/*

 * Copyright 1995-2025 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 "internal/numbers.h"

#include <limits.h>

#include <openssl/asn1.h>

#include <openssl/bn.h>

#include "asn1_local.h"

ASN1_INTEGER *ASN1_INTEGER_dup(const ASN1_INTEGER *x)

{

    return ASN1_STRING_dup(x);

}

int ASN1_INTEGER_cmp(const ASN1_INTEGER *x, const ASN1_INTEGER *y)

{

    int neg, ret;

    /* Compare signs */

    neg = x->type & V_ASN1_NEG;

    if (neg != (y->type & V_ASN1_NEG)) {

        if (neg)

            return -1;

        else

            return 1;

    }

    ret = ASN1_STRING_cmp(x, y);

    if (neg)

        return -ret;

    else

        return ret;

}

/*

 * This converts a big endian buffer and sign into its content encoding.

 * This is used for INTEGER and ENUMERATED types.

 * The internal representation is an ASN1_STRING whose data is a big endian

 * representation of the value, ignoring the sign. The sign is determined by

 * the type: if type & V_ASN1_NEG is true it is negative, otherwise positive.

 *

 * Positive integers are no problem: they are almost the same as the DER

 * encoding, except if the first byte is >= 0x80 we need to add a zero pad.

 *

 * Negative integers are a bit trickier...

 * The DER representation of negative integers is in 2s complement form.

 * The internal form is converted by complementing each octet and finally

 * adding one to the result. This can be done less messily with a little trick.

 * If the internal form has trailing zeroes then they will become FF by the

 * complement and 0 by the add one (due to carry) so just copy as many trailing

 * zeros to the destination as there are in the source. The carry will add one

 * to the last none zero octet: so complement this octet and add one and finally

 * complement any left over until you get to the start of the string.

 *

 * Padding is a little trickier too. If the first bytes is > 0x80 then we pad

 * with 0xff. However if the first byte is 0x80 and one of the following bytes

 * is non-zero we pad with 0xff. The reason for this distinction is that 0x80

 * followed by optional zeros isn't padded.

 */

/*

 * If |pad| is zero, the operation is effectively reduced to memcpy,

 * and if |pad| is 0xff, then it performs two's complement, ~dst + 1.

 * Note that in latter case sequence of zeros yields itself, and so

 * does 0x80 followed by any number of zeros. These properties are

 * used elsewhere below...

 */

static void twos_complement(unsigned char *dst, const unsigned char *src,

                            size_t len, unsigned char pad)

{

    unsigned int carry = pad & 1;

    /* Begin at the end of the encoding */

    if (len != 0) {

        /*

         * if len == 0 then src/dst could be NULL, and this would be undefined

         * behaviour.

         */

        dst += len;

        src += len;

    }

    /* two's complement value: ~value + 1 */

    while (len-- != 0) {

        *(--dst) = (unsigned char)(carry += *(--src) ^ pad);

        carry >>= 8;

    }

}

static size_t i2c_ibuf(const unsigned char *b, size_t blen, int neg,

                       unsigned char **pp)

{

    unsigned int pad = 0;

    size_t ret, i;

    unsigned char *p, pb = 0;

    if (b != NULL && blen) {

        ret = blen;

        i = b[0];

        if (!neg && (i > 127)) {

            pad = 1;

            pb = 0;

        } else if (neg) {

            pb = 0xFF;

            if (i > 128) {

                pad = 1;

            } else if (i == 128) {

                /*

                 * Special case [of minimal negative for given length]:

                 * if any other bytes non zero we pad, otherwise we don't.

                 */

                for (pad = 0, i = 1; i < blen; i++)

                    pad |= b[i];

                pb = pad != 0 ? 0xffU : 0;

                pad = pb & 1;

            }

        }

        ret += pad;

    } else {

        ret = 1;

        blen = 0;   /* reduce '(b == NULL || blen == 0)' to '(blen == 0)' */

    }

    if (pp == NULL || (p = *pp) == NULL)

        return ret;

    /*

     * This magically handles all corner cases, such as '(b == NULL ||

     * blen == 0)', non-negative value, "negative" zero, 0x80 followed

     * by any number of zeros...

