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

   1 /* -*-c-*-
   2  *
   3  * $Id: key-binary.c,v 1.7 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * Key binary encoding
   6  *
   7  * (c) 1999 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 <stdlib.h>
  33 #include <string.h>
  34
  35 #include <mLib/bits.h>
  36 #include <mLib/dstr.h>
  37 #include <mLib/sub.h>
  38 #include <mLib/sym.h>
  39
  40 #include "key-data.h"
  41 #include "mp.h"
  42 #include "mptext.h"
  43
  44 /*----- Main code ---------------------------------------------------------*/
  45
  46 /* --- @key_decode@ --- *
  47  *
  48  * Arguments:   @const void *p@ = pointer to buffer to read
  49  *              @size_t sz@ = size of the buffer
  50  *              @key_data *k@ = pointer to key data block to write to
  51  *
  52  * Returns:     Zero if everything worked, nonzero otherwise.
  53  *
  54  * Use:         Decodes a binary representation of a key.
  55  */
  56
  57 int key_decode(const void *p, size_t sz, key_data *k)
  58 {
  59   const octet *q = p;
  60   size_t psz;
  61   unsigned e;
  62
  63   /* --- Parse the header information --- *
  64    *
  65    * Make sure the size matches external reality.  Security holes have been
  66    * known to creep in without this sort of check.  (No, this isn't an after-
  67    * the-fact patch-up.)
  68    */
  69
  70   e = LOAD16(q);
  71   psz = LOAD16(q + 2);
  72   if (psz + 4 > sz)
  73     return (-1);
  74   k->e = e;
  75
  76   /* --- Now decide what to do --- */
  77
  78   switch (e & KF_ENCMASK) {
  79
  80     /* --- Plain binary data --- */
  81
  82     case KENC_BINARY:
  83     case KENC_ENCRYPT:
  84       k->u.k.k = sub_alloc(psz);
  85       memcpy(k->u.k.k, q + 4, psz);
  86       k->u.k.sz = psz;
  87       break;
  88
  89     /* --- Multiprecision integer data --- */
  90
  91     case KENC_MP:
  92       k->u.m = mp_loadb(k->e & KF_BURN ? MP_NEWSEC : MP_NEW, q + 4, psz);
  93       break;
  94
  95     /* --- String data --- */
  96
  97     case KENC_STRING:
  98       k->u.p = xmalloc(sz + 1);
  99       memcpy(k->u.p, q + 4, sz);
 100       k->u.p[sz] = 0;
 101       break;
 102
 103     /* --- Elliptic curve point data --- */
 104
 105     case KENC_EC: {
 106       size_t xsz, ysz;
 107       EC_CREATE(&k->u.e);
 108       if (!sz) break;
 109       if (sz < 2) return (-1);
 110       xsz = LOAD16(q + 4);
 111       if (sz < xsz + 4) return (-1);
 112       ysz = LOAD16(q + 6 + xsz);
 113       if (sz < xsz + ysz + 4) return (-1);
 114       k->u.e.x = mp_loadb(MP_NEW, q + 6, xsz);
 115       k->u.e.y = mp_loadb(MP_NEW, q + 6 + xsz, ysz);
 116     } break;
 117
 118     /* --- Structured key data --- */
 119
 120     case KENC_STRUCT: {
 121       dstr d = DSTR_INIT;
 122       key_struct *ks;
 123       unsigned f;
 124
 125       if ((k->e & ~KF_ENCMASK) || (psz & 3))
 126         return (-1);
 127       q += 4;
 128       sym_create(&k->u.s);
 129
 130       while (psz) {
 131
 132         /* --- Read the tag string --- */
 133
 134         DRESET(&d);
 135         sz = LOAD8(q);
 136         if (sz >= psz)
 137           goto fail;
 138         DPUTM(&d, q + 1, sz);
 139         DPUTZ(&d);
 140         sz = (sz + 4) & ~3;
 141         q += sz; psz -= sz;
 142
 143         /* --- Read the encoding and size --- */
 144
 145         e = LOAD16(q);
 146         sz = (LOAD16(q + 2) + 7) & ~3;
 147         if (sz > psz)
 148           goto fail;
 149
 150         /* --- Create a table node and fill it in --- */
 151
 152         ks = sym_find(&k->u.s, d.buf, d.len, sizeof(*ks), &f);
 153         if (f)
 154           goto fail;
 155         if (key_decode(q, sz, &ks->k)) {
 156           sym_remove(&k->u.s, ks);
 157           goto fail;
 158         }
 159         psz -= sz;
 160         q += sz;
 161       }
 162       dstr_destroy(&d);
 163       break;
 164
 165       /* --- Tidy up after a failure --- */
 166
 167     fail:
 168       dstr_destroy(&d);
 169       key_destroy(k);
 170       return (-1);
 171     } break;
 172
 173     /* --- Everything else --- */
 174
 175     default:
 176       return (-1);
 177   }
 178
 179   /* --- OK, that was good --- */
 180
 181   return (0);
 182 }
 183
 184 /* --- @key_encode@ --- *
 185  *
 186  * Arguments:   @key_data *k@ = pointer to key data block
 187  *              @dstr *d@ = pointer to destination string
 188  *              @const key_filter *kf@ = pointer to key selection block
 189  *
 190  * Returns:     Nonzero if an item was actually written.
