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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
30 #include "gnunet-service-cadet-new_connection.h"
31 #include "gnunet-service-cadet-new_tunnels.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 * Desirability of the path. How unique is it for the various peers
61 GNUNET_CONTAINER_HeapCostType desirability;
64 * Length of the @e entries array.
66 unsigned int entries_length;
72 * Calculate the path's desirability score.
74 * @param path path to calculate the score for
77 recalculate_path_desirability (struct CadetPeerPath *path)
81 for (unsigned int i=0;i<path->entries_length;i++)
83 struct CadetPeer *cp = path->entries[i]->peer;
85 result += GCP_get_desirability_of_path (cp,
88 path->desirability = (GNUNET_CONTAINER_HeapCostType) result;
93 * Return how much we like keeping the path. This is an aggregate
94 * score based on various factors, including the age of the path
95 * (older == better), and the value of this path to all of its ajacent
96 * peers. For example, long paths that end at a peer that we have no
97 * shorter way to reach are very desirable, while long paths that end
98 * at a peer for which we have a shorter way as well are much less
99 * desirable. Higher values indicate more valuable paths. The
100 * returned value should be used to decide which paths to remember.
102 * @param path path to return the length for
103 * @return desirability of the path, larger is more desirable
105 GNUNET_CONTAINER_HeapCostType
106 GCPP_get_desirability (const struct CadetPeerPath *path)
108 return path->desirability;
113 * Return connection to @a destination using @a path, or return
114 * NULL if no such connection exists.
116 * @param path path to traverse
117 * @param destination destination node to get to, must be on path
118 * @param off offset of @a destination on @a path
119 * @return NULL if we have no existing connection
120 * otherwise connection from us to @a destination via @a path
122 struct CadetConnection *
123 GCPP_get_connection (struct CadetPeerPath *path,
124 struct CadetPeer *destination,
127 struct CadetPeerPathEntry *entry;
129 GNUNET_assert (off < path->entries_length);
130 entry = path->entries[off];
131 GNUNET_assert (entry->peer == destination);
137 * Notify @a path that it is used for connection @a cc
138 * which ends at the path's offset @a off.
140 * @param path the path to remember the @a cc
141 * @param off the offset where the @a cc ends
142 * @param cc the connection to remember
145 GCPP_add_connection (struct CadetPeerPath *path,
147 struct CadetConnection *cc)
149 struct CadetPeerPathEntry *entry;
151 LOG (GNUNET_ERROR_TYPE_DEBUG,
152 "Adding connection %s to path %s at offset %u\n",
156 GNUNET_assert (off < path->entries_length);
157 entry = path->entries[off];
158 GNUNET_assert (NULL == entry->cc);
165 * Notify @a path that it is no longer used for connection @a cc which
166 * ended at the path's offset @a off.
168 * @param path the path to forget the @a cc
169 * @param off the offset where the @a cc ended
170 * @param cc the connection to forget
173 GCPP_del_connection (struct CadetPeerPath *path,
175 struct CadetConnection *cc)
177 struct CadetPeerPathEntry *entry;
179 LOG (GNUNET_ERROR_TYPE_DEBUG,
180 "Removing connection %s to path %s at offset %u\n",
184 GNUNET_assert (off < path->entries_length);
185 entry = path->entries[off];
186 GNUNET_assert (cc == entry->cc);
192 * This path is no longer needed, free resources.
194 * @param path path resources to free
197 path_destroy (struct CadetPeerPath *path)
199 LOG (GNUNET_ERROR_TYPE_DEBUG,
200 "Destroying path %s\n",
202 for (unsigned int i=0;i<path->entries_length;i++)
204 struct CadetPeerPathEntry *entry = path->entries[i];
206 if (NULL != entry->cc)
208 struct CadetTConnection *ct;
210 ct = GCC_get_ct (entry->cc);
212 GCT_connection_lost (ct);
213 GCC_destroy_without_tunnel (entry->cc);
217 GNUNET_free (path->entries);
223 * The owning peer of this path is no longer interested in maintaining
224 * it, so the path should be discarded or shortened (in case a
225 * previous peer on the path finds the path desirable).
