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

   1 /* -*-c-*-
   2  *
   3  * $Id$
   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  *
  51  * Returns:     The newly-read key data, or null if it failed.
  52  *
  53  * Use:         Decodes a binary representation of a key.
  54  */
  55
  56 key_data *key_decode(const void *p, size_t sz)
  57 {
  58   const octet *q = p;
  59   size_t psz;
  60   key_data *kd;
  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 (0);
  74
  75   /* --- Now decide what to do --- */
  76
  77   switch (e & KF_ENCMASK) {
  78
  79     /* --- Plain binary data --- */
  80
  81     case KENC_BINARY:
  82     case KENC_ENCRYPT:
  83       kd = key_newbinary(e, q + 4, psz);
  84       break;
  85
  86     /* --- Multiprecision integer data --- */
  87
  88     case KENC_MP:
  89       kd = key_newmp(e, mp_loadb(e & KF_BURN ? MP_NEWSEC : MP_NEW,
  90                                  q + 4, psz));
  91       break;
  92
  93     /* --- String data --- */
  94
  95     case KENC_STRING:
  96       kd = key_newraw(e);
  97       kd->u.p = xmalloc(sz + 1);
  98       memcpy(kd->u.p, q + 4, sz);
  99       kd->u.p[sz] = 0;
 100       break;
 101
 102     /* --- Elliptic curve point data --- */
 103
 104     case KENC_EC: {
 105       size_t xsz, ysz;
 106       kd = key_newraw(e);
 107       EC_CREATE(&kd->u.e);
 108       if (!sz) break;
 109       if (sz < 2) return (0);
 110       xsz = LOAD16(q + 4);
 111       if (sz < xsz + 4) return (0);
 112       ysz = LOAD16(q + 6 + xsz);
 113       if (sz < xsz + ysz + 4) return (0);
 114       kd->u.e.x = mp_loadb(MP_NEW, q + 6, xsz);
 115       kd->u.e.y = mp_loadb(MP_NEW, q + 8 + xsz, ysz);
 116     } break;
 117
 118     /* --- Structured key data --- */
 119
 120     case KENC_STRUCT: {
 121       dstr d = DSTR_INIT;
 122       key_data *nkd;
 123
 124       if ((e & ~KF_ENCMASK) || (psz & 3))
 125         return (0);
 126       q += 4;
 127       kd = key_newstruct();
 128
 129       while (psz) {
 130
 131         /* --- Read the tag string --- */
 132
 133         DRESET(&d);
 134         sz = LOAD8(q);
 135         if (sz >= psz)
 136           goto fail;
 137         DPUTM(&d, q + 1, sz);
 138         DPUTZ(&d);
 139         sz = (sz + 4) & ~3;
 140         q += sz; psz -= sz;
 141
 142         /* --- Read the encoding and size --- */
 143
 144         sz = (LOAD16(q + 2) + 7) & ~3;
 145         if (sz > psz)
 146           goto fail;
 147
 148         /* --- Create a table node and fill it in --- */
 149
 150         if ((nkd = key_decode(q, sz)) == 0)
 151           goto fail;
 152         key_structsteal(kd, d.buf, nkd);
 153         psz -= sz;
 154         q += sz;
 155       }
 156       dstr_destroy(&d);
 157       break;
 158
 159       /* --- Tidy up after a failure --- */
 160
 161     fail:
 162       dstr_destroy(&d);
 163       key_drop(kd);
 164       return (0);
 165     } break;
 166
 167     /* --- Everything else --- */
 168
 169     default:
 170       return (0);
 171   }
 172
 173   /* --- OK, that was good --- */
 174
 175   kd->e = e;
 176   return (kd);
 177 }
 178
 179 /* --- @key_encode@ --- *
 180  *
 181  * Arguments:   @key_data *k@ = pointer to key data block
 182  *              @dstr *d@ = pointer to destination string
 183  *              @const key_filter *kf@ = pointer to key selection block
 184  *
 185  * Returns:     Nonzero if an item was actually written.
 186  *
 187  * Use:         Encodes a key block as binary data.