 191  *
 192  * Use:         Encodes a key block as binary data.
 193  */
 194
 195 static int ksbyname(const void *a, const void *b) {
 196   key_struct *const *x = a, *const *y = b;
 197   return (strcmp(SYM_NAME(*x), SYM_NAME(*y)));
 198 }
 199
 200 int key_encode(key_data *k, dstr *d, const key_filter *kf)
 201 {
 202   int rc = 0;
 203   if (!KEY_MATCH(k, kf))
 204     return (0);
 205   switch (k->e & KF_ENCMASK) {
 206     case KENC_BINARY:
 207     case KENC_ENCRYPT: {
 208       char *p;
 209
 210       DENSURE(d, (k->u.k.sz + 7) & ~3);
 211       p = d->buf + d->len;
 212       STORE16(p, k->e);
 213       STORE16(p + 2, k->u.k.sz);
 214       d->len += 4;
 215       DPUTM(d, k->u.k.k, k->u.k.sz);
 216       rc = 1;
 217     } break;
 218
 219     case KENC_MP: {
 220       char *p;
 221       size_t sz = mp_octets(k->u.m);
 222
 223       DENSURE(d, (sz + 7) & ~3);
 224       p = d->buf + d->len;
 225       STORE16(p, k->e);
 226       STORE16(p + 2, sz);
 227       mp_storeb(k->u.m, p + 4, sz);
 228       d->len += sz + 4;
 229       rc = 1;
 230     } break;
 231
 232     case KENC_STRING: {
 233       char *p;
 234       size_t sz = strlen(k->u.p);
 235
 236       DENSURE(d, (sz + 7) & ~3);
 237       p = d->buf + d->len;
 238       STORE16(p, k->e);
 239       STORE16(p + 2, sz);
 240       memcpy(p + 4, k->u.p, sz);
 241       d->len += sz + 4;
 242       rc = 1;
 243     } break;
 244
 245     case KENC_EC: {
 246       char *p;
 247       size_t xsz = 0, ysz = 0;
 248       size_t sz;
 249
 250       if (EC_ATINF(&k->u.e))
 251         sz = 0;
 252       else {
 253         xsz = mp_octets(k->u.e.x);
 254         ysz = mp_octets(k->u.e.y);
 255         sz = xsz + ysz + 4;
 256       }
 257       DENSURE(d, (sz + 7) & ~3);
 258       p = d->buf + d->len;
 259       STORE16(p, k->e);
 260       STORE16(p + 2, sz);
 261       if (!EC_ATINF(&k->u.e)) {
 262         STORE16(p + 4, xsz);
 263         mp_storeb(k->u.e.x, p + 6, xsz);
 264         STORE16(p + 6 + xsz, ysz);
 265         mp_storeb(k->u.e.y, p + 8 + xsz, ysz);
 266       }
 267       d->len += sz + 4;
 268       rc = 1;
 269     } break;
 270
 271     case KENC_STRUCT: {
 272       size_t n;
 273       char *p;
 274       key_struct *ks, **ksv;
 275       size_t nks, j;
 276       sym_iter i;
 277
 278       n = d->len;
 279       DENSURE(d, 4);
 280       p = d->buf + n;
 281       STORE16(p, k->e & KF_ENCMASK);
 282       d->len += 4;
 283
 284       for (nks = 0, sym_mkiter(&i, &k->u.s);
 285            (ks = sym_next(&i)) != 0;
 286            nks++);
 287       if (nks) {
 288         ksv = xmalloc(nks * sizeof(*ksv));
 289         for (j = 0, sym_mkiter(&i, &k->u.s); (ks = sym_next(&i)) != 0; j++)
 290           ksv[j] = ks;
 291         qsort(ksv, nks, sizeof(*ksv), ksbyname);
 292         for (j = 0; j < nks; j++) {
 293           size_t o = d->len;
 294           ks = ksv[j];
 295           DENSURE(d, 1);
 296           *(octet *)(d->buf + d->len++) = strlen(SYM_NAME(ks));
 297           DPUTS(d, SYM_NAME(ks));
 298           while (d->len & 3)
 299             DPUTC(d, 0);
 300           if (key_encode(&ks->k, d, kf))
 301             rc = 1;
 302           else
 303             d->len = o;
 304         }
 305         xfree(ksv);
 306       }
 307       if (!rc)
 308         d->len = n;
 309       else {
 310         p = d->buf + n + 2;
 311         n = d->len - n - 4;
 312         STORE16(p,  n);
 313       }
 314     } break;
 315   }
 316   while (d->len & 3)
 317     DPUTC(d, 0);
 318   return (rc);
 319 }
 320
 321 /*----- That's all, folks -------------------------------------------------*/