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