482 lines
12 KiB
C
482 lines
12 KiB
C
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/* $OpenBSD: bn_ctx.c,v 1.16 2019/08/20 10:59:09 schwarze Exp $ */
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/* Written by Ulf Moeller for the OpenSSL project. */
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/* ====================================================================
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* Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@openssl.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*
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* This product includes cryptographic software written by Eric Young
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* (eay@cryptsoft.com). This product includes software written by Tim
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* Hudson (tjh@cryptsoft.com).
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*
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*/
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#if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
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#ifndef NDEBUG
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#define NDEBUG
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#endif
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#endif
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#include <stdio.h>
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#include <string.h>
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#include <openssl/opensslconf.h>
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#include <openssl/err.h>
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#include "bn_lcl.h"
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/* TODO list
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*
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* 1. Check a bunch of "(words+1)" type hacks in various bignum functions and
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* check they can be safely removed.
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* - Check +1 and other ugliness in BN_from_montgomery()
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*
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* 2. Consider allowing a BN_new_ex() that, at least, lets you specify an
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* appropriate 'block' size that will be honoured by bn_expand_internal() to
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* prevent piddly little reallocations. OTOH, profiling bignum expansions in
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* BN_CTX doesn't show this to be a big issue.
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*/
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/* How many bignums are in each "pool item"; */
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#define BN_CTX_POOL_SIZE 16
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/* The stack frame info is resizing, set a first-time expansion size; */
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#define BN_CTX_START_FRAMES 32
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/***********/
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/* BN_POOL */
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/***********/
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/* A bundle of bignums that can be linked with other bundles */
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typedef struct bignum_pool_item {
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/* The bignum values */
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BIGNUM vals[BN_CTX_POOL_SIZE];
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/* Linked-list admin */
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struct bignum_pool_item *prev, *next;
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} BN_POOL_ITEM;
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/* A linked-list of bignums grouped in bundles */
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typedef struct bignum_pool {
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/* Linked-list admin */
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BN_POOL_ITEM *head, *current, *tail;
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/* Stack depth and allocation size */
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unsigned used, size;
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} BN_POOL;
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static void BN_POOL_init(BN_POOL *);
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static void BN_POOL_finish(BN_POOL *);
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#ifndef OPENSSL_NO_DEPRECATED
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static void BN_POOL_reset(BN_POOL *);
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#endif
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static BIGNUM * BN_POOL_get(BN_POOL *);
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static void BN_POOL_release(BN_POOL *, unsigned int);
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/************/
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/* BN_STACK */
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/************/
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/* A wrapper to manage the "stack frames" */
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typedef struct bignum_ctx_stack {
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/* Array of indexes into the bignum stack */
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unsigned int *indexes;
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/* Number of stack frames, and the size of the allocated array */
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unsigned int depth, size;
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} BN_STACK;
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static void BN_STACK_init(BN_STACK *);
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static void BN_STACK_finish(BN_STACK *);
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#ifndef OPENSSL_NO_DEPRECATED
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static void BN_STACK_reset(BN_STACK *);
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#endif
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static int BN_STACK_push(BN_STACK *, unsigned int);
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static unsigned int BN_STACK_pop(BN_STACK *);
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/**********/
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/* BN_CTX */
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/**********/
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/* The opaque BN_CTX type */
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struct bignum_ctx {
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/* The bignum bundles */
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BN_POOL pool;
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/* The "stack frames", if you will */
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BN_STACK stack;
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/* The number of bignums currently assigned */
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unsigned int used;
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/* Depth of stack overflow */
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int err_stack;
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/* Block "gets" until an "end" (compatibility behaviour) */
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int too_many;
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};
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/* Enable this to find BN_CTX bugs */
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#ifdef BN_CTX_DEBUG
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static const char *ctxdbg_cur = NULL;
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static void
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ctxdbg(BN_CTX *ctx)
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{
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unsigned int bnidx = 0, fpidx = 0;
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BN_POOL_ITEM *item = ctx->pool.head;
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BN_STACK *stack = &ctx->stack;
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fprintf(stderr, "(%08x): ", (unsigned int)ctx);
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while (bnidx < ctx->used) {
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fprintf(stderr, "%03x ",
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item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax);
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if (!(bnidx % BN_CTX_POOL_SIZE))
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item = item->next;
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}
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fprintf(stderr, "\n");
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bnidx = 0;
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fprintf(stderr, " : ");
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while (fpidx < stack->depth) {
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while (bnidx++ < stack->indexes[fpidx])
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fprintf(stderr, " ");
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fprintf(stderr, "^^^ ");
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bnidx++;
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fpidx++;
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}
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fprintf(stderr, "\n");
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}
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#define CTXDBG_ENTRY(str, ctx) \
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do { \
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ctxdbg_cur = (str); \
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fprintf(stderr, "Starting %s\n", ctxdbg_cur); \
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ctxdbg(ctx); \
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} while(0)
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#define CTXDBG_EXIT(ctx) \
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do { \
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fprintf(stderr, "Ending %s\n", ctxdbg_cur); \
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ctxdbg(ctx); \
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} while(0)
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#define CTXDBG_RET(ctx,ret)
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#else
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#define CTXDBG_ENTRY(str, ctx)
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#define CTXDBG_EXIT(ctx)
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#define CTXDBG_RET(ctx,ret)
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#endif
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/* This function is an evil legacy and should not be used. This implementation
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* is WYSIWYG, though I've done my best. */
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#ifndef OPENSSL_NO_DEPRECATED
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void
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BN_CTX_init(BN_CTX *ctx)
