/* skclist.c - Build a list of secret keys
 * Copyright (C) 1998, 1999, 2000, 2001, 2006,
 *               2010 Free Software Foundation, Inc.
 *
 * 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 <http://www.gnu.org/licenses/>.
 */

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

#include "gpg.h"
#include "options.h"
#include "packet.h"
#include "status.h"
#include "keydb.h"
#include "util.h"
#include "i18n.h"


/* Return true if Libgcrypt's RNG is in faked mode.  */
int
random_is_faked (void)
{
  return !!gcry_control (GCRYCTL_FAKED_RANDOM_P, 0);
}


void
release_sk_list (SK_LIST sk_list)
{
  SK_LIST sk_rover;

  for (; sk_list; sk_list = sk_rover)
    {
      sk_rover = sk_list->next;
      free_public_key (sk_list->pk);
      xfree (sk_list);
    }
}


/* Check that we are only using keys which don't have
 * the string "(insecure!)" or "not secure" or "do not use"
 * in one of the user ids.  */
static int
is_insecure (PKT_public_key *pk)
{
  u32 keyid[2];
  KBNODE node = NULL, u;
  int insecure = 0;

  keyid_from_pk (pk, keyid);
  node = get_pubkeyblock (keyid);
  for (u = node; u; u = u->next)
    {
      if (u->pkt->pkttype == PKT_USER_ID)
	{
	  PKT_user_id *id = u->pkt->pkt.user_id;
	  if (id->attrib_data)
	    continue;		/* skip attribute packets */
	  if (strstr (id->name, "(insecure!)")
	      || strstr (id->name, "not secure")
	      || strstr (id->name, "do not use")
	      || strstr (id->name, "(INSECURE!)"))
	    {
	      insecure = 1;
	      break;
	    }
	}
    }
  release_kbnode (node);

  return insecure;
}

static int
key_present_in_sk_list (SK_LIST sk_list, PKT_public_key *pk)
{
  for (; sk_list; sk_list = sk_list->next)
    {
      if (!cmp_public_keys (sk_list->pk, pk))
	return 0;
    }
  return -1;
}

static int
is_duplicated_entry (strlist_t list, strlist_t item)
{
  for (; list && list != item; list = list->next)
    {
      if (!strcmp (list->d, item->d))
	return 1;
    }
  return 0;
}


gpg_error_t
build_sk_list (strlist_t locusr, SK_LIST *ret_sk_list, unsigned int use)
{
  gpg_error_t err;
  SK_LIST sk_list = NULL;

  if (!locusr) /* No user ids given - use the default key.  */
    {
      PKT_public_key *pk;

      pk = xmalloc_clear (sizeof *pk);
      pk->req_usage = use;
      if ((err = getkey_byname (NULL, pk, NULL, 1, NULL)))
	{
	  free_public_key (pk);
	  pk = NULL;
	  log_error ("no default secret key: %s\n", gpg_strerror (err));
	  write_status_text (STATUS_INV_SGNR, get_inv_recpsgnr_code (err));
	}
      else if ((err = openpgp_pk_test_algo2 (pk->pubkey_algo, use)))
	{
	  free_public_key (pk);
	  pk = NULL;
	  log_error ("invalid default secret key: %s\n", gpg_strerror (err));
	  write_status_text (STATUS_INV_SGNR, get_inv_recpsgnr_code (err));
	}
      else
	{
	  SK_LIST r;

	  if (random_is_faked () && !is_insecure (pk))
	    {
	      log_info (_("key is not flagged as insecure - "
			  "can't use it with the faked RNG!\n"));
	      free_public_key (pk);
	      pk = NULL;
	      write_status_text (STATUS_INV_SGNR,
				 get_inv_recpsgnr_code (GPG_ERR_NOT_TRUSTED));
	    }
	  else
	    {
	      r = xmalloc (sizeof *r);
	      r->pk = pk;
	      pk = NULL;
	      r->next = sk_list;
	      r->mark = 0;
	      sk_list = r;
	    }
	}
    }
  else /* Check the given user ids.  */
    {
      strlist_t locusr_orig = locusr;

      for (; locusr; locusr = locusr->next)
	{
	  PKT_public_key *pk;

	  err = 0;
	  /* Do an early check against duplicated entries.  However
	   * this won't catch all duplicates because the user IDs may
	   * be specified in different ways.  */
	  if (is_duplicated_entry (locusr_orig, locusr))
	    {
	      log_info (_("skipped \"%s\": duplicated\n"), locusr->d);
	      continue;
	    }
	  pk = xmalloc_clear (sizeof *pk);
	  pk->req_usage = use;
          if ((err = getkey_byname (NULL, pk, locusr->d, 1, NULL)))
	    {
	      free_public_key (pk);
	      pk = NULL;
	      log_error (_("skipped \"%s\": %s\n"),
			 locusr->d, gpg_strerror (err));
	      write_status_text_and_buffer
		(STATUS_INV_SGNR, get_inv_recpsgnr_code (err),
		 locusr->d, strlen (locusr->d), -1);
	    }
	  else if (!key_present_in_sk_list (sk_list, pk))
	    {
	      free_public_key (pk);
	      pk = NULL;
	      log_info (_("skipped: secret key already present\n"));
	    }
	  else if ((err = openpgp_pk_test_algo2 (pk->pubkey_algo, use)))
	    {
	      free_public_key (pk);
	      pk = NULL;
	      log_error ("skipped \"%s\": %s\n", locusr->d, gpg_strerror (err));
	      write_status_text_and_buffer
		(STATUS_INV_SGNR, get_inv_recpsgnr_code (err),
		 locusr->d, strlen (locusr->d), -1);
	    }
	  else
	    {
	      SK_LIST r;

	      if (pk->version == 4 && (use & PUBKEY_USAGE_SIG)
		  && pk->pubkey_algo == PUBKEY_ALGO_ELGAMAL_E)
		{
		  log_info (_("skipped \"%s\": %s\n"), locusr->d,
			    _("this is a PGP generated Elgamal key which"
			      " is not secure for signatures!"));
		  free_public_key (pk);
		  pk = NULL;
		  write_status_text_and_buffer
		    (STATUS_INV_SGNR,
		     get_inv_recpsgnr_code (GPG_ERR_WRONG_KEY_USAGE),
		     locusr->d, strlen (locusr->d), -1);
		}
	      else if (random_is_faked () && !is_insecure (pk))
		{
		  log_info (_("key is not flagged as insecure - "
			      "can't use it with the faked RNG!\n"));
		  free_public_key (pk);
		  pk = NULL;
		  write_status_text_and_buffer
		    (STATUS_INV_SGNR,
		     get_inv_recpsgnr_code (GPG_ERR_NOT_TRUSTED),
		     locusr->d, strlen (locusr->d), -1);
		}
	      else
		{
		  r = xmalloc (sizeof *r);
		  r->pk = pk;
		  pk = NULL;
		  r->next = sk_list;
		  r->mark = 0;
		  sk_list = r;
		}
	    }
	}
    }

  if (!err && !sk_list)
    {
      log_error ("no valid signators\n");
      write_status_text (STATUS_NO_SGNR, "0");
      err = gpg_error (GPG_ERR_NO_USER_ID);
    }

  if (err)
    release_sk_list (sk_list);
  else
    *ret_sk_list = sk_list;
  return err;
}