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21 * @file cadet/gnunet-service-cadet_paths.c
22 * @brief Information we track per path.
23 * @author Bartlomiej Polot
24 * @author Christian Grothoff
27 #include "gnunet-service-cadet_connection.h"
28 #include "gnunet-service-cadet_tunnels.h"
29 #include "gnunet-service-cadet_peer.h"
30 #include "gnunet-service-cadet_paths.h"
33 #define LOG(level, ...) GNUNET_log_from(level,"cadet-pat",__VA_ARGS__)
37 * Information regarding a possible path to reach a peer.
43 * Array of all the peers on the path. If @e hn is non-NULL, the
44 * last one is our owner.
46 struct CadetPeerPathEntry **entries;
49 * Node of this path in the owner's heap. Used to update our position
50 * in the heap whenever our @e desirability changes.
52 struct GNUNET_CONTAINER_HeapNode *hn;
55 * Desirability of the path. How unique is it for the various peers
58 GNUNET_CONTAINER_HeapCostType desirability;
61 * Length of the @e entries array.
63 unsigned int entries_length;
69 * Calculate the path's desirability score.
71 * @param path path to calculate the score for
74 recalculate_path_desirability (struct CadetPeerPath *path)
78 for (unsigned int i=0;i<path->entries_length;i++)
80 struct CadetPeer *cp = path->entries[i]->peer;
82 result += GCP_get_desirability_of_path (cp,
85 path->desirability = (GNUNET_CONTAINER_HeapCostType) result;
90 * Return how much we like keeping the path. This is an aggregate
91 * score based on various factors, including the age of the path
92 * (older == better), and the value of this path to all of its ajacent
93 * peers. For example, long paths that end at a peer that we have no
94 * shorter way to reach are very desirable, while long paths that end
95 * at a peer for which we have a shorter way as well are much less
96 * desirable. Higher values indicate more valuable paths. The
97 * returned value should be used to decide which paths to remember.
99 * @param path path to return the length for
100 * @return desirability of the path, larger is more desirable
102 GNUNET_CONTAINER_HeapCostType
103 GCPP_get_desirability (const struct CadetPeerPath *path)
105 return path->desirability;
110 * Return connection to @a destination using @a path, or return
111 * NULL if no such connection exists.
113 * @param path path to traverse
114 * @param destination destination node to get to, must be on path
115 * @param off offset of @a destination on @a path
116 * @return NULL if we have no existing connection
117 * otherwise connection from us to @a destination via @a path
119 struct CadetConnection *
120 GCPP_get_connection (struct CadetPeerPath *path,
121 struct CadetPeer *destination,
124 struct CadetPeerPathEntry *entry;
126 GNUNET_assert (off < path->entries_length);
127 entry = path->entries[off];
128 GNUNET_assert (entry->peer == destination);
134 * Notify @a path that it is used for connection @a cc
135 * which ends at the path's offset @a off.
137 * @param path the path to remember the @a cc
138 * @param off the offset where the @a cc ends
139 * @param cc the connection to remember
142 GCPP_add_connection (struct CadetPeerPath *path,
144 struct CadetConnection *cc)
146 struct CadetPeerPathEntry *entry;
148 LOG (GNUNET_ERROR_TYPE_DEBUG,
149 "Adding connection %s to path %s at offset %u\n",
153 GNUNET_assert (off < path->entries_length);
154 entry = path->entries[off];
155 GNUNET_assert (NULL == entry->cc);
156 GNUNET_assert (NULL != cc);
163 * Notify @a path that it is no longer used for connection @a cc which
164 * ended at the path's offset @a off.
166 * @param path the path to forget the @a cc
167 * @param off the offset where the @a cc ended
168 * @param cc the connection to forget
171 GCPP_del_connection (struct CadetPeerPath *path,
173 struct CadetConnection *cc)
175 struct CadetPeerPathEntry *entry;
177 LOG (GNUNET_ERROR_TYPE_DEBUG,
178 "Removing connection %s to path %s at offset %u\n",
182 GNUNET_assert (off < path->entries_length);
183 entry = path->entries[off];
184 GNUNET_assert (cc == entry->cc);
190 * This path is no longer needed, free resources.
192 * @param path path resources to free
195 path_destroy (struct CadetPeerPath *path)
197 LOG (GNUNET_ERROR_TYPE_DEBUG,
198 "Destroying path %s\n",
200 for (unsigned int i=0;i<path->entries_length;i++)
202 struct CadetPeerPathEntry *entry = path->entries[i];
204 if (NULL != entry->cc)
206 struct CadetTConnection *ct;
208 ct = GCC_get_ct (entry->cc);
210 GCT_connection_lost (ct);
211 GCC_destroy_without_tunnel (entry->cc);
215 GNUNET_free (path->entries);
221 * The owning peer of this path is no longer interested in maintaining
222 * it, so the path should be discarded or shortened (in case a
223 * previous peer on the path finds the path desirable).
