Commit e128f891 authored by Andy Polyakov's avatar Andy Polyakov
Browse files

asn1/x_long.c: remove conditions in inner loops and dependency on BN. 



Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
Reviewed-by: default avatarRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3152)
parent 3de47fb2

crypto/asn1/x_long.c

+47 −26
Original line number Diff line number Diff line
@@ -10,7 +10,6 @@ 
#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
@@ -56,11 +55,36 @@ static void long_free(ASN1_VALUE **pval, const ASN1_ITEM *it) 
    *(long *)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(ASN1_VALUE **pval, unsigned char *cont, int *putype,

                    const ASN1_ITEM *it)

{

    long ltmp;

    unsigned long utmp;

    unsigned long utmp, sign;

    int clen, pad, i;

    /* this exists to bypass broken gcc optimization */

    char *cp = (char *)pval;
@@ -75,11 +99,14 @@ static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype, 
     * cleanly handle the padding if only the MSB of the leading octet is

     * set.

     */

    if (ltmp < 0)

    if (ltmp < 0) {

        sign = 0xff;

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

    else

    } else {

        sign = 0;

        utmp = ltmp;

    clen = BN_num_bits_word(utmp);

    }

    clen = num_bits_ulong(utmp);

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

    if (!(clen & 0x7))

        pad = 1;
@@ -89,13 +116,11 @@ static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype, 
    /* Convert number of bits to number of octets */

    clen = (clen + 7) >> 3;



    if (cont) {

    if (cont != NULL) {

        if (pad)

            *cont++ = (ltmp < 0) ? 0xff : 0;

            *cont++ = (unsigned char)sign;

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

            cont[i] = (unsigned char)(utmp & 0xff);

            if (ltmp < 0)

                cont[i] ^= 0xff;

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

            utmp >>= 8;

        }

    }
@@ -105,9 +130,9 @@ static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype, 
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;

    int i;

    long ltmp;

    unsigned long utmp = 0;

    unsigned long utmp = 0, sign = 0x100;

    char *cp = (char *)pval;



    if (len > 1) {
@@ -120,12 +145,12 @@ static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len, 
        case 0xff:

            cont++;

            len--;

            neg = 0x80;

            sign = 0xff;

            break;

        case 0:

            cont++;

            len--;

            neg = 0;

            sign = 0;

            break;

        }

    }
@@ -133,33 +158,29 @@ static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len, 
        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);

        return 0;

    }

    if (neg == -1) {



    if (sign == 0x100) {

        /* Is it negative? */

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

            neg = 1;

            sign = 0xff;

        else

            neg = 0;

    } else if (neg == (cont[0] & 0x80)) {

            sign = 0;

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

        ASN1err(ASN1_F_LONG_C2I, ASN1_R_ILLEGAL_PADDING);

        return 0;

    }

    utmp = 0;

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

        utmp <<= 8;

        if (neg)

            utmp |= cont[i] ^ 0xff;

        else

            utmp |= cont[i];

        utmp |= cont[i] ^ sign;

    }

    ltmp = (long)utmp;

    if (ltmp < 0) {

        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);

        return 0;

    }

    if (neg) {

        ltmp = -ltmp;

        ltmp--;

    }

    if (sign)

        ltmp = -ltmp - 1;

    if (ltmp == it->size) {

        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);

        return 0;