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path: root/src/gnsrecord/gnsrecord_misc.c
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/*
     This file is part of GNUnet.
     Copyright (C) 2009-2013 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

/**
 * @file gnsrecord/gnsrecord_misc.c
 * @brief MISC functions related to GNS records
 * @author Martin Schanzenbach
 * @author Matthias Wachs
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_constants.h"
#include "gnunet_signatures.h"
#include "gnunet_arm_service.h"
#include "gnunet_gnsrecord_lib.h"
#include "gnunet_dnsparser_lib.h"
#include "gnunet_tun_lib.h"


#define LOG(kind, ...) GNUNET_log_from(kind, "gnsrecord", __VA_ARGS__)

/**
 * Convert a UTF-8 string to UTF-8 lowercase
 * @param src source string
 * @return converted result
 */
char *
GNUNET_GNSRECORD_string_to_lowercase(const char *src)
{
  char *res;

  res = GNUNET_strdup(src);
  GNUNET_STRINGS_utf8_tolower(src, res);
  return res;
}


/**
 * Convert a zone key to a string (for printing debug messages).
 * This is one of the very few calls in the entire API that is
 * NOT reentrant!
 *
 * @param z the zone key
 * @return string form; will be overwritten by next call to #GNUNET_GNSRECORD_z2s
 */
const char *
GNUNET_GNSRECORD_z2s(const struct GNUNET_CRYPTO_EcdsaPublicKey *z)
{
  static char buf[sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey) * 8];
  char *end;

  end = GNUNET_STRINGS_data_to_string((const unsigned char *)z,
                                      sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
                                      buf, sizeof(buf));
  if (NULL == end)
    {
      GNUNET_break(0);
      return NULL;
    }
  *end = '\0';
  return buf;
}


/**
 * Compares if two records are equal (ignoring flags such
 * as authority, private and pending, but not relative vs.
 * absolute expiration time).
 *
 * @param a record
 * @param b record
 * @return #GNUNET_YES if the records are equal or #GNUNET_NO if they are not
 */
int
GNUNET_GNSRECORD_records_cmp(const struct GNUNET_GNSRECORD_Data *a,
                             const struct GNUNET_GNSRECORD_Data *b)
{
  LOG(GNUNET_ERROR_TYPE_DEBUG,
      "Comparing records\n");
  if (a->record_type != b->record_type)
    {
      LOG(GNUNET_ERROR_TYPE_DEBUG,
          "Record type %lu != %lu\n", a->record_type, b->record_type);
      return GNUNET_NO;
    }
  if ((a->expiration_time != b->expiration_time) &&
      ((a->expiration_time != 0) && (b->expiration_time != 0)))
    {
      LOG(GNUNET_ERROR_TYPE_DEBUG,
          "Expiration time %llu != %llu\n",
          a->expiration_time,
          b->expiration_time);
      return GNUNET_NO;
    }
  if ((a->flags & GNUNET_GNSRECORD_RF_RCMP_FLAGS)
      != (b->flags & GNUNET_GNSRECORD_RF_RCMP_FLAGS))
    {
      LOG(GNUNET_ERROR_TYPE_DEBUG,
          "Flags %lu (%lu) != %lu (%lu)\n", a->flags,
          a->flags & GNUNET_GNSRECORD_RF_RCMP_FLAGS, b->flags,
          b->flags & GNUNET_GNSRECORD_RF_RCMP_FLAGS);
      return GNUNET_NO;
    }
  if (a->data_size != b->data_size)
    {
      LOG(GNUNET_ERROR_TYPE_DEBUG,
          "Data size %lu != %lu\n",
          a->data_size,
          b->data_size);
      return GNUNET_NO;
    }
  if (0 != memcmp(a->data, b->data, a->data_size))
    {
      LOG(GNUNET_ERROR_TYPE_DEBUG,
          "Data contents do not match\n");
      return GNUNET_NO;
    }
  LOG(GNUNET_ERROR_TYPE_DEBUG,
      "Records are equal\n");
  return GNUNET_YES;
}


