finish logic to maintain paths

6 files changed, 282 insertions, 155 deletions

diff --git a/src/cadet/gnunet-service-cadet-new_dht.c b/src/cadet/gnunet-service-cadet-new_dht.c
index 8cd3a648e..3cf3f0301 100644
--- a/src/cadet/gnunet-service-cadet-new_dht.c
+++ b/src/cadet/gnunet-service-cadet-new_dht.c
@@ -47,16 +47,6 @@ struct GCD_search_handle
    */
   struct GNUNET_DHT_GetHandle *dhtget;
 
-  /**
-   * Provided callback to call when a path is found.
-   */
-  GCD_search_callback callback;
-
-  /**
-   * Provided closure.
-   */
-  void *cls;
-
 };
 
 
@@ -86,7 +76,6 @@ static struct GNUNET_SCHEDULER_Task *announce_id_task;
 static struct GNUNET_TIME_Relative announce_delay;
 
 
-
 /**
  * Function to process paths received for a new peer addition. The recorded
  * paths form the initial tunnel, which can be optimized later.
@@ -114,19 +103,13 @@ dht_get_id_handler (void *cls, struct GNUNET_TIME_Absolute exp,
                     size_t size,
                     const void *data)
 {
-  struct GCD_search_handle *h = cls;
   const struct GNUNET_HELLO_Message *hello = data;
-  struct CadetPeerPath *p;
   struct CadetPeer *peer;
 
-  p = GCPP_path_from_dht (get_path,
+  GCPP_try_path_from_dht (get_path,
                           get_path_length,
                           put_path,
                           put_path_length);
-  h->callback (h->cls,
-               p);
-  GCPP_path_destroy (p);
-
   if ( (size >= sizeof (struct GNUNET_HELLO_Message)) &&
        (ntohs (hello->header.size) == size) &&
        (size == GNUNET_HELLO_size (hello)) )
@@ -280,14 +263,10 @@ GCD_shutdown (void)
  * Search DHT for paths to @a peeR_id
  *
  * @param peer_id peer to search for
- * @param callback function to call with results
- * @param callback_cls closure for @a callback
  * @return handle to abort search
  */
 struct GCD_search_handle *
-GCD_search (const struct GNUNET_PeerIdentity *peer_id,
-            GCD_search_callback callback,
-            void *callback_cls)
+GCD_search (const struct GNUNET_PeerIdentity *peer_id)
 {
   struct GNUNET_HashCode phash;
   struct GCD_search_handle *h;
@@ -307,8 +286,6 @@ GCD_search (const struct GNUNET_PeerIdentity *peer_id,
                  sizeof (*peer_id));
 
   h = GNUNET_new (struct GCD_search_handle);
-  h->callback = callback;
-  h->cls = callback_cls;
   h->dhtget = GNUNET_DHT_get_start (dht_handle,    /* handle */
                                     GNUNET_BLOCK_TYPE_DHT_HELLO, /* type */
                                     &phash,     /* key to search */
diff --git a/src/cadet/gnunet-service-cadet-new_dht.h b/src/cadet/gnunet-service-cadet-new_dht.h
index ff3923790..81f16ae99 100644
--- a/src/cadet/gnunet-service-cadet-new_dht.h
+++ b/src/cadet/gnunet-service-cadet-new_dht.h
@@ -47,18 +47,6 @@ struct GCD_search_handle;
 
 
 /**
- * Callback called on each path found over the DHT.
- *
- * @param cls Closure.
- * @param path An unchecked, unoptimized path to the target node.
- *             After callback will no longer be valid, unless #GCPP_acquire() is called!
- */
-typedef void
-(*GCD_search_callback) (void *cls,
-                        struct CadetPeerPath *path);
-
-
-/**
  * Initialize the DHT subsystem.
  *
  * @param c Configuration.
@@ -66,6 +54,7 @@ typedef void
 void
 GCD_init (const struct GNUNET_CONFIGURATION_Handle *c);
 
