openssl/crypto/asn1/x_long.c

/*
 * Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (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 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(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, 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)
{
    *(long *)pval = it->size;
    return 1;
}

static void long_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
{
    *(long *)pval = it->size;
}

static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
                    const ASN1_ITEM *it)
{
    long ltmp;
    unsigned long utmp;
    int clen, pad, i;
    /* this exists to bypass broken gcc optimization */
    char *cp = (char *)pval;

    /* use memcpy, because we may not be long aligned */
    memcpy(&ltmp, cp, sizeof(long));

    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)
        utmp = 0 - (unsigned long)ltmp - 1;
    else
        utmp = ltmp;
    clen = BN_num_bits_word(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) {
        if (pad)
            *cont++ = (ltmp < 0) ? 0xff : 0;
        for (i = clen - 1; i >= 0; i--) {
            cont[i] = (unsigned char)(utmp & 0xff);
            if (ltmp < 0)
                cont[i] ^= 0xff;
            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 neg = -1, i;
    long ltmp;
    unsigned long utmp = 0;
    char *cp = (char *)pval;

    if (len) {
        /*
         * 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--;
            neg = 1;
            break;
        case 0:
            cont++;
            len--;
            neg = 0;
            break;
        }
    }
    if (len > (int)sizeof(long)) {
        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
        return 0;
    }
    if (neg == -1) {
        /* Is it negative? */
        if (len && (cont[0] & 0x80))
            neg = 1;
        else
            neg = 0;
    }
    utmp = 0;
    for (i = 0; i < len; i++) {
        utmp <<= 8;
        if (neg)
            utmp |= cont[i] ^ 0xff;
        else
            utmp |= cont[i];
    }
    ltmp = (long)utmp;
    if (neg) {
        ltmp = -ltmp;
        ltmp--;
    }
    if (ltmp == it->size) {
        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
        return 0;
    }
    memcpy(cp, &ltmp, sizeof(long));
    return 1;
}

static int long_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it,
                      int indent, const ASN1_PCTX *pctx)
{
    return BIO_printf(out, "%ld\n", *(long *)pval);
}