view libtommath/bn_mp_radix_size.c @ 1861:2b3a8026a6ce

Add re-exec for server This allows ASLR to re-randomize the address space for every connection, preventing some vulnerabilities from being exploitable by repeated probing. Overhead (memory and time) is yet to be confirmed. At present this is only enabled on Linux. Other BSD platforms with fexecve() would probably also work though have not been tested.
author Matt Johnston <matt@ucc.asn.au>
date Sun, 30 Jan 2022 10:14:56 +0800
parents 1051e4eea25a
children
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#include "tommath_private.h"
#ifdef BN_MP_RADIX_SIZE_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

/* returns size of ASCII representation */
mp_err mp_radix_size(const mp_int *a, int radix, int *size)
{
   mp_err  err;
   int digs;
   mp_int   t;
   mp_digit d;

   *size = 0;

   /* make sure the radix is in range */
   if ((radix < 2) || (radix > 64)) {
      return MP_VAL;
   }

   if (MP_IS_ZERO(a)) {
      *size = 2;
      return MP_OKAY;
   }

   /* special case for binary */
   if (radix == 2) {
      *size = (mp_count_bits(a) + ((a->sign == MP_NEG) ? 1 : 0) + 1);
      return MP_OKAY;
   }

   /* digs is the digit count */
   digs = 0;

   /* if it's negative add one for the sign */
   if (a->sign == MP_NEG) {
      ++digs;
   }

   /* init a copy of the input */
   if ((err = mp_init_copy(&t, a)) != MP_OKAY) {
      return err;
   }

   /* force temp to positive */
   t.sign = MP_ZPOS;

   /* fetch out all of the digits */
   while (!MP_IS_ZERO(&t)) {
      if ((err = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) {
         goto LBL_ERR;
      }
      ++digs;
   }

   /* return digs + 1, the 1 is for the NULL byte that would be required. */
   *size = digs + 1;
   err = MP_OKAY;

LBL_ERR:
   mp_clear(&t);
   return err;
}

#endif