gnunet/src/peerinfo/gnunet-service-peerinfo.c

/*
     This file is part of GNUnet.
     (C) 2001-2014 Christian Grothoff (and other contributing authors)

     GNUnet 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, 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
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file peerinfo/gnunet-service-peerinfo.c
 * @brief maintains list of known peers
 *
 * Code to maintain the list of currently known hosts (in memory
 * structure of data/hosts/).
 *
 * @author Christian Grothoff
 */

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_hello_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_statistics_service.h"
#include "peerinfo.h"

/**
 * How often do we scan the HOST_DIR for new entries?
 */
#define DATA_HOST_FREQ GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 15)

/**
 * How often do we discard old entries in data/hosts/?
 */
#define DATA_HOST_CLEAN_FREQ GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 60)


/**
 * In-memory cache of known hosts.
 */
struct HostEntry
{

  /**
   * Identity of the peer.
   */
  struct GNUNET_PeerIdentity identity;

  /**
   * Hello for the peer (can be NULL)
   */
  struct GNUNET_HELLO_Message *hello;

  /**
   * Friend only hello for the peer (can be NULL)
   */
  struct GNUNET_HELLO_Message *friend_only_hello;

};

/**
 * Transmit context for GET requests
 */
struct TransmitContext
{
  /**
   * Server transmit context
   */
  struct GNUNET_SERVER_TransmitContext *tc;

  /**
   * Include friend only HELLOs #GNUNET_YES or #GNUNET_NO
   */
  int friend_only;
};


/**
 * Result of reading a file
 */
struct ReadHostFileContext
{
  /**
   * Hello for the peer (can be NULL)
   */
  struct GNUNET_HELLO_Message *hello;

  /**
   * Friend only hello for the peer (can be NULL)
   */
  struct GNUNET_HELLO_Message *friend_only_hello;
};


/**
 * Client notification context
 */
struct NotificationContext
{
  /**
   * Next in DLL
   */
  struct NotificationContext *prev;

  /**
   * Previous in DLL
   */
  struct NotificationContext *next;

  /**
   * Server client
   */
  struct GNUNET_SERVER_Client *client;

  /**
   * Interested in friend only HELLO?
   */
  int include_friend_only;
};


/**
 * The in-memory list of known hosts, mapping of
 * host IDs to 'struct HostEntry*' values.
 */
static struct GNUNET_CONTAINER_MultiPeerMap *hostmap;

/**
 * Clients to immediately notify about all changes.
 */
static struct GNUNET_SERVER_NotificationContext *notify_list;

/**
 * Directory where the hellos are stored in (peerinfo/)
 */
static char *networkIdDirectory;

/**
 * Handle for reporting statistics.
 */
static struct GNUNET_STATISTICS_Handle *stats;

/**
 * DLL of notification contexts: head
 */
static struct NotificationContext *nc_head;

/**
 * DLL of notification contexts: tail
 */
static struct NotificationContext *nc_tail;


/**
 * Notify all clients in the notify list about the
 * given host entry changing.
 *
 * @param he entry of the host for which we generate a notification
 * @param include_friend_only create public of friend-only message
 * @return generated notification message
 */
static struct InfoMessage *
make_info_message (const struct HostEntry *he,
                   int include_friend_only)
{
  struct InfoMessage *im;
  struct GNUNET_HELLO_Message *src;
  size_t hs;

  if (GNUNET_YES == include_friend_only)
  	src = he->friend_only_hello;
  else
  	src = he->hello;

  hs = (NULL == src) ? 0 : GNUNET_HELLO_size (src);
  im = GNUNET_malloc (sizeof (struct InfoMessage) + hs);
  im->header.size = htons (hs + sizeof (struct InfoMessage));
  im->header.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_INFO);
  im->peer = he->identity;
  if (NULL != src)
    memcpy (&im[1], src, hs);
  return im;
}


/**
 * Address iterator that causes expired entries to be discarded.
 *
 * @param cls pointer to the current time
 * @param address the address
 * @param expiration expiration time for the address
 * @return #GNUNET_NO if expiration smaller than the current time
 */
static int
discard_expired (void *cls,
                 const struct GNUNET_HELLO_Address *address,
                 struct GNUNET_TIME_Absolute expiration)
{
  const struct GNUNET_TIME_Absolute *now = cls;

  if (now->abs_value_us > expiration.abs_value_us)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("Removing expired address of transport `%s'\n"),
                address->transport_name);
    return GNUNET_NO;
  }
  return GNUNET_OK;
}


/**
 * Address iterator that counts the remaining addresses.
 *
 * @param cls pointer to the counter
 * @param address the address
 * @param expiration expiration time for the address
 * @return #GNUNET_OK (always)
 */
static int
count_addresses (void *cls,
                 const struct GNUNET_HELLO_Address *address,
                 struct GNUNET_TIME_Absolute expiration)
{
  unsigned int *cnt = cls;

