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21 * @file cadet/gnunet-service-cadet-new_paths.c
22 * @brief Information we track per path.
23 * @author Bartlomiej Polot
24 * @author Christian Grothoff
27 * - path desirability score calculations are not done
28 * (and will be tricky to have during path changes)
31 #include "gnunet-service-cadet-new_connection.h"
32 #include "gnunet-service-cadet-new_peer.h"
33 #include "gnunet-service-cadet-new_paths.h"
36 #define LOG(level, ...) GNUNET_log_from(level,"cadet-pat",__VA_ARGS__)
40 * Information regarding a possible path to reach a peer.
46 * Array of all the peers on the path. If @e hn is non-NULL, the
47 * last one is our owner.
49 struct CadetPeerPathEntry **entries;
52 * Node of this path in the owner's heap. Used to update our position
53 * in the heap whenever our @e desirability changes.
55 struct GNUNET_CONTAINER_HeapNode *hn;
58 * Connections using this path, by destination peer
59 * (each hop of the path could correspond to an
62 struct GNUNET_CONTAINER_MultiPeerMap *connections;
65 * Desirability of the path. How unique is it for the various peers
68 GNUNET_CONTAINER_HeapCostType desirability;
71 * Length of the @e entries array.
73 unsigned int entries_length;
79 * Return how much we like keeping the path. This is an aggregate
80 * score based on various factors, including the age of the path
81 * (older == better), and the value of this path to all of its ajacent
82 * peers. For example, long paths that end at a peer that we have no
83 * shorter way to reach are very desirable, while long paths that end
84 * at a peer for which we have a shorter way as well are much less
85 * desirable. Higher values indicate more valuable paths. The
86 * returned value should be used to decide which paths to remember.
88 * @param path path to return the length for
89 * @return desirability of the path, larger is more desirable
91 GNUNET_CONTAINER_HeapCostType
92 GCPP_get_desirability (const struct CadetPeerPath *path)
94 return path->desirability;
99 * Return connection to @a destination using @a path, or return
100 * NULL if no such connection exists.
102 * @param path path to traverse
103 * @param destination destination node to get to, must be on path
104 * @param off offset of @a destination on @a path
105 * @return NULL if we have no existing connection
106 * otherwise connection from us to @a destination via @a path
108 struct CadetConnection *
109 GCPP_get_connection (struct CadetPeerPath *path,
110 struct CadetPeer *destination,
113 struct CadetPeerPathEntry *entry;
115 GNUNET_assert (off < path->entries_length);
116 entry = path->entries[off];
117 GNUNET_assert (entry->peer == destination);
123 * Notify @a path that it is used for connection @a cc
124 * which ends at the path's offset @a off.
126 * @param path the path to remember the @a cc
127 * @param off the offset where the @a cc ends
128 * @param cc the connection to remember
131 GCPP_add_connection (struct CadetPeerPath *path,
133 struct CadetConnection *cc)
135 struct CadetPeerPathEntry *entry;
137 LOG (GNUNET_ERROR_TYPE_DEBUG,
138 "Adding connection %s to path %s at offset %u\n",
142 GNUNET_assert (off < path->entries_length);
143 entry = path->entries[off];
144 GNUNET_assert (NULL == entry->cc);
151 * Notify @a path that it is no longer used for connection @a cc which
152 * ended at the path's offset @a off.
154 * @param path the path to forget the @a cc
155 * @param off the offset where the @a cc ended
156 * @param cc the connection to forget
159 GCPP_del_connection (struct CadetPeerPath *path,
161 struct CadetConnection *cc)
163 struct CadetPeerPathEntry *entry;
165 LOG (GNUNET_ERROR_TYPE_DEBUG,
166 "Removing connection %s to path %s at offset %u\n",
170 GNUNET_assert (off < path->entries_length);
171 entry = path->entries[off];
172 GNUNET_assert (cc == entry->cc);
178 * This path is no longer needed, free resources.
180 * @param path path resources to free
183 path_destroy (struct CadetPeerPath *path)
185 LOG (GNUNET_ERROR_TYPE_DEBUG,
186 "Destroying path %s\n",
189 GNUNET_CONTAINER_multipeermap_size (path->connections));
190 GNUNET_CONTAINER_multipeermap_destroy (path->connections);
191 for (unsigned int i=0;i<path->entries_length;i++)
192 GNUNET_free (path->entries[i]);
193 GNUNET_free (path->entries);
199 * The owning peer of this path is no longer interested in maintaining
200 * it, so the path should be discarded or shortened (in case a
201 * previous peer on the path finds the path desirable).