+
 /**
  * Shut down the DHT subsystem.
  */
@@ -77,14 +66,10 @@ GCD_shutdown (void);
  * Search DHT for paths to @a peeR_id
  *
  * @param peer_id peer to search for
- * @param callback function to call with results
- * @param callback_cls closure for @a callback
  * @return handle to abort search
  */
 struct GCD_search_handle *
-GCD_search (const struct GNUNET_PeerIdentity *peer_id,
-            GCD_search_callback callback,
-            void *callback_cls);
+GCD_search (const struct GNUNET_PeerIdentity *peer_id);
 
 
 /**
diff --git a/src/cadet/gnunet-service-cadet-new_paths.c b/src/cadet/gnunet-service-cadet-new_paths.c
index 005d8e807..96f32a87b 100644
--- a/src/cadet/gnunet-service-cadet-new_paths.c
+++ b/src/cadet/gnunet-service-cadet-new_paths.c
@@ -24,6 +24,10 @@
  * @brief Information we track per path.
  * @author Bartlomiej Polot
  * @author Christian Grothoff
+ *
+ * TODO:
+ * - path desirability score calculations are not done
+ *   (and will be tricky to have during path changes)
  */
 #include "platform.h"
 #include "gnunet-service-cadet-new_peer.h"
@@ -69,7 +73,6 @@ struct CadetPeerPath
 };
 
 
-
 /**
  * Return how much we like keeping the path.  This is an aggregate
  * score based on various factors, including the age of the path
@@ -86,27 +89,7 @@ struct CadetPeerPath
 GNUNET_CONTAINER_HeapCostType
 GCPP_get_desirability (const struct CadetPeerPath *path)
 {
-  GNUNET_break (0);
-  return 0;
-}
-
-
-/**
- * The given peer @a cp used to own this @a path.  However, it is no
- * longer interested in maintaining it, so the path should be
- * discarded or shortened (in case a previous peer on the path finds
- * the path desirable).
- *
- * @param path the path that is being released
- * @param node entry in the heap of @a cp where this path is anchored
- *             should be used for updates to the desirability of this path
- */
-void
-GCPP_acquire (struct CadetPeerPath *path,
-              struct GNUNET_CONTAINER_HeapNode *node)
-{
-  GNUNET_assert (NULL == path->hn);
-  path->hn = node;
+  return path->desirability;
 }
 
 
@@ -226,7 +209,8 @@ GCPP_release (struct CadetPeerPath *path)
     /* see if new peer at the end likes this path any better */
     entry = &path->entries[path->entries_length - 1];
     path->hn = GCP_attach_path (entry->peer,
-                                path);
+                                path,
+                                path->entries_length);
     if (NULL != path->hn)
       return; /* yep, got attached, we are done. */
   }
@@ -275,17 +259,109 @@ GCPP_update_score (struct CadetPeerPath *path,
 