  (*cnt)++;
  return GNUNET_OK;
}


/**
 * Get the filename under which we would store the GNUNET_HELLO_Message
 * for the given host and protocol.
 *
 * @param id peer for which we need the filename for the HELLO
 * @return filename of the form DIRECTORY/HOSTID
 */
static char *
get_host_filename (const struct GNUNET_PeerIdentity *id)
{
  char *fn;

  if (NULL == networkIdDirectory)
    return NULL;
  GNUNET_asprintf (&fn, "%s%s%s", networkIdDirectory, DIR_SEPARATOR_STR,
                   GNUNET_i2s_full (id));
  return fn;
}


/**
 * Broadcast information about the given entry to all
 * clients that care.
 *
 * @param entry entry to broadcast about
 */
static void
notify_all (struct HostEntry *entry)
{
  struct InfoMessage *msg_pub;
  struct InfoMessage *msg_friend;
  struct NotificationContext *cur;

  msg_pub = make_info_message (entry, GNUNET_NO);
  msg_friend = make_info_message (entry, GNUNET_YES);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Notifying all clients about peer `%s'\n",
	      GNUNET_i2s(&entry->identity));
  for (cur = nc_head; NULL != cur; cur = cur->next)
  {
    if (GNUNET_NO == cur->include_friend_only)
      {
	GNUNET_SERVER_notification_context_unicast (notify_list,
						    cur->client,
						    &msg_pub->header,
						    GNUNET_NO);
      }
    if (GNUNET_YES == cur->include_friend_only)
    {
      GNUNET_SERVER_notification_context_unicast (notify_list,
						  cur->client,
						  &msg_friend->header,
						  GNUNET_NO);
    }
  }
  GNUNET_free (msg_pub);
  GNUNET_free (msg_friend);
}


/**
 * Bind a host address (hello) to a hostId.
 *
 * @param peer the peer for which this is a hello
 * @param hello the verified (!) hello message
 */
static void
update_hello (const struct GNUNET_PeerIdentity *peer,
              const struct GNUNET_HELLO_Message *hello);


/**
 * Try to read the HELLOs in the given filename and discard expired
 * addresses.  Removes the file if one the HELLO is malformed.  If all
 * addresses are expired, the HELLO is also removed (but the HELLO
 * with the public key is still returned if it was found and valid).
 * The file can contain multiple HELLO messages.
 *
 * @param fn name of the file
 * @param unlink_garbage if #GNUNET_YES, try to remove useless files
 * @param r ReadHostFileContext to store the resutl
 */
static void
read_host_file (const char *fn,
                int unlink_garbage,
                struct ReadHostFileContext *r)
{
  char buffer[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1] GNUNET_ALIGN;
  unsigned int size_total;
  struct GNUNET_TIME_Absolute now;
  unsigned int left;
  const struct GNUNET_HELLO_Message *hello;
  struct GNUNET_HELLO_Message *hello_clean;
  unsigned read_pos;
  int size_hello;

  r->friend_only_hello = NULL;
  r->hello = NULL;

  if (GNUNET_YES != GNUNET_DISK_file_test (fn))
    return;
  size_total = GNUNET_DISK_fn_read (fn, buffer, sizeof (buffer));
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Read %u bytes from `%s'\n",
              size_total,
              fn);
  if (size_total < sizeof (struct GNUNET_MessageHeader))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		_("Failed to parse HELLO in file `%s': %s\n"),
		fn, "Fail has invalid size");
    if ( (GNUNET_YES == unlink_garbage) &&
	 (0 != UNLINK (fn)) &&
	 (ENOENT != errno) )
      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
                                "unlink",
                                fn);
    return;
  }

  read_pos = 0;
  while (read_pos < size_total)
  {
    hello = (const struct GNUNET_HELLO_Message *) &buffer[read_pos];
    size_hello = GNUNET_HELLO_size (hello);
    if (0 == size_hello)
      {
	GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		    _("Failed to parse HELLO in file `%s'\n"),
		    fn);
	if ((GNUNET_YES == unlink_garbage) &&
	    (0 != UNLINK (fn)) &&
	    (ENOENT != errno) )
	  GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
                                    "unlink",
                                    fn);
	return;
      }

    now = GNUNET_TIME_absolute_get ();
    hello_clean = GNUNET_HELLO_iterate_addresses (hello, GNUNET_YES,
						  &discard_expired, &now);
    if (NULL == hello_clean)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  _("Failed to parse HELLO in file `%s'\n"),
                  fn);
      if ((GNUNET_YES == unlink_garbage) &&
          (0 != UNLINK (fn)) &&
          (ENOENT != errno) )
        GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
                                  "unlink",
                                  fn);
      return;
    }
    left = 0;
    (void) GNUNET_HELLO_iterate_addresses (hello_clean, GNUNET_NO,
					   &count_addresses, &left);

    if (0 == left)
    {
      GNUNET_free (hello_clean);
      break;
    }

    if (GNUNET_NO == GNUNET_HELLO_is_friend_only (hello_clean))
    {
      if (NULL == r->hello)
	r->hello = hello_clean;
      else
      {
	GNUNET_break (0);
	GNUNET_free (r->hello);
	r->hello = hello_clean;
      }
    }
    else
    {
      if (NULL == r->friend_only_hello)
	r->friend_only_hello = hello_clean;
      else
      {
	GNUNET_break (0);
	GNUNET_free (r->friend_only_hello);
	r->friend_only_hello = hello_clean;
      }
    }
    read_pos += size_hello;
  }

  if (0 == left)
  {
    /* no addresses left, remove from disk */
    if ( (GNUNET_YES == unlink_garbage) &&
         (0 != UNLINK (fn)) )
      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
                                "unlink",
                                fn);
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Found `%s' and `%s' HELLO message in file\n",
	      (NULL != r->hello) ? "public" : "NON-public",
	      (NULL != r->friend_only_hello) ? "friend only" : "NO friend only");
}


