retry faster
[oweals/gnunet.git] / src / topology / gnunet-daemon-topology.c
index 4db35a17c7a1f1aa289827ef19e32521c5732e92..08b1ba1c3c0effb852fa29cbd34b8880afc645ca 100644 (file)
@@ -1,10 +1,10 @@
 /*
      This file is part of GNUnet.
-     (C) 2007, 2008, 2009 Christian Grothoff (and other contributing authors)
+     (C) 2007, 2008, 2009, 2010 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 2, or (at your
+     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
 
 /**
  * @file topology/gnunet-daemon-topology.c
- * @brief code for bootstrapping via topology servers
+ * @brief code for maintaining the mesh topology
  * @author Christian Grothoff
- *
- * TODO: 
- * - blacklisting & respect for blacklist
- * - calculate target_connection_count!
- * - calculate peer_search retry delay 
  */
 
 #include <stdlib.h>
 #include "platform.h"
+#include "gnunet_constants.h"
 #include "gnunet_core_service.h"
 #include "gnunet_protocols.h"
 #include "gnunet_peerinfo_service.h"
+#include "gnunet_statistics_service.h"
+#include "gnunet_transport_service.h"
 #include "gnunet_util_lib.h"
 
 
-#define DEBUG_TOPOLOGY GNUNET_NO
+#define DEBUG_TOPOLOGY GNUNET_YES
+
+/**
+ * For how long do we blacklist a peer after a failed connection
+ * attempt?
+ */
+#define GREYLIST_AFTER_ATTEMPT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 15)
+
+/**
+ * For how long do we blacklist a friend after a failed connection
+ * attempt?
+ */
+#define GREYLIST_AFTER_ATTEMPT_FRIEND GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 2)
+
+/**
+ * For how long do we blacklist anyone under any cirumstances after a failed connection
+ * attempt?
+ */
+#define GREYLIST_AFTER_ATTEMPT_MIN GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 15)
 
+/**
+ * For how long do we blacklist anyone under any cirumstances after a failed connection
+ * attempt?
+ */
+#define GREYLIST_AFTER_ATTEMPT_MAX GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 1)
 
 /**
- * List of neighbours and friends.
+ * How often do we at most advertise any HELLO to a peer?
  */
-struct FriendList
+#define HELLO_ADVERTISEMENT_MIN_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 4)
+
+/**
+ * How often do we at most advertise the same HELLO to the same peer?
+ */
+#define HELLO_ADVERTISEMENT_MIN_REPEAT_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 4)
+
+
+/**
+ * Record for neighbours, friends and blacklisted peers.
+ */
+struct Peer
 {
+  /**
+   * Which peer is this entry about?
+   */
+  struct GNUNET_PeerIdentity pid;
 
   /**
-   * This is a linked list.
+   * Our handle for the request to transmit HELLOs to this peer; NULL
+   * if no such request is pending.
    */
-  struct FriendList *next;
+  struct GNUNET_CORE_TransmitHandle *hello_req;  
 
   /**
-   * Is this peer listed here because he is a friend?
+   * Our handle for the request to connect to this peer; NULL if no
+   * such request is pending.
    */
-  int is_friend;
+  struct GNUNET_CORE_PeerRequestHandle *connect_req;  
 
   /**
-   * Are we connected to this peer right now?
+   * Pointer to the HELLO message of this peer; can be NULL.
    */
-  int is_connected;
+  struct GNUNET_HELLO_Message *hello;
+
+  /**
+   * Bloom filter used to mark which peers already got the HELLO
+   * from this peer.
+   */
+  struct GNUNET_CONTAINER_BloomFilter *filter;
 
   /**
    * Until what time should we not try to connect again
    * to this peer?
    */
-  struct GNUNET_TIME_Absolute blacklisted_until;
+  struct GNUNET_TIME_Absolute greylisted_until;
 
   /**
-   * ID of the peer.
+   * Next time we are allowed to transmit a HELLO to this peer?
    */
-  struct GNUNET_PeerIdentity id;
-  
+  struct GNUNET_TIME_Absolute next_hello_allowed;
+
+  /**
+   * When should we reset the bloom filter of this entry?
+   */
+  struct GNUNET_TIME_Absolute filter_expiration;
+
+  /**
+   * ID of task we use to wait for the time to send the next HELLO
+   * to this peer.
+   */
+  GNUNET_SCHEDULER_TaskIdentifier hello_delay_task;
+
+  /**
+   * ID of task we use to clear peers from the greylist.
+   */
+  GNUNET_SCHEDULER_TaskIdentifier greylist_clean_task;
+
+  /**
+   * How often have we tried so far?
+   */
+  unsigned int connect_attempts;
+
+  /**
+   * Is this peer listed here because he is a friend?
+   */
+  int is_friend;
+
+  /**
+   * Are we connected to this peer right now?
+   */
+  int is_connected;
+
 };
 
 
 /**
- * Our scheduler.
+ * Our peerinfo notification context.  We use notification
+ * to instantly learn about new peers as they are discovered.
  */
-static struct GNUNET_SCHEDULER_Handle * sched;
+static struct GNUNET_PEERINFO_NotifyContext *peerinfo_notify;
 
 /**
  * Our configuration.
  */
-static struct GNUNET_CONFIGURATION_Handle * cfg;
-   
+static const struct GNUNET_CONFIGURATION_Handle *cfg;
+
 /**
  * Handle to the core API.
  */
 static struct GNUNET_CORE_Handle *handle;
 
+/**
+ * Handle to the transport API.
+ */
+static struct GNUNET_TRANSPORT_Handle *transport;
+
 /**
  * Identity of this peer.
  */
 static struct GNUNET_PeerIdentity my_identity;
-        
+
 /**
- * Linked list of all of our friends and all of our current
- * neighbours.
+ * All of our friends, all of our current neighbours and all peers for
+ * which we have HELLOs.  So pretty much everyone.  Maps peer identities
+ * to 'struct Peer *' values.
  */
-static struct FriendList *friends;
+static struct GNUNET_CONTAINER_MultiHashMap *peers;
+
+/**
+ * Handle for reporting statistics.
+ */
+static struct GNUNET_STATISTICS_Handle *stats;
+
+/**
+ * Blacklist (NULL if we have none).
+ */
+static struct GNUNET_TRANSPORT_Blacklist *blacklist;
 
 /**
  * Flag to disallow non-friend connections (pure F2F mode).
@@ -116,344 +208,784 @@ static unsigned int minimum_friend_count;
  * Number of peers (friends and others) that we are currently connected to.
  */
 static unsigned int connection_count;
+
 /**
  * Target number of connections.
  */
 static unsigned int target_connection_count;
+
 /**
  * Number of friends that we are currently connected to.
  */
 static unsigned int friend_count;
+
 /**
  * Should the topology daemon try to establish connections?
  */
 static int autoconnect;
 