227 * @param path the path that is being released
230 GCPP_release (struct CadetPeerPath *path)
232 struct CadetPeerPathEntry *entry;
234 LOG (GNUNET_ERROR_TYPE_DEBUG,
235 "Owner releases path %s\n",
238 entry = path->entries[path->entries_length - 1];
241 /* cut 'off' end of path */
242 GCP_path_entry_remove (entry->peer,
244 path->entries_length - 1);
245 path->entries_length--; /* We don't bother shrinking the 'entries' array,
246 as it's probably not worth it. */
248 if (0 == path->entries_length)
251 /* see if new peer at the end likes this path any better */
252 entry = path->entries[path->entries_length - 1];
253 path->hn = GCP_attach_path (entry->peer,
255 path->entries_length - 1,
257 if (NULL != path->hn)
258 return; /* yep, got attached, we are done. */
261 /* nobody wants us, discard the path */
267 * Updates the score for an entry on the path based
268 * on our experiences with using @a path.
270 * @param path the path to update
271 * @param off offset of the entry to update
272 * @param delta change in the score to apply
275 GCPP_update_score (struct CadetPeerPath *path,
279 struct CadetPeerPathEntry *entry;
281 GNUNET_assert (off < path->entries_length);
282 entry = path->entries[off];
284 /* Add delta, with checks for overflows */
287 if (delta + entry->score < entry->score)
288 entry->score = INT_MAX;
290 entry->score += delta;
294 if (delta + entry->score > entry->score)
295 entry->score = INT_MIN;
297 entry->score += delta;
299 recalculate_path_desirability (path);
304 * Closure for #find_peer_at() and #check_match().
306 struct CheckMatchContext
310 * Set to a matching path, if any.
312 struct CadetPeerPath *match;
315 * Array the combined paths.
317 struct CadetPeer **cpath;
320 * How long is the @e cpath array?
322 unsigned int cpath_length;
328 * Check if the given path is identical on all of the
329 * hops until @a off, and not longer than @a off. If the
330 * @a path matches, store it in `match`.
332 * @param cls the `struct CheckMatchContext` to check against
333 * @param path the path to check
334 * @param off offset to check at
335 * @return #GNUNET_YES (continue to iterate), or if found #GNUNET_NO
338 check_match (void *cls,
339 struct CadetPeerPath *path,
342 struct CheckMatchContext *cm_ctx = cls;
344 GNUNET_assert (path->entries_length > off);
345 if ( (path->entries_length != off + 1) &&
346 (off + 1 != cm_ctx->cpath_length) )
348 LOG (GNUNET_ERROR_TYPE_DEBUG,
349 "check_match missmatch because path %s is too long (%u vs. %u vs. %u)\n",
351 path->entries_length,
353 cm_ctx->cpath_length);
354 return GNUNET_YES; /* too long, goes somewhere else already, thus cannot be useful */
356 for (unsigned int i=0;i<off;i++)
357 if (cm_ctx->cpath[i] !=
358 GCPP_get_peer_at_offset (path,
361 LOG (GNUNET_ERROR_TYPE_DEBUG,
362 "check_match path %s missmatches at offset %u\n",
365 return GNUNET_YES; /* missmatch, ignore */
367 LOG (GNUNET_ERROR_TYPE_DEBUG,
368 "check_match found match with path %s\n",
370 cm_ctx->match = path;
371 return GNUNET_NO; /* match, we are done! */
376 * Extend path @a path by the @a num_peers from the @a peers
377 * array, assuming the owners past the current owner want it.