/**
 * Add a host to the list and notify clients about this event
 *
 * @param identity the identity of the host
 * @return the HostEntry
 */
static struct HostEntry *
add_host_to_known_hosts (const struct GNUNET_PeerIdentity *identity)
{
  struct HostEntry *entry;
  struct ReadHostFileContext r;
  char *fn;

  entry = GNUNET_CONTAINER_multipeermap_get (hostmap, identity);
  if (NULL == entry)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Adding new peer `%s'\n",
                GNUNET_i2s (identity));
    GNUNET_STATISTICS_update (stats, gettext_noop ("# peers known"), 1,
			      GNUNET_NO);
    entry = GNUNET_new (struct HostEntry);
    entry->identity = *identity;
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_CONTAINER_multipeermap_put (hostmap,
                                                      &entry->identity,
                                                      entry,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
    notify_all (entry);
    fn = get_host_filename (identity);
    if (NULL != fn)
    {
      read_host_file (fn, GNUNET_YES, &r);
      if (NULL != r.hello)
      	update_hello (identity, r.hello);
      if (NULL != r.friend_only_hello)
      	update_hello (identity, r.friend_only_hello);
      GNUNET_free_non_null (r.hello);
      GNUNET_free_non_null (r.friend_only_hello);
      GNUNET_free (fn);
    }
  }
  return entry;
}


/**
 * Remove a file that should not be there.  LOG
 * success or failure.
 *
 * @param fullname name of the file to remove
 */
static void
remove_garbage (const char *fullname)
{
  if (0 == UNLINK (fullname))
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING | GNUNET_ERROR_TYPE_BULK,
                _("File `%s' in directory `%s' does not match naming convention. Removed.\n"),
                fullname,
                networkIdDirectory);
  else
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
                              "unlink",
                              fullname);
}


/**
 * Closure for #hosts_directory_scan_callback().
 */
struct DirScanContext
{
  /**
   * #GNUNET_YES if we should remove files that are broken,
   * #GNUNET_NO if the directory we are iterating over should
   * be treated as read-only by us.
   */
  int remove_files;

  /**
   * Counter for the number of (valid) entries found, incremented
   * by one for each match.
   */
  unsigned int matched;
};


/**
 * Function that is called on each HELLO file in a particular directory.
 * Try to parse the file and add the HELLO to our list.
 *
 * @param cls pointer to 'unsigned int' to increment for each file, or NULL
 *            if the file is from a read-only, read-once resource directory
 * @param fullname name of the file to parse
 * @return #GNUNET_OK (continue iteration)
 */
static int
hosts_directory_scan_callback (void *cls,
                               const char *fullname)
{
  struct DirScanContext *dsc = cls;
  struct GNUNET_PeerIdentity identity;
  struct ReadHostFileContext r;
  const char *filename;
  struct GNUNET_PeerIdentity id_public;
  struct GNUNET_PeerIdentity id_friend;
  struct GNUNET_PeerIdentity id;

  if (GNUNET_YES != GNUNET_DISK_file_test (fullname))
    return GNUNET_OK;           /* ignore non-files */

  filename = strrchr (fullname, DIR_SEPARATOR);
  if ((NULL == filename) || (1 > strlen (filename)))
    filename = fullname;
  else
    filename ++;

  read_host_file (fullname, dsc->remove_files, &r);
  if ( (NULL == r.hello) && (NULL == r.friend_only_hello))
    return GNUNET_OK;
  if (NULL != r.friend_only_hello)
  {
    if (GNUNET_OK != GNUNET_HELLO_get_id (r.friend_only_hello, &id_friend))
      if (GNUNET_YES == dsc->remove_files)
      {
	remove_garbage (fullname);
	return GNUNET_OK;
      }
    id = id_friend;
  }
  if (NULL != r.hello)
  {
    if (GNUNET_OK != GNUNET_HELLO_get_id (r.hello, &id_public))
      if (GNUNET_YES == dsc->remove_files)
      {
	remove_garbage (fullname);
	return GNUNET_OK;
      }
    id = id_public;
  }

  if ( (NULL != r.hello) && (NULL != r.friend_only_hello) &&
       (0 != memcmp (&id_friend, &id_public, sizeof (id_friend))) )
  {
    /* HELLOs are not for the same peer */
    GNUNET_break (0);
    if (GNUNET_YES == dsc->remove_files)
      remove_garbage (fullname);
    return GNUNET_OK;
  }
  if (GNUNET_OK ==
      GNUNET_CRYPTO_eddsa_public_key_from_string (filename,
                                                  strlen (filename),
                                                  &identity.public_key))
  {
    if (0 != memcmp (&id, &identity, sizeof (id_friend)))
    {
      /* HELLOs are not for the same peer */
      GNUNET_break (0);
      if (GNUNET_YES == dsc->remove_files)
	remove_garbage (fullname);
      return GNUNET_OK;
    }
  }