 
+/**
+ * Function that decides if a connection is acceptable or not.  
+ * If we have a blacklist, only friends are allowed, so the check
+ * is rather simple.
+ *
+ * @param cls closure
+ * @param pid peer to approve or disapproave
+ * @return GNUNET_OK if the connection is allowed
+ */
+static int
+blacklist_check (void *cls,
+                const struct GNUNET_PeerIdentity *pid)
+{
+  struct Peer *pos;
+
+  pos = GNUNET_CONTAINER_multihashmap_get (peers, &pid->hashPubKey);
+  if ( (pos != NULL) &&
+       (pos->is_friend == GNUNET_YES) )
+    return GNUNET_OK;
+  GNUNET_STATISTICS_update (stats,
+                           gettext_noop ("# peers blacklisted"),
+                           1,
+                           GNUNET_NO);
+  return GNUNET_SYSERR;
+}
+
 
 /**
- * Force a disconnect from the specified peer.
+ * Whitelist all peers that we blacklisted; we've passed
+ * the minimum number of friends.
  */
 static void
-force_disconnect (const struct GNUNET_PeerIdentity *peer)
+whitelist_peers ()
 {
-  GNUNET_CORE_peer_configure (handle,
-                             peer,
-                             GNUNET_TIME_UNIT_FOREVER_REL,
-                             0,
-                             0,
-                             0,
-                             NULL,
-                             NULL);
+  if (blacklist != NULL)
+    {
+      GNUNET_TRANSPORT_blacklist_cancel (blacklist);
+      blacklist = NULL;
+    }
+}
+
+
+/**
+ * Function called by core when our attempt to connect succeeded.
+ *
+ * @param cls the 'struct Peer' for which we issued the connect request
+ * @param success was the request transmitted
+ */
+static void
+connect_completed_callback (void *cls,
+                           int success)
+{
+  struct Peer *pos = cls;
+
+  pos->connect_req = NULL;
 }
 
 
 /**
- * Function called by core when our attempt to connect
- * succeeded.  Does nothing.
+ * Check if an additional connection from the given peer is allowed.
+ * 
+ * @param peer connection to check
+ * @return GNUNET_OK if the connection is allowed
  */
-static size_t 
-ready_callback (void *cls,
-               size_t size, void *buf)
+static int
+is_connection_allowed (struct Peer *peer)
 {
-  return 0;
+  if (0 == memcmp (&my_identity, 
+                  &peer->pid, 
+                  sizeof (struct GNUNET_PeerIdentity)))
+    return GNUNET_SYSERR;       /* disallow connections to self */
+  if (peer->is_friend)
+    return GNUNET_OK;
+  if (GNUNET_YES == friends_only)
+    {
+#if DEBUG_TOPOLOGY
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                 "Determined that `%s' is not allowed to connect (not a friend)\n",
+                 GNUNET_i2s (&peer->pid));
+#endif       
+      return GNUNET_SYSERR;
+    }
+  if (friend_count >= minimum_friend_count)
+    return GNUNET_OK;
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Determined that `%s' is not allowed to connect (not enough connected friends)\n",
+             GNUNET_i2s (&peer->pid));
+#endif       
+  return GNUNET_SYSERR;
 }
 
 
+/**
+ * Free all resources associated with the given peer.
+ *
+ * @param cls closure (not used)
+ * @param pid identity of the peer
+ * @param value peer to free
+ * @return GNUNET_YES (always: continue to iterate)
+ */
+static int
+free_peer (void *cls,
+          const GNUNET_HashCode *pid,
+          void *value)
+{
+  struct Peer *pos = value;
+
+  GNUNET_break (GNUNET_OK == 
+               GNUNET_CONTAINER_multihashmap_remove (peers,
+                                                     pid,
+                                                     pos));
+  if (pos->hello_req != NULL)
+    GNUNET_CORE_notify_transmit_ready_cancel (pos->hello_req);
+  if (pos->connect_req != NULL)
+    GNUNET_CORE_peer_request_connect_cancel (pos->connect_req);              
+  if (pos->hello_delay_task != GNUNET_SCHEDULER_NO_TASK)
+    GNUNET_SCHEDULER_cancel (pos->hello_delay_task);
+  if (pos->greylist_clean_task != GNUNET_SCHEDULER_NO_TASK)
+    GNUNET_SCHEDULER_cancel (pos->greylist_clean_task);
+  GNUNET_free_non_null (pos->hello);   
+  if (pos->filter != NULL)
+    GNUNET_CONTAINER_bloomfilter_free (pos->filter);
+  GNUNET_free (pos);
+  return GNUNET_YES;
+}
+
+
+/**
+ * Discard peer entries for greylisted peers
+ * where the greylisting has expired.
+ *
+ * @param cls 'struct Peer' to greylist
+ * @param tc scheduler context
+ */
+static void
+remove_from_greylist (void *cls,
+                     const struct GNUNET_SCHEDULER_TaskContext *tc);
+
+
 /**
  * Try to connect to the specified peer.
  *
- * @param pos NULL if not in friend list yet
+ * @param pos peer to connect to
  */
 static void
-attempt_connect (const struct GNUNET_PeerIdentity *peer,
-                struct FriendList *pos)
+attempt_connect (struct Peer *pos)
 {
-  /* FIXME: do blacklist! */
-  GNUNET_CORE_notify_transmit_ready (handle,
-                                    0 /* priority */,
-                                    GNUNET_TIME_UNIT_MINUTES,
-                                    peer,
-                                    sizeof(struct GNUNET_MessageHeader),
-                                    &ready_callback,
-                                    NULL);
+  struct GNUNET_TIME_Relative rem;
+  
+  if ( (connection_count >= target_connection_count) &&
+       (friend_count >= minimum_friend_count) )
+    return;
+  if (GNUNET_YES == pos->is_connected)
+    return;
+  if (GNUNET_OK != is_connection_allowed (pos))
+    return;
+  if (GNUNET_TIME_absolute_get_remaining (pos->greylisted_until).rel_value > 0)
+    return;
+  if (GNUNET_YES == pos->is_friend)
+    rem = GREYLIST_AFTER_ATTEMPT_FRIEND;
+  else
+    rem = GREYLIST_AFTER_ATTEMPT;
+  rem = GNUNET_TIME_relative_multiply (rem, connection_count);
+  rem = GNUNET_TIME_relative_divide (rem, target_connection_count);
+  if (pos->connect_attempts > 30)
+    pos->connect_attempts = 30;
+  rem = GNUNET_TIME_relative_multiply (rem, 1 << (++pos->connect_attempts));
+  rem = GNUNET_TIME_relative_max (rem,
+                                 GREYLIST_AFTER_ATTEMPT_MIN);
+  rem = GNUNET_TIME_relative_min (rem,
+                                 GREYLIST_AFTER_ATTEMPT_MAX);
+  pos->greylisted_until = GNUNET_TIME_relative_to_absolute (rem);
+  if (pos->greylist_clean_task != GNUNET_SCHEDULER_NO_TASK)
+    GNUNET_SCHEDULER_cancel (pos->greylist_clean_task);
+  pos->greylist_clean_task 
+    = GNUNET_SCHEDULER_add_delayed (rem,
+                                   &remove_from_greylist,
+                                   pos);
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Asking  to connect to `%s'\n",
+             GNUNET_i2s (&pos->pid));
+#endif
+  GNUNET_STATISTICS_update (stats,
+                           gettext_noop ("# connect requests issued to core"),
+                           1,
+                           GNUNET_NO);
+  pos->connect_req = GNUNET_CORE_peer_request_connect (handle,
+                                                      GNUNET_TIME_UNIT_MINUTES,
+                                                      &pos->pid,
+                                                      &connect_completed_callback,
+                                                      pos);
 }
 
