/* $OpenBSD: bn_print.c,v 1.37 2022/11/26 16:08:51 tb Exp $ */
/* 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.]
 */

#include <ctype.h>
#include <limits.h>
#include <stdio.h>

#include <openssl/opensslconf.h>

#include <openssl/bio.h>
#include <openssl/buffer.h>
#include <openssl/err.h>

#include "bn_local.h"

static const char Hex[]="0123456789ABCDEF";

/* Must 'free' the returned data */
char *
BN_bn2hex(const BIGNUM *a)
{
	int i, j, v, z = 0;
	char *buf;
	char *p;

	buf = malloc(BN_is_negative(a) + a->top * BN_BYTES * 2 + 2);
	if (buf == NULL) {
		BNerror(ERR_R_MALLOC_FAILURE);
		goto err;
	}
	p = buf;
	if (BN_is_negative(a))
		*p++ = '-';
	if (BN_is_zero(a))
		*p++ = '0';
	for (i = a->top - 1; i >=0; i--) {
		for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
			/* strip leading zeros */
			v = ((int)(a->d[i] >> (long)j)) & 0xff;
			if (z || (v != 0)) {
				*p++ = Hex[v >> 4];
				*p++ = Hex[v & 0x0f];
				z = 1;
			}
		}
	}
	*p = '\0';

err:
	return (buf);
}

/* Must 'free' the returned data */
char *
BN_bn2dec(const BIGNUM *a)
{
	int i = 0, num, bn_data_num, ok = 0;
	char *buf = NULL;
	char *p;
	BIGNUM *t = NULL;
	BN_ULONG *bn_data = NULL, *lp;

	if (BN_is_zero(a)) {
		buf = malloc(BN_is_negative(a) + 2);
		if (buf == NULL) {
			BNerror(ERR_R_MALLOC_FAILURE);
			goto err;
		}
		p = buf;
		if (BN_is_negative(a))
			*p++ = '-';
		*p++ = '0';
		*p++ = '\0';
		return (buf);
	}

	/* get an upper bound for the length of the decimal integer
	 * num <= (BN_num_bits(a) + 1) * log(2)
	 *     <= 3 * BN_num_bits(a) * 0.1001 + log(2) + 1     (rounding error)
	 *     <= BN_num_bits(a)/10 + BN_num_bits/1000 + 1 + 1
	 */
	i = BN_num_bits(a) * 3;
	num = (i / 10 + i / 1000 + 1) + 1;
	bn_data_num = num / BN_DEC_NUM + 1;
	bn_data = reallocarray(NULL, bn_data_num, sizeof(BN_ULONG));
	buf = malloc(num + 3);
	if ((buf == NULL) || (bn_data == NULL)) {
		BNerror(ERR_R_MALLOC_FAILURE);
		goto err;
	}
	if ((t = BN_dup(a)) == NULL)
		goto err;

#define BUF_REMAIN (num+3 - (size_t)(p - buf))
	p = buf;
	lp = bn_data;
	if (BN_is_negative(t))
		*p++ = '-';

	while (!BN_is_zero(t)) {
		if (lp - bn_data >= bn_data_num)
			goto err;
		*lp = BN_div_word(t, BN_DEC_CONV);
		if (*lp == (BN_ULONG)-1)
			goto err;
		lp++;
	}
	lp--;
	/* We now have a series of blocks, BN_DEC_NUM chars
	 * in length, where the last one needs truncation.
	 * The blocks need to be reversed in order. */
	snprintf(p, BUF_REMAIN, BN_DEC_FMT1, *lp);
	while (*p)
		p++;
	while (lp != bn_data) {
		lp--;
		snprintf(p, BUF_REMAIN, BN_DEC_FMT2, *lp);
		while (*p)
			p++;
	}
	ok = 1;

err:
	free(bn_data);
	BN_free(t);
	if (!ok && buf) {
		free(buf);
		buf = NULL;
	}

	return (buf);
}

int
BN_hex2bn(BIGNUM **bn, const char *a)
{
	BIGNUM *ret = NULL;
	BN_ULONG l = 0;
	int neg = 0, h, m, i,j, k, c;
	int num;

	if ((a == NULL) || (*a == '\0'))
		return (0);

	if (*a == '-') {
		neg = 1;
		a++;
	}

	for (i = 0; i <= (INT_MAX / 4) && isxdigit((unsigned char)a[i]); i++)
		;
	if (i > INT_MAX / 4)
		return (0);

	num = i + neg;
	if (bn == NULL)
		return (num);

