git.distorted.org.uk Git - u/mdw/catacomb/blob - buf.c

   1 /* -*-c-*-
   2  *
   3  * $Id: buf.c,v 1.4 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * Buffer handling
   6  *
   7  * (c) 2001 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Header files ------------------------------------------------------*/
  31
  32 #include <string.h>
  33
  34 #include "mp.h"
  35 #include "ec.h"
  36 #include "buf.h"
  37
  38 /*----- Main code ---------------------------------------------------------*/
  39
  40 /* --- @buf_init@ --- *
  41  *
  42  * Arguments:   @buf *b@ = pointer to a buffer block
  43  *              @void *p@ = pointer to a buffer
  44  *              @size_t sz@ = size of the buffer
  45  *
  46  * Returns:     ---
  47  *
  48  * Use:         Initializes the buffer block appropriately.
  49  */
  50
  51 void buf_init(buf *b, void *p, size_t sz)
  52 {
  53   b->base = b->p = p;
  54   b->limit = b->p + sz;
  55   b->f = 0;
  56 }
  57
  58 /* --- @buf_break@ --- *
  59  *
  60  * Arguments:   @buf *b@ = pointer to a buffer block
  61  *
  62  * Returns:     Some negative value.
  63  *
  64  * Use:         Marks a buffer as broken.
  65  */
  66
  67 int buf_break(buf *b) { b->f |= BF_BROKEN; return (-1); }
  68
  69 /* --- @buf_flip@ --- *
  70  *
  71  * Arguments:   @buf *b@ = pointer to a buffer block
  72  *
  73  * Returns:     ---
  74  *
  75  * Use:         Flips a buffer so that if you've just been writing to it,
  76  *              you can now read from the bit you've written.
  77  */
  78
  79 void buf_flip(buf *b)
  80 {
  81   b->limit = b->p;
  82   b->p = b->base;
  83 }
  84
  85 /* --- @buf_ensure@ --- *
  86  *
  87  * Arguments:   @buf *b@ = pointer to a buffer block
  88  *              @size_t sz@ = size of data wanted
  89  *
  90  * Returns:     Zero if it worked, nonzero if there wasn't enough space.
  91  *
  92  * Use:         Ensures that there are @sz@ bytes still in the buffer.
  93  */
  94
  95 int buf_ensure(buf *b, size_t sz) { return (BENSURE(b, sz)); }
  96
  97 /* --- @buf_get@ --- *
  98  *
  99  * Arguments:   @buf *b@ = pointer to a buffer block
 100  *              @size_t sz@ = size of the buffer
 101  *
 102  * Returns:     Pointer to the place in the buffer.
 103  *
 104  * Use:         Reserves a space in the buffer of the requested size, and
 105  *              returns its start address.
 106  */
 107
 108 void *buf_get(buf *b, size_t sz)
 109 {
 110   void *p;
 111   if (BENSURE(b, sz))
 112     return (0);
 113   p = BCUR(b);
 114   BSTEP(b, sz);
 115   return (p);
 116 }
 117
 118 /* --- @buf_put@ --- *
 119  *
 120  * Arguments:   @buf *b@ = pointer to a buffer block
 121  *              @const void *p@ = pointer to a buffer
 122  *              @size_t sz@ = size of the buffer
 123  *
 124  * Returns:     Zero if it worked, nonzero if there wasn't enough space.
 125  *
 126  * Use:         Fetches data from some place and puts it in the buffer
 127  */
 128
 129 int buf_put(buf *b, const void *p, size_t sz)
 130 {
 131   if (BENSURE(b, sz))
 132     return (-1);
 133   memcpy(BCUR(b), p, sz);
 134   BSTEP(b, sz);
 135   return (0);
 136 }
 137
 138 /* --- @buf_getbyte@ --- *
 139  *
 140  * Arguments:   @buf *b@ = pointer to a buffer block
 141  *
 142  * Returns:     A byte, or less than zero if there wasn't a byte there.
 143  *
 144  * Use:         Gets a single byte from a buffer.
 145  */
 146
 147 int buf_getbyte(buf *b)
 148 {
 149   if (BENSURE(b, 1))
 150     return (-1);
 151   return (*b->p++);
 152 }
 153
 154 /* --- @buf_putbyte@ --- *
 155  *
 156  * Arguments:   @buf *b@ = pointer to a buffer block
 157  *              @int ch@ = byte to write
 158  *
 159  * Returns:     Zero if OK, nonzero if there wasn't enough space.
 160  *
 161  * Use:         Puts a single byte in a buffer.
 162  */
 163
 164 int buf_putbyte(buf *b, int ch)
 165 {
 166   if (BENSURE(b, 1))
 167     return (-1);
 168   *b->p++ = ch;
 169   return (0);
 170 }
 171
 172 /* --- @buf_getu16@ --- *
 173  *
 174  * Arguments:   @buf *b@ = pointer to a buffer block
 175  *              @uint16 *w@ = where to put the word
 176  *
 177  * Returns:     Zero if OK, or nonzero if there wasn't a word there.
 178  *
 179  * Use:         Gets a 16-bit word from a buffer.