     */

    *p = pb;

    p += pad;       /* yes, p[0] can be written twice, but it's little

                     * price to pay for eliminated branches */

    twos_complement(p, b, blen, pb);

    *pp += ret;

    return ret;

}

/*

 * convert content octets into a big endian buffer. Returns the length

 * of buffer or 0 on error: for malformed INTEGER. If output buffer is

 * NULL just return length.

 */

static size_t c2i_ibuf(unsigned char *b, int *pneg,

                       const unsigned char *p, size_t plen)

{

    int neg, pad;

    /* Zero content length is illegal */

    if (plen == 0) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_ZERO_CONTENT);

        return 0;

    }

    neg = p[0] & 0x80;

    if (pneg)

        *pneg = neg;

    /* Handle common case where length is 1 octet separately */

    if (plen == 1) {

        if (b != NULL) {

            if (neg)

                b[0] = (p[0] ^ 0xFF) + 1;

            else

                b[0] = p[0];

        }

        return 1;

    }

    pad = 0;

    if (p[0] == 0) {

        pad = 1;

    } else if (p[0] == 0xFF) {

        size_t i;

        /*

         * Special case [of "one less minimal negative" for given length]:

         * if any other bytes non zero it was padded, otherwise not.

         */

        for (pad = 0, i = 1; i < plen; i++)

            pad |= p[i];

        pad = pad != 0 ? 1 : 0;

    }

    /* reject illegal padding: first two octets MSB can't match */

    if (pad && (neg == (p[1] & 0x80))) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_PADDING);

        return 0;

    }

    /* skip over pad */

    p += pad;

    plen -= pad;

    if (b != NULL)

        twos_complement(b, p, plen, neg ? 0xffU : 0);

    return plen;

}

int ossl_i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)

{

    unsigned char *ptr = pp != NULL ? *pp : NULL;

    size_t ret = i2c_ibuf(a->data, a->length, a->type & V_ASN1_NEG, &ptr);

    if (ret > INT_MAX) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_LARGE);

        return 0;

    }

    if (pp != NULL)

        *pp = ptr;

    return (int)ret;

}

/* Convert big endian buffer into uint64_t, return 0 on error */

static int asn1_get_uint64(uint64_t *pr, const unsigned char *b, size_t blen)

{

    size_t i;

    uint64_t r;

    if (blen > sizeof(*pr)) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_LARGE);

        return 0;

    }

    if (b == NULL)

        return 0;

    for (r = 0, i = 0; i < blen; i++) {

        r <<= 8;

        r |= b[i];

    }

    *pr = r;

    return 1;

}

/*

 * Write uint64_t to big endian buffer and return offset to first

 * written octet. In other words it returns offset in range from 0

 * to 7, with 0 denoting 8 written octets and 7 - one.

 */

static size_t asn1_put_uint64(unsigned char b[sizeof(uint64_t)], uint64_t r)

{

    size_t off = sizeof(uint64_t);

    do {

        b[--off] = (unsigned char)r;

    } while (r >>= 8);

    return off;

}

/*

 * Absolute value of INT64_MIN: we can't just use -INT64_MIN as gcc produces

 * overflow warnings.

 */

#define ABS_INT64_MIN ((uint64_t)INT64_MAX + (-(INT64_MIN + INT64_MAX)))

/* signed version of asn1_get_uint64 */

static int asn1_get_int64(int64_t *pr, const unsigned char *b, size_t blen,

                          int neg)

{

    uint64_t r;

    if (asn1_get_uint64(&r, b, blen) == 0)

        return 0;

    if (neg) {

        if (r <= INT64_MAX) {

            /*

             * Most significant bit is guaranteed to be clear, negation

             * is guaranteed to be meaningful in platform-neutral sense.

