/*

 * Copyright 2000-2020 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>

#define COPY_SIZE(a, b) (sizeof(a) < sizeof(b) ? sizeof(a) : sizeof(b))

/*

 * Custom primitive type for long handling. This converts between an

 * ASN1_INTEGER and a long directly.

 */

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

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

static int long_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,

                    const ASN1_ITEM *it);

static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,

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

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

                      int indent, const ASN1_PCTX *pctx);

static ASN1_PRIMITIVE_FUNCS long_pf = {

    NULL, 0,

    long_new,

    long_free,

    long_free,                  /* Clear should set to initial value */

    long_c2i,

    long_i2c,

    long_print

};

ASN1_ITEM_start(LONG)

        ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &long_pf, ASN1_LONG_UNDEF, "LONG"

ASN1_ITEM_end(LONG)

ASN1_ITEM_start(ZLONG)

        ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &long_pf, 0, "ZLONG"

ASN1_ITEM_end(ZLONG)

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

{

    memcpy(pval, &it->size, COPY_SIZE(*pval, it->size));

    return 1;

}

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

{

    memcpy(pval, &it->size, COPY_SIZE(*pval, it->size));

}

/*

 * Originally BN_num_bits_word was called to perform this operation, but

 * trouble is that there is no guarantee that sizeof(long) equals to

 * sizeof(BN_ULONG). BN_ULONG is a configurable type that can be as wide

 * as long, but also double or half...

 */

static int num_bits_ulong(unsigned long value)

{

    size_t i;

    unsigned long ret = 0;

    /*

     * It is argued that *on average* constant counter loop performs

     * not worse [if not better] than one with conditional break or

     * mask-n-table-lookup-style, because of branch misprediction

     * penalties.

     */

    for (i = 0; i < sizeof(value) * 8; i++) {

        ret += (value != 0);

        value >>= 1;

    }

    return (int)ret;

}

static int long_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,

                    const ASN1_ITEM *it)

{

    long ltmp;

    unsigned long utmp, sign;

    int clen, pad, i;

    memcpy(&ltmp, pval, COPY_SIZE(*pval, ltmp));

    if (ltmp == it->size)

        return -1;

    /*

     * Convert the long to positive: we subtract one if negative so we can

     * cleanly handle the padding if only the MSB of the leading octet is

     * set.

     */

    if (ltmp < 0) {

        sign = 0xff;

        utmp = 0 - (unsigned long)ltmp - 1;

    } else {

        sign = 0;

        utmp = ltmp;

    }

    clen = num_bits_ulong(utmp);

    /* If MSB of leading octet set we need to pad */

    if (!(clen & 0x7))

        pad = 1;

    else

        pad = 0;

    /* Convert number of bits to number of octets */

    clen = (clen + 7) >> 3;

    if (cont != NULL) {

        if (pad)

            *cont++ = (unsigned char)sign;

        for (i = clen - 1; i >= 0; i--) {

            cont[i] = (unsigned char)(utmp ^ sign);

            utmp >>= 8;

        }

    }

    return clen + pad;

}

static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,

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

{

    int i;

    long ltmp;

    unsigned long utmp = 0, sign = 0x100;

    if (len > 1) {

        /*

         * Check possible pad byte.  Worst case, we're skipping past actual

         * content, but since that's only with 0x00 and 0xff and we set neg

         * accordingly, the result will be correct in the end anyway.

         */

        switch (cont[0]) {

        case 0xff:

            cont++;

            len--;

            sign = 0xff;

            break;

        case 0:

            cont++;

            len--;

            sign = 0;

            break;

        }

    }

    if (len > (int)sizeof(long)) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);

        return 0;

    }

    if (sign == 0x100) {

        /* Is it negative? */

        if (len && (cont[0] & 0x80))

            sign = 0xff;

        else

            sign = 0;

    } else if (((sign ^ cont[0]) & 0x80) == 0) { /* same sign bit? */

        ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_PADDING);

        return 0;

    }

    utmp = 0;

    for (i = 0; i < len; i++) {

        utmp <<= 8;

        utmp |= cont[i] ^ sign;

    }

    ltmp = (long)utmp;

    if (ltmp < 0) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);

        return 0;

    }

    if (sign)

        ltmp = -ltmp - 1;

    if (ltmp == it->size) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);

        return 0;

    }

    memcpy(pval, &ltmp, COPY_SIZE(*pval, ltmp));

    return 1;

}

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

                      int indent, const ASN1_PCTX *pctx)

{

    long l;

    memcpy(&l, pval, COPY_SIZE(*pval, l));

    return BIO_printf(out, "%ld\n", l);

}