-
/*
This file is part of GNUnet.
Copyright (C) 2001-2017 GNUnet e.V.
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
-
/**
* @file cadet/gnunet-service-cadet-new_paths.c
* @brief Information we track per path.
* @author Bartlomiej Polot
* @author Christian Grothoff
+ *
+ * TODO:
+ * - path desirability score calculations are not done
*/
#include "platform.h"
+#include "gnunet-service-cadet-new_connection.h"
+#include "gnunet-service-cadet-new_peer.h"
#include "gnunet-service-cadet-new_paths.h"
+
+#define LOG(level, ...) GNUNET_log_from(level,"cadet-pat",__VA_ARGS__)
+
+
+/**
+ * Information regarding a possible path to reach a peer.
+ */
+struct CadetPeerPath
+{
+
+ /**
+ * Array of all the peers on the path. If @e hn is non-NULL, the
+ * last one is our owner.
+ */
+ struct CadetPeerPathEntry **entries;
+
+ /**
+ * Node of this path in the owner's heap. Used to update our position
+ * in the heap whenever our @e desirability changes.
+ */
+ struct GNUNET_CONTAINER_HeapNode *hn;
+
+ /**
+ * Desirability of the path. How unique is it for the various peers
+ * on it?
+ */
+ GNUNET_CONTAINER_HeapCostType desirability;
+
+ /**
+ * Length of the @e entries array.
+ */
+ unsigned int entries_length;
+
+};
+
+
+/**
+ * Calculate the path's desirability score.
+ *
+ * @param path path to calculate the score for
+ */
+static void
+recalculate_path_desirability (struct CadetPeerPath *path)
+{
+ /* FIXME: update path desirability! */
+ GNUNET_break (0); // not implemented
+}
+
+
/**
- * Create a peer path based on the result of a DHT lookup.
+ * Return how much we like keeping the path. This is an aggregate
+ * score based on various factors, including the age of the path
+ * (older == better), and the value of this path to all of its ajacent
+ * peers. For example, long paths that end at a peer that we have no
+ * shorter way to reach are very desirable, while long paths that end
+ * at a peer for which we have a shorter way as well are much less
+ * desirable. Higher values indicate more valuable paths. The
+ * returned value should be used to decide which paths to remember.
+ *
+ * @param path path to return the length for
+ * @return desirability of the path, larger is more desirable
+ */
+GNUNET_CONTAINER_HeapCostType
+GCPP_get_desirability (const struct CadetPeerPath *path)
+{
+ return path->desirability;
+}
+
+
+/**
+ * Return connection to @a destination using @a path, or return
+ * NULL if no such connection exists.
+ *
+ * @param path path to traverse
+ * @param destination destination node to get to, must be on path
+ * @param off offset of @a destination on @a path
+ * @return NULL if we have no existing connection
+ * otherwise connection from us to @a destination via @a path
+ */
+struct CadetConnection *
+GCPP_get_connection (struct CadetPeerPath *path,
+ struct CadetPeer *destination,
+ unsigned int off)
+{
+ struct CadetPeerPathEntry *entry;
+
+ GNUNET_assert (off < path->entries_length);
+ entry = path->entries[off];
+ GNUNET_assert (entry->peer == destination);
+ return entry->cc;
+}
+
+
+/**
+ * Notify @a path that it is used for connection @a cc
+ * which ends at the path's offset @a off.
+ *
+ * @param path the path to remember the @a cc
+ * @param off the offset where the @a cc ends
+ * @param cc the connection to remember
+ */
+void
+GCPP_add_connection (struct CadetPeerPath *path,
+ unsigned int off,
+ struct CadetConnection *cc)
+{
+ struct CadetPeerPathEntry *entry;
+
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Adding connection %s to path %s at offset %u\n",
+ GCC_2s (cc),
+ GCPP_2s (path),
+ off);
+ GNUNET_assert (off < path->entries_length);
+ entry = path->entries[off];
+ GNUNET_assert (NULL == entry->cc);
+ entry->cc = cc;
+}
+
+
+
+/**
+ * Notify @a path that it is no longer used for connection @a cc which
+ * ended at the path's offset @a off.
+ *
+ * @param path the path to forget the @a cc
+ * @param off the offset where the @a cc ended
+ * @param cc the connection to forget
+ */
+void
+GCPP_del_connection (struct CadetPeerPath *path,
+ unsigned int off,
+ struct CadetConnection *cc)
+{
+ struct CadetPeerPathEntry *entry;
+
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Removing connection %s to path %s at offset %u\n",
+ GCC_2s (cc),
+ GCPP_2s (path),
+ off);
+ GNUNET_assert (off < path->entries_length);
+ entry = path->entries[off];
+ GNUNET_assert (cc == entry->cc);
+ entry->cc = NULL;
+}
+
+
+/**
+ * This path is no longer needed, free resources.
