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

   1 /* -*-c-*-
   2  *
   3  * Key binary encoding
   4  *
   5  * (c) 1999 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Catacomb.
  11  *
  12  * Catacomb is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Catacomb is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with Catacomb; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 /*----- Header files ------------------------------------------------------*/
  29
  30 #include <stdlib.h>
  31 #include <string.h>
  32
  33 #include <mLib/bits.h>
  34 #include <mLib/dstr.h>
  35 #include <mLib/sub.h>
  36 #include <mLib/sym.h>
  37
  38 #include "key-data.h"
  39 #include "mp.h"
  40 #include "mptext.h"
  41
  42 /*----- Main code ---------------------------------------------------------*/
  43
  44 /* --- @key_decode@ --- *
  45  *
  46  * Arguments:   @const void *p@ = pointer to buffer to read
  47  *              @size_t sz@ = size of the buffer
  48  *
  49  * Returns:     The newly-read key data, or null if it failed.
  50  *
  51  * Use:         Decodes a binary representation of a key.
  52  */
  53
  54 key_data *key_decode(const void *p, size_t sz)
  55 {
  56   const octet *q = p;
  57   size_t psz;
  58   key_data *kd;
  59   unsigned e;
  60
  61   /* --- Parse the header information --- *
  62    *
  63    * Make sure the size matches external reality.  Security holes have been
  64    * known to creep in without this sort of check.  (No, this isn't an after-
  65    * the-fact patch-up.)
  66    */
  67
  68   e = LOAD16(q);
  69   psz = LOAD16(q + 2);
  70   if (psz + 4 > sz)
  71     return (0);
  72
  73   /* --- Now decide what to do --- */
  74
  75   switch (e & KF_ENCMASK) {
  76
  77     /* --- Plain binary data --- */
  78
  79     case KENC_BINARY:
  80     case KENC_ENCRYPT:
  81       kd = key_newbinary(e, q + 4, psz);
  82       break;
  83
  84     /* --- Multiprecision integer data --- */
  85
  86     case KENC_MP:
  87       kd = key_newmp(e, mp_loadb(e & KF_BURN ? MP_NEWSEC : MP_NEW,
  88                                  q + 4, psz));
  89       break;
  90
  91     /* --- String data --- */
  92
  93     case KENC_STRING:
  94       kd = key_newraw(e);
  95       kd->u.p = xmalloc(sz + 1);
  96       memcpy(kd->u.p, q + 4, sz);
  97       kd->u.p[sz] = 0;
  98       break;
  99
 100     /* --- Elliptic curve point data --- */
 101
 102     case KENC_EC: {
 103       size_t xsz, ysz;
 104       kd = key_newraw(e);
 105       EC_CREATE(&kd->u.e);
 106       if (!sz) break;
 107       if (sz < 2) return (0);
 108       xsz = LOAD16(q + 4);
 109       if (sz < xsz + 4) return (0);
 110       ysz = LOAD16(q + 6 + xsz);
 111       if (sz < xsz + ysz + 4) return (0);
 112       kd->u.e.x = mp_loadb(MP_NEW, q + 6, xsz);
 113       kd->u.e.y = mp_loadb(MP_NEW, q + 8 + xsz, ysz);
 114     } break;
 115
 116     /* --- Structured key data --- */
 117
 118     case KENC_STRUCT: {
 119       dstr d = DSTR_INIT;
 120       key_data *nkd;
 121
 122       if ((e & ~KF_ENCMASK) || (psz & 3))
 123         return (0);
 124       q += 4;
 125       kd = key_newstruct();
 126
 127       while (psz) {
 128
 129         /* --- Read the tag string --- */
 130
 131         DRESET(&d);
 132         sz = LOAD8(q);
 133         if (sz >= psz)
 134           goto fail;
 135         DPUTM(&d, q + 1, sz);
 136         DPUTZ(&d);
 137         sz = (sz + 4) & ~3;
 138         q += sz; psz -= sz;
 139
 140         /* --- Read the encoding and size --- */
 141
 142         sz = (LOAD16(q + 2) + 7) & ~3;
 143         if (sz > psz)
 144           goto fail;
 145
 146         /* --- Create a table node and fill it in --- */
 147
 148         if ((nkd = key_decode(q, sz)) == 0)
 149           goto fail;
 150         key_structsteal(kd, d.buf, nkd);
 151         psz -= sz;
 152         q += sz;
 153       }
 154       dstr_destroy(&d);
 155       break;
 156
 157       /* --- Tidy up after a failure --- */
 158
 159     fail:
 160       dstr_destroy(&d);
 161       key_drop(kd);
 162       return (0);
 163     } break;
 164
 165     /* --- Everything else --- */
 166
 167     default:
 168       return (0);
 169   }
 170
 171   /* --- OK, that was good --- */
 172
 173   kd->e = e;
 174   return (kd);
 175 }
 176
 177 /* --- @key_encode@ --- *
 178  *
 179  * Arguments:   @key_data *k@ = pointer to key data block
 180  *              @dstr *d@ = pointer to destination string
 181  *              @const key_filter *kf@ = pointer to key selection block
 182  *
 183  * Returns:     Nonzero if an item was actually written.