             */

            *pr = -(int64_t)r;

        } else if (r == ABS_INT64_MIN) {

            /*

             * This never happens if INT64_MAX == ABS_INT64_MIN, e.g.

             * on ones'-complement system.

             */

            *pr = (int64_t)(0 - r);

        } else {

            ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_SMALL);

            return 0;

        }

    } else {

        if (r <= INT64_MAX) {

            *pr = (int64_t)r;

        } else {

            ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_LARGE);

            return 0;

        }

    }

    return 1;

}

/* Convert ASN1 INTEGER content octets to ASN1_INTEGER structure */

ASN1_INTEGER *ossl_c2i_ASN1_INTEGER(ASN1_INTEGER **a, const unsigned char **pp,

                                    long len)

{

    ASN1_INTEGER *ret = NULL;

    size_t r;

    int neg;

    r = c2i_ibuf(NULL, NULL, *pp, len);

    if (r == 0)

        return NULL;

    if ((a == NULL) || ((*a) == NULL)) {

        ret = ASN1_INTEGER_new();

        if (ret == NULL)

            return NULL;

        ret->type = V_ASN1_INTEGER;

    } else

        ret = *a;

    if (r > INT_MAX || ASN1_STRING_set(ret, NULL, (int)r) == 0) {

        ERR_raise(ERR_LIB_ASN1, ERR_R_ASN1_LIB);

        goto err;

    }

    c2i_ibuf(ret->data, &neg, *pp, len);

    if (neg != 0)

        ret->type |= V_ASN1_NEG;

    else

        ret->type &= ~V_ASN1_NEG;

    *pp += len;

    if (a != NULL)

        (*a) = ret;

    return ret;

 err:

    if (a == NULL || *a != ret)

        ASN1_INTEGER_free(ret);

    return NULL;

}

static int asn1_string_get_int64(int64_t *pr, const ASN1_STRING *a, int itype)

{

    if (a == NULL) {

        ERR_raise(ERR_LIB_ASN1, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    if ((a->type & ~V_ASN1_NEG) != itype) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_WRONG_INTEGER_TYPE);

        return 0;

    }

    return asn1_get_int64(pr, a->data, a->length, a->type & V_ASN1_NEG);

}

static int asn1_string_set_int64(ASN1_STRING *a, int64_t r, int itype)

{

    unsigned char tbuf[sizeof(r)];

    size_t off;

    a->type = itype;

    if (r < 0) {

        /*

         * Most obvious '-r' triggers undefined behaviour for most

         * common INT64_MIN. Even though below '0 - (uint64_t)r' can

         * appear two's-complement centric, it does produce correct/

         * expected result even on ones' complement. This is because

         * cast to unsigned has to change bit pattern...

         */

        off = asn1_put_uint64(tbuf, 0 - (uint64_t)r);

        a->type |= V_ASN1_NEG;

    } else {

        off = asn1_put_uint64(tbuf, r);

        a->type &= ~V_ASN1_NEG;

    }

    return ASN1_STRING_set(a, tbuf + off, (int)(sizeof(tbuf) - off));

}

static int asn1_string_get_uint64(uint64_t *pr, const ASN1_STRING *a,

                                  int itype)

{

    if (a == NULL) {

        ERR_raise(ERR_LIB_ASN1, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    if ((a->type & ~V_ASN1_NEG) != itype) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_WRONG_INTEGER_TYPE);

        return 0;

    }

    if (a->type & V_ASN1_NEG) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_NEGATIVE_VALUE);

        return 0;

    }

    return asn1_get_uint64(pr, a->data, a->length);

}

static int asn1_string_set_uint64(ASN1_STRING *a, uint64_t r, int itype)

{

    unsigned char tbuf[sizeof(r)];

    size_t off;

    a->type = itype;

    off = asn1_put_uint64(tbuf, r);

    return ASN1_STRING_set(a, tbuf + off, (int)(sizeof(tbuf) - off));

}

/*

 * This is a version of d2i_ASN1_INTEGER that ignores the sign bit of ASN1

 * integers: some broken software can encode a positive INTEGER with its MSB

 * set as negative (it doesn't add a padding zero).

