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

   1 /* -*-c-*-
   2  *
   3  * Key textual 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 <ctype.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33
  34 #include <mLib/base64.h>
  35 #include <mLib/bits.h>
  36 #include <mLib/dstr.h>
  37 #include <mLib/sub.h>
  38 #include <mLib/sym.h>
  39 #include <mLib/url.h>
  40
  41 #include "key-data.h"
  42 #include "mp.h"
  43 #include "mptext.h"
  44
  45 /*----- Main code ---------------------------------------------------------*/
  46
  47 /* --- @key_read@ --- *
  48  *
  49  * Arguments:   @const char *p@ = pointer to textual key representation
  50  *              @char **pp@ = where to store the end pointer
  51  *
  52  * Returns:     The newly-read key data, or null if it failed.
  53  *
  54  * Use:         Parses a textual key description.
  55  */
  56
  57 key_data *key_read(const char *p, char **pp)
  58 {
  59   unsigned e;
  60   key_data *kd;
  61
  62   /* --- Read the encoding type --- *
  63    *
  64    * The key format is `[FLAGS:]DATA'.  If there is no encoding type
  65    * named, assume that it's `binary' for backwards compatibility.
  66    */
  67
  68   if (strchr(p, ':') == 0)
  69     e = 0;
  70   else {
  71     char *q;
  72     if (key_readflags(p, &q, &e, 0))
  73       return (0);
  74     p = q + 1;
  75   }
  76
  77   /* --- Now scan the data based on the encoding type --- */
  78
  79   switch (e & KF_ENCMASK) {
  80
  81     /* --- Binary encoding --- *
  82      *
  83      * Simply read out the Base64-encoded data.  Since `,' and `]' are our
  84      * delimeter characters, and they can't appear in Base64-encoded data, I
  85      * can just do a simple search to find the end of the encoded data.
  86      */
  87
  88     case KENC_BINARY:
  89     case KENC_ENCRYPT: {
  90       dstr d = DSTR_INIT;
  91       base64_ctx b;
  92       size_t sz = strcspn(p, ",]");
  93
  94       base64_init(&b);
  95       base64_decode(&b, p, sz, &d);
  96       base64_decode(&b, 0, 0, &d);
  97       kd = key_newbinary(e, d.buf, d.len);
  98       dstr_destroy(&d);
  99       p += sz;
 100     } break;
 101
 102     /* --- Multiprecision integer encoding --- *
 103      *
 104      * Multiprecision integers have a convenient reading function.
 105      */
 106
 107     case KENC_MP: {
 108       char *q;
 109       mp *m = mp_readstring(e & KF_BURN ? MP_NEWSEC : MP_NEW, p, &q, 0);
 110       if (!m)
 111         return (0);
 112       kd = key_newmp(e, m);
 113       MP_DROP(m);
 114       p = q;
 115     } break;
 116
 117     /* --- String encoding --- *
 118      *
 119      * We use form-urlencoding to ensure that evil characters don't get out.
 120      */
 121
 122     case KENC_STRING: {
 123       dstr d = DSTR_INIT;
 124       size_t sz = strcspn(p, ",]");
 125       const char *l = p + sz;
 126       unsigned int ch;
 127       int x, n;
 128
 129       while (p < l) {
 130         switch (*p) {
 131           case '+':
 132             DPUTC(&d, ' '); break;
 133           case '%':
 134             x = sscanf(p + 1, "%2x%n", &ch, &n);
 135             if (x == 1) { DPUTC(&d, ch); p += n; break; }
 136           default:
 137             DPUTC(&d, *p); break;
 138         }
 139         p++;
 140       }
 141       DPUTZ(&d);
 142       kd = key_newstring(e, d.buf);
 143       dstr_destroy(&d);
 144     } break;
 145
 146     /* --- Elliptic curve encoding --- *
 147      *
 148      * Again, we have a convenient function.  Assume for now that points
 149      * aren't secret.  (Reasonably safe.)
 150      */
 151
 152     case KENC_EC: {
 153       ec pt = EC_INIT;
 154       qd_parse qd;
 155       qd.p = p;
 156       qd.e = 0;
 157       if (!ec_ptparse(&qd, &pt))
 158         return (0);
 159       kd = key_newec(e, &pt);
 160       EC_DESTROY(&pt);
 161       p = qd.p;
 162     } break;
 163
 164     /* --- Structured information encoding --- *
 165      *
 166      * The format for structured key data is `[NAME=KEY,...]', where the
 167      * brackets are part of the syntax.  Structured keys have no flags apart
 168      * from the encoding.
 169      *
 170      * The binary encoding only allows names up to 255 bytes long.  Check for
 171      * this here.
