mdw@git.distorted.org.uk Git - 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 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 "group.h"
  31 #include "dh.h"
  32
  33 /*----- Main code ---------------------------------------------------------*/
  34
  35 /* --- @group_parse@ --- *
  36  *
  37  * Arguments:   @qd_parse *qd@ = quick-and-dirty parser
  38  *
  39  * Returns:     Group pointer, or null for failure.
  40  *
  41  * Use:         Parses a group description and returns the group.  This has
  42  *              the form `TYPE { SPEC }' where TYPE is `prime' or `ec', and
  43  *              SPEC is the appropriate kind of group specification of the
  44  *              given type.
  45  */
  46
  47 group *group_parse(qd_parse *qd)
  48 {
  49   group *g = 0;
  50
  51   switch (qd_enum(qd, "prime,ec")) {
  52     case 0: {
  53       dh_param dp;
  54       qd_delim(qd, '{');
  55       if (dh_parse(qd, &dp)) goto ouch;
  56       qd_delim(qd, '}');
  57       g = group_prime(&dp);
  58       dh_paramfree(&dp);
  59     } break;
  60     case 1: {
  61       ec_info ei;
  62       qd_delim(qd, '{');
  63       if (ec_infoparse(qd, &ei)) goto ouch;
  64       qd_delim(qd, '}');
  65       g = group_ec(&ei);
  66     } break;
  67   }
  68   if (!g) qd->e = "bad group parameters";
  69 ouch:
  70   return (g);
  71 }
  72
  73 /* --- @group_fromstring@ --- *
  74  *
  75  * Arguments:   @const char *p@ = pointer to string to read
  76  *              @group **gg@ = where to put the group pointer
  77  *
  78  * Returns:     Null if OK, or an error string.
  79  *
  80  * Use:         Parses a group spec from a string, and returns the group.
  81  */
  82
  83 const char *group_fromstring(const char *p, group **gg)
  84 {
  85   group *g;
  86   qd_parse qd;
  87
  88   qd.p = p;
  89   qd.e = 0;
  90   if ((g = group_parse(&qd)) == 0) return (qd.e);
  91   if (!qd_eofp(&qd)) { G_DESTROYGROUP(g); return ("junk at end of string"); }
  92   *gg = g;
  93   return (0);
  94 }
  95
  96 /*----- That's all, folks -------------------------------------------------*/