  /* ok, found something valid, remember HELLO */
  add_host_to_known_hosts (&id);
  if (NULL != r.hello)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Updating peer `%s' public HELLO \n",
		GNUNET_i2s (&id));
    update_hello (&id, r.hello);
    GNUNET_free (r.hello);
  }
  if (NULL != r.friend_only_hello)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Updating peer `%s' friend only HELLO \n",
		GNUNET_i2s (&id));
    update_hello (&id, r.friend_only_hello);
    GNUNET_free (r.friend_only_hello);
  }
  dsc->matched++;
  return GNUNET_OK;
}


/**
 * Call this method periodically to scan data/hosts for new hosts.
 *
 * @param cls unused
 * @param tc scheduler context, aborted if reason is shutdown
 */
static void
cron_scan_directory_data_hosts (void *cls,
                                const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  static unsigned int retries;
  struct DirScanContext dsc;

  if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
    return;
  if (GNUNET_SYSERR == GNUNET_DISK_directory_create (networkIdDirectory))
  {
    GNUNET_SCHEDULER_add_delayed_with_priority (DATA_HOST_FREQ,
						GNUNET_SCHEDULER_PRIORITY_IDLE,
						&cron_scan_directory_data_hosts, NULL);
    return;
  }
  dsc.matched = 0;
  dsc.remove_files = GNUNET_YES;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO | GNUNET_ERROR_TYPE_BULK,
              _("Scanning directory `%s'\n"),
              networkIdDirectory);
  GNUNET_DISK_directory_scan (networkIdDirectory,
                              &hosts_directory_scan_callback, &dsc);
  if ((0 == dsc.matched) && (0 == (++retries & 31)))
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING | GNUNET_ERROR_TYPE_BULK,
                _("Still no peers found in `%s'!\n"),
                networkIdDirectory);
  GNUNET_SCHEDULER_add_delayed_with_priority (DATA_HOST_FREQ,
					      GNUNET_SCHEDULER_PRIORITY_IDLE,
					      &cron_scan_directory_data_hosts,
					      NULL);
}


/**
 * Update the HELLO of a friend by merging the addresses.
 *
 * @param hello original hello
 * @param friend_hello hello with additional addresses
 * @return merged HELLO
 */
static struct GNUNET_HELLO_Message *
update_friend_hello (const struct GNUNET_HELLO_Message *hello,
		     const struct GNUNET_HELLO_Message *friend_hello)
{
  struct GNUNET_HELLO_Message * res;
  struct GNUNET_HELLO_Message * tmp;
  struct GNUNET_CRYPTO_EddsaPublicKey pk;

  if (NULL != friend_hello)
  {
    res = GNUNET_HELLO_merge (hello, friend_hello);
    GNUNET_assert (GNUNET_YES == GNUNET_HELLO_is_friend_only (res));
    return res;
  }

  if (GNUNET_OK !=
      GNUNET_HELLO_get_key (hello, &pk))
  {
    GNUNET_break (0);
    return NULL;
  }
  tmp = GNUNET_HELLO_create (&pk, NULL, NULL, GNUNET_YES);
  res = GNUNET_HELLO_merge (hello, tmp);
  GNUNET_free (tmp);
  GNUNET_assert (GNUNET_YES == GNUNET_HELLO_is_friend_only (res));
  return res;
}


/**
 * Bind a host address (hello) to a hostId.
 *
 * @param peer the peer for which this is a hello
 * @param hello the verified (!) hello message
 */
static void
update_hello (const struct GNUNET_PeerIdentity *peer,
              const struct GNUNET_HELLO_Message *hello)
{
  char *fn;
  struct HostEntry *host;
  struct GNUNET_HELLO_Message *mrg;
  struct GNUNET_HELLO_Message **dest;
  struct GNUNET_TIME_Absolute delta;
  unsigned int cnt;
  unsigned int size;
  int friend_hello_type;
  int store_hello;
  int store_friend_hello;
  int pos;
  char *buffer;

  host = GNUNET_CONTAINER_multipeermap_get (hostmap, peer);
  GNUNET_assert (NULL != host);

  friend_hello_type = GNUNET_HELLO_is_friend_only (hello);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Updating %s HELLO for `%s'\n",
              (GNUNET_YES == friend_hello_type) ? "friend-only" : "public",
              GNUNET_i2s (peer));

  dest = NULL;
  if (GNUNET_YES == friend_hello_type)
  {
    dest = &host->friend_only_hello;
  }
  else
  {
    dest = &host->hello;
  }