+ *
+ * @param path path resources to free
+ */
+static void
+path_destroy (struct CadetPeerPath *path)
+{
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Destroying path %s\n",
+ GCPP_2s (path));
+ for (unsigned int i=0;i<path->entries_length;i++)
+ GNUNET_free (path->entries[i]);
+ GNUNET_free (path->entries);
+ GNUNET_free (path);
+}
+
+
+/**
+ * The owning peer of this path 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)
+{
+ struct CadetPeerPathEntry *entry;
+
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Owner releases path %s\n",
+ GCPP_2s (path));
+ path->hn = NULL;
+ entry = path->entries[path->entries_length - 1];
+ while (1)
+ {
+ /* cut 'off' end of path */
+ GCP_path_entry_remove (entry->peer,
+ entry,
+ path->entries_length - 1);
+ path->entries_length--; /* We don't bother shrinking the 'entries' array,
+ as it's probably not worth it. */
+ GNUNET_free (entry);
+ if (0 == path->entries_length)
+ break; /* the end */
+
+ /* 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->entries_length - 1,
+ GNUNET_NO);
+ if (NULL != path->hn)
+ return; /* yep, got attached, we are done. */
+ }
+
+ /* nobody wants us, discard the path */
+ path_destroy (path);
+}
+
+
+/**
+ * Updates the score for an entry on the path based
+ * on our experiences with using @a path.
+ *
+ * @param path the path to update
+ * @param off offset of the entry to update
+ * @param delta change in the score to apply
+ */
+void
+GCPP_update_score (struct CadetPeerPath *path,
+ unsigned int off,
+ int delta)
+{
+ struct CadetPeerPathEntry *entry;
+
+ GNUNET_assert (off < path->entries_length);
+ entry = path->entries[off];
+
+ /* Add delta, with checks for overflows */
+ if (delta >= 0)
+ {
+ if (delta + entry->score < entry->score)
+ entry->score = INT_MAX;
+ else
+ entry->score += delta;
+ }
+ else
+ {
+ if (delta + entry->score > entry->score)
+ entry->score = INT_MIN;
+ else
+ entry->score += delta;
+ }
+ recalculate_path_desirability (path);
+}
+
+
+/**
+ * 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;
+
+ /**
+ * How long is the @e cpath array?
+ */
+ unsigned int cpath_length;
+
+};
+
+
+/**
+ * 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`.
+ *
+ * @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;
+
+ GNUNET_assert (path->entries_length > off);
+ if ( (path->entries_length != off + 1) &&
+ (off + 1 != cm_ctx->cpath_length) )
+ {
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "check_match missmatch because path %s is too long (%u vs. %u vs. %u)\n",
+ GCPP_2s (path),
+ path->entries_length,
+ off + 1,
+ cm_ctx->cpath_length);
+ return GNUNET_YES; /* too long, goes somewhere else already, thus cannot be useful */
+ }
+ for (unsigned int i=0;i<off;i++)
+ if (cm_ctx->cpath[i] !=
+ GCPP_get_peer_at_offset (path,
+ i))
+ {
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "check_match path %s missmatches at offset %u\n",
+ GCPP_2s (path),
+ i);
+ return GNUNET_YES; /* missmatch, ignore */
+ }
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "check_match found match with path %s\n",
+ GCPP_2s (path));
+ 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.
+ *
+ * @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
+ * @param force force attachment, even if we have other
+ * paths already
+ */
+static void
+extend_path (struct CadetPeerPath *path,
+ struct CadetPeer **peers,
+ unsigned int num_peers,
+ int force)
+{
+ unsigned int old_len = path->entries_length;
+ struct GNUNET_CONTAINER_HeapNode *hn;
+ int i;
+
+ /* Expand path */
+ GNUNET_array_grow (path->entries,
+ path->entries_length,
+ old_len + num_peers);
+ for (i=num_peers-1;i >= 0;i--)
+ {
+ struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
+
+ path->entries[old_len + i] = entry;
+ entry->peer = peers[i];
+ entry->path = path;
+ }
+ for (i=num_peers-1;i >= 0;i--)
+ {
+ struct CadetPeerPathEntry *entry = path->entries[old_len + i];
+
+ GCP_path_entry_add (entry->peer,
+ entry,
+ old_len + 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--)
+ {
+ struct CadetPeerPathEntry *entry = path->entries[old_len + i];
+
+ path->entries_length = old_len + i + 1;
+ recalculate_path_desirability (path);
+ hn = GCP_attach_path (peers[i],
+ path,
+ old_len + (unsigned int) i,
+ GNUNET_YES);
+ if (NULL != hn)
+ break;
+ GCP_path_entry_remove (entry->peer,
+ entry,
+ old_len + i);
+ GNUNET_free (entry);
+ path->entries[old_len + i] = NULL;
+ }
+ if (NULL == hn)
+ {
+ /* none of the peers is interested in this path;
+ shrink path back */
+ GNUNET_array_grow (path->entries,
+ path->entries_length,
+ old_len);
+ return;
+ }
+ GCP_detach_path (path->entries[old_len-1]->peer,
+ path,
+ path->hn);
+ path->hn = hn;
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Extended path %s\n",
+ GCPP_2s (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.