203 * @param path the path that is being released
206 GCPP_release (struct CadetPeerPath *path)
208 struct CadetPeerPathEntry *entry;
210 LOG (GNUNET_ERROR_TYPE_DEBUG,
211 "Owner releases path %s\n",
214 entry = path->entries[path->entries_length - 1];
217 /* cut 'off' end of path, verifying it is not in use */
218 GNUNET_assert (NULL ==
219 GNUNET_CONTAINER_multipeermap_get (path->connections,
220 GCP_get_id (entry->peer)));
221 GCP_path_entry_remove (entry->peer,
223 path->entries_length - 1);
224 path->entries_length--; /* We don't bother shrinking the 'entries' array,
225 as it's probably not worth it. */
227 if (0 == path->entries_length)
230 /* see if new peer at the end likes this path any better */
231 entry = path->entries[path->entries_length - 1];
232 path->hn = GCP_attach_path (entry->peer,
234 path->entries_length,
236 if (NULL != path->hn)
237 return; /* yep, got attached, we are done. */
240 /* nobody wants us, discard the path */
246 * Updates the score for an entry on the path based
247 * on our experiences with using @a path.
249 * @param path the path to update
250 * @param off offset of the entry to update
251 * @param delta change in the score to apply
254 GCPP_update_score (struct CadetPeerPath *path,
258 struct CadetPeerPathEntry *entry;
260 GNUNET_assert (off < path->entries_length);
261 entry = path->entries[off];
263 /* Add delta, with checks for overflows */
266 if (delta + entry->score < entry->score)
267 entry->score = INT_MAX;
269 entry->score += delta;
273 if (delta + entry->score > entry->score)
274 entry->score = INT_MIN;
276 entry->score += delta;
279 /* FIXME: update path desirability! */
284 * Closure for #find_peer_at() and #check_match().
286 struct CheckMatchContext
290 * Set to a matching path, if any.
292 struct CadetPeerPath *match;
295 * Array the combined paths.
297 struct CadetPeer **cpath;
300 * How long is the @e cpath array?
302 unsigned int cpath_length;
308 * Check if the given path is identical on all of the
309 * hops until @a off, and not longer than @a off. If the
310 * @a path matches, store it in `match`.
312 * @param cls the `struct CheckMatchContext` to check against
313 * @param path the path to check
314 * @param off offset to check at
315 * @return #GNUNET_YES (continue to iterate), or if found #GNUNET_NO
318 check_match (void *cls,
319 struct CadetPeerPath *path,
322 struct CheckMatchContext *cm_ctx = cls;
324 GNUNET_assert (path->entries_length > off);
325 if ( (path->entries_length != off + 1) &&
326 (off + 1 != cm_ctx->cpath_length) )
328 LOG (GNUNET_ERROR_TYPE_DEBUG,
329 "check_match missmatch because path %s is too long (%u vs. %u vs. %u)\n",
331 path->entries_length,
333 cm_ctx->cpath_length);
334 return GNUNET_YES; /* too long, goes somewhere else already, thus cannot be useful */
336 for (unsigned int i=0;i<off;i++)
337 if (cm_ctx->cpath[i] !=
338 GCPP_get_peer_at_offset (path,
341 LOG (GNUNET_ERROR_TYPE_DEBUG,
342 "check_match path %s missmatches at offset %u\n",
345 return GNUNET_YES; /* missmatch, ignore */
347 LOG (GNUNET_ERROR_TYPE_DEBUG,
348 "check_match found match with path %s\n",
350 cm_ctx->match = path;
351 return GNUNET_NO; /* match, we are done! */
356 * Extend path @a path by the @a num_peers from the @a peers
357 * array, assuming the owners past the current owner want it.