  if (NULL == (*dest))
  {
    (*dest) = GNUNET_malloc (GNUNET_HELLO_size (hello));
    memcpy ((*dest), hello, GNUNET_HELLO_size (hello));
  }
  else
  {
    mrg = GNUNET_HELLO_merge ((*dest), hello);
    delta = GNUNET_HELLO_equals (mrg, (*dest), GNUNET_TIME_absolute_get ());
    if (delta.abs_value_us == GNUNET_TIME_UNIT_FOREVER_ABS.abs_value_us)
    {
      /* no differences, just ignore the update */
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "No change in %s HELLO for `%s'\n",
                  (GNUNET_YES == friend_hello_type) ? "friend-only" : "public",
                  GNUNET_i2s (peer));
      GNUNET_free (mrg);
      return;
    }
    GNUNET_free ((*dest));
    (*dest) = mrg;
  }

  if ( (NULL != (host->hello)) &&
       (GNUNET_NO == friend_hello_type) )
  {
    /* Update friend only hello */
    mrg = update_friend_hello (host->hello, host->friend_only_hello);
    if (NULL != host->friend_only_hello)
      GNUNET_free (host->friend_only_hello);
    host->friend_only_hello = mrg;
  }

  if (NULL != host->hello)
    GNUNET_assert ((GNUNET_NO ==
                    GNUNET_HELLO_is_friend_only (host->hello)));
  if (NULL != host->friend_only_hello)
    GNUNET_assert ((GNUNET_YES ==
                    GNUNET_HELLO_is_friend_only (host->friend_only_hello)));

  fn = get_host_filename (peer);
  if ( (NULL != fn) &&
       (GNUNET_OK ==
        GNUNET_DISK_directory_create_for_file (fn)) )
  {
    store_hello = GNUNET_NO;
    size = 0;
    cnt = 0;
    if (NULL != host->hello)
      (void) GNUNET_HELLO_iterate_addresses (host->hello,
					     GNUNET_NO,
                                             &count_addresses,
                                             &cnt);
    if (cnt > 0)
    {
      store_hello = GNUNET_YES;
      size += GNUNET_HELLO_size (host->hello);
    }
    cnt = 0;
    if (NULL != host->friend_only_hello)
      (void) GNUNET_HELLO_iterate_addresses (host->friend_only_hello,
                                             GNUNET_NO,
					     &count_addresses,
                                             &cnt);
    store_friend_hello = GNUNET_NO;
    if (0 < cnt)
    {
      store_friend_hello = GNUNET_YES;
      size += GNUNET_HELLO_size (host->friend_only_hello);
    }

    if ( (GNUNET_NO == store_hello) &&
         (GNUNET_NO == store_friend_hello) )
    {
      /* no valid addresses, don't put HELLO on disk; in fact,
	 if one exists on disk, remove it */
      (void) UNLINK (fn);
    }
    else
    {
      buffer = GNUNET_malloc (size);
      pos = 0;

      if (GNUNET_YES == store_hello)
      {
	memcpy (buffer, host->hello,
                GNUNET_HELLO_size (host->hello));
	pos += GNUNET_HELLO_size (host->hello);
      }
      if (GNUNET_YES == store_friend_hello)
      {
	memcpy (&buffer[pos], host->friend_only_hello, GNUNET_HELLO_size (host->friend_only_hello));
	pos += GNUNET_HELLO_size (host->friend_only_hello);
      }
      GNUNET_assert (pos == size);

      if (GNUNET_SYSERR == GNUNET_DISK_fn_write (fn, buffer, size,
						 GNUNET_DISK_PERM_USER_READ |
						 GNUNET_DISK_PERM_USER_WRITE |
						 GNUNET_DISK_PERM_GROUP_READ |
						 GNUNET_DISK_PERM_OTHER_READ))
	GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING, "write", fn);
      else
	GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                    "Stored %s %s HELLO in %s  with total size %u\n",
		    (GNUNET_YES == store_friend_hello) ? "friend-only": "",
		    (GNUNET_YES == store_hello) ? "public": "",
		    fn, size);
      GNUNET_free (buffer);
    }
  }
  GNUNET_free_non_null (fn);
  notify_all (host);
}


/**
 * Do transmit info about peer to given host.
 *
 * @param cls NULL to hit all hosts, otherwise specifies a particular target
 * @param key hostID
 * @param value information to transmit
 * @return #GNUNET_YES (continue to iterate)
 */
static int
add_to_tc (void *cls,
           const struct GNUNET_PeerIdentity *key,
           void *value)
{
  struct TransmitContext *tc = cls;
  struct HostEntry *pos = value;
  struct InfoMessage *im;
  uint16_t hs;
  char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1] GNUNET_ALIGN;

  hs = 0;
  im = (struct InfoMessage *) buf;

