git.distorted.org.uk Git - u/mdw/catacomb/blob - math/group-parse.c

   1 /* -*-c-*-
   2  *
   3  * Parse group description strings
   4  *
   5  * (c) 2004 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial IP Encryption (TrIPE).
  11  *
  12  * TrIPE is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * TrIPE 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 General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with TrIPE; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 /*----- Header files ------------------------------------------------------*/
  28
  29 #include "group.h"
  30 #include "dh.h"
  31
  32 /*----- Main code ---------------------------------------------------------*/
  33
  34 /* --- @group_parse@ --- *
  35  *
  36  * Arguments:   @qd_parse *qd@ = quick-and-dirty parser
  37  *
  38  * Returns:     Group pointer, or null for failure.
  39  *
  40  * Use:         Parses a group description and returns the group.  This has
  41  *              the form `TYPE { SPEC }' where TYPE is `prime' or `ec', and
  42  *              SPEC is the appropriate kind of group specification of the
  43  *              given type.
  44  */
  45
  46 group *group_parse(qd_parse *qd)
  47 {
  48   group *g = 0;
  49
  50   switch (qd_enum(qd, "prime,ec")) {
  51     case 0: {
  52       dh_param dp;
  53       qd_delim(qd, '{');
  54       if (dh_parse(qd, &dp)) goto ouch;
  55       qd_delim(qd, '}');
  56       g = group_prime(&dp);
  57       dh_paramfree(&dp);
  58     } break;
  59     case 1: {
  60       ec_info ei;
  61       qd_delim(qd, '{');
  62       if (ec_infoparse(qd, &ei)) goto ouch;
  63       qd_delim(qd, '}');
  64       g = group_ec(&ei);
  65     } break;
  66   }
  67   if (!g) qd->e = "bad group parameters";
  68 ouch:
  69   return (g);
  70 }
  71
  72 /* --- @group_fromstring@ --- *
  73  *
  74  * Arguments:   @const char *p@ = pointer to string to read
  75  *              @group **gg@ = where to put the group pointer
  76  *
  77  * Returns:     Null if OK, or an error string.
  78  *
  79  * Use:         Parses a group spec from a string, and returns the group.
  80  */
  81
  82 const char *group_fromstring(const char *p, group **gg)
  83 {
  84   group *g;
  85   qd_parse qd;
  86
  87   qd.p = p;
  88   qd.e = 0;
  89   if ((g = group_parse(&qd)) == 0) return (qd.e);
  90   if (!qd_eofp(&qd)) { G_DESTROYGROUP(g); return ("junk at end of string"); }
  91   *gg = g;
  92   return (0);
  93 }
  94
  95 /*----- That's all, folks -------------------------------------------------*/