/*
     This file is part of GNUnet.
     Copyright (C) 2012, 2013, 2014, 2017, 2018 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 zonemaster/gnunet-service-zonemaster.c
 * @brief publish records from namestore to GNUnet name system
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_dnsparser_lib.h"
#include "gnunet_dht_service.h"
#include "gnunet_namestore_service.h"
#include "gnunet_statistics_service.h"


#define LOG_STRERROR_FILE(kind, syscall, \
                          filename) GNUNET_log_from_strerror_file (kind, "util", \
                                                                   syscall, \
                                                                   filename)


/**
 * How often should we (re)publish each record before
 * it expires?
 */
#define PUBLISH_OPS_PER_EXPIRATION 4

/**
 * How often do we measure the delta between desired zone
 * iteration speed and actual speed, and tell statistics
 * service about it?
 */
#define DELTA_INTERVAL 100

/**
 * How many records do we fetch in one shot from the namestore?
 */
#define NS_BLOCK_SIZE 1000

/**
 * How many pending DHT operations do we allow at most?
 */
#define DHT_QUEUE_LIMIT 2000

/**
 * How many events may the namestore give us before it has to wait
 * for us to keep up?
 */
#define NAMESTORE_QUEUE_LIMIT 50

/**
 * The initial interval in milliseconds btween puts in
 * a zone iteration
 */
#define INITIAL_ZONE_ITERATION_INTERVAL GNUNET_TIME_UNIT_MILLISECONDS

/**
 * The upper bound for the zone iteration interval
 * (per record).
 */
#define MAXIMUM_ZONE_ITERATION_INTERVAL GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_MINUTES, 15)

/**
 * The factor the current zone iteration interval is divided by for each
 * additional new record
 */
#define LATE_ITERATION_SPEEDUP_FACTOR 2

/**
 * What replication level do we use for DHT PUT operations?
 */
#define DHT_GNS_REPLICATION_LEVEL 5


/**
 * Handle for DHT PUT activity triggered from the namestore monitor.
 */
struct DhtPutActivity
{
  /**
   * Kept in a DLL.
   */
  struct DhtPutActivity *next;

  /**
   * Kept in a DLL.
   */
  struct DhtPutActivity *prev;

  /**
   * Handle for the DHT PUT operation.
   */
  struct GNUNET_DHT_PutHandle *ph;

  /**
   * When was this PUT initiated?
   */
  struct GNUNET_TIME_Absolute start_date;
};


/**
 * Handle to the statistics service
 */
static struct GNUNET_STATISTICS_Handle *statistics;

/**
 * Our handle to the DHT
 */
static struct GNUNET_DHT_Handle *dht_handle;

/**
 * Our handle to the namestore service
 */
static struct GNUNET_NAMESTORE_Handle *namestore_handle;

/**
 * Handle to iterate over our authoritative zone in namestore
 */
static struct GNUNET_NAMESTORE_ZoneIterator *namestore_iter;

/**
 * Head of iteration put activities; kept in a DLL.
 */
static struct DhtPutActivity *it_head;

/**
 * Tail of iteration put activities; kept in a DLL.
 */
static struct DhtPutActivity *it_tail;

/**
 * Number of entries in the DHT queue #it_head.
 */
static unsigned int dht_queue_length;

/**
 * Useful for zone update for DHT put
 */
static unsigned long long num_public_records;

/**
 * Last seen record count
 */
static unsigned long long last_num_public_records;

/**
 * Number of successful put operations performed in the current
 * measurement cycle (as measured in #check_zone_namestore_next()).
 */
static unsigned long long put_cnt;

/**
 * What is the frequency at which we currently would like
 * to perform DHT puts (per record)?  Calculated in
 * update_velocity() from the #zone_publish_time_window()
 * and the total number of record sets we have (so far)
 * observed in the zone.
 */
static struct GNUNET_TIME_Relative target_iteration_velocity_per_record;

/**
 * Minimum relative expiration time of records seem during the current
 * zone iteration.
 */
static struct GNUNET_TIME_Relative min_relative_record_time;

/**
 * Minimum relative expiration time of records seem during the last
 * zone iteration.
 */
static struct GNUNET_TIME_Relative last_min_relative_record_time;

/**
 * Default time window for zone iteration
 */
static struct GNUNET_TIME_Relative zone_publish_time_window_default;

/**
 * Time window for zone iteration, adjusted based on relative record
 * expiration times in our zone.
 */
static struct GNUNET_TIME_Relative zone_publish_time_window;

