common/sexputil.c

   1 /* sexputil.c - Utility fnctions for S-expressions.
   2  * Copyright (C) 2005 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  19  */
  20
  21 /* This file implements a few utility functions useful when working
  22    with canonical encrypted S-expresions (i.e. not the S-exprssion
  23    objects from libgcrypt).  */
  24
  25 #include <config.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30 #include <errno.h>
  31 #ifdef HAVE_LOCALE_H
  32 #include <locale.h>
  33 #endif
  34
  35 #include "util.h"
  36
  37
  38 /* Return the so called "keygrip" which is the SHA-1 hash of the
  39    public key parameters expressed in a way depended on the algorithm.
  40
  41    KEY is expected to be an canonical encoded S-expression with a
  42    public or private key. KEYLEN is the length of that buffer.
  43
  44    GRIP must be at least 20 bytes long On success 0 is return, on
  45    error an aerror code. */
  46 gpg_error_t
  47 keygrip_from_canon_sexp (const unsigned char *key, size_t keylen,
  48                          unsigned char *grip)
  49 {
  50   gpg_error_t err;
  51   gcry_sexp_t sexp;
  52
  53   if (!grip)
  54     return gpg_error (GPG_ERR_INV_VALUE);
  55   err = gcry_sexp_sscan (&sexp, NULL, (const char *)key, keylen);
  56   if (err)
  57     return err;
  58   if (!gcry_pk_get_keygrip (sexp, grip))
  59     err = gpg_error (GPG_ERR_INTERNAL);
  60   gcry_sexp_release (sexp);
  61   return err;
  62 }
  63
  64
  65 /* Compare two simple S-expressions like "(3:foo)".  Returns 0 if they
  66    are identical or !0 if they are not.  Not that this function can't
  67    be used for sorting. */
  68 int
  69 cmp_simple_canon_sexp (const unsigned char *a_orig,
  70                        const unsigned char *b_orig)
  71 {
  72   const char *a = (const char *)a_orig;
  73   const char *b = (const char *)b_orig;
  74   unsigned long n1, n2;
  75   char *endp;
  76
  77   if (!a && !b)
  78     return 0; /* Both are NULL, they are identical. */
  79   if (!a || !b)
  80     return 1; /* One is NULL, they are not identical. */
  81   if (*a != '(' || *b != '(')
  82     log_bug ("invalid S-exp in cmp_simple_canon_sexp\n");
  83
  84   a++;
  85   n1 = strtoul (a, &endp, 10);
  86   a = endp;
  87   b++;
  88   n2 = strtoul (b, &endp, 10);
  89   b = endp;
  90
  91   if (*a != ':' || *b != ':' )
  92     log_bug ("invalid S-exp in cmp_simple_canon_sexp\n");
  93   if (n1 != n2)
  94     return 1; /* Not the same. */
  95
  96   for (a++, b++; n1; n1--, a++, b++)
  97     if (*a != *b)
  98       return 1; /* Not the same. */
  99   return 0;
 100 }
 101
 102
 103 /* Create a simple S-expression from the hex string at LIBNE.  Returns
 104    a newly allocated buffer with that canonical encoded S-expression
 105    or NULL in case of an error.  On return the number of characters
 106    scanned in LINE will be stored at NSCANNED.  This fucntions stops
 107    converting at the first character not representing a hexdigit. Odd
 108    numbers of hex digits are allowed; a leading zero is then
 109    assumed. If no characters have been found, NULL is returned.*/
 110 unsigned char *
 111 make_simple_sexp_from_hexstr (const char *line, size_t *nscanned)
 112 {
 113   size_t n, len;
 114   const char *s;
 115   unsigned char *buf;
 116   unsigned char *p;
 117   char numbuf[50];
 118
 119   for (n=0, s=line; hexdigitp (s); s++, n++)
 120     ;
 121   if (nscanned)
 122     *nscanned = n;
 123   if (!n)
 124     return NULL;
 125   len = ((n+1) & ~0x01)/2;
 126   sprintf (numbuf, "(%u:", (unsigned int)len);
 127   buf = xtrymalloc (strlen (numbuf) + len + 1 + 1);
 128   if (!buf)
 129     return NULL;
 130   p = (unsigned char *)stpcpy ((char *)buf, numbuf);
 131   s = line;
 132   if ((n&1))
 133     {
 134       *p++ = xtoi_1 (s);
 135       s++;
 136       n--;
 137     }
 138   for (; n > 1; n -=2, s += 2)
 139     *p++ = xtoi_2 (s);
 140   *p++ = ')';
 141   *p = 0; /* (Not really neaded.) */
 142
 143   return buf;
 144 }