  if ( (NULL != pos->hello) &&
       (GNUNET_NO == tc->friend_only) )
  {
  	/* Copy public HELLO */
    hs = GNUNET_HELLO_size (pos->hello);
    GNUNET_assert (hs < GNUNET_SERVER_MAX_MESSAGE_SIZE -
                   sizeof (struct InfoMessage));
    memcpy (&im[1], pos->hello, hs);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending public HELLO with size %u for peer `%4s'\n",
    		hs, GNUNET_i2s (key));
  }
  else if ( (NULL != pos->friend_only_hello) &&
            (GNUNET_YES == tc->friend_only) )
  {
  	/* Copy friend only HELLO */
    hs = GNUNET_HELLO_size (pos->friend_only_hello);
    GNUNET_assert (hs < GNUNET_SERVER_MAX_MESSAGE_SIZE -
                   sizeof (struct InfoMessage));
    memcpy (&im[1], pos->friend_only_hello, hs);
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending friend-only HELLO with size %u for peer `%4s'\n",
    		hs,
                GNUNET_i2s (key));
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Adding no HELLO for peer `%s'\n",
                GNUNET_i2s (key));
  }

  im->header.type = htons (GNUNET_MESSAGE_TYPE_PEERINFO_INFO);
  im->header.size = htons (sizeof (struct InfoMessage) + hs);
  im->reserved = htonl (0);
  im->peer = pos->identity;
  GNUNET_SERVER_transmit_context_append_message (tc->tc, &im->header);
  return GNUNET_YES;
}


/**
 * @brief delete expired HELLO entries in directory
 *
 * @param cls pointer to current time (`struct GNUNET_TIME_Absolute *`)
 * @param fn filename to test to see if the HELLO expired
 * @return #GNUNET_OK (continue iteration)
 */
static int
discard_hosts_helper (void *cls,
                      const char *fn)
{
  struct GNUNET_TIME_Absolute *now = cls;
  char buffer[GNUNET_SERVER_MAX_MESSAGE_SIZE - 1] GNUNET_ALIGN;
  const struct GNUNET_HELLO_Message *hello;
  struct GNUNET_HELLO_Message *new_hello;
  int read_size;
  unsigned int cur_hello_size;
  unsigned int new_hello_size;
  int read_pos;
  int write_pos;
  unsigned int cnt;
  char *writebuffer;

  read_size = GNUNET_DISK_fn_read (fn, buffer, sizeof (buffer));
  if (read_size < sizeof (struct GNUNET_MessageHeader))
  {
    if (0 != UNLINK (fn))
      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING |
                                GNUNET_ERROR_TYPE_BULK, "unlink", fn);
    return GNUNET_OK;
  }

  writebuffer = GNUNET_malloc (read_size);
  read_pos = 0;
  write_pos = 0;
  while (read_pos < read_size)
  {
    /* Check each HELLO */
    hello = (const struct GNUNET_HELLO_Message *) &buffer[read_pos];
    cur_hello_size = GNUNET_HELLO_size (hello);
    if (0 == cur_hello_size)
    {
      /* Invalid data, discard */
      if (0 != UNLINK (fn))
	GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING |
				  GNUNET_ERROR_TYPE_BULK,
                                  "unlink", fn);
      return GNUNET_OK;
    }
    new_hello = GNUNET_HELLO_iterate_addresses (hello,
                                                GNUNET_YES,
                                                &discard_expired, now);
    cnt = 0;
    if (NULL != new_hello)
      (void) GNUNET_HELLO_iterate_addresses (hello,
                                             GNUNET_NO,
                                             &count_addresses, &cnt);
    if ( (NULL != new_hello) && (0 < cnt) )
    {
      /* Store new HELLO to write it when done */
      new_hello_size = GNUNET_HELLO_size (new_hello);
      memcpy (&writebuffer[write_pos], new_hello, new_hello_size);
      write_pos += new_hello_size;
    }
    read_pos += cur_hello_size;
    GNUNET_free_non_null (new_hello);
  }

  if (0 < write_pos)
  {
      GNUNET_DISK_fn_write (fn, writebuffer,write_pos,
                            GNUNET_DISK_PERM_USER_READ |
                            GNUNET_DISK_PERM_USER_WRITE |
                            GNUNET_DISK_PERM_GROUP_READ |
                            GNUNET_DISK_PERM_OTHER_READ);
  }
  else if (0 != UNLINK (fn))
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING |
                              GNUNET_ERROR_TYPE_BULK,
                              "unlink", fn);

  GNUNET_free (writebuffer);
  return GNUNET_OK;
}


/**
 * Call this method periodically to scan peerinfo/ for ancient
 * HELLOs to expire.
 *
 * @param cls unused
 * @param tc scheduler context, aborted if reason is shutdown
 */
static void
cron_clean_data_hosts (void *cls,
                       const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct GNUNET_TIME_Absolute now;

  if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
    return;
  now = GNUNET_TIME_absolute_get ();
  GNUNET_log (GNUNET_ERROR_TYPE_INFO | GNUNET_ERROR_TYPE_BULK,
              _("Cleaning up directory `%s'\n"),
              networkIdDirectory);
  GNUNET_DISK_directory_scan (networkIdDirectory,
                              &discard_hosts_helper,
                              &now);
  GNUNET_SCHEDULER_add_delayed (DATA_HOST_CLEAN_FREQ,
                                &cron_clean_data_hosts,
                                NULL);
}