/**
 * When did we last start measuring the #DELTA_INTERVAL successful
 * DHT puts? Used for velocity calculations.
 */
static struct GNUNET_TIME_Absolute last_put_100;

/**
 * By how much should we try to increase our per-record iteration speed
 * (over the desired speed calculated directly from the #put_interval)?
 * Basically this value corresponds to the per-record CPU time overhead
 * we have.
 */
static struct GNUNET_TIME_Relative sub_delta;

/**
 * zone publish task
 */
static struct GNUNET_SCHEDULER_Task *zone_publish_task;

/**
 * How many more values are left for the current query before we need
 * to explicitly ask the namestore for more?
 */
static unsigned int ns_iteration_left;

/**
 * #GNUNET_YES if zone has never been published before
 */
static int first_zone_iteration;

/**
 * Optimize block insertion by caching map of private keys to
 * public keys in memory?
 */
static int cache_keys;


/**
 * Task run during shutdown.
 *
 * @param cls unused
 * @param tc unused
 */
static void
shutdown_task (void *cls)
{
  struct DhtPutActivity *ma;

  (void) cls;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Shutting down!\n");
  while (NULL != (ma = it_head))
  {
    GNUNET_DHT_put_cancel (ma->ph);
    dht_queue_length--;
    GNUNET_CONTAINER_DLL_remove (it_head,
                                 it_tail,
                                 ma);
    dht_queue_length--;
    GNUNET_free (ma);
  }
  if (NULL != statistics)
  {
    GNUNET_STATISTICS_destroy (statistics,
                               GNUNET_NO);
    statistics = NULL;
  }
  if (NULL != zone_publish_task)
  {
    GNUNET_SCHEDULER_cancel (zone_publish_task);
    zone_publish_task = NULL;
  }
  if (NULL != namestore_iter)
  {
    GNUNET_NAMESTORE_zone_iteration_stop (namestore_iter);
    namestore_iter = NULL;
  }
  if (NULL != namestore_handle)
  {
    GNUNET_NAMESTORE_disconnect (namestore_handle);
    namestore_handle = NULL;
  }
  if (NULL != dht_handle)
  {
    GNUNET_DHT_disconnect (dht_handle);
    dht_handle = NULL;
  }
}


/**
 * Method called periodically that triggers iteration over authoritative records
 *
 * @param cls NULL
 */
static void
publish_zone_namestore_next (void *cls)
{
  (void) cls;
  zone_publish_task = NULL;
  GNUNET_assert (NULL != namestore_iter);
  GNUNET_assert (0 == ns_iteration_left);
  ns_iteration_left = NS_BLOCK_SIZE;
  GNUNET_NAMESTORE_zone_iterator_next (namestore_iter,
                                       NS_BLOCK_SIZE);
}


/**
 * Periodically iterate over our zone and store everything in dht
 *
 * @param cls NULL
 */
static void
publish_zone_dht_start (void *cls);


/**
 * Calculate #target_iteration_velocity_per_record.
 */
static void
calculate_put_interval ()
{
  if (0 == num_public_records)
  {
    /**
     * If no records are known (startup) or none present
     * we can safely set the interval to the value for a single
     * record
     */target_iteration_velocity_per_record = zone_publish_time_window;
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
                "No records in namestore database.\n");
  }
  else
  {
    last_min_relative_record_time
      = GNUNET_TIME_relative_min (last_min_relative_record_time,
                                  min_relative_record_time);
    zone_publish_time_window
      = GNUNET_TIME_relative_min (GNUNET_TIME_relative_divide (
                                    last_min_relative_record_time,
                                    PUBLISH_OPS_PER_EXPIRATION),
                                  zone_publish_time_window_default);
    target_iteration_velocity_per_record
      = GNUNET_TIME_relative_divide (zone_publish_time_window,
                                     last_num_public_records);
  }
  target_iteration_velocity_per_record
    = GNUNET_TIME_relative_min (target_iteration_velocity_per_record,
                                MAXIMUM_ZONE_ITERATION_INTERVAL);
  GNUNET_STATISTICS_set (statistics,
                         "Minimum relative record expiration (in μs)",
                         last_min_relative_record_time.rel_value_us,
                         GNUNET_NO);
  GNUNET_STATISTICS_set (statistics,
                         "Zone publication time window (in μs)",
                         zone_publish_time_window.rel_value_us,
                         GNUNET_NO);
  GNUNET_STATISTICS_set (statistics,
                         "Target zone iteration velocity (μs)",
                         target_iteration_velocity_per_record.rel_value_us,
                         GNUNET_NO);
}