359 * @param path path to extend
360 * @param peers list of peers beyond the end of @a path
361 * @param num_peers length of the @a peers array
362 * @param force force attachment, even if we have other
366 extend_path (struct CadetPeerPath *path,
367 struct CadetPeer **peers,
368 unsigned int num_peers,
371 unsigned int old_len = path->entries_length;
372 struct GNUNET_CONTAINER_HeapNode *hn;
375 /* If we extend an existing path, detach it from the
376 old owner and re-attach to the new one */
378 for (i=num_peers-1;i>=0;i--)
380 /* FIXME: note that path->desirability is used, but not yet updated here! */
381 hn = GCP_attach_path (peers[i],
383 old_len + (unsigned int) i,
389 return; /* none of the peers is interested in this path */
390 GCP_detach_path (path->entries[old_len-1]->peer,
394 GNUNET_array_grow (path->entries,
395 path->entries_length,
399 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
401 path->entries[old_len + i] = entry;
402 entry->peer = peers[i];
404 GCP_path_entry_add (entry->peer,
408 LOG (GNUNET_ERROR_TYPE_DEBUG,
409 "Extended path %s\n",
415 * Create a peer path based on the result of a DHT lookup. If we
416 * already know this path, or one that is longer, simply return NULL.
417 * Otherwise, we try to extend an existing path, or create a new one
420 * @param get_path path of the get request
421 * @param get_path_length lenght of @a get_path
422 * @param put_path path of the put request
423 * @param put_path_length length of the @a put_path
424 * @return a path through the network
427 GCPP_try_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
428 unsigned int get_path_length,
429 const struct GNUNET_PeerIdentity *put_path,
430 unsigned int put_path_length)
432 struct CadetPeer *cpath[get_path_length + put_path_length];
433 struct CheckMatchContext cm_ctx;
434 struct CadetPeerPath *path;
435 struct GNUNET_CONTAINER_HeapNode *hn;
438 /* precompute 'cpath' so we can avoid doing the lookups lots of times */
439 for (unsigned int off=0;off<get_path_length + put_path_length;off++)
441 const struct GNUNET_PeerIdentity *pid;
443 pid = (off < get_path_length)
444 ? &get_path[get_path_length - off]
445 : &put_path[get_path_length + put_path_length - off];
446 cpath[off] = GCP_get (pid,
450 /* First figure out if this path is a subset of an existing path, an
451 extension of an existing path, or a new path. */
452 cm_ctx.cpath_length = get_path_length + put_path_length;
453 cm_ctx.cpath = cpath;
455 for (i=get_path_length + put_path_length-1;i>=0;i--)
457 GCP_iterate_paths_at (cpath[i],
461 if (NULL != cm_ctx.match)
463 if (i == get_path_length + put_path_length - 1)
465 /* Existing path includes this one, nothing to do! */
466 LOG (GNUNET_ERROR_TYPE_DEBUG,
467 "Path discovered from DHT is already known\n");
470 if (cm_ctx.match->entries_length == i + 1)
472 /* Existing path ends in the middle of new path, extend it! */
473 LOG (GNUNET_ERROR_TYPE_DEBUG,
474 "Trying to extend existing path %s by additional links discovered from DHT\n",
475 GCPP_2s (cm_ctx.match));
476 extend_path (cm_ctx.match,
478 get_path_length + put_path_length - i,
485 /* No match at all, create completely new path */
486 path = GNUNET_new (struct CadetPeerPath);
488 /* First, try to attach it */
490 for (i=get_path_length + put_path_length-1;i>=0;i--)
492 path->entries_length = i + 1;
493 /* FIXME: note that path->desirability is used, but not yet initialized here! */
494 hn = GCP_attach_path (cpath[i],
503 /* None of the peers on the path care about it. */
504 LOG (GNUNET_ERROR_TYPE_DEBUG,
505 "Path discovered from DHT is not interesting to us\n");
510 path->entries_length = i + 1;
511 path->entries = GNUNET_new_array (path->entries_length,
512 struct CadetPeerPathEntry *);
515 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
517 path->entries[i] = entry;
518 entry->peer = cpath[i];
520 GCP_path_entry_add (entry->peer,
524 LOG (GNUNET_ERROR_TYPE_DEBUG,
525 "Created new path %s based on information from DHT\n",
531 * We got an incoming connection, obtain the corresponding path.