379 * @param path path to extend
380 * @param peers list of peers beyond the end of @a path
381 * @param num_peers length of the @a peers array
382 * @param force force attachment, even if we have other
386 extend_path (struct CadetPeerPath *path,
387 struct CadetPeer **peers,
388 unsigned int num_peers,
391 unsigned int old_len = path->entries_length;
392 struct GNUNET_CONTAINER_HeapNode *hn;
396 GNUNET_array_grow (path->entries,
397 path->entries_length,
398 old_len + num_peers);
399 for (i=num_peers-1;i >= 0;i--)
401 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
403 path->entries[old_len + i] = entry;
404 entry->peer = peers[i];
407 for (i=num_peers-1;i >= 0;i--)
409 struct CadetPeerPathEntry *entry = path->entries[old_len + i];
411 GCP_path_entry_add (entry->peer,
416 /* If we extend an existing path, detach it from the
417 old owner and re-attach to the new one */
419 for (i=num_peers-1;i>=0;i--)
421 struct CadetPeerPathEntry *entry = path->entries[old_len + i];
423 path->entries_length = old_len + i + 1;
424 recalculate_path_desirability (path);
425 hn = GCP_attach_path (peers[i],
427 old_len + (unsigned int) i,
431 GCP_path_entry_remove (entry->peer,
435 path->entries[old_len + i] = NULL;
439 /* none of the peers is interested in this path;
441 GNUNET_array_grow (path->entries,
442 path->entries_length,
446 GCP_detach_path (path->entries[old_len-1]->peer,
450 LOG (GNUNET_ERROR_TYPE_DEBUG,
451 "Extended path %s\n",
457 * Create a peer path based on the result of a DHT lookup. If we
458 * already know this path, or one that is longer, simply return NULL.
459 * Otherwise, we try to extend an existing path, or create a new one
462 * @param get_path path of the get request
463 * @param get_path_length lenght of @a get_path
464 * @param put_path path of the put request
465 * @param put_path_length length of the @a put_path
466 * @return a path through the network
469 GCPP_try_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
470 unsigned int get_path_length,
471 const struct GNUNET_PeerIdentity *put_path,
472 unsigned int put_path_length)
474 struct CadetPeer *cpath[get_path_length + put_path_length];
475 struct CheckMatchContext cm_ctx;
476 struct CadetPeerPath *path;
477 struct GNUNET_CONTAINER_HeapNode *hn;
480 unsigned int total_len;
482 /* precompute 'cpath' so we can avoid doing the lookups lots of times */
484 total_len = get_path_length + put_path_length;
485 for (unsigned int off=0;off<total_len;off++)
487 const struct GNUNET_PeerIdentity *pid;
489 pid = (off < get_path_length)
490 ? &get_path[get_path_length - off]
491 : &put_path[get_path_length + put_path_length - off];
492 cpath[off - skip] = GCP_get (pid,
494 /* Check that no peer is twice on the path */
495 for (unsigned int i=0;i<off;i++)
497 if (cpath[i] == cpath[off])
506 /* First figure out if this path is a subset of an existing path, an
507 extension of an existing path, or a new path. */
508 cm_ctx.cpath_length = total_len;
509 cm_ctx.cpath = cpath;
511 for (i=total_len-1;i>=0;i--)
513 GCP_iterate_paths_at (cpath[i],
517 if (NULL != cm_ctx.match)
519 if (i == total_len - 1)
521 /* Existing path includes this one, nothing to do! */
522 LOG (GNUNET_ERROR_TYPE_DEBUG,
523 "Path discovered from DHT is already known\n");
526 if (cm_ctx.match->entries_length == i + 1)
528 /* Existing path ends in the middle of new path, extend it! */
529 LOG (GNUNET_ERROR_TYPE_DEBUG,
530 "Trying to extend existing path %s by additional links discovered from DHT\n",
531 GCPP_2s (cm_ctx.match));
532 extend_path (cm_ctx.match,
541 /* No match at all, create completely new path */
542 path = GNUNET_new (struct CadetPeerPath);
543 path->entries_length = total_len;
544 path->entries = GNUNET_new_array (path->entries_length,
545 struct CadetPeerPathEntry *);
546 for (i=path->entries_length-1;i>=0;i--)
548 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
550 path->entries[i] = entry;
551 entry->peer = cpath[i];
554 for (i=path->entries_length-1;i>=0;i--)
556 struct CadetPeerPathEntry *entry = path->entries[i];
558 GCP_path_entry_add (entry->peer,
563 /* Finally, try to attach it */
565 for (i=total_len-1;i>=0;i--)
567 struct CadetPeerPathEntry *entry = path->entries[i];
569 path->entries_length = i + 1;
570 recalculate_path_desirability (path);
571 hn = GCP_attach_path (cpath[i],
577 GCP_path_entry_remove (entry->peer,
581 path->entries[i] = NULL;
585 /* None of the peers on the path care about it. */
586 LOG (GNUNET_ERROR_TYPE_DEBUG,
587 "Path discovered from DHT is not interesting to us\n");
588 GNUNET_free (path->entries);
593 /* Shrink path to actual useful length */
594 GNUNET_array_grow (path->entries,
595 path->entries_length,
597 LOG (GNUNET_ERROR_TYPE_DEBUG,
598 "Created new path %s based on information from DHT\n",
604 * We got an incoming connection, obtain the corresponding path.
