programs/pluto/mp_defs.c

   1 /* some multiprecision utilities
   2  * Copyright (C) 1998-2001  D. Hugh Redelmeier.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the
   6  * Free Software Foundation; either version 2 of the License, or (at your
   7  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * for more details.
  13  *
  14  * RCSID $Id: mp_defs.c,v 1.1 2006/01/05 12:37:11 as Exp $
  15  */
  16
  17 #include <freeswan.h>
  18
  19 #include "constants.h"
  20 #include "defs.h"
  21 #include "mp_defs.h"
  22 #include "log.h"
  23
  24 /* Convert MP_INT to network form (binary octets, big-endian).
  25  * We do the malloc; caller must eventually do free.
  26  */
  27 chunk_t
  28 mpz_to_n(const MP_INT *mp, size_t bytes)
  29 {
  30     chunk_t r;
  31     MP_INT temp1, temp2;
  32     int i;
  33
  34     r.len = bytes;
  35     r.ptr = alloc_bytes(r.len, "host representation of large integer");
  36
  37     mpz_init(&temp1);
  38     mpz_init(&temp2);
  39
  40     mpz_set(&temp1, mp);
  41
  42     for (i = r.len-1; i >= 0; i--)
  43     {
  44         r.ptr[i] = mpz_mdivmod_ui(&temp2, NULL, &temp1, 1 << BITS_PER_BYTE);
  45         mpz_set(&temp1, &temp2);
  46     }
  47
  48     passert(mpz_sgn(&temp1) == 0);      /* we must have done all the bits */
  49     mpz_clear(&temp1);
  50     mpz_clear(&temp2);
  51
  52     return r;
  53 }
  54
  55 /* Convert network form (binary bytes, big-endian) to MP_INT.
  56  * The *mp must not be previously mpz_inited.
  57  */
  58 void
  59 n_to_mpz(MP_INT *mp, const u_char *nbytes, size_t nlen)
  60 {
  61     size_t i;
  62
  63     mpz_init_set_ui(mp, 0);
  64
  65     for (i = 0; i != nlen; i++)
  66     {
  67         mpz_mul_ui(mp, mp, 1 << BITS_PER_BYTE);
  68         mpz_add_ui(mp, mp, nbytes[i]);
  69     }
  70 }