 
 /**
- * Is this peer one of our friends?
+ * Discard peer entries for greylisted peers
+ * where the greylisting has expired.
+ *
+ * @param cls 'struct Peer' to greylist
+ * @param tc scheduler context
  */
-static int
-is_friend (const struct GNUNET_PeerIdentity * peer)
+static void
+remove_from_greylist (void *cls,
+                     const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
-  struct FriendList *pos;
+  struct Peer *pos = cls;
+  struct GNUNET_TIME_Relative rem;
 
-  pos = friends;
-  while (pos != NULL)
+  pos->greylist_clean_task = GNUNET_SCHEDULER_NO_TASK;
+  rem = GNUNET_TIME_absolute_get_remaining (pos->greylisted_until);
+  if (rem.rel_value == 0)
     {
-      if ( (GNUNET_YES == pos->is_friend) &&
-          (0 == memcmp (&pos->id, peer, sizeof (struct GNUNET_PeerIdentity))) )
-       return GNUNET_YES;
-      pos = pos->next;
+      attempt_connect (pos);
+    }
+  else
+    {
+      pos->greylist_clean_task 
+       = GNUNET_SCHEDULER_add_delayed (rem,
+                                       &remove_from_greylist,
+                                       pos);
+    }
+  if ( (GNUNET_NO == pos->is_friend) &&
+       (GNUNET_NO == pos->is_connected) )
+    {
+      free_peer (NULL, &pos->pid.hashPubKey, pos);
+      return;
     }
-  return GNUNET_NO;
 }
 
 
 /**
- * Check if an additional connection from the given peer is allowed.
+ * Create a new entry in the peer list.
+ *
+ * @param peer identity of the new entry
+ * @param hello hello message, can be NULL
+ * @param is_friend is the new entry for a friend?
+ * @return the new entry
  */
-static int
-is_connection_allowed (const struct GNUNET_PeerIdentity * peer)
+static struct Peer *
+make_peer (const struct
+          GNUNET_PeerIdentity * peer,
+          const struct GNUNET_HELLO_Message *hello,
+          int is_friend)
 {
-  if (0 == memcmp (&my_identity, peer, sizeof (struct GNUNET_PeerIdentity)))
-    return GNUNET_SYSERR;       /* disallow connections to self */
-  if (is_friend (peer))
-    return GNUNET_OK;
-  if (GNUNET_YES == friends_only)
-    return GNUNET_SYSERR;
-  if (friend_count >= minimum_friend_count)
-    return GNUNET_OK;
-  return GNUNET_SYSERR;
+  struct Peer *ret;
+  
+  ret = GNUNET_malloc (sizeof (struct Peer));
+  ret->pid = *peer;
+  ret->is_friend = is_friend;
+  if (hello != NULL)
+    {
+      ret->hello = GNUNET_malloc (GNUNET_HELLO_size (hello));
+      memcpy (ret->hello, hello,
+             GNUNET_HELLO_size (hello));
+    }
+  GNUNET_break (GNUNET_OK ==
+               GNUNET_CONTAINER_multihashmap_put (peers,
+                                                  &peer->hashPubKey,
+                                                  ret,
+                                                  GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+  return ret;
 }
 
 
 /**
- * Method called whenever a peer connects.
+ * Setup bloom filter for the given peer entry.
  *
- * @param cls closure
- * @param peer peer identity this notification is about
+ * @param peer entry to initialize
  */
-static void connect_notify (void *cls,
-                           const struct
-                           GNUNET_PeerIdentity * peer)
+static void
+setup_filter (struct Peer *peer)
 {
-  struct FriendList *pos;
+  /* 2^{-5} chance of not sending a HELLO to a peer is
+     acceptably small (if the filter is 50% full);
+     64 bytes of memory are small compared to the rest
+     of the data structure and would only really become
+     "useless" once a HELLO has been passed on to ~100
+     other peers, which is likely more than enough in
+     any case; hence 64, 5 as bloomfilter parameters. */
+  peer->filter = GNUNET_CONTAINER_bloomfilter_load (NULL, 64, 5);
+  peer->filter_expiration = GNUNET_TIME_relative_to_absolute (HELLO_ADVERTISEMENT_MIN_REPEAT_FREQUENCY);
+  /* never send a peer its own HELLO */
+  GNUNET_CONTAINER_bloomfilter_add (peer->filter, &peer->pid.hashPubKey);
+}
 
-  connection_count++;
-  pos = friends;
-  while (pos != NULL)
+
+/**
+ * Function to fill send buffer with HELLO.
+ *
+ * @param cls 'struct Peer' of the target peer
+ * @param size number of bytes available in buf
+ * @param buf where the callee should write the message
+ * @return number of bytes written to buf
+ */
+static size_t
+hello_advertising_ready (void *cls,
+                        size_t size,
+                        void *buf);
+
+
+
+
+/**
+ * Closure for 'find_advertisable_hello'.
+ */
+struct FindAdvHelloContext {
+
+  /**
+   * Peer we want to advertise to.
+   */
+  struct Peer *peer;
+
+  /**
+   * Where to store the result (peer selected for advertising).
+   */
+  struct Peer *result;
+
+  /**
+   * Maximum HELLO size we can use right now.
+   */
+  size_t max_size;
+
+  struct GNUNET_TIME_Relative next_adv;
+};
+
+
+/**
+ * Find a peer that would be reasonable for advertising.
+ *
+ * @param cls closure
+ * @param pid identity of a peer
+ * @param value 'struct Peer*' for the peer we are considering 
+ * @return GNUNET_YES (continue iteration)
+ */
+static int
+find_advertisable_hello (void *cls,
+                        const GNUNET_HashCode *pid,
+                        void *value)
+{
+  struct FindAdvHelloContext *fah = cls;
+  struct Peer *pos = value;
+  struct GNUNET_TIME_Relative rst_time;
+  size_t hs;
+
+  if (pos == fah->peer)
+    return GNUNET_YES;
+  if (pos->hello == NULL)
+    return GNUNET_YES;
+  rst_time = GNUNET_TIME_absolute_get_remaining (pos->filter_expiration);
+  if (0 == rst_time.rel_value)
     {
-      if ( (GNUNET_YES == pos->is_friend) &&
-          (0 == memcmp (&pos->id, peer, sizeof (struct GNUNET_PeerIdentity))) )
-       {
-         GNUNET_assert (GNUNET_NO == pos->is_connected);
-         pos->is_connected = GNUNET_YES;
-         friend_count++;         
-         return;
-       }
-      pos = pos->next;
+      /* time to discard... */
+      GNUNET_CONTAINER_bloomfilter_free (pos->filter);
+      setup_filter (pos);
     }
-  pos = GNUNET_malloc (sizeof(struct FriendList));
-  pos->id = *peer;
-  pos->is_connected = GNUNET_YES;
-  pos->next = friends;
-  friends = pos;
-  if (GNUNET_OK != is_connection_allowed (peer))
-    force_disconnect (peer);
+  fah->next_adv = GNUNET_TIME_relative_min (rst_time,
+                                           fah->next_adv);
+  hs = GNUNET_HELLO_size (pos->hello);
+  if (hs > fah->max_size)
+    return GNUNET_YES;
+  if (GNUNET_NO ==
+      GNUNET_CONTAINER_bloomfilter_test (pos->filter,
+                                        &fah->peer->pid.hashPubKey))
+    fah->result = pos;    
+  return GNUNET_YES;
 }
 