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{
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/* Assume the caller obtained the context via BN_CTX_new() and so is
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* trying to reset it for use. Nothing else makes sense, least of all
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* binary compatibility from a time when they could declare a static
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* variable. */
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BN_POOL_reset(&ctx->pool);
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BN_STACK_reset(&ctx->stack);
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ctx->used = 0;
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ctx->err_stack = 0;
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ctx->too_many = 0;
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}
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#endif
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BN_CTX *
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BN_CTX_new(void)
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{
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BN_CTX *ret = malloc(sizeof(BN_CTX));
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if (!ret) {
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BNerror(ERR_R_MALLOC_FAILURE);
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return NULL;
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}
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/* Initialise the structure */
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BN_POOL_init(&ret->pool);
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BN_STACK_init(&ret->stack);
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ret->used = 0;
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ret->err_stack = 0;
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ret->too_many = 0;
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return ret;
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}
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void
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BN_CTX_free(BN_CTX *ctx)
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{
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if (ctx == NULL)
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return;
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#ifdef BN_CTX_DEBUG
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{
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BN_POOL_ITEM *pool = ctx->pool.head;
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fprintf(stderr, "BN_CTX_free, stack-size=%d, pool-bignums=%d\n",
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ctx->stack.size, ctx->pool.size);
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fprintf(stderr, "dmaxs: ");
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while (pool) {
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unsigned loop = 0;
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while (loop < BN_CTX_POOL_SIZE)
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fprintf(stderr, "%02x ",
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pool->vals[loop++].dmax);
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pool = pool->next;
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}
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fprintf(stderr, "\n");
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}
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#endif
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BN_STACK_finish(&ctx->stack);
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BN_POOL_finish(&ctx->pool);
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free(ctx);
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}
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void
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BN_CTX_start(BN_CTX *ctx)
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{
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CTXDBG_ENTRY("BN_CTX_start", ctx);
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/* If we're already overflowing ... */
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if (ctx->err_stack || ctx->too_many)
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ctx->err_stack++;
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/* (Try to) get a new frame pointer */
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else if (!BN_STACK_push(&ctx->stack, ctx->used)) {
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BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
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ctx->err_stack++;
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}
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CTXDBG_EXIT(ctx);
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}
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void
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BN_CTX_end(BN_CTX *ctx)
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{
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if (ctx == NULL)
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return;
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CTXDBG_ENTRY("BN_CTX_end", ctx);
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if (ctx->err_stack)
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ctx->err_stack--;
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else {
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unsigned int fp = BN_STACK_pop(&ctx->stack);
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/* Does this stack frame have anything to release? */
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if (fp < ctx->used)
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BN_POOL_release(&ctx->pool, ctx->used - fp);
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ctx->used = fp;
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/* Unjam "too_many" in case "get" had failed */
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ctx->too_many = 0;
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}
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CTXDBG_EXIT(ctx);
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}
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BIGNUM *
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BN_CTX_get(BN_CTX *ctx)
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{
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BIGNUM *ret;
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CTXDBG_ENTRY("BN_CTX_get", ctx);
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if (ctx->err_stack || ctx->too_many)
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return NULL;
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if ((ret = BN_POOL_get(&ctx->pool)) == NULL) {
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/* Setting too_many prevents repeated "get" attempts from
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* cluttering the error stack. */
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ctx->too_many = 1;
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BNerror(BN_R_TOO_MANY_TEMPORARY_VARIABLES);
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return NULL;
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}
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/* OK, make sure the returned bignum is "zero" */
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BN_zero(ret);
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ctx->used++;
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CTXDBG_RET(ctx, ret);
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return ret;
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}
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/************/
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/* BN_STACK */
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/************/
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static void
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BN_STACK_init(BN_STACK *st)
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{
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st->indexes = NULL;
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st->depth = st->size = 0;
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}
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static void
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BN_STACK_finish(BN_STACK *st)
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{
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if (st->size)
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free(st->indexes);
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}
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#ifndef OPENSSL_NO_DEPRECATED
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static void
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BN_STACK_reset(BN_STACK *st)
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{
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st->depth = 0;
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}
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#endif
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static int
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BN_STACK_push(BN_STACK *st, unsigned int idx)
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{
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if (st->depth == st->size)
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/* Need to expand */
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{
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unsigned int newsize = (st->size ?
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(st->size * 3 / 2) : BN_CTX_START_FRAMES);
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unsigned int *newitems = reallocarray(NULL,
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newsize, sizeof(unsigned int));
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if (!newitems)
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return 0;
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if (st->depth)
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memcpy(newitems, st->indexes, st->depth *
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sizeof(unsigned int));
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if (st->size)
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free(st->indexes);
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st->indexes = newitems;
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st->size = newsize;
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}
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st->indexes[(st->depth)++] = idx;
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return 1;
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}
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static unsigned int
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BN_STACK_pop(BN_STACK *st)
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{
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return st->indexes[--(st->depth)];
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}
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||
|
|
|
||
|
|
/***********/
|
||
|
|
/* 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;
|
||
|
|
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 = 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--;
|
||
|
|
}
|
||
|
|
}
|