225 * @param path the path that is being released
228 GCPP_release (struct CadetPeerPath *path)
230 struct CadetPeerPathEntry *entry;
233 LOG (GNUNET_ERROR_TYPE_DEBUG,
234 "Owner releases path %s\n",
237 entry = path->entries[path->entries_length - 1];
238 GNUNET_assert (path == entry->path);
241 /* cut 'off' end of path */
242 GNUNET_assert (NULL == entry->cc);
243 GCP_path_entry_remove (entry->peer,
245 path->entries_length - 1);
246 path->entries_length--; /* We don't bother shrinking the 'entries' array,
247 as it's probably not worth it. */
249 if (0 == path->entries_length)
252 /* see if new peer at the end likes this path any better */
253 entry = path->entries[path->entries_length - 1];
254 GNUNET_assert (path == entry->path);
255 force = (NULL == entry->cc) ? GNUNET_NO : GNUNET_YES;
256 path->hn = GCP_attach_path (entry->peer,
258 path->entries_length - 1,
260 if (NULL != path->hn)
261 return; /* yep, got attached, we are done. */
262 GNUNET_assert (GNUNET_NO == force);
265 /* nobody wants us, discard the path */
271 * Updates the score for an entry on the path based
272 * on our experiences with using @a path.
274 * @param path the path to update
275 * @param off offset of the entry to update
276 * @param delta change in the score to apply
279 GCPP_update_score (struct CadetPeerPath *path,
283 struct CadetPeerPathEntry *entry;
285 GNUNET_assert (off < path->entries_length);
286 entry = path->entries[off];
288 /* Add delta, with checks for overflows */
291 if (delta + entry->score < entry->score)
292 entry->score = INT_MAX;
294 entry->score += delta;
298 if (delta + entry->score > entry->score)
299 entry->score = INT_MIN;
301 entry->score += delta;
303 recalculate_path_desirability (path);
308 * Closure for #find_peer_at() and #check_match().
310 struct CheckMatchContext
314 * Set to a matching path, if any.
316 struct CadetPeerPath *match;
319 * Array the combined paths.
321 struct CadetPeer **cpath;
324 * How long is the @e cpath array?
326 unsigned int cpath_length;
332 * Check if the given path is identical on all of the
333 * hops until @a off, and not longer than @a off. If the
334 * @a path matches, store it in `match`.
336 * @param cls the `struct CheckMatchContext` to check against
337 * @param path the path to check
338 * @param off offset to check at
339 * @return #GNUNET_YES (continue to iterate), or if found #GNUNET_NO
342 check_match (void *cls,
343 struct CadetPeerPath *path,
346 struct CheckMatchContext *cm_ctx = cls;
348 GNUNET_assert (path->entries_length > off);
349 if ( (path->entries_length != off + 1) &&
350 (off + 1 != cm_ctx->cpath_length) )
352 LOG (GNUNET_ERROR_TYPE_DEBUG,
353 "check_match missmatch because path %s is too long (%u vs. %u vs. %u)\n",
355 path->entries_length,
357 cm_ctx->cpath_length);
358 return GNUNET_YES; /* too long, goes somewhere else already, thus cannot be useful */
360 for (unsigned int i=0;i<off;i++)
361 if (cm_ctx->cpath[i] !=
362 GCPP_get_peer_at_offset (path,
365 LOG (GNUNET_ERROR_TYPE_DEBUG,
366 "check_match path %s missmatches at offset %u\n",
369 return GNUNET_YES; /* missmatch, ignore */
371 LOG (GNUNET_ERROR_TYPE_DEBUG,
372 "check_match found match with path %s\n",
374 cm_ctx->match = path;
375 return GNUNET_NO; /* match, we are done! */
380 * Extend path @a path by the @a num_peers from the @a peers
381 * array, assuming the owners past the current owner want it.