/**
 * Re-calculate our velocity and the desired velocity.
 * We have succeeded in making #DELTA_INTERVAL puts, so
 * now calculate the new desired delay between puts.
 *
 * @param cnt how many records were processed since the last call?
 */
static void
update_velocity (unsigned int cnt)
{
  struct GNUNET_TIME_Relative delta;
  unsigned long long pct = 0;

  if (0 == cnt)
    return;
  /* How fast were we really? */
  delta = GNUNET_TIME_absolute_get_duration (last_put_100);
  delta.rel_value_us /= cnt;
  last_put_100 = GNUNET_TIME_absolute_get ();

  /* calculate expected frequency */
  if ((num_public_records > last_num_public_records) &&
      (GNUNET_NO == first_zone_iteration))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Last record count was lower than current record count.  Reducing interval.\n");
    last_num_public_records = num_public_records
                              * LATE_ITERATION_SPEEDUP_FACTOR;
    calculate_put_interval ();
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Desired global zone iteration interval is %s/record!\n",
              GNUNET_STRINGS_relative_time_to_string (
                target_iteration_velocity_per_record,
                GNUNET_YES));

  /* Tell statistics actual vs. desired speed */
  GNUNET_STATISTICS_set (statistics,
                         "Current zone iteration velocity (μs/record)",
                         delta.rel_value_us,
                         GNUNET_NO);
  /* update "sub_delta" based on difference, taking
     previous sub_delta into account! */
  if (target_iteration_velocity_per_record.rel_value_us > delta.rel_value_us)
  {
    /* We were too fast, reduce sub_delta! */
    struct GNUNET_TIME_Relative corr;

    corr = GNUNET_TIME_relative_subtract (target_iteration_velocity_per_record,
                                          delta);
    if (sub_delta.rel_value_us > delta.rel_value_us)
    {
      /* Reduce sub_delta by corr */
      sub_delta = GNUNET_TIME_relative_subtract (sub_delta,
                                                 corr);
    }
    else
    {
      /* We're doing fine with waiting the full time, this
         should theoretically only happen if we run at
         infinite speed. */
      sub_delta = GNUNET_TIME_UNIT_ZERO;
    }
  }
  else if (target_iteration_velocity_per_record.rel_value_us <
           delta.rel_value_us)
  {
    /* We were too slow, increase sub_delta! */
    struct GNUNET_TIME_Relative corr;

    corr = GNUNET_TIME_relative_subtract (delta,
                                          target_iteration_velocity_per_record);
    sub_delta = GNUNET_TIME_relative_add (sub_delta,
                                          corr);
    if (sub_delta.rel_value_us >
        target_iteration_velocity_per_record.rel_value_us)
    {
      /* CPU overload detected, we cannot go at desired speed,
         as this would mean using a negative delay. */
      /* compute how much faster we would want to be for
         the desired velocity */
      if (0 == target_iteration_velocity_per_record.rel_value_us)
        pct = UINT64_MAX;     /* desired speed is infinity ... */
      else
        pct = (sub_delta.rel_value_us
               - target_iteration_velocity_per_record.rel_value_us) * 100LLU
              / target_iteration_velocity_per_record.rel_value_us;
      sub_delta = target_iteration_velocity_per_record;
    }
  }
  GNUNET_STATISTICS_set (statistics,
                         "# size of the DHT queue (it)",
                         dht_queue_length,
                         GNUNET_NO);
  GNUNET_STATISTICS_set (statistics,
                         "% speed increase needed for target velocity",
                         pct,
                         GNUNET_NO);
  GNUNET_STATISTICS_set (statistics,
                         "# records processed in current iteration",
                         num_public_records,
                         GNUNET_NO);
}


/**
 * Check if the current zone iteration needs to be continued
 * by calling #publish_zone_namestore_next(), and if so with what delay.
 */
static void
check_zone_namestore_next ()
{
  struct GNUNET_TIME_Relative delay;