/**
 * Handle HELLO-message.
 *
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_hello (void *cls,
              struct GNUNET_SERVER_Client *client,
              const struct GNUNET_MessageHeader *message)
{
  const struct GNUNET_HELLO_Message *hello;
  struct GNUNET_PeerIdentity pid;

  hello = (const struct GNUNET_HELLO_Message *) message;
  if (GNUNET_OK != GNUNET_HELLO_get_id (hello, &pid))
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s' message received for peer `%4s'\n",
              "HELLO",
              GNUNET_i2s (&pid));
  add_host_to_known_hosts (&pid);
  update_hello (&pid, hello);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Handle GET-message.
 *
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_get (void *cls,
            struct GNUNET_SERVER_Client *client,
            const struct GNUNET_MessageHeader *message)
{
  const struct ListPeerMessage *lpm;
  struct TransmitContext tcx;

  lpm = (const struct ListPeerMessage *) message;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s' message received for peer `%4s'\n",
              "GET",
              GNUNET_i2s (&lpm->peer));
  tcx.friend_only = ntohl (lpm->include_friend_only);
  tcx.tc = GNUNET_SERVER_transmit_context_create (client);
  GNUNET_CONTAINER_multipeermap_get_multiple (hostmap, &lpm->peer,
                                              &add_to_tc, &tcx);
  GNUNET_SERVER_transmit_context_append_data (tcx.tc, NULL, 0,
                                              GNUNET_MESSAGE_TYPE_PEERINFO_INFO_END);
  GNUNET_SERVER_transmit_context_run (tcx.tc, GNUNET_TIME_UNIT_FOREVER_REL);
}


/**
 * Handle GET-ALL-message.
 *
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_get_all (void *cls, struct GNUNET_SERVER_Client *client,
                const struct GNUNET_MessageHeader *message)
{
  const struct ListAllPeersMessage *lapm;
  struct TransmitContext tcx;

  lapm = (const struct ListAllPeersMessage *) message;
  tcx.friend_only = ntohl (lapm->include_friend_only);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "`%s' message received\n",
              "GET_ALL");
  GNUNET_SERVER_disable_receive_done_warning (client);
  tcx.tc = GNUNET_SERVER_transmit_context_create (client);
  GNUNET_CONTAINER_multipeermap_iterate (hostmap,
                                         &add_to_tc,
                                         &tcx);
  GNUNET_SERVER_transmit_context_append_data (tcx.tc, NULL, 0,
                                              GNUNET_MESSAGE_TYPE_PEERINFO_INFO_END);
  GNUNET_SERVER_transmit_context_run (tcx.tc, GNUNET_TIME_UNIT_FOREVER_REL);
}



/**
 * Pass the given client the information we have in the respective
 * host entry; the client is already in the notification context.
 *
 * @param cls the `struct GNUNET_SERVER_Client` to notify
 * @param key key for the value (unused)
 * @param value the `struct HostEntry` to notify the client about
 * @return #GNUNET_YES (always, continue to iterate)
 */
static int
do_notify_entry (void *cls,
                 const struct GNUNET_PeerIdentity *key,
                 void *value)
{
  struct NotificationContext *nc = cls;
  struct HostEntry *he = value;
  struct InfoMessage *msg;

  if ( (NULL == he->hello) &&
       (GNUNET_NO == nc->include_friend_only) )
  {
    /* We have no public hello  */
    return GNUNET_YES;
  }

  if ( (NULL == he->friend_only_hello) &&
       (GNUNET_YES == nc->include_friend_only) )
  {
    /* We have no friend hello */
    return GNUNET_YES;
  }

  msg = make_info_message (he, nc->include_friend_only);
  GNUNET_SERVER_notification_context_unicast (notify_list,
					      nc->client,
					      &msg->header,
					      GNUNET_NO);
  GNUNET_free (msg);
  return GNUNET_YES;
}


/**
 * Handle NOTIFY-message.
 *
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_notify (void *cls,
               struct GNUNET_SERVER_Client *client,
               const struct GNUNET_MessageHeader *message)
{
  struct NotifyMessage *nm = (struct NotifyMessage *) message;
  struct NotificationContext *nc;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "`%s' message received\n",
	      "NOTIFY");
  nc = GNUNET_new (struct NotificationContext);
  nc->client = client;
  nc->include_friend_only = ntohl (nm->include_friend_only);

  GNUNET_CONTAINER_DLL_insert (nc_head, nc_tail, nc);
  GNUNET_SERVER_client_mark_monitor (client);
	GNUNET_SERVER_notification_context_add (notify_list, client);
  GNUNET_CONTAINER_multipeermap_iterate (hostmap, &do_notify_entry, nc);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Client disconnect callback
 *
 * @param cls unused
 * @param client server client
 */
static void
disconnect_cb (void *cls,
               struct GNUNET_SERVER_Client *client)
{
  struct NotificationContext *cur;

  for (cur = nc_head; NULL != cur; cur = cur->next)
    if (cur->client == client)
      break;
  if (NULL == cur)
    return;
  GNUNET_CONTAINER_DLL_remove (nc_head, nc_tail, cur);
  GNUNET_free (cur);
}