 */

ASN1_INTEGER *d2i_ASN1_UINTEGER(ASN1_INTEGER **a, const unsigned char **pp,

                                long length)

{

    ASN1_INTEGER *ret = NULL;

    const unsigned char *p;

    unsigned char *s;

    long len = 0;

    int inf, tag, xclass;

    int i = 0;

    if ((a == NULL) || ((*a) == NULL)) {

        if ((ret = ASN1_INTEGER_new()) == NULL)

            return NULL;

        ret->type = V_ASN1_INTEGER;

    } else

        ret = (*a);

    p = *pp;

    inf = ASN1_get_object(&p, &len, &tag, &xclass, length);

    if (inf & 0x80) {

        i = ASN1_R_BAD_OBJECT_HEADER;

        goto err;

    }

    if (tag != V_ASN1_INTEGER) {

        i = ASN1_R_EXPECTING_AN_INTEGER;

        goto err;

    }

    if (len < 0) {

        i = ASN1_R_ILLEGAL_NEGATIVE_VALUE;

        goto err;

    }

    /*

     * We must OPENSSL_malloc stuff, even for 0 bytes otherwise it signifies

     * a missing NULL parameter.

     */

    s = OPENSSL_malloc((int)len + 1);

    if (s == NULL)

        goto err;

    ret->type = V_ASN1_INTEGER;

    if (len) {

        if ((*p == 0) && (len != 1)) {

            p++;

            len--;

        }

        memcpy(s, p, (int)len);

        p += len;

    }

    ASN1_STRING_set0(ret, s, (int)len);

    if (a != NULL)

        (*a) = ret;

    *pp = p;

    return ret;

 err:

    if (i != 0)

        ERR_raise(ERR_LIB_ASN1, i);

    if ((a == NULL) || (*a != ret))

        ASN1_INTEGER_free(ret);

    return NULL;

}

static ASN1_STRING *bn_to_asn1_string(const BIGNUM *bn, ASN1_STRING *ai,

                                      int atype)

{

    ASN1_INTEGER *ret;

    int len;

    if (ai == NULL) {

        ret = ASN1_STRING_type_new(atype);

    } else {

        ret = ai;

        ret->type = atype;

    }

    if (ret == NULL) {

        ERR_raise(ERR_LIB_ASN1, ERR_R_NESTED_ASN1_ERROR);

        goto err;

    }

    if (BN_is_negative(bn) && !BN_is_zero(bn))

        ret->type |= V_ASN1_NEG_INTEGER;

    len = BN_num_bytes(bn);

    if (len == 0)

        len = 1;

    if (ASN1_STRING_set(ret, NULL, len) == 0) {

        ERR_raise(ERR_LIB_ASN1, ERR_R_ASN1_LIB);

        goto err;

    }

    /* Correct zero case */

    if (BN_is_zero(bn))

        ret->data[0] = 0;

    else

        len = BN_bn2bin(bn, ret->data);

    ret->length = len;

    return ret;

 err:

    if (ret != ai)

        ASN1_INTEGER_free(ret);

    return NULL;

}

static BIGNUM *asn1_string_to_bn(const ASN1_INTEGER *ai, BIGNUM *bn,

                                 int itype)

{

    BIGNUM *ret;

    if ((ai->type & ~V_ASN1_NEG) != itype) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_WRONG_INTEGER_TYPE);

        return NULL;

    }

    ret = BN_bin2bn(ai->data, ai->length, bn);

    if (ret == NULL) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_BN_LIB);

        return NULL;

    }

    if (ai->type & V_ASN1_NEG)

        BN_set_negative(ret, 1);

    return ret;

}

int ASN1_INTEGER_get_int64(int64_t *pr, const ASN1_INTEGER *a)

