/* card-tool-misc.c - Helper functions for gpg-card-tool
 * Copyright (C) 2019 g10 Code GmbH
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * GnuPG is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <https://www.gnu.org/licenses/>.
 * SPDX-License-Identifier: GPL-3.0-or-later
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>

#include "../common/util.h"
#include "../common/i18n.h"
#include "../common/openpgpdefs.h"
#include "card-tool.h"

/* Return the key info object for the key KEYREF.  If it is not found
 * NULL is returned.  */
key_info_t
find_kinfo (card_info_t info, const char *keyref)
{
  key_info_t kinfo;

  for (kinfo = info->kinfo; kinfo; kinfo = kinfo->next)
    if (!strcmp (kinfo->keyref, keyref))
      return kinfo;
  return NULL;
}


/* Convert STRING into a newly allocated buffer while translating the
 * hex numbers.  Blanks and colons are allowed to separate pairs of
 * hex digits.  Returns NULL on error or a newly malloced buffer and
 * its length in LENGTH.  */
void *
hex_to_buffer (const char *string, size_t *r_length)
{
  unsigned char *buffer;
  const char *s;
  size_t n;

  buffer = xtrymalloc (strlen (string)+1);
  if (!buffer)
    return NULL;
  for (s=string, n=0; *s; s++)
    {
      if (ascii_isspace (*s) || *s == ':')
        continue;
      if (hexdigitp (s) && hexdigitp (s+1))
        {
          buffer[n++] = xtoi_2 (s);
          s++;
        }
      else
        {
          xfree (buffer);
          gpg_err_set_errno (EINVAL);
          return NULL;
        }
    }
  *r_length = n;
  return buffer;
}



/* Given the public key S_PKEY, return a new buffer with a descriptive
 * string for its algorithm.  This function always returns a string. */
char *
pubkey_algo_string (gcry_sexp_t s_pkey)
{
  const char *prefix;
  gcry_sexp_t l1;
  char *algoname;
  int algo;
  char *result;

  l1 = gcry_sexp_find_token (s_pkey, "public-key", 0);
  if (!l1)
    return xstrdup ("E_no_key");
  {
    gcry_sexp_t l_tmp = gcry_sexp_cadr (l1);
    gcry_sexp_release (l1);
    l1 = l_tmp;
  }
  algoname = gcry_sexp_nth_string (l1, 0);
  gcry_sexp_release (l1);
  if (!algoname)
    return xstrdup ("E_no_algo");

  algo = gcry_pk_map_name (algoname);
  switch (algo)
    {
    case GCRY_PK_RSA: prefix = "rsa"; break;
    case GCRY_PK_ELG: prefix = "elg"; break;
    case GCRY_PK_DSA: prefix = "dsa"; break;
    case GCRY_PK_ECC: prefix = "";  break;
    default:          prefix = NULL; break;
    }

  if (prefix && *prefix)
    result = xasprintf ("%s%u", prefix, gcry_pk_get_nbits (s_pkey));
  else if (prefix)
    {
      const char *curve = gcry_pk_get_curve (s_pkey, 0, NULL);
      const char *name = openpgp_oid_to_curve
        (openpgp_curve_to_oid (curve, NULL), 0);

      if (name)
        result = xstrdup (name);
      else if (curve)
        result = xasprintf ("X_%s", curve);
      else
        result = xstrdup ("E_unknown");
    }
  else
    result = xasprintf ("X_algo_%d", algo);

  xfree (algoname);
  return result;
}