/*

 * Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include "internal/cryptlib.h"

#include <openssl/asn1t.h>

#include <openssl/bn.h>

/*

 * Custom primitive type for BIGNUM handling. This reads in an ASN1_INTEGER

 * as a BIGNUM directly. Currently it ignores the sign which isn't a problem

 * since all BIGNUMs used are non negative and anything that looks negative

 * is normally due to an encoding error.

 */

#define BN_SENSITIVE    1

static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it);

static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it);

static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it);

static int bn_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,

                  const ASN1_ITEM *it);

static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,

                  int utype, char *free_cont, const ASN1_ITEM *it);

static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,

                         int utype, char *free_cont, const ASN1_ITEM *it);

static int bn_print(BIO *out, const ASN1_VALUE **pval, const ASN1_ITEM *it,

                    int indent, const ASN1_PCTX *pctx);

static ASN1_PRIMITIVE_FUNCS bignum_pf = {

    NULL, 0,

    bn_new,

    bn_free,

    0,

    bn_c2i,

    bn_i2c,

    bn_print

};

static ASN1_PRIMITIVE_FUNCS cbignum_pf = {

    NULL, 0,

    bn_secure_new,

    bn_free,

    0,

    bn_secure_c2i,

    bn_i2c,

    bn_print

};

ASN1_ITEM_start(BIGNUM)

        ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &bignum_pf, 0, "BIGNUM"

ASN1_ITEM_end(BIGNUM)

ASN1_ITEM_start(CBIGNUM)

        ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &cbignum_pf, BN_SENSITIVE, "CBIGNUM"

ASN1_ITEM_end(CBIGNUM)

static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it)

{

    *pval = (ASN1_VALUE *)BN_new();

    if (*pval != NULL)

        return 1;

    else

        return 0;

}

static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it)

{

    *pval = (ASN1_VALUE *)BN_secure_new();

    if (*pval != NULL)

        return 1;

    else

        return 0;

}

static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it)

{

    if (*pval == NULL)

        return;

    if (it->size & BN_SENSITIVE)

        BN_clear_free((BIGNUM *)*pval);

    else

        BN_free((BIGNUM *)*pval);

    *pval = NULL;

}

static int bn_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,

                  const ASN1_ITEM *it)

{

    BIGNUM *bn;

    int pad;

    if (*pval == NULL)

        return -1;

    bn = (BIGNUM *)*pval;

    /* If MSB set in an octet we need a padding byte */

    if (BN_num_bits(bn) & 0x7)

        pad = 0;

    else

        pad = 1;

    if (cont) {

        if (pad)

            *cont++ = 0;

        BN_bn2bin(bn, cont);

    }

    return pad + BN_num_bytes(bn);

}

static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,

                  int utype, char *free_cont, const ASN1_ITEM *it)

{

    BIGNUM *bn;

    if (*pval == NULL && !bn_new(pval, it))

        return 0;

    bn = (BIGNUM *)*pval;

    if (!BN_bin2bn(cont, len, bn)) {

        bn_free(pval, it);

        return 0;

    }

    return 1;

}

static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,

                         int utype, char *free_cont, const ASN1_ITEM *it)

{

    int ret;

    BIGNUM *bn;

    if (*pval == NULL && !bn_secure_new(pval, it))

        return 0;

    ret = bn_c2i(pval, cont, len, utype, free_cont, it);

    if (!ret)

        return 0;

    /* Set constant-time flag for all secure BIGNUMS */

    bn = (BIGNUM *)*pval;

    BN_set_flags(bn, BN_FLG_CONSTTIME);

    return ret;

}

static int bn_print(BIO *out, const ASN1_VALUE **pval, const ASN1_ITEM *it,

                    int indent, const ASN1_PCTX *pctx)

{

    if (!BN_print(out, *(BIGNUM **)pval))

        return 0;

    if (BIO_puts(out, "\n") <= 0)

        return 0;

    return 1;

}