 
 /**
- * Disconnect from all non-friends (we're below quota).
+ * Calculate when we would like to send the next HELLO to this
+ * peer and ask for it.
+ *
+ * @param cls for which peer to schedule the HELLO
+ * @param tc task context
  */
-static void 
-drop_non_friends () 
+static void
+schedule_next_hello (void *cls,
+                    const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
-  struct FriendList *pos;
+  struct Peer *pl = cls;
+  struct FindAdvHelloContext fah;
+  size_t next_want;
+  struct GNUNET_TIME_Relative delay;
+  pl->hello_delay_task = GNUNET_SCHEDULER_NO_TASK;
+  if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
+    return; /* we're out of here */
+  if (pl->hello_req != NULL)
+    return; /* did not finish sending the previous one */
+  /* find applicable HELLOs */
+  fah.peer = pl;
+  fah.result = NULL;
+  fah.max_size = GNUNET_SERVER_MAX_MESSAGE_SIZE - 1;
+  fah.next_adv = GNUNET_TIME_UNIT_FOREVER_REL;
+  GNUNET_CONTAINER_multihashmap_iterate (peers,
+                                        &find_advertisable_hello,
+                                        &fah);
+  pl->hello_delay_task 
+    = GNUNET_SCHEDULER_add_delayed (fah.next_adv,
+                                   &schedule_next_hello,
+                                   pl);
+  if (fah.result == NULL)
+    return;   
+  next_want = GNUNET_HELLO_size (fah.result->hello);
+  delay = GNUNET_TIME_absolute_get_remaining (pl->next_hello_allowed);
+  if (delay.rel_value == 0)
+    {
+      /* now! */
+      pl->hello_req = GNUNET_CORE_notify_transmit_ready (handle, 0,
+                                                        GNUNET_CONSTANTS_SERVICE_TIMEOUT,
+                                                        &pl->pid,
+                                                        next_want,
+                                                        &hello_advertising_ready,
+                                                        pl);
+    }
+}
+
 
-  pos = friends;
-  while (pos != NULL)
+/**
+ * Cancel existing requests for sending HELLOs to this peer
+ * and recalculate when we should send HELLOs to it based
+ * on our current state (something changed!).
+ *
+ * @param cls closure, 'struct Peer' to skip, or NULL
+ * @param pid identity of a peer
+ * @param value 'struct Peer*' for the peer
+ * @return GNUNET_YES (always)
+ */
+static int
+reschedule_hellos (void *cls,
+                  const GNUNET_HashCode *pid,
+                  void *value)
+{
+  struct Peer *peer = value;
+  struct Peer *skip = cls;
+
+  if (skip == peer)
+    return GNUNET_YES;
+  if (! peer->is_connected) 
+    return GNUNET_YES;
+  if (peer->hello_req != NULL)
     {
-      if (GNUNET_NO == pos->is_friend)
-       {
-         GNUNET_assert (GNUNET_YES == pos->is_connected);
-         force_disconnect (&pos->id);
-       }
-      pos = pos->next;
+      GNUNET_CORE_notify_transmit_ready_cancel (peer->hello_req);
+      peer->hello_req = NULL;
+    }
+  if (peer->hello_delay_task != GNUNET_SCHEDULER_NO_TASK)
+    {
+      GNUNET_SCHEDULER_cancel (peer->hello_delay_task);
+      peer->hello_delay_task = GNUNET_SCHEDULER_NO_TASK;
     }
+  peer->hello_delay_task 
+    = GNUNET_SCHEDULER_add_now (&schedule_next_hello,
+                               peer);
+  return GNUNET_YES;
 }
 
 
 /**
- * Method called whenever a peer disconnects.
+ * Method called whenever a peer connects.
  *
  * @param cls closure
  * @param peer peer identity this notification is about
+ * @param atsi performance data
  */
-static void disconnect_notify (void *cls,
-                              const struct
-                              GNUNET_PeerIdentity * peer)
+static void 
+connect_notify (void *cls,
+               const struct
+               GNUNET_PeerIdentity * peer,
+               const struct GNUNET_TRANSPORT_ATS_Information *atsi)
 {
-  struct FriendList *pos;
-  struct FriendList *prev;
+  struct Peer *pos;
+
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Core told us that we are connecting to `%s'\n",
+             GNUNET_i2s (peer));
+#endif
+  if (0 == memcmp(&my_identity, peer, sizeof(struct GNUNET_PeerIdentity)))
+    return;
 
-  connection_count--;
-  pos = friends;
-  prev = NULL;
-  while (pos != NULL)
+  connection_count++;
+  GNUNET_STATISTICS_set (stats,
+                        gettext_noop ("# peers connected"),
+                        connection_count,
+                        GNUNET_NO);
+  pos = GNUNET_CONTAINER_multihashmap_get (peers, &peer->hashPubKey);
+  if (pos == NULL)    
     {
-      if (0 == memcmp (&pos->id, peer, sizeof (struct GNUNET_PeerIdentity)))
-       {
-         GNUNET_assert (GNUNET_YES == pos->is_connected);
-         pos->is_connected = GNUNET_NO;
-         if (GNUNET_YES == pos->is_friend)
-           {
-             friend_count--;
-             if (friend_count < minimum_friend_count)
-               {
-                 /* disconnect from all non-friends */
-                 drop_non_friends ();
-                 attempt_connect (peer, pos);
-               }
-           }
-         else
-           {
-             /* free entry */
-             if (prev == NULL)
-               friends = pos->next;
-             else
-               prev->next = pos->next;
-             GNUNET_free (pos);
-           }
-         return;
-       }
-      prev = pos;
-      pos = pos->next;
-    } 
-  GNUNET_break (0);
+      pos = make_peer (peer, NULL, GNUNET_NO);
+      GNUNET_break (GNUNET_OK == is_connection_allowed (pos));
+    }
+  else
+    {
+      GNUNET_assert (GNUNET_NO == pos->is_connected);
+      pos->greylisted_until.abs_value = 0; /* remove greylisting */
+    }
+  pos->is_connected = GNUNET_YES;
+  pos->connect_attempts = 0; /* re-set back-off factor */
+  if (pos->is_friend)
+    {
+      if ( (friend_count == minimum_friend_count - 1) &&
+          (GNUNET_YES != friends_only) )       
+       whitelist_peers ();       
+      friend_count++;
+      GNUNET_STATISTICS_set (stats,
+                            gettext_noop ("# friends connected"),
+                            friend_count,
+                            GNUNET_NO);
+    }
+  reschedule_hellos (NULL, &peer->hashPubKey, pos);
 }
 