{

    return asn1_string_get_int64(pr, a, V_ASN1_INTEGER);

}

int ASN1_INTEGER_set_int64(ASN1_INTEGER *a, int64_t r)

{

    return asn1_string_set_int64(a, r, V_ASN1_INTEGER);

}

int ASN1_INTEGER_get_uint64(uint64_t *pr, const ASN1_INTEGER *a)

{

    return asn1_string_get_uint64(pr, a, V_ASN1_INTEGER);

}

int ASN1_INTEGER_set_uint64(ASN1_INTEGER *a, uint64_t r)

{

    return asn1_string_set_uint64(a, r, V_ASN1_INTEGER);

}

int ASN1_INTEGER_set(ASN1_INTEGER *a, long v)

{

    return ASN1_INTEGER_set_int64(a, v);

}

long ASN1_INTEGER_get(const ASN1_INTEGER *a)

{

    int i;

    int64_t r;

    if (a == NULL)

        return 0;

    i = ASN1_INTEGER_get_int64(&r, a);

    if (i == 0)

        return -1;

    if (r > LONG_MAX || r < LONG_MIN)

        return -1;

    return (long)r;

}

ASN1_INTEGER *BN_to_ASN1_INTEGER(const BIGNUM *bn, ASN1_INTEGER *ai)

{

    return bn_to_asn1_string(bn, ai, V_ASN1_INTEGER);

}

BIGNUM *ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai, BIGNUM *bn)

{

    return asn1_string_to_bn(ai, bn, V_ASN1_INTEGER);

}

int ASN1_ENUMERATED_get_int64(int64_t *pr, const ASN1_ENUMERATED *a)

{

    return asn1_string_get_int64(pr, a, V_ASN1_ENUMERATED);

}

int ASN1_ENUMERATED_set_int64(ASN1_ENUMERATED *a, int64_t r)

{

    return asn1_string_set_int64(a, r, V_ASN1_ENUMERATED);

}

int ASN1_ENUMERATED_set(ASN1_ENUMERATED *a, long v)

{

    return ASN1_ENUMERATED_set_int64(a, v);

}

long ASN1_ENUMERATED_get(const ASN1_ENUMERATED *a)

{

    int i;

    int64_t r;

    if (a == NULL)

        return 0;

    if ((a->type & ~V_ASN1_NEG) != V_ASN1_ENUMERATED)

        return -1;

    if (a->length > (int)sizeof(long))

        return 0xffffffffL;

    i = ASN1_ENUMERATED_get_int64(&r, a);

    if (i == 0)

        return -1;

    if (r > LONG_MAX || r < LONG_MIN)

        return -1;

    return (long)r;

}

ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(const BIGNUM *bn, ASN1_ENUMERATED *ai)

{

    return bn_to_asn1_string(bn, ai, V_ASN1_ENUMERATED);

}

BIGNUM *ASN1_ENUMERATED_to_BN(const ASN1_ENUMERATED *ai, BIGNUM *bn)

{

    return asn1_string_to_bn(ai, bn, V_ASN1_ENUMERATED);

}

/* Internal functions used by x_int64.c */

int ossl_c2i_uint64_int(uint64_t *ret, int *neg,

                        const unsigned char **pp, long len)

{

    unsigned char buf[sizeof(uint64_t)];

    size_t buflen;

    buflen = c2i_ibuf(NULL, NULL, *pp, len);

    if (buflen == 0)

        return 0;

    if (buflen > sizeof(uint64_t)) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_TOO_LARGE);

        return 0;

    }

    (void)c2i_ibuf(buf, neg, *pp, len);

    return asn1_get_uint64(ret, buf, buflen);

}

int ossl_i2c_uint64_int(unsigned char *p, uint64_t r, int neg)

{

    unsigned char buf[sizeof(uint64_t)];

    size_t off;

    off = asn1_put_uint64(buf, r);

    return (int)i2c_ibuf(buf + off, sizeof(buf) - off, neg, &p);

}