533 * @param path_length number of segments on the @a path
534 * @param pids path through the network, in reverse order (we are at the end at index @a path_length)
535 * @return corresponding path object
537 struct CadetPeerPath *
538 GCPP_get_path_from_route (unsigned int path_length,
539 const struct GNUNET_PeerIdentity *pids)
541 struct CheckMatchContext cm_ctx;
542 struct CadetPeer *cpath[path_length];
543 struct CadetPeerPath *path;
545 /* precompute inverted 'cpath' so we can avoid doing the lookups and
546 have the correct order */
547 for (unsigned int off=0;off<path_length;off++)
548 cpath[off] = GCP_get (&pids[path_length - 1 - off],
551 /* First figure out if this path is a subset of an existing path, an
552 extension of an existing path, or a new path. */
553 cm_ctx.cpath = cpath;
554 cm_ctx.cpath_length = path_length;
556 for (int i=path_length-1;i>=0;i--)
558 GCP_iterate_paths_at (cpath[i],
562 if (NULL != cm_ctx.match)
564 if (i == path_length - 1)
566 /* Existing path includes this one, return the match! */
567 LOG (GNUNET_ERROR_TYPE_DEBUG,
568 "Returning existing path %s as inverse for incoming connection\n",
569 GCPP_2s (cm_ctx.match));
572 if (cm_ctx.match->entries_length == i + 1)
574 /* Existing path ends in the middle of new path, extend it! */
575 LOG (GNUNET_ERROR_TYPE_DEBUG,
576 "Extending existing path %s to create inverse for incoming connection\n",
577 GCPP_2s (cm_ctx.match));
578 extend_path (cm_ctx.match,
582 /* Check that extension was successful */
583 GNUNET_assert (cm_ctx.match->entries_length == path_length);
586 /* Eh, we found a match but couldn't use it? Something is wrong. */
591 /* No match at all, create completely new path */
592 path = GNUNET_new (struct CadetPeerPath);
593 path->entries_length = path_length;
594 path->entries = GNUNET_new_array (path->entries_length,
595 struct CadetPeerPathEntry *);
596 for (int i=path_length-1;i>=0;i--)
598 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
600 path->entries[i] = entry;
601 entry->peer = cpath[i];
603 GCP_path_entry_add (entry->peer,
607 LOG (GNUNET_ERROR_TYPE_DEBUG,
608 "Created new path %s to create inverse for incoming connection\n",
610 path->hn = GCP_attach_path (cpath[path_length - 1],
619 * Return the length of the path. Excludes one end of the
620 * path, so the loopback path has length 0.
622 * @param path path to return the length for
623 * @return number of peers on the path
626 GCPP_get_length (struct CadetPeerPath *path)
628 return path->entries_length;
633 * Find peer's offset on path.
635 * @param path path to search
636 * @param cp peer to look for
637 * @return offset of @a cp on @a path, or UINT_MAX if not found
640 GCPP_find_peer (struct CadetPeerPath *path,
641 struct CadetPeer *cp)
643 for (unsigned int off = 0;
644 off < path->entries_length;
646 if (cp == GCPP_get_peer_at_offset (path,
654 * Obtain the peer at offset @a off in @a path.
656 * @param path peer path to inspect
657 * @param off offset to return, must be smaller than path length
658 * @return the peer at offset @a off
661 GCPP_get_peer_at_offset (struct CadetPeerPath *path,
664 GNUNET_assert (off < path->entries_length);
665 return path->entries[off]->peer;
670 * Convert a path to a human-readable string.
672 * @param path path to convert
673 * @return string, to be freed by caller (unlike other *_2s APIs!)
676 GCPP_2s (struct CadetPeerPath *path)
678 static char buf[2048];
680 const unsigned int max_plen = (sizeof(buf) - 16) / 5 - 2; /* 5 characters per entry */
683 for (unsigned int i = 0;
684 i < path->entries_length;
687 if ( (path->entries_length > max_plen) &&
688 (i == max_plen / 2) )
689 off += GNUNET_snprintf (&buf[off],
692 if ( (path->entries_length > max_plen) &&
693 (i > max_plen / 2) &&
694 (i < path->entries_length - max_plen / 2) )
696 off += GNUNET_snprintf (&buf[off],
699 GNUNET_i2s (GCP_get_id (GCPP_get_peer_at_offset (path,
701 (i == path->entries_length -1) ? "" : "-");
703 GNUNET_snprintf (&buf[off],
711 /* end of gnunet-service-cadet-new_paths.c */