 184  *
 185  * Use:         Encodes a key block as binary data.
 186  */
 187
 188 static int ksbyname(const void *a, const void *b) {
 189   key_struct *const *x = a, *const *y = b;
 190   return (strcmp(SYM_NAME(*x), SYM_NAME(*y)));
 191 }
 192
 193 int key_encode(key_data *k, dstr *d, const key_filter *kf)
 194 {
 195   int rc = 0;
 196   if (!KEY_MATCH(k, kf))
 197     return (0);
 198   switch (k->e & KF_ENCMASK) {
 199     case KENC_BINARY:
 200     case KENC_ENCRYPT: {
 201       char *p;
 202
 203       DENSURE(d, (k->u.k.sz + 7) & ~3);
 204       p = d->buf + d->len;
 205       STORE16(p, k->e);
 206       STORE16(p + 2, k->u.k.sz);
 207       d->len += 4;
 208       DPUTM(d, k->u.k.k, k->u.k.sz);
 209       rc = 1;
 210     } break;
 211
 212     case KENC_MP: {
 213       char *p;
 214       size_t sz = mp_octets(k->u.m);
 215
 216       DENSURE(d, (sz + 7) & ~3);
 217       p = d->buf + d->len;
 218       STORE16(p, k->e);
 219       STORE16(p + 2, sz);
 220       mp_storeb(k->u.m, p + 4, sz);
 221       d->len += sz + 4;
 222       rc = 1;
 223     } break;
 224
 225     case KENC_STRING: {
 226       char *p;
 227       size_t sz = strlen(k->u.p);
 228
 229       DENSURE(d, (sz + 7) & ~3);
 230       p = d->buf + d->len;
 231       STORE16(p, k->e);
 232       STORE16(p + 2, sz);
 233       memcpy(p + 4, k->u.p, sz);
 234       d->len += sz + 4;
 235       rc = 1;
 236     } break;
 237
 238     case KENC_EC: {
 239       char *p;
 240       size_t xsz = 0, ysz = 0;
 241       size_t sz;
 242
 243       if (EC_ATINF(&k->u.e))
 244         sz = 0;
 245       else {
 246         xsz = mp_octets(k->u.e.x);
 247         ysz = mp_octets(k->u.e.y);
 248         sz = xsz + ysz + 4;
 249       }
 250       DENSURE(d, (sz + 7) & ~3);
 251       p = d->buf + d->len;
 252       STORE16(p, k->e);
 253       STORE16(p + 2, sz);
 254       if (!EC_ATINF(&k->u.e)) {
 255         STORE16(p + 4, xsz);
 256         mp_storeb(k->u.e.x, p + 6, xsz);
 257         STORE16(p + 6 + xsz, ysz);
 258         mp_storeb(k->u.e.y, p + 8 + xsz, ysz);
 259       }
 260       d->len += sz + 4;
 261       rc = 1;
 262     } break;
 263
 264     case KENC_STRUCT: {
 265       size_t n;
 266       char *p;
 267       key_struct *ks, **ksv;
 268       size_t nks, j;
 269       sym_iter i;
 270
 271       n = d->len;
 272       DENSURE(d, 4);
 273       p = d->buf + n;
 274       STORE16(p, k->e & KF_ENCMASK);
 275       d->len += 4;
 276
 277       for (nks = 0, sym_mkiter(&i, &k->u.s);
 278            (ks = sym_next(&i)) != 0;
 279            nks++);
 280       if (nks) {
 281         ksv = xmalloc(nks * sizeof(*ksv));
 282         for (j = 0, sym_mkiter(&i, &k->u.s); (ks = sym_next(&i)) != 0; j++)
 283           ksv[j] = ks;
 284         qsort(ksv, nks, sizeof(*ksv), ksbyname);
 285         for (j = 0; j < nks; j++) {
 286           size_t o = d->len;
 287           ks = ksv[j];
 288           DENSURE(d, 1);
 289           *(octet *)(d->buf + d->len++) = strlen(SYM_NAME(ks));
 290           DPUTS(d, SYM_NAME(ks));
 291           while (d->len & 3)
 292             DPUTC(d, 0);
 293           if (key_encode(ks->k, d, kf))
 294             rc = 1;
 295           else
 296             d->len = o;
 297         }
 298         xfree(ksv);
 299       }
 300       if (!rc)
 301         d->len = n;
 302       else {
 303         p = d->buf + n + 2;
 304         n = d->len - n - 4;
 305         STORE16(p,  n);
 306       }
 307     } break;
 308   }
 309   while (d->len & 3)
 310     DPUTC(d, 0);
 311   return (rc);
 312 }
 313
 314 /*----- That's all, folks -------------------------------------------------*/