 
 /**
- * Create a peer path based on the result of a DHT lookup.
- * If we already know this path, or one that is longer,
- * simply return NULL.
+ * Closure for #find_peer_at() and #check_match().
+ */
+struct CheckMatchContext
+{
+
+  /**
+   * Set to a matching path, if any.
+   */
+  struct CadetPeerPath *match;
+
+  /**
+   * Array the combined paths.
+   */
+  struct CadetPeer **cpath;
+
+};
+
+
+/**
+ * Check if the given path is identical on all of the
+ * hops until @a off, and not longer than @a off.  If the
+ * @a path matches, store it in `match`.
  *
- * FIXME: change API completely!
- * Should in here create path transiently, then call
- * callback, and then do path destroy (if applicable)
- * without returning in the middle.
+ * @param cls the `struct CheckMatchContext` to check against
+ * @param path the path to check
+ * @param off offset to check at
+ * @return #GNUNET_YES (continue to iterate), or if found #GNUNET_NO
+ */
+static int
+check_match (void *cls,
+             struct CadetPeerPath *path,
+             unsigned int off)
+{
+  struct CheckMatchContext *cm_ctx = cls;
+
+  if (path->entries_length > off)
+    return GNUNET_YES; /* too long, cannot be useful */
+  for (unsigned int i=0;i<off;i++)
+    if (cm_ctx->cpath[i] !=
+        GCPP_get_peer_at_offset (path,
+                                 i))
+      return GNUNET_YES; /* missmatch, ignore */
+  cm_ctx->match = path;
+  return GNUNET_NO; /* match, we are done! */
+}
+
+
+/**
+ * Extend path @a path by the @a num_peers from the @a peers
+ * array, assuming the owners past the current owner want it.
  *
- * FIXME: also need to nicely handle case that this path
- * extends (lengthens!) an existing path.
+ * @param path path to extend
+ * @param peers list of peers beyond the end of @a path
+ * @param num_peers length of the @a peers array
+ */
+static void
+extend_path (struct CadetPeerPath *path,
+             struct CadetPeer **peers,
+             unsigned int num_peers)
+{
+  unsigned int old_len = path->entries_length;
+  struct GNUNET_CONTAINER_HeapNode *hn;
+  int i;
+
+  /* If we extend an existing path, detach it from the
+     old owner and re-attach to the new one */
+  hn = NULL;
+  for (i=num_peers-1;i>=0;i--)
+  {
+    /* FIXME: note that path->desirability is used, but not yet updated here! */
+    hn = GCP_attach_path (peers[i],
+                          path,
+                          old_len + (unsigned int) i);
+    if (NULL != hn)
+      break;
+  }
+  if (NULL == hn)
+    return; /* none of the peers is interested in this path */
+  GCP_detach_path (path->entries[old_len-1].peer,
+                   path,
+                   path->hn);
+  path->hn = hn;
+  GNUNET_array_grow (path->entries,
+                     path->entries_length,
+                     old_len + i);
+  for (;i >= 0;i--)
+  {
+    struct CadetPeerPathEntry *entry = &path->entries[old_len + i];
+
+    entry->peer = peers[i];
+    entry->path = path;
+    GCP_path_entry_add (entry->peer,
+                        entry,
+                        old_len + i);
+  }
+}
+
+
+/**
+ * Create a peer path based on the result of a DHT lookup.  If we
+ * already know this path, or one that is longer, simply return NULL.
+ * Otherwise, we try to extend an existing path, or create a new one
+ * if applicable.
  *
  * @param get_path path of the get request
  * @param get_path_length lenght of @a get_path
@@ -293,47 +369,93 @@ GCPP_update_score (struct CadetPeerPath *path,
  * @param put_path_length length of the @a put_path
  * @return a path through the network
  */
-struct CadetPeerPath *
-GCPP_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
-                    unsigned int get_path_length,
-                    const struct GNUNET_PeerIdentity *put_path,
-                    unsigned int put_path_length)
+void
+GCPP_try_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
+                        unsigned int get_path_length,
+                        const struct GNUNET_PeerIdentity *put_path,
+                        unsigned int put_path_length)
 {
+  struct CheckMatchContext cm_ctx;
+  struct CadetPeer *cpath[get_path_length + put_path_length];
   struct CadetPeerPath *path;
+  struct GNUNET_CONTAINER_HeapNode *hn;
+  int i;
+
+  /* precompute 'cpath' so we can avoid doing the lookups lots of times */
+  for (unsigned int off=0;off<get_path_length + put_path_length;off++)
+  {
+    const struct GNUNET_PeerIdentity *pid;
+
+    pid = (off < get_path_length)
+      ? &get_path[get_path_length - off]
+      : &put_path[get_path_length + put_path_length - off];
+    cpath[off] = GCP_get (pid,
+                          GNUNET_YES);
+  }
 