 172      */
 173
 174     case KENC_STRUCT: {
 175       dstr d = DSTR_INIT;
 176       key_data *nkd;
 177       char *q;
 178
 179       /* --- Read the opening bracket --- */
 180
 181       kd = key_newstruct();
 182       if (*p != '[')
 183         return (0);
 184       p++;
 185
 186       /* --- Read named key subparts --- */
 187
 188       for (;;) {
 189         size_t sz;
 190
 191         /* --- Stop if there's a close-bracket --- *
 192          *
 193          * This allows `[]' to be an empty structured key, which is good.  It
 194          * also makes `[foo=enc:bar,]' legal, and that's less good but I can
 195          * live with it.
 196          */
 197
 198         if (*p == ']')
 199           break;
 200
 201         /* --- Read the name out and check the length --- */
 202
 203         if ((q = strchr(p, '=')) == 0)
 204           goto fail;
 205         sz = q - p;
 206         if (sz >= 256)
 207           goto fail;
 208         DRESET(&d);
 209         DPUTM(&d, p, sz);
 210         DPUTZ(&d);
 211
 212         /* --- Read the key data for the subkey --- */
 213
 214         if ((nkd = key_read(q + 1, &q)) == 0)
 215           goto fail;
 216         key_structsteal(kd, d.buf, nkd);
 217         p = q;
 218
 219         /* --- Read the comma or close-bracket --- */
 220
 221         if (*p == ']')
 222           break;
 223         else if (*p == ',')
 224           p++;
 225         else
 226           goto fail;
 227       }
 228
 229       /* --- Step past the close bracket --- */
 230
 231       p++;
 232       dstr_destroy(&d);
 233       break;
 234
 235       /* --- Tidy up after a failure --- */
 236
 237     fail:
 238       dstr_destroy(&d);
 239       return (0);
 240     } break;
 241
 242     /* --- Anything else is unknown --- */
 243
 244     default:
 245       return (0);
 246   }
 247
 248   /* --- Return the end pointer --- */
 249
 250   kd->e = e;
 251   if (pp)
 252     *pp = (char *)p;
 253   return (kd);
 254 }
 255
 256 /* --- @key_write@ --- *
 257  *
 258  * Arguments:   @key_data *k@ = pointer to key data
 259  *              @dstr *d@ = destination string to write on
 260  *              @const key_filter *kf@ = pointer to key selection block
 261  *
 262  * Returns:     Nonzero if an item was actually written.
 263  *
 264  * Use:         Writes a key in a textual encoding.
 265  */
 266
 267 int key_write(key_data *k, dstr *d, const key_filter *kf)
 268 {
 269   int rc = 0;
 270   if (!KEY_MATCH(k, kf))
 271     return (0);
 272   switch (k->e & KF_ENCMASK) {
 273     case KENC_BINARY:
 274     case KENC_ENCRYPT: {
 275       base64_ctx b;
 276
 277       if ((k->e & KF_ENCMASK) == KENC_BINARY)
 278         key_writeflags(k->e, d);
 279       else
 280         DPUTS(d, "encrypt,secret");
 281       DPUTC(d, ':');
 282       base64_init(&b);
 283       b.indent = "";
 284       b.maxline = 0;
 285       base64_encode(&b, k->u.k.k, k->u.k.sz, d);
 286       base64_encode(&b, 0, 0, d);
 287       rc = 1;
 288     } break;
 289     case KENC_MP:
 290       key_writeflags(k->e, d);
 291       DPUTC(d, ':');
 292       mp_writedstr(k->u.m, d, 10);
 293       rc = 1;
 294       break;
 295     case KENC_STRING: {
 296       const char *p = k->u.p;
 297       key_writeflags(k->e, d);
 298       DPUTC(d, ':');
 299       while (*p) {
 300         if (*p == ' ') DPUTC(d, '+');
 301         else if (!isalnum((unsigned char)*p)) dstr_putf(d, "%%%02x", *p);
 302         else DPUTC(d, *p);
 303         p++;
 304       }
 305       rc = 1;
 306     } break;
 307     case KENC_EC:
 308       key_writeflags(k->e, d);
 309       DPUTS(d, ":0x"); mp_writedstr(k->u.e.x, d, 16);
 310       DPUTS(d, ",0x"); mp_writedstr(k->u.e.y, d, 16);
 311       rc = 1;
 312       break;
 313     case KENC_STRUCT: {
 314       key_subkeyiter i;
 315       const char *tag;
 316       char del = 0;
 317       size_t n = d->len;
 318
 319       DPUTS(d, "struct:[");
 320       for (key_mksubkeyiter(&i, k); key_nextsubkey(&i, &tag, &k); ) {
 321         size_t o = d->len;
 322         if (del)
 323           DPUTC(d, del);
 324         DPUTS(d, tag);
 325         DPUTC(d, '=');
 326         if (!key_write(k, d, kf))
 327           d->len = o;
 328         else {
 329           del = ',';
 330           rc = 1;
 331         }
 332       }
 333       if (!rc)
 334         d->len = n;
 335       else
 336         DPUTC(d, ']');
 337     } break;
 338   }
 339   DPUTZ(d);
 340
 341   return (rc);
 342 }
 343
 344 /*----- That's all, folks -------------------------------------------------*/