  if (0 != ns_iteration_left)
    return; /* current NAMESTORE iteration not yet done */
  update_velocity (put_cnt);
  put_cnt = 0;
  delay = GNUNET_TIME_relative_subtract (target_iteration_velocity_per_record,
                                         sub_delta);
  /* We delay *once* per #NS_BLOCK_SIZE, so we need to multiply the
     per-record delay calculated so far with the #NS_BLOCK_SIZE */
  GNUNET_STATISTICS_set (statistics,
                         "Current artificial NAMESTORE delay (μs/record)",
                         delay.rel_value_us,
                         GNUNET_NO);
  delay = GNUNET_TIME_relative_multiply (delay,
                                         NS_BLOCK_SIZE);
  /* make sure we do not overshoot because of the #NS_BLOCK_SIZE factor */
  delay = GNUNET_TIME_relative_min (MAXIMUM_ZONE_ITERATION_INTERVAL,
                                    delay);
  /* no delays on first iteration */
  if (GNUNET_YES == first_zone_iteration)
    delay = GNUNET_TIME_UNIT_ZERO;
  GNUNET_assert (NULL == zone_publish_task);
  zone_publish_task = GNUNET_SCHEDULER_add_delayed (delay,
                                                    &publish_zone_namestore_next,
                                                    NULL);
}


/**
 * Continuation called from DHT once the PUT operation is done.
 *
 * @param cls a `struct DhtPutActivity`
 */
static void
dht_put_continuation (void *cls)
{
  struct DhtPutActivity *ma = cls;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "PUT complete\n");
  dht_queue_length--;
  GNUNET_CONTAINER_DLL_remove (it_head,
                               it_tail,
                               ma);
  GNUNET_free (ma);
}


/**
 * Convert namestore records from the internal format to that
 * suitable for publication (removes private records, converts
 * to absolute expiration time).
 *
 * @param rd input records
 * @param rd_count size of the @a rd and @a rd_public arrays
 * @param rd_public where to write the converted records
 * @return number of records written to @a rd_public
 */
static unsigned int
convert_records_for_export (const struct GNUNET_GNSRECORD_Data *rd,
                            unsigned int rd_count,
                            struct GNUNET_GNSRECORD_Data *rd_public)
{
  struct GNUNET_TIME_Absolute now;
  unsigned int rd_public_count;

  rd_public_count = 0;
  now = GNUNET_TIME_absolute_get ();
  for (unsigned int i = 0; i < rd_count; i++)
  {
    if (0 != (rd[i].flags & GNUNET_GNSRECORD_RF_PRIVATE))
      continue;
    if ((0 == (rd[i].flags & GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION)) &&
        (rd[i].expiration_time < now.abs_value_us))
      continue;   /* record already expired, skip it */
    if (0 != (rd[i].flags & GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION))
    {
      /* GNUNET_GNSRECORD_block_create will convert to absolute time;
         we just need to adjust our iteration frequency */
      min_relative_record_time.rel_value_us =
        GNUNET_MIN (rd[i].expiration_time,
                    min_relative_record_time.rel_value_us);
    }
    rd_public[rd_public_count++] = rd[i];
  }
  return rd_public_count;
}


/**
 * Store GNS records in the DHT.
 *
 * @param key key of the zone
 * @param label label to store under
 * @param rd_public public record data
 * @param rd_public_count number of records in @a rd_public
 * @param ma handle for the put operation
 * @return DHT PUT handle, NULL on error
 */
static struct GNUNET_DHT_PutHandle *
perform_dht_put (const struct GNUNET_IDENTITY_PrivateKey *key,
                 const char *label,
                 const struct GNUNET_GNSRECORD_Data *rd_public,
                 unsigned int rd_public_count,
                 struct DhtPutActivity *ma)
{
  struct GNUNET_GNSRECORD_Block *block;
  struct GNUNET_HashCode query;
  struct GNUNET_TIME_Absolute expire;
  size_t block_size;
  struct GNUNET_DHT_PutHandle *ret;

  expire = GNUNET_GNSRECORD_record_get_expiration_time (rd_public_count,
                                                        rd_public);
  if (cache_keys)
    block = GNUNET_GNSRECORD_block_create2 (key,
                                            expire,
                                            label,
                                            rd_public,
                                            rd_public_count);
  else
    block = GNUNET_GNSRECORD_block_create (key,
                                           expire,
                                           label,
                                           rd_public,
                                           rd_public_count);
  if (NULL == block)
  {
    GNUNET_break (0);
    return NULL;   /* whoops */
  }
  block_size = GNUNET_GNSRECORD_block_get_size (block);
  GNUNET_GNSRECORD_query_from_private_key (key,
                                           label,
                                           &query);
  GNUNET_STATISTICS_update (statistics,
                            "DHT put operations initiated",
                            1,
                            GNUNET_NO);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Storing %u record(s) for label `%s' in DHT with expiration `%s' under key %s\n",
              rd_public_count,
              label,
              GNUNET_STRINGS_absolute_time_to_string (expire),
              GNUNET_h2s (&query));
  num_public_records++;
  ret = GNUNET_DHT_put (dht_handle,
                        &query,
                        DHT_GNS_REPLICATION_LEVEL,
                        GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
                        GNUNET_BLOCK_TYPE_GNS_NAMERECORD,
                        block_size,
                        block,
                        expire,
                        &dht_put_continuation,
                        ma);
  GNUNET_free (block);
  return ret;
}