+ * 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_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)
{
- GNUNET_break (0);
- return NULL;
+ struct CadetPeer *cpath[get_path_length + put_path_length];
+ struct CheckMatchContext cm_ctx;
+ 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_length = get_path_length + put_path_length;
+ 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! */
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Path discovered from DHT is already known\n");
+ return;
+ }
+ if (cm_ctx.match->entries_length == i + 1)
+ {
+ /* Existing path ends in the middle of new path, extend it! */
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Trying to extend existing path %s by additional links discovered from DHT\n",
+ GCPP_2s (cm_ctx.match));
+ extend_path (cm_ctx.match,
+ &cpath[i],
+ get_path_length + put_path_length - i,
+ GNUNET_NO);
+ return;
+ }
+ }
+ }
+
+ /* No match at all, create completely new path */
+ path = GNUNET_new (struct CadetPeerPath);
+ path->entries_length = get_path_length + put_path_length;
+ path->entries = GNUNET_new_array (path->entries_length,
+ struct CadetPeerPathEntry *);
+ for (i=path->entries_length-1;i>=0;i--)
+ {
+ struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
+
+ path->entries[i] = entry;
+ entry->peer = cpath[i];
+ entry->path = path;
+ }
+ for (i=path->entries_length-1;i>=0;i--)
+ {
+ struct CadetPeerPathEntry *entry = path->entries[i];
+
+ GCP_path_entry_add (entry->peer,
+ entry,
+ i);
+ }
+
+ /* Finally, try to attach it */
+ hn = NULL;
+ for (i=get_path_length + put_path_length-1;i>=0;i--)
+ {
+ struct CadetPeerPathEntry *entry = path->entries[i];
+
+ path->entries_length = i + 1;
+ recalculate_path_desirability (path);
+ hn = GCP_attach_path (cpath[i],
+ path,
+ (unsigned int) i,
+ GNUNET_NO);
+ if (NULL != hn)
+ break;
+ GCP_path_entry_remove (entry->peer,
+ entry,
+ i);
+ GNUNET_free (entry);
+ path->entries[i] = NULL;
+ }
+ if (NULL == hn)
+ {
+ /* None of the peers on the path care about it. */
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Path discovered from DHT is not interesting to us\n");
+ GNUNET_free (path->entries);
+ GNUNET_free (path);
+ return;
+ }
+ path->hn = hn;
+ /* Shrink path to actual useful length */
+ GNUNET_array_grow (path->entries,
+ path->entries_length,
+ i + 1);
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Created new path %s based on information from DHT\n",
+ GCPP_2s (path));
}
/**
- * Destroy a path, we no longer need it.
+ * We got an incoming connection, obtain the corresponding path.
*
- * @param p path to destroy.
