bn_lib.c

mediastreamer2是开源的网络传输媒体流的库

/* crypto/bn/bn_lib.c */
/* Copyright (C) 1995-1998 Eric Young ([e-mail])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([e-mail]).
 * 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 ([e-mail]).
 * 
 * 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 ([e-mail])"
 *    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 ([e-mail])"
 * 
 * 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.]
 */

#ifndef BN_DEBUG
# undef NDEBUG /* avoid conflicting definitions */
# define NDEBUG
#endif

#include <assert.h>
#include <limits.h>
#include <stdio.h>
#include "cryptlib.h"
#include "bn_lcl.h"

const char *BN_version="Big Number" OPENSSL_VERSION_PTEXT;

/* This stuff appears to be completely unused, so is deprecated */
#ifndef OPENSSL_NO_DEPRECATED
/* For a 32 bit machine
 * 2 -   4 ==  128
 * 3 -   8 ==  256
 * 4 -  16 ==  512
 * 5 -  32 == 1024
 * 6 -  64 == 2048
 * 7 - 128 == 4096
 * 8 - 256 == 8192
 */
static int bn_limit_bits=0;
static int bn_limit_num=8;        /* (1<<bn_limit_bits) */
static int bn_limit_bits_low=0;
static int bn_limit_num_low=8;    /* (1<<bn_limit_bits_low) */
static int bn_limit_bits_high=0;
static int bn_limit_num_high=8;   /* (1<<bn_limit_bits_high) */
static int bn_limit_bits_mont=0;
static int bn_limit_num_mont=8;   /* (1<<bn_limit_bits_mont) */

void BN_set_params(int mult, int high, int low, int mont)
	{
	if (mult >= 0)
		{
		if (mult > (int)(sizeof(int)*8)-1)
			mult=sizeof(int)*8-1;
		bn_limit_bits=mult;
		bn_limit_num=1<<mult;
		}
	if (high >= 0)
		{
		if (high > (int)(sizeof(int)*8)-1)
			high=sizeof(int)*8-1;
		bn_limit_bits_high=high;
		bn_limit_num_high=1<<high;
		}
	if (low >= 0)
		{
		if (low > (int)(sizeof(int)*8)-1)
			low=sizeof(int)*8-1;
		bn_limit_bits_low=low;
		bn_limit_num_low=1<<low;
		}
	if (mont >= 0)
		{
		if (mont > (int)(sizeof(int)*8)-1)
			mont=sizeof(int)*8-1;
		bn_limit_bits_mont=mont;
		bn_limit_num_mont=1<<mont;
		}
	}

int BN_get_params(int which)
	{
	if      (which == 0) return(bn_limit_bits);
	else if (which == 1) return(bn_limit_bits_high);
	else if (which == 2) return(bn_limit_bits_low);
	else if (which == 3) return(bn_limit_bits_mont);
	else return(0);
	}
#endif

const BIGNUM *BN_value_one(void)
	{
	static BN_ULONG data_one=1L;
	static BIGNUM const_one={&data_one,1,1,0,BN_FLG_STATIC_DATA};

	return(&const_one);
	}

char *BN_options(void)
	{
	static int init=0;
	static char data[16];

	if (!init)
		{
		init++;
#ifdef BN_LLONG
		BIO_snprintf(data,sizeof data,"bn(%d,%d)",
			     (int)sizeof(BN_ULLONG)*8,(int)sizeof(BN_ULONG)*8);
#else
		BIO_snprintf(data,sizeof data,"bn(%d,%d)",
			     (int)sizeof(BN_ULONG)*8,(int)sizeof(BN_ULONG)*8);
#endif
		}
	return(data);
	}

int BN_num_bits_word(BN_ULONG l)
	{
	static const char bits[256]={
		0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,
		5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
		6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
		6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
		8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
		8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
		8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
		8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
		8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
		8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
		8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
		8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
		};

#if defined(SIXTY_FOUR_BIT_LONG)
	if (l & 0xffffffff00000000L)
		{
		if (l & 0xffff000000000000L)
			{
			if (l & 0xff00000000000000L)
				{
				return(bits[(int)(l>>56)]+56);
				}
			else	return(bits[(int)(l>>48)]+48);
			}
		else
			{
			if (l & 0x0000ff0000000000L)
				{
				return(bits[(int)(l>>40)]+40);
				}
			else	return(bits[(int)(l>>32)]+32);
			}
		}
	else
#else
#ifdef SIXTY_FOUR_BIT
	if (l & 0xffffffff00000000LL)
		{
		if (l & 0xffff000000000000LL)
			{
			if (l & 0xff00000000000000LL)
				{
				return(bits[(int)(l>>56)]+56);
				}
			else	return(bits[(int)(l>>48)]+48);
			}
		else
			{
			if (l & 0x0000ff0000000000LL)
				{
				return(bits[(int)(l>>40)]+40);
				}
			else	return(bits[(int)(l>>32)]+32);
			}
		}
	else
#endif
#endif
		{
#if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
		if (l & 0xffff0000L)
			{
			if (l & 0xff000000L)
				return(bits[(int)(l>>24L)]+24);
			else	return(bits[(int)(l>>16L)]+16);
			}
		else
#endif
			{
#if defined(SIXTEEN_BIT) || defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
			if (l & 0xff00L)
				return(bits[(int)(l>>8)]+8);
			else	
#endif
				return(bits[(int)(l   )]  );
			}
		}
	}