/**
 * We encountered an error in our zone iteration.
 *
 * @param cls NULL
 */
static void
zone_iteration_error (void *cls)
{
  (void) cls;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Got disconnected from namestore database, retrying.\n");
  namestore_iter = NULL;
  /* We end up here on error/disconnect/shutdown, so potentially
     while a zone publish task or a DHT put is still running; hence
     we need to cancel those. */
  if (NULL != zone_publish_task)
  {
    GNUNET_SCHEDULER_cancel (zone_publish_task);
    zone_publish_task = NULL;
  }
  zone_publish_task = GNUNET_SCHEDULER_add_now (&publish_zone_dht_start,
                                                NULL);
}


/**
 * Zone iteration is completed.
 *
 * @param cls NULL
 */
static void
zone_iteration_finished (void *cls)
{
  (void) cls;
  /* we're done with one iteration, calculate when to do the next one */
  namestore_iter = NULL;
  last_num_public_records = num_public_records;
  first_zone_iteration = GNUNET_NO;
  last_min_relative_record_time = min_relative_record_time;
  calculate_put_interval ();
  /* reset for next iteration */
  min_relative_record_time
    = GNUNET_TIME_UNIT_FOREVER_REL;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Zone iteration finished. Adjusted zone iteration interval to %s\n",
              GNUNET_STRINGS_relative_time_to_string (
                target_iteration_velocity_per_record,
                GNUNET_YES));
  GNUNET_STATISTICS_set (statistics,
                         "Target zone iteration velocity (μs)",
                         target_iteration_velocity_per_record.rel_value_us,
                         GNUNET_NO);
  GNUNET_STATISTICS_set (statistics,
                         "Number of public records in DHT",
                         last_num_public_records,
                         GNUNET_NO);
  GNUNET_assert (NULL == zone_publish_task);
  if (0 == last_num_public_records)
  {
    zone_publish_task = GNUNET_SCHEDULER_add_delayed (
      target_iteration_velocity_per_record,
      &publish_zone_dht_start,
      NULL);
  }
  else
  {
    zone_publish_task = GNUNET_SCHEDULER_add_now (&publish_zone_dht_start,
                                                  NULL);
  }
}


/**
 * Function used to put all records successively into the DHT.
 *
 * @param cls the closure (NULL)
 * @param key the private key of the authority (ours)
 * @param label the name of the records, NULL once the iteration is done
 * @param rd_count the number of records in @a rd
 * @param rd the record data
 */
static void
put_gns_record (void *cls,
                const struct GNUNET_IDENTITY_PrivateKey *key,
                const char *label,
                unsigned int rd_count,
                const struct GNUNET_GNSRECORD_Data *rd)
{
  struct GNUNET_GNSRECORD_Data rd_public[rd_count];
  unsigned int rd_public_count;
  struct DhtPutActivity *ma;

  (void) cls;
  ns_iteration_left--;
  rd_public_count = convert_records_for_export (rd,
                                                rd_count,
                                                rd_public);
  if (0 == rd_public_count)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Record set empty, moving to next record set\n");
    check_zone_namestore_next ();
    return;
  }
  /* We got a set of records to publish */
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Starting DHT PUT\n");
  ma = GNUNET_new (struct DhtPutActivity);
  ma->start_date = GNUNET_TIME_absolute_get ();
  ma->ph = perform_dht_put (key,
                            label,
                            rd_public,
                            rd_public_count,
                            ma);
  put_cnt++;
  if (0 == put_cnt % DELTA_INTERVAL)
    update_velocity (DELTA_INTERVAL);
  check_zone_namestore_next ();
  if (NULL == ma->ph)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "Could not perform DHT PUT, is the DHT running?\n");
    GNUNET_free (ma);
    return;
  }
  dht_queue_length++;
  GNUNET_CONTAINER_DLL_insert_tail (it_head,
                                    it_tail,
                                    ma);
  if (dht_queue_length > DHT_QUEUE_LIMIT)
  {
    ma = it_head;
    GNUNET_CONTAINER_DLL_remove (it_head,
                                 it_tail,
                                 ma);
    GNUNET_DHT_put_cancel (ma->ph);
    dht_queue_length--;
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "DHT PUT unconfirmed after %s, aborting PUT\n",
                GNUNET_STRINGS_relative_time_to_string (
                  GNUNET_TIME_absolute_get_duration (ma->start_date),
                  GNUNET_YES));
    GNUNET_free (ma);
  }
}