/**
 * Release memory taken by a host entry.
 *
 * @param cls NULL
 * @param key key of the host entry
 * @param value the `struct HostEntry` to free
 * @return #GNUNET_YES (continue to iterate)
 */
static int
free_host_entry (void *cls,
                 const struct GNUNET_PeerIdentity *key,
                 void *value)
{
  struct HostEntry *he = value;

  GNUNET_free_non_null (he->hello);
  GNUNET_free_non_null (he->friend_only_hello);
  GNUNET_free (he);
  return GNUNET_YES;
}


/**
 * Clean up our state.  Called during shutdown.
 *
 * @param cls unused
 * @param tc scheduler task context, unused
 */
static void
shutdown_task (void *cls,
               const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct NotificationContext *cur;
  struct NotificationContext *next;

  GNUNET_SERVER_notification_context_destroy (notify_list);
  notify_list = NULL;

  for (cur = nc_head; NULL != cur; cur = next)
  {
    next = cur->next;
    GNUNET_CONTAINER_DLL_remove (nc_head, nc_tail, cur);
    GNUNET_free (cur);
  }
  GNUNET_CONTAINER_multipeermap_iterate (hostmap,
                                         &free_host_entry,
                                         NULL);
  GNUNET_CONTAINER_multipeermap_destroy (hostmap);
  if (NULL != stats)
  {
    GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
    stats = NULL;
  }
}


/**
 * Start up peerinfo service.
 *
 * @param cls closure
 * @param server the initialized server
 * @param cfg configuration to use
 */
static void
run (void *cls,
     struct GNUNET_SERVER_Handle *server,
     const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  static const struct GNUNET_SERVER_MessageHandler handlers[] = {
    {&handle_hello, NULL, GNUNET_MESSAGE_TYPE_HELLO, 0},
    {&handle_get, NULL, GNUNET_MESSAGE_TYPE_PEERINFO_GET,
     sizeof (struct ListPeerMessage)},
    {&handle_get_all, NULL, GNUNET_MESSAGE_TYPE_PEERINFO_GET_ALL,
     sizeof (struct ListAllPeersMessage)},
    {&handle_notify, NULL, GNUNET_MESSAGE_TYPE_PEERINFO_NOTIFY,
     sizeof (struct NotifyMessage)},
    {NULL, NULL, 0, 0}
  };
  char *peerdir;
  char *ip;
  struct DirScanContext dsc;
  int noio;
  int use_included;

  hostmap = GNUNET_CONTAINER_multipeermap_create (1024, GNUNET_YES);
  stats = GNUNET_STATISTICS_create ("peerinfo", cfg);
  notify_list = GNUNET_SERVER_notification_context_create (server, 0);
  noio = GNUNET_CONFIGURATION_get_value_yesno (cfg, "peerinfo", "NO_IO");
  use_included = GNUNET_CONFIGURATION_get_value_yesno (cfg,
                                                       "peerinfo",
                                                       "USE_INCLUDED_HELLOS");
  if (GNUNET_SYSERR == use_included)
    use_included = GNUNET_NO;
  GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
                                &shutdown_task,
                                NULL);
  if (GNUNET_YES != noio)
  {
    GNUNET_assert (GNUNET_OK ==
		   GNUNET_CONFIGURATION_get_value_filename (cfg, "peerinfo",
							    "HOSTS",
							    &networkIdDirectory));
    if (GNUNET_OK !=
	GNUNET_DISK_directory_create (networkIdDirectory))
    {
      GNUNET_SCHEDULER_shutdown ();
      return;
    }

    GNUNET_SCHEDULER_add_with_priority (GNUNET_SCHEDULER_PRIORITY_IDLE,
					&cron_scan_directory_data_hosts, NULL);

    GNUNET_SCHEDULER_add_with_priority (GNUNET_SCHEDULER_PRIORITY_IDLE,
					&cron_clean_data_hosts, NULL);
    if (GNUNET_YES == use_included)
    {
      ip = GNUNET_OS_installation_get_path (GNUNET_OS_IPK_DATADIR);
      GNUNET_asprintf (&peerdir,
                       "%shellos",
                       ip);
      GNUNET_free(ip);

      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                  _("Importing HELLOs from `%s'\n"),
                  peerdir);
      dsc.matched = 0;
      dsc.remove_files = GNUNET_NO;

      GNUNET_DISK_directory_scan (peerdir,
                                  &hosts_directory_scan_callback,
                                  &dsc);
      GNUNET_free (peerdir);
    }
    else
    {
      GNUNET_log(GNUNET_ERROR_TYPE_INFO,
                 _("Skipping import of included HELLOs\n"));
    }
  }
  GNUNET_SERVER_add_handlers (server, handlers);
  GNUNET_SERVER_disconnect_notify (server,
                                   &disconnect_cb,
                                   NULL);
}


/**
 * The main function for the peerinfo service.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc,
      char *const *argv)
{
  int ret;

  ret =
      (GNUNET_OK ==
       GNUNET_SERVICE_run (argc, argv,
                           "peerinfo",
                           GNUNET_SERVICE_OPTION_NONE,
                           &run, NULL)) ? 0 : 1;
  GNUNET_free_non_null (networkIdDirectory);
  return ret;
}


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