-/**
- * Find more peers that we should connect to and ask the
- * core to establish connections.
- */
-static void
-find_more_peers (void *cls,
-                const struct GNUNET_SCHEDULER_TaskContext *tc);
-
 
 /**
- * Determine when we should try again to find more peers and
- * schedule the task.
- */ 
-static void
-schedule_peer_search ()
+ * Try to add more peers to our connection set.
+ *
+ * @param cls closure, not used
+ * @param pid identity of a peer
+ * @param value 'struct Peer*' for the peer
+ * @return GNUNET_YES (continue to iterate)
+ */
+static int
+try_add_peers (void *cls,
+              const GNUNET_HashCode *pid,
+              void *value)
 {
-  struct GNUNET_TIME_Relative delay;
-  
-  /* FIXME: calculate reasonable delay here */
-  delay = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES,
-                                        42);
-  GNUNET_SCHEDULER_add_delayed (sched,
-                               GNUNET_NO,
-                               GNUNET_SCHEDULER_PRIORITY_DEFAULT,
-                               GNUNET_SCHEDULER_NO_PREREQUISITE_TASK,
-                               delay,
-                               &find_more_peers,
-                               NULL);
+  struct Peer *pos = value;
+
+  attempt_connect (pos);
+  return GNUNET_YES;
 }
 
 
 /**
- * Peerinfo calls this function to let us know about a
- * possible peer that we might want to connect to.
+ * Method called whenever a peer disconnects.
+ *
+ * @param cls closure
+ * @param peer peer identity this notification is about
  */
-static void
-process_peer (void *cls,
-             const struct GNUNET_PeerIdentity * peer,
-             const struct GNUNET_HELLO_Message * hello,
-             uint32_t trust)
+static void 
+disconnect_notify (void *cls,
+                  const struct
+                  GNUNET_PeerIdentity * peer)
 {
-  struct FriendList *pos;
+  struct Peer *pos;
 
-  if (peer == NULL)
+  if (0 == memcmp(&my_identity, peer, sizeof(struct GNUNET_PeerIdentity)))
+    return;
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Core told us that we disconnected from `%s'\n",
+             GNUNET_i2s (peer));
+#endif       
+  pos = GNUNET_CONTAINER_multihashmap_get (peers,
+                                          &peer->hashPubKey);
+  if (pos == NULL)
     {
-      /* last call, schedule 'find_more_peers' again... */
-      schedule_peer_search ();
+      GNUNET_break (0);
       return;
     }
-  if (hello == NULL)
+  if (pos->is_connected != GNUNET_YES)
     {
-      /* no HELLO known; can not connect, ignore! */
+      GNUNET_break (0);
       return;
     }
-  if (0 == memcmp (&my_identity,
-                   peer, sizeof (struct GNUNET_PeerIdentity)))
-    return;  /* that's me! */
-
-  pos = friends;
-  while (pos != NULL)
+  connection_count--;
+  GNUNET_STATISTICS_set (stats,
+                        gettext_noop ("# peers connected"),
+                        connection_count,
+                        GNUNET_NO);
+  if (pos->is_friend)
     {
-      if (0 == memcmp (&pos->id, peer, sizeof (struct GNUNET_PeerIdentity)))
-       {
-         if (GNUNET_YES == pos->is_connected)
-           return;
-         /* FIXME: check blacklisted... */
-         if (GNUNET_YES == pos->is_friend)
-           {
-             attempt_connect (peer, pos);
-             return;
-           }
-       }
-      pos = pos->next;
+      friend_count--; 
+      GNUNET_STATISTICS_set (stats,
+                            gettext_noop ("# friends connected"),
+                            friend_count,
+                            GNUNET_NO);
     }
-  if (GNUNET_YES == friends_only)
-    return;
-  if (friend_count < minimum_friend_count)
-    return;
-  attempt_connect (peer, NULL);
+  if ( (connection_count < target_connection_count) ||
+       (friend_count < minimum_friend_count) )
+    GNUNET_CONTAINER_multihashmap_iterate (peers,
+                                          &try_add_peers,
+                                          NULL);
+  if ( (friend_count < minimum_friend_count) &&
+       (blacklist == NULL) )
+    blacklist = GNUNET_TRANSPORT_blacklist (cfg,
+                                           &blacklist_check, NULL);
 }
 
 
 /**
- * Try to add more friends to our connection set.
+ * Iterator called on each address.
+ *
+ * @param cls flag that we will set if we see any addresses
+ * @param tname name of the transport
+ * @param expiration when will the given address expire
+ * @param addr the address of the peer
+ * @param addrlen number of bytes in addr
+ * @return GNUNET_SYSERR always, to terminate iteration
  */
-static void
-try_add_friends ()
+static int
+address_iterator (void *cls,
+                 const char *tname,
+                 struct GNUNET_TIME_Absolute expiration,
+                 const void *addr, 
+                 uint16_t addrlen)
 {
-  struct FriendList *pos;
+  int *flag = cls;
+  *flag = GNUNET_YES;
+  return GNUNET_SYSERR;
+}
+
 