/**
 * Periodically iterate over all zones and store everything in DHT
 *
 * @param cls NULL
 */
static void
publish_zone_dht_start (void *cls)
{
  (void) cls;
  zone_publish_task = NULL;
  GNUNET_STATISTICS_update (statistics,
                            "Full zone iterations launched",
                            1,
                            GNUNET_NO);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Starting DHT zone update!\n");
  /* start counting again */
  num_public_records = 0;
  GNUNET_assert (NULL == namestore_iter);
  ns_iteration_left = 1;
  namestore_iter
    = GNUNET_NAMESTORE_zone_iteration_start (namestore_handle,
                                             NULL, /* All zones */
                                             &zone_iteration_error,
                                             NULL,
                                             &put_gns_record,
                                             NULL,
                                             &zone_iteration_finished,
                                             NULL);
  GNUNET_assert (NULL != namestore_iter);
}


/**
 * Performe zonemaster duties: watch namestore, publish records.
 *
 * @param cls closure
 * @param server the initialized server
 * @param c configuration to use
 */
static void
run (void *cls,
     const struct GNUNET_CONFIGURATION_Handle *c,
     struct GNUNET_SERVICE_Handle *service)
{
  unsigned long long max_parallel_bg_queries = 128;

  (void) cls;
  (void) service;
  last_put_100 = GNUNET_TIME_absolute_get ();  /* first time! */
  min_relative_record_time
    = GNUNET_TIME_UNIT_FOREVER_REL;
  target_iteration_velocity_per_record = INITIAL_ZONE_ITERATION_INTERVAL;
  namestore_handle = GNUNET_NAMESTORE_connect (c);
  if (NULL == namestore_handle)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _ ("Failed to connect to the namestore!\n"));
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  cache_keys = GNUNET_CONFIGURATION_get_value_yesno (c,
                                                     "namestore",
                                                     "CACHE_KEYS");
  zone_publish_time_window_default = GNUNET_DHT_DEFAULT_REPUBLISH_FREQUENCY;
  if (GNUNET_OK ==
      GNUNET_CONFIGURATION_get_value_time (c,
                                           "zonemaster",
                                           "ZONE_PUBLISH_TIME_WINDOW",
                                           &zone_publish_time_window_default))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Time window for zone iteration: %s\n",
                GNUNET_STRINGS_relative_time_to_string (
                  zone_publish_time_window,
                  GNUNET_YES));
  }
  zone_publish_time_window = zone_publish_time_window_default;
  if (GNUNET_OK ==
      GNUNET_CONFIGURATION_get_value_number (c,
                                             "zonemaster",
                                             "MAX_PARALLEL_BACKGROUND_QUERIES",
                                             &max_parallel_bg_queries))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Number of allowed parallel background queries: %llu\n",
                max_parallel_bg_queries);
  }
  if (0 == max_parallel_bg_queries)
    max_parallel_bg_queries = 1;
  dht_handle = GNUNET_DHT_connect (c,
                                   (unsigned int) max_parallel_bg_queries);
  if (NULL == dht_handle)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _ ("Could not connect to DHT!\n"));
    GNUNET_SCHEDULER_add_now (&shutdown_task,
                              NULL);
    return;
  }

  /* Schedule periodic put for our records. */
  first_zone_iteration = GNUNET_YES;
  statistics = GNUNET_STATISTICS_create ("zonemaster",
                                         c);
  GNUNET_STATISTICS_set (statistics,
                         "Target zone iteration velocity (μs)",
                         target_iteration_velocity_per_record.rel_value_us,
                         GNUNET_NO);
  zone_publish_task = GNUNET_SCHEDULER_add_now (&publish_zone_dht_start,
                                                NULL);
  GNUNET_SCHEDULER_add_shutdown (&shutdown_task,
                                 NULL);
}


/**
 * Define "main" method using service macro.
 */
GNUNET_SERVICE_MAIN
  ("zonemaster",
  GNUNET_SERVICE_OPTION_NONE,
  &run,
  NULL,
  NULL,
  NULL,
  GNUNET_MQ_handler_end ());


/* end of gnunet-service-zonemaster.c */