 180  */
 181
 182 int buf_getu16(buf *b, uint16 *w)
 183 {
 184   if (BENSURE(b, 2))
 185     return (-1);
 186   *w = LOAD16(b->p);
 187   BSTEP(b, 2);
 188   return (0);
 189 }
 190
 191 /* --- @buf_putu16@ --- *
 192  *
 193  * Arguments:   @buf *b@ = pointer to a buffer block
 194  *              @uint16 w@ = word to write
 195  *
 196  * Returns:     Zero if OK, nonzero if there wasn't enough space.
 197  *
 198  * Use:         Puts a 16-but word in a buffer.
 199  */
 200
 201 int buf_putu16(buf *b, uint16 w)
 202 {
 203   if (BENSURE(b, 2))
 204     return (-1);
 205   STORE16(b->p, w);
 206   BSTEP(b, 2);
 207   return (0);
 208 }
 209
 210 /* --- @buf_getu32@ --- *
 211  *
 212  * Arguments:   @buf *b@ = pointer to a buffer block
 213  *              @uint32 *w@ = where to put the word
 214  *
 215  * Returns:     Zero if OK, or nonzero if there wasn't a word there.
 216  *
 217  * Use:         Gets a 32-bit word from a buffer.
 218  */
 219
 220 int buf_getu32(buf *b, uint32 *w)
 221 {
 222   if (BENSURE(b, 4))
 223     return (-1);
 224   *w = LOAD32(b->p);
 225   BSTEP(b, 4);
 226   return (0);
 227 }
 228
 229 /* --- @buf_putu32@ --- *
 230  *
 231  * Arguments:   @buf *b@ = pointer to a buffer block
 232  *              @uint32 w@ = word to write
 233  *
 234  * Returns:     Zero if OK, nonzero if there wasn't enough space.
 235  *
 236  * Use:         Puts a 32-but word in a buffer.
 237  */
 238
 239 int buf_putu32(buf *b, uint32 w)
 240 {
 241   if (BENSURE(b, 4))
 242     return (-1);
 243   STORE32(b->p, w);
 244   BSTEP(b, 4);
 245   return (0);
 246 }
 247
 248 /* --- @buf_getmp@ --- *
 249  *
 250  * Arguments:   @buf *b@ = pointer to a buffer block
 251  *
 252  * Returns:     A multiprecision integer, or null if there wasn't one there.
 253  *
 254  * Use:         Gets a multiprecision integer from a buffer.
 255  */
 256
 257 mp *buf_getmp(buf *b)
 258 {
 259   uint16 sz;
 260   size_t n;
 261   mp *m;
 262   if (buf_getu16(b, &sz) || buf_ensure(b, sz))
 263     return (0);
 264   m = mp_loadb(MP_NEW, BCUR(b), sz);
 265   n = mp_octets(m);
 266   if (n != sz && n != 0 && sz != 1) {
 267     mp_drop(m);
 268     return (0);
 269   }
 270   BSTEP(b, sz);
 271   return (m);
 272 }
 273
 274 /* --- @buf_putmp@ --- *
 275  *
 276  * Arguments:   @buf *b@ = pointer to a buffer block
 277  *              @mp *m@ = a multiprecision integer
 278  *
 279  * Returns:     Zero if it worked, nonzero if there wasn't enough space.
 280  *
 281  * Use:         Puts a multiprecision integer to a buffer.
 282  */
 283
 284 int buf_putmp(buf *b, mp *m)
 285 {
 286   size_t sz = mp_octets(m);
 287   assert(sz < MASK16);
 288   if (!sz) sz = 1;
 289   if (buf_putu16(b, sz) || buf_ensure(b, sz))
 290     return (-1);
 291   mp_storeb(m, BCUR(b), sz);
 292   BSTEP(b, sz);
 293   return (0);
 294 }
 295
 296 /* --- @buf_getec@ --- *
 297  *
 298  * Arguments:   @buf *b@ = pointer to a buffer block
 299  *              @ec *p@ = where to put the point
 300  *
 301  * Returns:     Zero if it worked, nonzero if it failed.
 302  *
 303  * Use:         Gets a multiprecision integer from a buffer.  The point must
 304  *              be initialized.
 305  */
 306
 307 int buf_getec(buf *b, ec *p)
 308 {
 309   mp *x = 0, *y = 0;
 310   uint16 n;
 311   if (buf_ensure(b, 2)) return (-1);
 312   n = LOAD16(BCUR(b)); if (!n) { BSTEP(b, 2); EC_SETINF(p); return (0); }
 313   if ((x = buf_getmp(b)) == 0 || (y = buf_getmp(b)) == 0) {
 314     mp_drop(x); mp_drop(y); return (-1);
 315   }
 316   EC_DESTROY(p); p->x = x; p->y = y; p->z = 0;
 317   return (0);
 318 }
 319
 320 /* --- @buf_putec@ --- *
 321  *
 322  * Arguments:   @buf *b@ = pointer to a buffer block
 323  *              @ec *p@ = an elliptic curve point
 324  *
 325  * Returns:     Zero if it worked, nonzero if there wasn't enough space.
 326  *
 327  * Use:         Puts an elliptic curve point to a buffer.
 328  */
 329
 330 int buf_putec(buf *b, ec *p)
 331 {
 332   if (EC_ATINF(p)) return (buf_putu16(b, 0));
 333   if (buf_putmp(b, p->x) || buf_putmp(b, p->y)) return (-1);
 334   return (0);
 335 }
 336
 337 /*----- That's all, folks -------------------------------------------------*/