int BN_num_bits(const BIGNUM *a)
	{
	int i = a->top - 1;
	bn_check_top(a);

	if (BN_is_zero(a)) return 0;
	return ((i*BN_BITS2) + BN_num_bits_word(a->d[i]));
	}

void BN_clear_free(BIGNUM *a)
	{
	int i;

	if (a == NULL) return;
	bn_check_top(a);
	if (a->d != NULL)
		{
		OPENSSL_cleanse(a->d,a->dmax*sizeof(a->d[0]));
		if (!(BN_get_flags(a,BN_FLG_STATIC_DATA)))
			OPENSSL_free(a->d);
		}
	i=BN_get_flags(a,BN_FLG_MALLOCED);
	OPENSSL_cleanse(a,sizeof(BIGNUM));
	if (i)
		OPENSSL_free(a);
	}

void BN_free(BIGNUM *a)
	{
	if (a == NULL) return;
	bn_check_top(a);
	if ((a->d != NULL) && !(BN_get_flags(a,BN_FLG_STATIC_DATA)))
		OPENSSL_free(a->d);
	if (a->flags & BN_FLG_MALLOCED)
		OPENSSL_free(a);
	else
		{
#ifndef OPENSSL_NO_DEPRECATED
		a->flags|=BN_FLG_FREE;
#endif
		a->d = NULL;
		}
	}

void BN_init(BIGNUM *a)
	{
	memset(a,0,sizeof(BIGNUM));
	bn_check_top(a);
	}

BIGNUM *BN_new(void)
	{
	BIGNUM *ret;

	if ((ret=(BIGNUM *)OPENSSL_malloc(sizeof(BIGNUM))) == NULL)
		{
		BNerr(BN_F_BN_NEW,ERR_R_MALLOC_FAILURE);
		return(NULL);
		}
	ret->flags=BN_FLG_MALLOCED;
	ret->top=0;
	ret->neg=0;
	ret->dmax=0;
	ret->d=NULL;
	bn_check_top(ret);
	return(ret);
	}

/* This is used both by bn_expand2() and bn_dup_expand() */
/* The caller MUST check that words > b->dmax before calling this */
static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
	{
	BN_ULONG *A,*a = NULL;
	const BN_ULONG *B;
	int i;

	bn_check_top(b);

	if (words > (INT_MAX/(4*BN_BITS2)))
		{
		BNerr(BN_F_BN_EXPAND_INTERNAL,BN_R_BIGNUM_TOO_LONG);
		return NULL;
		}
	if (BN_get_flags(b,BN_FLG_STATIC_DATA))
		{
		BNerr(BN_F_BN_EXPAND_INTERNAL,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
		return(NULL);
		}
	a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*words);
	if (A == NULL)
		{
		BNerr(BN_F_BN_EXPAND_INTERNAL,ERR_R_MALLOC_FAILURE);
		return(NULL);
		}
#if 1
	B=b->d;
	/* Check if the previous number needs to be copied */
	if (B != NULL)
		{
		for (i=b->top>>2; i>0; i--,A+=4,B+=4)
			{
			/*
			 * The fact that the loop is unrolled
			 * 4-wise is a tribute to Intel. It's
			 * the one that doesn't have enough
			 * registers to accomodate more data.
			 * I'd unroll it 8-wise otherwise:-)
			 *
			 *		<[e-mail]>
			 */
			BN_ULONG a0,a1,a2,a3;
			a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
			A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
			}
		switch (b->top&3)
			{
		case 3:	A[2]=B[2];
		case 2:	A[1]=B[1];
		case 1:	A[0]=B[0];
		case 0: /* workaround for ultrix cc: without 'case 0', the optimizer does
		         * the switch table by doing a=top&3; a--; goto jump_table[a];
		         * which fails for top== 0 */
			;
			}
		}

#else
	memset(A,0,sizeof(BN_ULONG)*words);
	memcpy(A,b->d,sizeof(b->d[0])*b->top);
#endif
		
	return(a);
	}

/* This is an internal function that can be used instead of bn_expand2()
 * when there is a need to copy BIGNUMs instead of only expanding the
 * data part, while still expanding them.
 * Especially useful when needing to expand BIGNUMs that are declared
 * 'const' and should therefore not be changed.
 * The reason to use this instead of a BN_dup() followed by a bn_expand2()
 * is memory allocation overhead.  A BN_dup() followed by a bn_expand2()
 * will allocate new memory for the BIGNUM data twice, and free it once,
 * while bn_dup_expand() makes sure allocation is made only once.
 */

#ifndef OPENSSL_NO_DEPRECATED
BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
	{
	BIGNUM *r = NULL;

	bn_check_top(b);

	/* This function does not work if
	 *      words <= b->dmax && top < words
	 * because BN_dup() does not preserve 'dmax'!
	 * (But bn_dup_expand() is not used anywhere yet.)
	 */

	if (words > b->dmax)
		{
		BN_ULONG *a = bn_expand_internal(b, words);

		if (a)
			{
			r = BN_new();
			if (r)
				{
				r->top = b->top;
				r->dmax = words;
				r->neg = b->neg;
				r->d = a;
				}
			else
				{
				/* r == NULL, BN_new failure */
				OPENSSL_free(a);