383 * @param path path to extend
384 * @param peers list of peers beyond the end of @a path
385 * @param num_peers length of the @a peers array
386 * @param force force attachment, even if we have other
390 extend_path (struct CadetPeerPath *path,
391 struct CadetPeer **peers,
392 unsigned int num_peers,
395 unsigned int old_len = path->entries_length;
399 GNUNET_array_grow (path->entries,
400 path->entries_length,
401 old_len + num_peers);
402 for (i=num_peers-1;i >= 0;i--)
404 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
406 path->entries[old_len + i] = entry;
407 entry->peer = peers[i];
410 for (i=num_peers-1;i >= 0;i--)
412 struct CadetPeerPathEntry *entry = path->entries[old_len + i];
414 GCP_path_entry_add (entry->peer,
419 /* If we extend an existing path, detach it from the
420 old owner and re-attach to the new one */
421 GCP_detach_path (path->entries[old_len-1]->peer,
425 for (i=num_peers-1;i>=0;i--)
427 struct CadetPeerPathEntry *entry = path->entries[old_len + i];
429 path->entries_length = old_len + i + 1;
430 recalculate_path_desirability (path);
431 path->hn = GCP_attach_path (peers[i],
433 old_len + (unsigned int) i,
435 if (NULL != path->hn)
437 GNUNET_assert (NULL == entry->cc);
438 GCP_path_entry_remove (entry->peer,
442 path->entries[old_len + i] = NULL;
444 if (NULL == path->hn)
446 /* none of the peers is interested in this path;
447 shrink path back and re-attach. */
448 GNUNET_array_grow (path->entries,
449 path->entries_length,
451 path->hn = GCP_attach_path (path->entries[old_len - 1]->peer,
455 GNUNET_assert (NULL != path->hn);
458 LOG (GNUNET_ERROR_TYPE_DEBUG,
459 "Extended path %s\n",
465 * Create a peer path based on the result of a DHT lookup. If we
466 * already know this path, or one that is longer, simply return NULL.
467 * Otherwise, we try to extend an existing path, or create a new one
470 * @param get_path path of the get request
471 * @param get_path_length lenght of @a get_path
472 * @param put_path path of the put request
473 * @param put_path_length length of the @a put_path
474 * @return a path through the network
477 GCPP_try_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
478 unsigned int get_path_length,
479 const struct GNUNET_PeerIdentity *put_path,
480 unsigned int put_path_length)
482 struct CadetPeer *cpath[get_path_length + put_path_length];
483 struct CheckMatchContext cm_ctx;
484 struct CadetPeerPath *path;
485 struct GNUNET_CONTAINER_HeapNode *hn;
488 unsigned int total_len;
490 /* precompute 'cpath' so we can avoid doing the lookups lots of times */
494 sizeof (cpath)); /* Just to trigger harder errors later. */
495 total_len = get_path_length + put_path_length;
496 for (unsigned int off=0;off<total_len;off++)
498 const struct GNUNET_PeerIdentity *pid;
500 pid = (off < get_path_length)
501 ? &get_path[get_path_length - off]
502 : &put_path[get_path_length + put_path_length - off];
503 cpath[off - skip] = GCP_get (pid,
505 /* Check that no peer is twice on the path */
506 for (unsigned int i=0;i<off - skip;i++)
508 if (cpath[i] == cpath[off - skip])
517 /* First figure out if this path is a subset of an existing path, an
518 extension of an existing path, or a new path. */
519 cm_ctx.cpath_length = total_len;
520 cm_ctx.cpath = cpath;
522 for (i=total_len-1;i>=0;i--)
524 GCP_iterate_paths_at (cpath[i],
528 if (NULL != cm_ctx.match)
530 if (i == total_len - 1)
532 /* Existing path includes this one, nothing to do! */
533 LOG (GNUNET_ERROR_TYPE_DEBUG,
534 "Path discovered from DHT is already known\n");
537 if (cm_ctx.match->entries_length == i + 1)
539 /* Existing path ends in the middle of new path, extend it! */
540 LOG (GNUNET_ERROR_TYPE_DEBUG,
541 "Trying to extend existing path %s by additional links discovered from DHT\n",
542 GCPP_2s (cm_ctx.match));
543 extend_path (cm_ctx.match,
552 /* No match at all, create completely new path */
553 path = GNUNET_new (struct CadetPeerPath);
554 path->entries_length = total_len;
555 path->entries = GNUNET_new_array (path->entries_length,
556 struct CadetPeerPathEntry *);
557 for (i=path->entries_length-1;i>=0;i--)
559 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
561 path->entries[i] = entry;
562 entry->peer = cpath[i];
565 for (i=path->entries_length-1;i>=0;i--)
567 struct CadetPeerPathEntry *entry = path->entries[i];
569 GCP_path_entry_add (entry->peer,
574 /* Finally, try to attach it */
576 for (i=total_len-1;i>=0;i--)
578 struct CadetPeerPathEntry *entry = path->entries[i];
580 path->entries_length = i + 1;
581 recalculate_path_desirability (path);
582 hn = GCP_attach_path (cpath[i],
588 GCP_path_entry_remove (entry->peer,
592 path->entries[i] = NULL;
596 /* None of the peers on the path care about it. */
597 LOG (GNUNET_ERROR_TYPE_DEBUG,
598 "Path discovered from DHT is not interesting to us\n");
599 GNUNET_free (path->entries);
604 /* Shrink path to actual useful length */
605 GNUNET_array_grow (path->entries,
606 path->entries_length,
608 LOG (GNUNET_ERROR_TYPE_DEBUG,
609 "Created new path %s based on information from DHT\n",
615 * We got an incoming connection, obtain the corresponding path.
