
393	}
394	p->current = p->head;
395	p->used = 0;
396	}
5f747c7f	397	#endif
5c98b2ca GT	398
	399	static BIGNUM BN_POOL_get(BN_POOL p)
	400	{
	401	if(p->used == p->size)
	402	{
	403	BIGNUM *bn;
	404	unsigned int loop = 0;
	405	BN_POOL_ITEM *item = OPENSSL_malloc(sizeof(BN_POOL_ITEM));
	406	if(!item) return NULL;
	407	/* Initialise the structure */
	408	bn = item->vals;
	409	while(loop++ < BN_CTX_POOL_SIZE)
	410	BN_init(bn++);
	411	item->prev = p->tail;
	412	item->next = NULL;
	413	/* Link it in */
	414	if(!p->head)
	415	p->head = p->current = p->tail = item;
	416	else
	417	{
	418	p->tail->next = item;
	419	p->tail = item;
	420	p->current = item;
	421	}
	422	p->size += BN_CTX_POOL_SIZE;
	423	p->used++;
	424	/* Return the first bignum from the new pool */
	425	return item->vals;
	426	}
	427	if(!p->used)
	428	p->current = p->head;
	429	else if((p->used % BN_CTX_POOL_SIZE) == 0)
	430	p->current = p->current->next;
	431	return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE);
	432	}
	433
	434	static void BN_POOL_release(BN_POOL *p, unsigned int num)
	435	{
	436	unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
	437	p->used -= num;
	438	while(num--)
	439	{
	440	bn_check_top(p->current->vals + offset);
	441	if(!offset)
	442	{
	443	offset = BN_CTX_POOL_SIZE - 1;
	444	p->current = p->current->prev;
	445	}
	446	else
	447	offset--;
	448	}
9b141126	449	}
5c98b2ca	450