+  /* First figure out if this path is a subset of an existing path, an
+     extension of an existing path, or a new path. */
+  cm_ctx.cpath = cpath;
+  cm_ctx.match = NULL;
+  for (i=get_path_length + put_path_length-1;i>=0;i--)
+  {
+    GCP_iterate_paths_at (cpath[i],
+                          (unsigned int) i,
+                          &check_match,
+                          &cm_ctx);
+    if (NULL != cm_ctx.match)
+    {
+      if (i == get_path_length + put_path_length - 1)
+      {
+        /* Existing path includes this one, nothing to do! */
+        return;
+      }
+      if (cm_ctx.match->entries_length == i + 1)
+      {
+        /* Existing path ends in the middle of new path, extend it! */
+        extend_path (cm_ctx.match,
+                     &cpath[i],
+                     get_path_length + put_path_length - i);
+        return;
+      }
+    }
+  }
+
+  /* No match at all, create completely new path */
   path = GNUNET_new (struct CadetPeerPath);
-  path->entries_length = get_path_length + put_path_length;
+
+  /* First, try to attach it */
+  hn = NULL;
+  for (i=get_path_length + put_path_length-1;i>=0;i--)
+  {
+    path->entries_length = i;
+    /* FIXME: note that path->desirability is used, but not yet initialized here! */
+    hn = GCP_attach_path (cpath[i],
+                          path,
+                          (unsigned int) i);
+    if (NULL != hn)
+      break;
+  }
+  if (NULL == hn)
+  {
+    /* None of the peers on the path care about it. */
+    GNUNET_free (path);
+    return;
+  }
+  path->hn = hn;
+  path->entries_length = i;
   path->entries = GNUNET_new_array (path->entries_length,
                                     struct CadetPeerPathEntry);
-  for (unsigned int i=0;i<get_path_length + put_path_length;i++)
+  for (;i>=0;i--)
   {
     struct CadetPeerPathEntry *entry = &path->entries[i];
-    const struct GNUNET_PeerIdentity *pid;
 
-    pid = (i < get_path_length) ? &get_path[get_path_length - i] : &put_path[path->entries_length - i];
-    entry->peer = GCP_get (pid,
-                           GNUNET_YES);
+    entry->peer = cpath[i];
     entry->path = path;
     GCP_path_entry_add (entry->peer,
                         entry,
                         i);
   }
-  GNUNET_break (0);
-  return NULL;
-}
-
-
-/**
- * Destroy a path, we no longer need it.
- *
- * @param p path to destroy.
- */
-void
-GCPP_path_destroy (struct CadetPeerPath *path)
-{
-  if (NULL != path->hn)
-    return; /* path was attached, to be kept! */
-  path_destroy (path);
 }
 
 
diff --git a/src/cadet/gnunet-service-cadet-new_paths.h b/src/cadet/gnunet-service-cadet-new_paths.h
index 4b47784a0..f08d4a705 100644
--- a/src/cadet/gnunet-service-cadet-new_paths.h
+++ b/src/cadet/gnunet-service-cadet-new_paths.h
@@ -32,30 +32,21 @@
 #include "gnunet-service-cadet-new.h"
 
 /**
- * Create a peer path based on the result of a DHT lookup.
- * If we already know this path, or one that is longer,
- * simply return NULL.
+ * Create a peer path based on the result of a DHT lookup.  If we
+ * already know this path, or one that is longer, simply return NULL.
+ * Otherwise, we try to extend an existing path, or create a new one
+ * if applicable.
  *
  * @param get_path path of the get request
  * @param get_path_length lenght of @a get_path
  * @param put_path path of the put request
  * @param put_path_length length of the @a put_path
- * @return a path through the network
- */
-struct CadetPeerPath *
-GCPP_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
-                    unsigned int get_path_length,
-                    const struct GNUNET_PeerIdentity *put_path,
-                    unsigned int put_path_length);
-
-
-/**
- * Destroy a path, we no longer need it.
- *
- * @param path path to destroy.
  */
 void
-GCPP_path_destroy (struct CadetPeerPath *path);
+GCPP_try_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
+                        unsigned int get_path_length,
+                        const struct GNUNET_PeerIdentity *put_path,
+                        unsigned int put_path_length);
 