/**
 * Returns the expiration time of the given block of records. The block
 * expiration time is the expiration time of the record with smallest
 * expiration time.
 *
 * @param rd_count number of records given in @a rd
 * @param rd array of records
 * @return absolute expiration time
 */
struct GNUNET_TIME_Absolute
GNUNET_GNSRECORD_record_get_expiration_time(unsigned int rd_count,
                                            const struct GNUNET_GNSRECORD_Data *rd)
{
  struct GNUNET_TIME_Absolute expire;
  struct GNUNET_TIME_Absolute at;
  struct GNUNET_TIME_Relative rt;
  struct GNUNET_TIME_Absolute at_shadow;
  struct GNUNET_TIME_Relative rt_shadow;

  if (NULL == rd)
    return GNUNET_TIME_UNIT_ZERO_ABS;
  expire = GNUNET_TIME_UNIT_FOREVER_ABS;
  for (unsigned int c = 0; c < rd_count; c++)
    {
      if (0 != (rd[c].flags & GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION))
        {
          rt.rel_value_us = rd[c].expiration_time;
          at = GNUNET_TIME_relative_to_absolute(rt);
        }
      else
        {
          at.abs_value_us = rd[c].expiration_time;
        }

      for (unsigned int c2 = 0; c2 < rd_count; c2++)
        {
          /* Check for shadow record */
          if ((c == c2) ||
              (rd[c].record_type != rd[c2].record_type) ||
              (0 == (rd[c2].flags & GNUNET_GNSRECORD_RF_SHADOW_RECORD)))
            continue;
          /* We have a shadow record */
          if (0 != (rd[c2].flags & GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION))
            {
              rt_shadow.rel_value_us = rd[c2].expiration_time;
              at_shadow = GNUNET_TIME_relative_to_absolute(rt_shadow);
            }
          else
            {
              at_shadow.abs_value_us = rd[c2].expiration_time;
            }
          at = GNUNET_TIME_absolute_max(at,
                                        at_shadow);
        }
      expire = GNUNET_TIME_absolute_min(at,
                                        expire);
    }
  LOG(GNUNET_ERROR_TYPE_DEBUG,
      "Determined expiration time for block with %u records to be %s\n",
      rd_count,
      GNUNET_STRINGS_absolute_time_to_string(expire));
  return expire;
}


/**
 * Test if a given record is expired.
 *
 * @return #GNUNET_YES if the record is expired,
 *         #GNUNET_NO if not
 */
int
GNUNET_GNSRECORD_is_expired(const struct GNUNET_GNSRECORD_Data *rd)
{
  struct GNUNET_TIME_Absolute at;

  if (0 != (rd->flags & GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION))
    return GNUNET_NO;
  at.abs_value_us = rd->expiration_time;
  return (0 == GNUNET_TIME_absolute_get_remaining(at).rel_value_us) ? GNUNET_YES : GNUNET_NO;
}


/**
 * Convert public key to the respective absolute domain name in the
 * ".zkey" pTLD.
 * This is one of the very few calls in the entire API that is
 * NOT reentrant!
 *
 * @param pkey a public key with a point on the eliptic curve
 * @return string "X.zkey" where X is the public
 *         key in an encoding suitable for DNS labels.
 */
const char *
GNUNET_GNSRECORD_pkey_to_zkey(const struct GNUNET_CRYPTO_EcdsaPublicKey *pkey)
{
  static char ret[128];
  char *pkeys;

  pkeys = GNUNET_CRYPTO_ecdsa_public_key_to_string(pkey);
  GNUNET_snprintf(ret,
                  sizeof(ret),
                  "%s",
                  pkeys);
  GNUNET_free(pkeys);
  return ret;
}


/**
 * Convert an absolute domain name to the
 * respective public key.
 *
 * @param zkey string encoding the coordinates of the public
 *         key in an encoding suitable for DNS labels.
 * @param pkey set to a public key on the eliptic curve
 * @return #GNUNET_SYSERR if @a zkey has the wrong syntax
 */
int
GNUNET_GNSRECORD_zkey_to_pkey(const char *zkey,
                              struct GNUNET_CRYPTO_EcdsaPublicKey *pkey)
{
  if (GNUNET_OK !=
      GNUNET_CRYPTO_ecdsa_public_key_from_string(zkey,
                                                 strlen(zkey),
                                                 pkey))
    return GNUNET_SYSERR;
  return GNUNET_OK;
}


/* end of gnsrecord_misc.c */