 188  */
 189
 190 static int ksbyname(const void *a, const void *b) {
 191   key_struct *const *x = a, *const *y = b;
 192   return (strcmp(SYM_NAME(*x), SYM_NAME(*y)));
 193 }
 194
 195 int key_encode(key_data *k, dstr *d, const key_filter *kf)
 196 {
 197   int rc = 0;
 198   if (!KEY_MATCH(k, kf))
 199     return (0);
 200   switch (k->e & KF_ENCMASK) {
 201     case KENC_BINARY:
 202     case KENC_ENCRYPT: {
 203       char *p;
 204
 205       DENSURE(d, (k->u.k.sz + 7) & ~3);
 206       p = d->buf + d->len;
 207       STORE16(p, k->e);
 208       STORE16(p + 2, k->u.k.sz);
 209       d->len += 4;
 210       DPUTM(d, k->u.k.k, k->u.k.sz);
 211       rc = 1;
 212     } break;
 213
 214     case KENC_MP: {
 215       char *p;
 216       size_t sz = mp_octets(k->u.m);
 217
 218       DENSURE(d, (sz + 7) & ~3);
 219       p = d->buf + d->len;
 220       STORE16(p, k->e);
 221       STORE16(p + 2, sz);
 222       mp_storeb(k->u.m, p + 4, sz);
 223       d->len += sz + 4;
 224       rc = 1;
 225     } break;
 226
 227     case KENC_STRING: {
 228       char *p;
 229       size_t sz = strlen(k->u.p);
 230
 231       DENSURE(d, (sz + 7) & ~3);
 232       p = d->buf + d->len;
 233       STORE16(p, k->e);
 234       STORE16(p + 2, sz);
 235       memcpy(p + 4, k->u.p, sz);
 236       d->len += sz + 4;
 237       rc = 1;
 238     } break;
 239
 240     case KENC_EC: {
 241       char *p;
 242       size_t xsz = 0, ysz = 0;
 243       size_t sz;
 244
 245       if (EC_ATINF(&k->u.e))
 246         sz = 0;
 247       else {
 248         xsz = mp_octets(k->u.e.x);
 249         ysz = mp_octets(k->u.e.y);
 250         sz = xsz + ysz + 4;
 251       }
 252       DENSURE(d, (sz + 7) & ~3);
 253       p = d->buf + d->len;
 254       STORE16(p, k->e);
 255       STORE16(p + 2, sz);
 256       if (!EC_ATINF(&k->u.e)) {
 257         STORE16(p + 4, xsz);
 258         mp_storeb(k->u.e.x, p + 6, xsz);
 259         STORE16(p + 6 + xsz, ysz);
 260         mp_storeb(k->u.e.y, p + 8 + xsz, ysz);
 261       }
 262       d->len += sz + 4;
 263       rc = 1;
 264     } break;
 265
 266     case KENC_STRUCT: {
 267       size_t n;
 268       char *p;
 269       key_struct *ks, **ksv;
 270       size_t nks, j;
 271       sym_iter i;
 272
 273       n = d->len;
 274       DENSURE(d, 4);
 275       p = d->buf + n;
 276       STORE16(p, k->e & KF_ENCMASK);
 277       d->len += 4;
 278
 279       for (nks = 0, sym_mkiter(&i, &k->u.s);
 280            (ks = sym_next(&i)) != 0;
 281            nks++);
 282       if (nks) {
 283         ksv = xmalloc(nks * sizeof(*ksv));
 284         for (j = 0, sym_mkiter(&i, &k->u.s); (ks = sym_next(&i)) != 0; j++)
 285           ksv[j] = ks;
 286         qsort(ksv, nks, sizeof(*ksv), ksbyname);
 287         for (j = 0; j < nks; j++) {
 288           size_t o = d->len;
 289           ks = ksv[j];
 290           DENSURE(d, 1);
 291           *(octet *)(d->buf + d->len++) = strlen(SYM_NAME(ks));
 292           DPUTS(d, SYM_NAME(ks));
 293           while (d->len & 3)
 294             DPUTC(d, 0);
 295           if (key_encode(ks->k, d, kf))
 296             rc = 1;
 297           else
 298             d->len = o;
 299         }
 300         xfree(ksv);
 301       }
 302       if (!rc)
 303         d->len = n;
 304       else {
 305         p = d->buf + n + 2;
 306         n = d->len - n - 4;
 307         STORE16(p,  n);
 308       }
 309     } break;
 310   }
 311   while (d->len & 3)
 312     DPUTC(d, 0);
 313   return (rc);
 314 }
 315
 316 /*----- That's all, folks -------------------------------------------------*/