+ * @param path_length number of segments on the @a path
+ * @param pids path through the network, in reverse order (we are at the end at index @a path_length)
+ * @return corresponding path object
*/
-void
-GCPP_path_destroy (struct CadetPeerPath *p)
+struct CadetPeerPath *
+GCPP_get_path_from_route (unsigned int path_length,
+ const struct GNUNET_PeerIdentity *pids)
{
- GNUNET_assert (0);
+ struct CheckMatchContext cm_ctx;
+ struct CadetPeer *cpath[path_length];
+ struct CadetPeerPath *path;
+
+ /* precompute inverted 'cpath' so we can avoid doing the lookups and
+ have the correct order */
+ for (unsigned int off=0;off<path_length;off++)
+ cpath[off] = GCP_get (&pids[path_length - 1 - off],
+ 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.cpath_length = path_length;
+ cm_ctx.match = NULL;
+ for (int i=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 == path_length - 1)
+ {
+ /* Existing path includes this one, return the match! */
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Returning existing path %s as inverse for incoming connection\n",
+ GCPP_2s (cm_ctx.match));
+ return cm_ctx.match;
+ }
+ if (cm_ctx.match->entries_length == i + 1)
+ {
+ /* Existing path ends in the middle of new path, extend it! */
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Extending existing path %s to create inverse for incoming connection\n",
+ GCPP_2s (cm_ctx.match));
+ extend_path (cm_ctx.match,
+ &cpath[i],
+ path_length - i,
+ GNUNET_YES);
+ /* Check that extension was successful */
+ GNUNET_assert (cm_ctx.match->entries_length == path_length);
+ return cm_ctx.match;
+ }
+ /* Eh, we found a match but couldn't use it? Something is wrong. */
+ GNUNET_break (0);
+ }
+ }
+
+ /* No match at all, create completely new path */
+ path = GNUNET_new (struct CadetPeerPath);
+ path->entries_length = path_length;
+ path->entries = GNUNET_new_array (path->entries_length,
+ struct CadetPeerPathEntry *);
+ for (int i=path_length-1;i>=0;i--)
+ {
+ struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
+
+ path->entries[i] = entry;
+ entry->peer = cpath[i];
+ entry->path = path;
+ }
+ for (int i=path_length-1;i>=0;i--)
+ {
+ struct CadetPeerPathEntry *entry = path->entries[i];
+
+ GCP_path_entry_add (entry->peer,
+ entry,
+ i);
+ }
+ recalculate_path_desirability (path);
+ LOG (GNUNET_ERROR_TYPE_DEBUG,
+ "Created new path %s to create inverse for incoming connection\n",
+ GCPP_2s (path));
+ path->hn = GCP_attach_path (cpath[path_length - 1],
+ path,
+ path_length - 1,
+ GNUNET_YES);
+ return path;
}
unsigned int
GCPP_get_length (struct CadetPeerPath *path)
{
- GNUNET_assert (0);
- return -1;
+ return path->entries_length;
+}
+
+
+/**
+ * Find peer's offset on path.
+ *
+ * @param path path to search
+ * @param cp peer to look for
+ * @return offset of @a cp on @a path, or UINT_MAX if not found
+ */
+unsigned int
+GCPP_find_peer (struct CadetPeerPath *path,
+ struct CadetPeer *cp)
+{
+ for (unsigned int off = 0;
+ off < path->entries_length;
+ off++)
+ if (cp == GCPP_get_peer_at_offset (path,
+ off))
+ return off;
+ return UINT_MAX;
}
/**
- * Obtain the identity of the peer at offset @a off in @a path.
+ * Obtain the peer at offset @a off in @a path.
*
* @param path peer path to inspect
* @param off offset to return, must be smaller than path length
- * @param[out] pid where to write the pid, must not be NULL
+ * @return the peer at offset @a off
*/
-void
-GCPP_get_pid_at_offset (struct CadetPeerPath *path,
- unsigned int off,
- struct GNUNET_PeerIdentity *pid)
+struct CadetPeer *
+GCPP_get_peer_at_offset (struct CadetPeerPath *path,
+ unsigned int off)
{
- GNUNET_assert (0);
+ GNUNET_assert (off < path->entries_length);
+ return path->entries[off]->peer;
+}
+
+
+/**
+ * Convert a path to a human-readable string.
+ *
+ * @param path path to convert
+ * @return string, to be freed by caller (unlike other *_2s APIs!)
+ */
+const char *
+GCPP_2s (struct CadetPeerPath *path)
+{
+ static char buf[2048];
+ size_t off;
+ const unsigned int max_plen = (sizeof(buf) - 16) / 5 - 2; /* 5 characters per entry */
+
+ off = 0;
+ for (unsigned int i = 0;
+ i < path->entries_length;
+ i++)
+ {
+ if ( (path->entries_length > max_plen) &&
+ (i == max_plen / 2) )
+ off += GNUNET_snprintf (&buf[off],
+ sizeof (buf) - off,
+ "...-");
+ if ( (path->entries_length > max_plen) &&
+ (i > max_plen / 2) &&
+ (i < path->entries_length - max_plen / 2) )
+ continue;
+ off += GNUNET_snprintf (&buf[off],
+ sizeof (buf) - off,
+ "%s%s",
+ GNUNET_i2s (GCP_get_id (GCPP_get_peer_at_offset (path,
+ i))),
+ (i == path->entries_length -1) ? "" : "-");
+ }
+ GNUNET_snprintf (&buf[off],
+ sizeof (buf) - off,
+ "(%p)",
+ path);
+ return buf;
}
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