 
 /**
@@ -149,21 +140,6 @@ GCPP_get_desirability (const struct CadetPeerPath *path);
  * the path desirable).
  *
  * @param path the path that is being released
- * @param node entry in the heap of @a cp where this path is anchored
- *             should be used for updates to the desirability of this path
- */
-void
-GCPP_acquire (struct CadetPeerPath *path,
-              struct GNUNET_CONTAINER_HeapNode *node);
-
-
-/**
- * The given peer @a cp used to own this @a path.  However, it is no
- * longer interested in maintaining it, so the path should be
- * discarded or shortened (in case a previous peer on the path finds
- * the path desirable).
- *
- * @param path the path that is being released
  */
 void
 GCPP_release (struct CadetPeerPath *path);
diff --git a/src/cadet/gnunet-service-cadet-new_peer.c b/src/cadet/gnunet-service-cadet-new_peer.c
index 8c8b23820..9878c540e 100644
--- a/src/cadet/gnunet-service-cadet-new_peer.c
+++ b/src/cadet/gnunet-service-cadet-new_peer.c
@@ -385,19 +385,22 @@ GCP_path_entry_remove (struct CadetPeer *cp,
  * has plenty of paths, return NULL.
  *
  * @param cp peer to which the @a path leads to
- * @param path a path looking for an owner
+ * @param path a path looking for an owner; may not be fully initialized yet!
+ * @param off offset of @a cp in @a path
  * @return NULL if this peer does not care to become a new owner,
  *         otherwise the node in the peer's path heap for the @a path.
  */
 struct GNUNET_CONTAINER_HeapNode *
 GCP_attach_path (struct CadetPeer *cp,
-                 struct CadetPeerPath *path)
+                 struct CadetPeerPath *path,
+                 unsigned int off)
 {
   GNUNET_CONTAINER_HeapCostType desirability;
   struct CadetPeerPath *root;
   GNUNET_CONTAINER_HeapCostType root_desirability;
   struct GNUNET_CONTAINER_HeapNode *hn;
 
+  /* FIXME: desirability is not yet initialized; tricky! */
   desirability = GCPP_get_desirability (path);
   if (GNUNET_NO ==
       GNUNET_CONTAINER_heap_peek2 (cp->path_heap,
@@ -443,24 +446,21 @@ GCP_attach_path (struct CadetPeer *cp,
 
 
 /**
- * Function called when the DHT finds a @a path to the peer (@a cls).
+ * This peer can no longer own @a path as the path
+ * has been extended and a peer further down the line
+ * is now the new owner.
  *
- * @param cls the `struct CadetPeer`
- * @param path the path that was found
+ * @param cp old owner of the @a path
+ * @param path path where the ownership is lost
+ * @param hn note in @a cp's path heap that must be deleted
  */
-static void
-dht_result_cb (void *cls,
-               struct CadetPeerPath *path)
+void
+GCP_detach_path (struct CadetPeer *cp,
+                 struct CadetPeerPath *path,
+                 struct GNUNET_CONTAINER_HeapNode *hn)
 {
-  struct CadetPeer *cp = cls;
-  struct GNUNET_CONTAINER_HeapNode *hn;
-
-  hn = GCP_attach_path (cp,
-                        path);
-  if (NULL == hn)
-    return;
-  GCPP_acquire (path,
-                hn);
+  GNUNET_assert (path ==
+                 GNUNET_CONTAINER_heap_remove_node (hn));
 }
 