617 * @param path_length number of segments on the @a path
618 * @param pids path through the network, in reverse order (we are at the end at index @a path_length)
619 * @return corresponding path object
621 struct CadetPeerPath *
622 GCPP_get_path_from_route (unsigned int path_length,
623 const struct GNUNET_PeerIdentity *pids)
625 struct CheckMatchContext cm_ctx;
626 struct CadetPeer *cpath[path_length];
627 struct CadetPeerPath *path;
629 /* precompute inverted 'cpath' so we can avoid doing the lookups and
630 have the correct order */
631 for (unsigned int off=0;off<path_length;off++)
632 cpath[off] = GCP_get (&pids[path_length - 1 - off],
635 /* First figure out if this path is a subset of an existing path, an
636 extension of an existing path, or a new path. */
637 cm_ctx.cpath = cpath;
638 cm_ctx.cpath_length = path_length;
640 for (int i=path_length-1;i>=0;i--)
642 GCP_iterate_paths_at (cpath[i],
646 if (NULL != cm_ctx.match)
648 if (i == path_length - 1)
650 /* Existing path includes this one, return the match! */
651 LOG (GNUNET_ERROR_TYPE_DEBUG,
652 "Returning existing path %s as inverse for incoming connection\n",
653 GCPP_2s (cm_ctx.match));
656 if (cm_ctx.match->entries_length == i + 1)
658 /* Existing path ends in the middle of new path, extend it! */
659 LOG (GNUNET_ERROR_TYPE_DEBUG,
660 "Extending existing path %s to create inverse for incoming connection\n",
661 GCPP_2s (cm_ctx.match));
662 extend_path (cm_ctx.match,
666 /* Check that extension was successful */
667 GNUNET_assert (cm_ctx.match->entries_length == path_length);
670 /* Eh, we found a match but couldn't use it? Something is wrong. */
675 /* No match at all, create completely new path */
676 path = GNUNET_new (struct CadetPeerPath);
677 path->entries_length = path_length;
678 path->entries = GNUNET_new_array (path->entries_length,
679 struct CadetPeerPathEntry *);
680 for (int i=path_length-1;i>=0;i--)
682 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
684 path->entries[i] = entry;
685 entry->peer = cpath[i];
688 for (int i=path_length-1;i>=0;i--)
690 struct CadetPeerPathEntry *entry = path->entries[i];
692 GCP_path_entry_add (entry->peer,
696 recalculate_path_desirability (path);
697 LOG (GNUNET_ERROR_TYPE_DEBUG,
698 "Created new path %s to create inverse for incoming connection\n",
700 path->hn = GCP_attach_path (cpath[path_length - 1],
709 * Return the length of the path. Excludes one end of the
710 * path, so the loopback path has length 0.
712 * @param path path to return the length for
713 * @return number of peers on the path
716 GCPP_get_length (struct CadetPeerPath *path)
718 return path->entries_length;
723 * Find peer's offset on path.
725 * @param path path to search
726 * @param cp peer to look for
727 * @return offset of @a cp on @a path, or UINT_MAX if not found
730 GCPP_find_peer (struct CadetPeerPath *path,
731 struct CadetPeer *cp)
733 for (unsigned int off = 0;
734 off < path->entries_length;
736 if (cp == GCPP_get_peer_at_offset (path,
744 * Obtain the peer at offset @a off in @a path.
746 * @param path peer path to inspect
747 * @param off offset to return, must be smaller than path length
748 * @return the peer at offset @a off
751 GCPP_get_peer_at_offset (struct CadetPeerPath *path,
754 GNUNET_assert (off < path->entries_length);
755 return path->entries[off]->peer;
760 * Convert a path to a human-readable string.
762 * @param path path to convert
763 * @return string, to be freed by caller (unlike other *_2s APIs!)
766 GCPP_2s (struct CadetPeerPath *path)
768 static char buf[2048];
770 const unsigned int max_plen = (sizeof(buf) - 16) / 5 - 2; /* 5 characters per entry */
773 for (unsigned int i = 0;
774 i < path->entries_length;
777 if ( (path->entries_length > max_plen) &&
778 (i == max_plen / 2) )
779 off += GNUNET_snprintf (&buf[off],
782 if ( (path->entries_length > max_plen) &&
783 (i > max_plen / 2) &&
784 (i < path->entries_length - max_plen / 2) )
786 off += GNUNET_snprintf (&buf[off],
789 GNUNET_i2s (GCP_get_id (GCPP_get_peer_at_offset (path,
791 (i == path->entries_length -1) ? "" : "-");
793 GNUNET_snprintf (&buf[off],
801 /* end of gnunet-service-cadet-new_paths.c */