-  pos = friends;
-  while (pos != NULL)
+/**
+ * We've gotten a HELLO from another peer.  Consider it for
+ * advertising.
+ *
+ * @param hello the HELLO we got
+ */
+static void
+consider_for_advertising (const struct GNUNET_HELLO_Message *hello)
+{
+  int have_address;
+  struct GNUNET_PeerIdentity pid;
+  struct GNUNET_TIME_Absolute dt;
+  struct GNUNET_HELLO_Message *nh;
+  struct Peer *peer;
+  uint16_t size;
+
+  if (GNUNET_OK != GNUNET_HELLO_get_id (hello, &pid))
+    {
+       GNUNET_break (0);
+       return;
+    }
+  if (0 == memcmp (&pid,
+                  &my_identity,
+                  sizeof (struct GNUNET_PeerIdentity)))
+    return; /* that's me! */
+  have_address = GNUNET_NO;
+  GNUNET_HELLO_iterate_addresses (hello,
+                                 GNUNET_NO,
+                                 &address_iterator,
+                                 &have_address);
+  if (GNUNET_NO == have_address)
+    return; /* no point in advertising this one... */
+  peer = GNUNET_CONTAINER_multihashmap_get (peers,
+                                           &pid.hashPubKey);
+  if (peer == NULL)
+    {
+      peer = make_peer (&pid, hello, GNUNET_NO);
+    }
+  else if (peer->hello != NULL)
+    {
+      dt = GNUNET_HELLO_equals (peer->hello,
+                               hello,
+                               GNUNET_TIME_absolute_get());
+      if (dt.abs_value == GNUNET_TIME_UNIT_FOREVER_ABS.abs_value)
+       return; /* nothing new here */
+    }
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Found `%s' from peer `%s' for advertising\n",
+             "HELLO",
+             GNUNET_i2s (&pid));
+#endif 
+  if (peer->hello != NULL)
     {
-      /* FIXME: check friends for blacklisting... */
-      if ( (GNUNET_YES == pos->is_friend) &&
-          (GNUNET_YES != pos->is_connected) )
-       attempt_connect (&pos->id, pos);
-      pos = pos->next;
+      nh = GNUNET_HELLO_merge (peer->hello,
+                              hello);
+      GNUNET_free (peer->hello);
+      peer->hello = nh;
     }
+  else
+    {
+      size = GNUNET_HELLO_size (hello);
+      peer->hello = GNUNET_malloc (size);
+      memcpy (peer->hello, hello, size);
+    }
+  if (peer->filter != NULL)
+    GNUNET_CONTAINER_bloomfilter_free (peer->filter);
+  setup_filter (peer);
+  /* since we have a new HELLO to pick from, re-schedule all
+     HELLO requests that are not bound by the HELLO send rate! */
+  GNUNET_CONTAINER_multihashmap_iterate (peers,
+                                        &reschedule_hellos,
+                                        peer);
 }
 
 
 /**
- * Find more peers that we should connect to and ask the
- * core to establish connections.
+ * PEERINFO calls this function to let us know about a possible peer
+ * that we might want to connect to.
+ *
+ * @param cls closure (not used)
+ * @param peer potential peer to connect to
+ * @param hello HELLO for this peer (or NULL)
  */
 static void
-find_more_peers (void *cls,
-                const struct GNUNET_SCHEDULER_TaskContext *tc)
+process_peer (void *cls,
+             const struct GNUNET_PeerIdentity *peer,
+             const struct GNUNET_HELLO_Message *hello)
 {
-  if (target_connection_count <= connection_count)
+  struct Peer *pos;
+
+  GNUNET_assert (peer != NULL);
+  if (0 == memcmp (&my_identity,
+                   peer, sizeof (struct GNUNET_PeerIdentity)))
+    return;  /* that's me! */
+  if (hello == NULL)
     {
-      schedule_peer_search ();
+      /* free existing HELLO, if any */
+      pos = GNUNET_CONTAINER_multihashmap_get (peers,
+                                              &peer->hashPubKey);
+      if (NULL != pos)
+       {
+         GNUNET_free_non_null (pos->hello);
+         pos->hello = NULL;
+         if (pos->filter != NULL)
+           {
+             GNUNET_CONTAINER_bloomfilter_free (pos->filter);
+             pos->filter = NULL;
+           }
+         if ( (! pos->is_connected) &&
+              (! pos->is_friend) &&
+              (0 == GNUNET_TIME_absolute_get_remaining (pos->greylisted_until).rel_value) )
+           free_peer (NULL, &pos->pid.hashPubKey, pos);
+       }
       return;
     }
-  if ( (GNUNET_YES == friends_only) ||
-       (friend_count < minimum_friend_count) )
+  consider_for_advertising (hello);
+  pos = GNUNET_CONTAINER_multihashmap_get (peers,
+                                          &peer->hashPubKey);
+  if (pos == NULL)
+    pos = make_peer (peer, hello, GNUNET_NO);
+  GNUNET_assert (NULL != pos);
+  if (GNUNET_YES == pos->is_connected)
     {
-      try_add_friends ();
-      schedule_peer_search ();
+#if DEBUG_TOPOLOGY
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                 "Already connected to peer `%s'\n",
+                 GNUNET_i2s (peer));
+#endif 
       return;
     }
-  GNUNET_PEERINFO_for_all (cfg,
-                          sched,
-                          NULL,
-                          0, GNUNET_TIME_UNIT_FOREVER_REL,
-                          &process_peer, NULL);
+  if (GNUNET_TIME_absolute_get_remaining (pos->greylisted_until).rel_value > 0)
+    {
+#if DEBUG_TOPOLOGY
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                 "Already tried peer `%s' recently\n",
+                 GNUNET_i2s (peer));
+#endif 
+      return; /* peer still greylisted */
+    }
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Considering connecting to peer `%s'\n",
+             GNUNET_i2s (peer));
+#endif 
+  attempt_connect (pos);
 }
 
 
@@ -479,60 +1011,59 @@ core_init (void *cls,
     {
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  _("Failed to connect to core service, can not manage topology!\n"));
-      return; 
+      GNUNET_SCHEDULER_shutdown ();
+      return;
     }
   handle = server;
   my_identity = *my_id;
-  if (autoconnect)
-    GNUNET_SCHEDULER_add_delayed (sched,
-                                 GNUNET_NO,
-                                 GNUNET_SCHEDULER_PRIORITY_DEFAULT,
-                                 GNUNET_SCHEDULER_NO_PREREQUISITE_TASK,
-                                 GNUNET_TIME_UNIT_SECONDS /* give core time to tell us about existing connections */,
-                                 &find_more_peers,
-                                 NULL);
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "I am peer `%s'\n",
+             GNUNET_i2s (my_id));
+#endif         
+  peerinfo_notify = GNUNET_PEERINFO_notify (cfg, &process_peer,
+                                           NULL);
 }
 
 
-/**
- * gnunet-daemon-topology command line options.
- */
-static struct GNUNET_GETOPT_CommandLineOption options[] = {
-  GNUNET_GETOPT_OPTION_END
-};
-
-
 /**
  * Read the friends file.
  */
 static void
-read_friends_file (struct GNUNET_CONFIGURATION_Handle *cfg)
+read_friends_file (const struct GNUNET_CONFIGURATION_Handle *cfg)
 {
   char *fn;
   char *data;
   size_t pos;
-  GNUNET_HashCode hc;
+  struct GNUNET_PeerIdentity pid;
   struct stat frstat;
   struct GNUNET_CRYPTO_HashAsciiEncoded enc;
   unsigned int entries_found;
-  struct FriendList *fl;
+  struct Peer *fl;
 