 
@@ -502,9 +502,7 @@ consider_peer_activate (struct CadetPeer *cp)
     if ( (NULL == cp->search_h) &&
          (DESIRED_CONNECTIONS_PER_TUNNEL < cp->num_paths) )
       cp->search_h
-        = GCD_search (&cp->pid,
-                      &dht_result_cb,
-                      cp);
+        = GCD_search (&cp->pid);
   }
   else
   {
@@ -640,6 +638,41 @@ GCP_iterate_paths (struct CadetPeer *peer,
 
 
 /**
+ * Iterate over the paths to @a peer where
+ * @a peer is at distance @a dist from us.
+ *
+ * @param peer Peer to get path info.
+ * @param dist desired distance of @a peer to us on the path
+ * @param callback Function to call for every path.
+ * @param callback_cls Closure for @a callback.
+ * @return Number of iterated paths.
+ */
+unsigned int
+GCP_iterate_paths_at (struct CadetPeer *peer,
+                      unsigned int dist,
+                      GCP_PathIterator callback,
+                      void *callback_cls)
+{
+  unsigned int ret = 0;
+
+  if (dist<peer->path_dll_length)
+    return 0;
+  for (struct CadetPeerPathEntry *pe = peer->path_heads[dist];
+       NULL != pe;
+       pe = pe->next)
+  {
+    if (GNUNET_NO ==
+        callback (callback_cls,
+                  pe->path,
+                  dist))
+      return ret;
+    ret++;
+  }
+  return ret;
+}
+
+
+/**
  * Get the tunnel towards a peer.
  *
  * @param peer Peer to get from.
diff --git a/src/cadet/gnunet-service-cadet-new_peer.h b/src/cadet/gnunet-service-cadet-new_peer.h
index e1c8476d1..780640674 100644
--- a/src/cadet/gnunet-service-cadet-new_peer.h
+++ b/src/cadet/gnunet-service-cadet-new_peer.h
@@ -120,6 +120,23 @@ GCP_iterate_paths (struct CadetPeer *cp,
 
 
 /**
+ * Iterate over the paths to @a peer where
+ * @a peer is at distance @a dist from us.
+ *
+ * @param peer Peer to get path info.
+ * @param dist desired distance of @a peer to us on the path
+ * @param callback Function to call for every path.
+ * @param callback_cls Closure for @a callback.
+ * @return Number of iterated paths.
+ */
+unsigned int
+GCP_iterate_paths_at (struct CadetPeer *peer,
+                      unsigned int dist,
+                      GCP_PathIterator callback,
+                      void *callback_cls);
+
+
+/**
  * Remove an entry from the DLL of all of the paths that this peer is on.
  *
  * @param cp peer to modify
@@ -174,13 +191,30 @@ GCP_drop_tunnel (struct CadetPeer *cp,
  * has plenty of paths, return NULL.
  *
  * @param cp peer to which the @a path leads to
- * @param path a path looking for an owner
+ * @param path a path looking for an owner; may not be fully initialized yet!
+ * @param off offset of @a cp in @a path
  * @return NULL if this peer does not care to become a new owner,
  *         otherwise the node in the peer's path heap for the @a path.
  */
 struct GNUNET_CONTAINER_HeapNode *
 GCP_attach_path (struct CadetPeer *cp,
-                 struct CadetPeerPath *path);
+                 struct CadetPeerPath *path,
+                 unsigned int off);
+
+
+/**
+ * This peer can no longer own @a path as the path
+ * has been extended and a peer further down the line
+ * is now the new owner.
+ *
+ * @param cp old owner of the @a path
+ * @param path path where the ownership is lost
+ * @param hn note in @a cp's path heap that must be deleted
+ */
+void
+GCP_detach_path (struct CadetPeer *cp,
+                 struct CadetPeerPath *path,
+                 struct GNUNET_CONTAINER_HeapNode *hn);
 
 
 /**