	/* a is the start of the hex digits, and it is 'i' long */
	if (*bn == NULL) {
		if ((ret = BN_new()) == NULL)
			return (0);
	} else {
		ret = *bn;
		BN_zero(ret);
	}

	/* i is the number of hex digits */
	if (!bn_expand(ret, i * 4))
		goto err;

	j = i; /* least significant 'hex' */
	m = 0;
	h = 0;
	while (j > 0) {
		m = ((BN_BYTES * 2) <= j) ? (BN_BYTES * 2) : j;
		l = 0;
		for (;;) {
			c = a[j - m];
			if ((c >= '0') && (c <= '9'))
				k = c - '0';
			else if ((c >= 'a') && (c <= 'f'))
				k = c - 'a' + 10;
			else if ((c >= 'A') && (c <= 'F'))
				k = c - 'A' + 10;
			else
				k = 0; /* paranoia */
			l = (l << 4) | k;

			if (--m <= 0) {
				ret->d[h++] = l;
				break;
			}
		}
		j -= (BN_BYTES * 2);
	}
	ret->top = h;
	bn_correct_top(ret);
	ret->neg = neg;

	*bn = ret;
	return (num);

err:
	if (*bn == NULL)
		BN_free(ret);
	return (0);
}

int
BN_dec2bn(BIGNUM **bn, const char *a)
{
	BIGNUM *ret = NULL;
	BN_ULONG l = 0;
	int neg = 0, i, j;
	int num;

	if ((a == NULL) || (*a == '\0'))
		return (0);
	if (*a == '-') {
		neg = 1;
		a++;
	}

	for (i = 0; i <= (INT_MAX / 4) && isdigit((unsigned char)a[i]); i++)
		;
	if (i > INT_MAX / 4)
		return (0);

	num = i + neg;
	if (bn == NULL)
		return (num);

	/* a is the start of the digits, and it is 'i' long.
	 * We chop it into BN_DEC_NUM digits at a time */
	if (*bn == NULL) {
		if ((ret = BN_new()) == NULL)
			return (0);
	} else {
		ret = *bn;
		BN_zero(ret);
	}

	/* i is the number of digits, a bit of an over expand */
	if (!bn_expand(ret, i * 4))
		goto err;

	j = BN_DEC_NUM - (i % BN_DEC_NUM);
	if (j == BN_DEC_NUM)
		j = 0;
	l = 0;
	while (*a) {
		l *= 10;
		l += *a - '0';
		a++;
		if (++j == BN_DEC_NUM) {
			if (!BN_mul_word(ret, BN_DEC_CONV))
				goto err;
			if (!BN_add_word(ret, l))
				goto err;
			l = 0;
			j = 0;
		}
	}
	ret->neg = neg;

	bn_correct_top(ret);
	*bn = ret;
	return (num);

err:
	if (*bn == NULL)
		BN_free(ret);
	return (0);
}

int
BN_asc2bn(BIGNUM **bn, const char *a)
{
	const char *p = a;
	if (*p == '-')
		p++;

	if (p[0] == '0' && (p[1] == 'X' || p[1] == 'x')) {
		if (!BN_hex2bn(bn, p + 2))
			return 0;
	} else {
		if (!BN_dec2bn(bn, p))
			return 0;
	}
	if (*a == '-')
		(*bn)->neg = 1;
	return 1;
}

#ifndef OPENSSL_NO_BIO
int
BN_print_fp(FILE *fp, const BIGNUM *a)
{
	BIO *b;
	int ret;

	if ((b = BIO_new(BIO_s_file())) == NULL)
		return (0);
	BIO_set_fp(b, fp, BIO_NOCLOSE);
	ret = BN_print(b, a);
	BIO_free(b);
	return (ret);
}

int
BN_print(BIO *bp, const BIGNUM *a)
{
	int i, j, v, z = 0;
	int ret = 0;

	if ((a->neg) && (BIO_write(bp, "-", 1) != 1))
		goto end;
	if (BN_is_zero(a) && (BIO_write(bp, "0", 1) != 1))
		goto end;
	for (i = a->top - 1; i >= 0; i--) {
		for (j = BN_BITS2 - 4; j >= 0; j -= 4) {
			/* strip leading zeros */
			v = ((int)(a->d[i] >> (long)j)) & 0x0f;
			if (z || (v != 0)) {
				if (BIO_write(bp, &(Hex[v]), 1) != 1)
					goto end;
				z = 1;
			}
		}
	}
	ret = 1;

end:
	return (ret);
}
#endif

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

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