-  fn = NULL;
-  GNUNET_CONFIGURATION_get_value_filename (cfg,
-                                          "TOPOLOGY",
-                                          "FRIENDS",
-                                          &fn);
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_filename (cfg,
+                                              "TOPOLOGY",
+                                              "FRIENDS",
+                                              &fn))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                 _("Option `%s' in section `%s' not specified!\n"),
+                 "FRIENDS",
+                 "TOPOLOGY");
+      return;
+    }
   if (GNUNET_OK != GNUNET_DISK_file_test (fn))
-    GNUNET_DISK_file_write (fn, NULL, 0, "600");
+    GNUNET_DISK_fn_write (fn, NULL, 0, 
+                         GNUNET_DISK_PERM_USER_READ
+                         | GNUNET_DISK_PERM_USER_WRITE);
   if (0 != STAT (fn, &frstat))
     {
       if ((friends_only) || (minimum_friend_count > 0))
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                     _("Could not read friends list `%s'\n"), fn);
-         GNUNET_free (fn);
-          return;
-        }
+       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                   _("Could not read friends list `%s'\n"), fn);
+      GNUNET_free (fn);
+      return;
     }
   if (frstat.st_size == 0)
     {
@@ -540,11 +1071,18 @@ read_friends_file (struct GNUNET_CONFIGURATION_Handle *cfg)
                  _("Friends file `%s' is empty.\n"),
                  fn);
       GNUNET_free (fn);
-      return; 
+      return;
     }
   data = GNUNET_malloc_large (frstat.st_size);
+  if (data == NULL)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                 _("Failed to read friends list from `%s': out of memory\n"), fn);
+      GNUNET_free (fn);
+      return;
+    }
   if (frstat.st_size !=
-      GNUNET_DISK_file_read (fn, frstat.st_size, data))
+      GNUNET_DISK_fn_read (fn, data, frstat.st_size))
     {
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  _("Failed to read friends list from `%s'\n"), fn);
@@ -554,24 +1092,24 @@ read_friends_file (struct GNUNET_CONFIGURATION_Handle *cfg)
     }
   entries_found = 0;
   pos = 0;
-  while ((pos < frstat.st_size) && isspace (data[pos]))
+  while ((pos < frstat.st_size) && isspace ( (unsigned char) data[pos]))
     pos++;
   while ((frstat.st_size >= sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)) &&
         (pos <= frstat.st_size - sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)))
     {
       memcpy (&enc, &data[pos], sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded));
-      if (!isspace (enc.encoding[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1]))
+      if (!isspace ( (unsigned char) enc.encoding[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1]))
        {
          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                      _("Syntax error in topology specification at offset %llu, skipping bytes.\n"),
                      (unsigned long long) pos);
          pos++;
-         while ((pos < frstat.st_size) && (!isspace (data[pos])))
+         while ((pos < frstat.st_size) && (!isspace ( (unsigned char) data[pos])))
            pos++;
          continue;
        }
       enc.encoding[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] = '\0';
-      if (GNUNET_OK != GNUNET_CRYPTO_hash_from_string ((char *) &enc, &hc))
+      if (GNUNET_OK != GNUNET_CRYPTO_hash_from_string ((char *) &enc, &pid.hashPubKey))
        {
          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                      _("Syntax error in topology specification at offset %llu, skipping bytes `%s'.\n"),
@@ -580,19 +1118,35 @@ read_friends_file (struct GNUNET_CONFIGURATION_Handle *cfg)
        }
       else
        {
-         entries_found++;
-         fl = GNUNET_malloc (sizeof(struct FriendList));
-         fl->is_friend = GNUNET_YES;
-         fl->id.hashPubKey = hc;
-         fl->next = friends;
-         friends = fl;
+         if (0 != memcmp (&pid,
+                          &my_identity,
+                          sizeof (struct GNUNET_PeerIdentity)))
+           {
+             entries_found++;
+             fl = make_peer (&pid,
+                             NULL,
+                             GNUNET_YES);
+             GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                         _("Found friend `%s' in configuration\n"),
+                         GNUNET_i2s (&fl->pid));
+           }
+         else
+           {
+             GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                         _("Found myself `%s' in friend list (useless, ignored)\n"),
+                         GNUNET_i2s (&pid));
+           }
        }
       pos = pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded);
-      while ((pos < frstat.st_size) && isspace (data[pos]))
+      while ((pos < frstat.st_size) && isspace ( (unsigned char) data[pos]))
        pos++;
     }
   GNUNET_free (data);
   GNUNET_free (fn);
+  GNUNET_STATISTICS_update (stats,
+                           gettext_noop ("# friends in configuration"),
+                           entries_found,
+                           GNUNET_NO);
   if ( (minimum_friend_count > entries_found) &&
        (friends_only == GNUNET_NO) )
     {
@@ -608,57 +1162,250 @@ read_friends_file (struct GNUNET_CONFIGURATION_Handle *cfg)
 }
 
 
+/**
+ * This function is called whenever an encrypted HELLO message is
+ * received.
+ *
+ * @param cls closure
+ * @param other the other peer involved (sender or receiver, NULL
+ *        for loopback messages where we are both sender and receiver)
+ * @param message the actual HELLO message
+ * @param atsi performance data
+ * @return GNUNET_OK to keep the connection open,
+ *         GNUNET_SYSERR to close it (signal serious error)
+ */
+static int
+handle_encrypted_hello (void *cls,
+                       const struct GNUNET_PeerIdentity * other,
+                       const struct GNUNET_MessageHeader *
+                       message,
+                       const struct GNUNET_TRANSPORT_ATS_Information *atsi)
+{
+  struct Peer *peer;
+  struct GNUNET_PeerIdentity pid;
+
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Received encrypted `%s' from peer `%s'",
+             "HELLO",
+             GNUNET_i2s (other));
+#endif         
+  if (GNUNET_OK !=
+      GNUNET_HELLO_get_id ((const struct GNUNET_HELLO_Message*) message,
+                          &pid))
+    {
+      GNUNET_break_op (0);
+      return GNUNET_SYSERR;
+    }
+  GNUNET_STATISTICS_update (stats,
+                           gettext_noop ("# HELLO messages received"),
+                           1,
+                           GNUNET_NO);
+  peer = GNUNET_CONTAINER_multihashmap_get (peers,
+                                           &pid.hashPubKey);
+  if (peer == NULL)
+    {
+      if ( (GNUNET_YES == friends_only) ||
+          (friend_count < minimum_friend_count) )
+       return GNUNET_OK;      
+    }
+  else
+    {
+      if ( (GNUNET_YES != peer->is_friend) &&
+          (GNUNET_YES == friends_only) )
+       return GNUNET_OK;
+      if ( (GNUNET_YES != peer->is_friend) &&
+          (friend_count < minimum_friend_count) )
+       return GNUNET_OK;      
+    }
+  if (transport != NULL)
+    GNUNET_TRANSPORT_offer_hello (transport,
+                                 message);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Function to fill send buffer with HELLO.
+ *
+ * @param cls 'struct Peer' of the target peer
+ * @param size number of bytes available in buf
+ * @param buf where the callee should write the message
+ * @return number of bytes written to buf
+ */
+static size_t
+hello_advertising_ready (void *cls,
+                        size_t size,
+                        void *buf)
+{
+  struct Peer *pl = cls;
+  struct FindAdvHelloContext fah;
+  size_t want;
+
+  pl->hello_req = NULL;
+  /* find applicable HELLOs */
+  fah.peer = pl;
+  fah.result = NULL;
+  fah.max_size = size;
+  fah.next_adv = GNUNET_TIME_UNIT_FOREVER_REL;
+  GNUNET_CONTAINER_multihashmap_iterate (peers,
+                                        &find_advertisable_hello,
+                                        &fah);
+  want = 0;
+  if (fah.result != NULL)
+    {
+      want = GNUNET_HELLO_size (fah.result->hello);
+      GNUNET_assert (want <= size);
+      memcpy (buf, fah.result->hello, want);
+      GNUNET_CONTAINER_bloomfilter_add (fah.result->filter,
+                                       &pl->pid.hashPubKey);
+#if DEBUG_TOPOLOGY
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                 "Sending `%s' with %u bytes",
+                 "HELLO",
+                 (unsigned int) want);
+#endif         
+      GNUNET_STATISTICS_update (stats,
+                               gettext_noop ("# HELLO messages gossipped"),
+                               1,
+                               GNUNET_NO);    
+    }
+  pl->next_hello_allowed = GNUNET_TIME_relative_to_absolute (HELLO_ADVERTISEMENT_MIN_FREQUENCY);
+  pl->hello_delay_task 
+    = GNUNET_SCHEDULER_add_now (&schedule_next_hello,
+                               pl);
+  return want;
+}
+
+
+/**
+ * Last task run during shutdown.  Disconnects us from
+ * the transport and core.
+ *
+ * @param cls unused, NULL
+ * @param tc scheduler context
+ */
+static void
+cleaning_task (void *cls, 
+              const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  if (NULL != peerinfo_notify)
+    {
+      GNUNET_PEERINFO_notify_cancel (peerinfo_notify);
+      peerinfo_notify = NULL;
+    }
+  GNUNET_TRANSPORT_disconnect (transport);
+  transport = NULL;
+  GNUNET_CONTAINER_multihashmap_iterate (peers,
+                                        &free_peer,
+                                        NULL);
+  GNUNET_CONTAINER_multihashmap_destroy (peers);
+  if (handle != NULL)
+    {
+      GNUNET_CORE_disconnect (handle);
+      handle = NULL;
+    }
+  whitelist_peers ();
+  if (stats != NULL)
+    {
+      GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
+      stats = NULL;
+    }
+}
+
+
 /**
  * Main function that will be run.
  *
  * @param cls closure
- * @param s the scheduler to use
  * @param args remaining command-line arguments
  * @param cfgfile name of the configuration file used (for saving, can be NULL!)
  * @param c configuration
  */
-static void 
+static void
 run (void *cls,
-     struct GNUNET_SCHEDULER_Handle * s,
      char *const *args,
      const char *cfgfile,
-     struct GNUNET_CONFIGURATION_Handle * c)
+     const struct GNUNET_CONFIGURATION_Handle * c)
 {
-  struct GNUNET_CORE_MessageHandler handlers[] = 
+  struct GNUNET_CORE_MessageHandler handlers[] =
     {
+      { &handle_encrypted_hello, GNUNET_MESSAGE_TYPE_HELLO, 0},
       { NULL, 0, 0 }
     };
   unsigned long long opt;
 
-  sched = s;
   cfg = c;
+  stats = GNUNET_STATISTICS_create ("topology", cfg);
   autoconnect = GNUNET_CONFIGURATION_get_value_yesno (cfg,
                                                      "TOPOLOGY",
-                                                     "AUTOCONNECT"); 
+                                                     "AUTOCONNECT");
   friends_only = GNUNET_CONFIGURATION_get_value_yesno (cfg,
                                                       "TOPOLOGY",
                                                       "FRIENDS-ONLY");
-  opt = 0;
-  GNUNET_CONFIGURATION_get_value_number (cfg,
-                                        "TOPOLOGY",
-                                        "MINIMUM-FRIENDS",
-                                        &opt);
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_number (cfg,
+                                            "TOPOLOGY",
+                                            "MINIMUM-FRIENDS",
+                                            &opt))
+    opt = 0;
   minimum_friend_count = (unsigned int) opt;
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_number (cfg,
+                                            "TOPOLOGY",
+                                            "TARGET-CONNECTION-COUNT",
+                                            &opt))
+    opt = 16;
+  target_connection_count = (unsigned int) opt;
+  peers = GNUNET_CONTAINER_multihashmap_create (target_connection_count * 2);
 
   if ( (friends_only == GNUNET_YES) ||
        (minimum_friend_count > 0) )
     read_friends_file (cfg);
-  GNUNET_CORE_connect (sched,
-                      cfg,
-                      GNUNET_TIME_UNIT_FOREVER_REL,
-                      NULL,
-                      &core_init,
-                      &connect_notify,
-                      &disconnect_notify,
-                      NULL,
-                      NULL, GNUNET_NO,
-                      NULL, GNUNET_NO,
-                      handlers);
+#if DEBUG_TOPOLOGY
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+             "Topology would like %u connections with at least %u friends (%s)\n",
+             target_connection_count,
+             minimum_friend_count,
+             autoconnect ? "autoconnect enabled" : "autoconnect disabled");
+#endif       
+  if (friend_count < minimum_friend_count) 
+    blacklist = GNUNET_TRANSPORT_blacklist (cfg,
+                                           &blacklist_check, NULL);
+  transport = GNUNET_TRANSPORT_connect (cfg,
+                                       NULL,
+                                       NULL,
+                                       NULL,
+                                       NULL,
+                                       NULL);
+  handle = GNUNET_CORE_connect (cfg,
+                               1,
+                               NULL,
+                               &core_init,
+                               &connect_notify,
+                               &disconnect_notify, 
+                               NULL,
+                               NULL, GNUNET_NO,
+                               NULL, GNUNET_NO,
+                               handlers);
+  GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
+                                &cleaning_task, NULL);
+  if (NULL == transport)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                 _("Failed to connect to `%s' service.\n"),
+                 "transport");
+      GNUNET_SCHEDULER_shutdown ();
+      return;
+    }
+  if (NULL == handle)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                 _("Failed to connect to `%s' service.\n"),
+                 "core");
+      GNUNET_SCHEDULER_shutdown ();
+      return;
+    }
 }
 
 
@@ -672,12 +1419,15 @@ run (void *cls,
 int
 main (int argc, char *const *argv)
 {
+  static const struct GNUNET_GETOPT_CommandLineOption options[] = {
+    GNUNET_GETOPT_OPTION_END
+  };
   int ret;
 
   ret = (GNUNET_OK ==
          GNUNET_PROGRAM_run (argc,
                              argv,
-                             "topology", 
+                             "topology",
                             _("GNUnet topology control (maintaining P2P mesh and F2F constraints)"),
                             options,
                             &run, NULL)) ? 0 : 1;