606 * @param path_length number of segments on the @a path
607 * @param pids path through the network, in reverse order (we are at the end at index @a path_length)
608 * @return corresponding path object
610 struct CadetPeerPath *
611 GCPP_get_path_from_route (unsigned int path_length,
612 const struct GNUNET_PeerIdentity *pids)
614 struct CheckMatchContext cm_ctx;
615 struct CadetPeer *cpath[path_length];
616 struct CadetPeerPath *path;
618 /* precompute inverted 'cpath' so we can avoid doing the lookups and
619 have the correct order */
620 for (unsigned int off=0;off<path_length;off++)
621 cpath[off] = GCP_get (&pids[path_length - 1 - off],
624 /* First figure out if this path is a subset of an existing path, an
625 extension of an existing path, or a new path. */
626 cm_ctx.cpath = cpath;
627 cm_ctx.cpath_length = path_length;
629 for (int i=path_length-1;i>=0;i--)
631 GCP_iterate_paths_at (cpath[i],
635 if (NULL != cm_ctx.match)
637 if (i == path_length - 1)
639 /* Existing path includes this one, return the match! */
640 LOG (GNUNET_ERROR_TYPE_DEBUG,
641 "Returning existing path %s as inverse for incoming connection\n",
642 GCPP_2s (cm_ctx.match));
645 if (cm_ctx.match->entries_length == i + 1)
647 /* Existing path ends in the middle of new path, extend it! */
648 LOG (GNUNET_ERROR_TYPE_DEBUG,
649 "Extending existing path %s to create inverse for incoming connection\n",
650 GCPP_2s (cm_ctx.match));
651 extend_path (cm_ctx.match,
655 /* Check that extension was successful */
656 GNUNET_assert (cm_ctx.match->entries_length == path_length);
659 /* Eh, we found a match but couldn't use it? Something is wrong. */
664 /* No match at all, create completely new path */
665 path = GNUNET_new (struct CadetPeerPath);
666 path->entries_length = path_length;
667 path->entries = GNUNET_new_array (path->entries_length,
668 struct CadetPeerPathEntry *);
669 for (int i=path_length-1;i>=0;i--)
671 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
673 path->entries[i] = entry;
674 entry->peer = cpath[i];
677 for (int i=path_length-1;i>=0;i--)
679 struct CadetPeerPathEntry *entry = path->entries[i];
681 GCP_path_entry_add (entry->peer,
685 recalculate_path_desirability (path);
686 LOG (GNUNET_ERROR_TYPE_DEBUG,
687 "Created new path %s to create inverse for incoming connection\n",
689 path->hn = GCP_attach_path (cpath[path_length - 1],
698 * Return the length of the path. Excludes one end of the
699 * path, so the loopback path has length 0.
701 * @param path path to return the length for
702 * @return number of peers on the path
705 GCPP_get_length (struct CadetPeerPath *path)
707 return path->entries_length;
712 * Find peer's offset on path.
714 * @param path path to search
715 * @param cp peer to look for
716 * @return offset of @a cp on @a path, or UINT_MAX if not found
719 GCPP_find_peer (struct CadetPeerPath *path,
720 struct CadetPeer *cp)
722 for (unsigned int off = 0;
723 off < path->entries_length;
725 if (cp == GCPP_get_peer_at_offset (path,
733 * Obtain the peer at offset @a off in @a path.
735 * @param path peer path to inspect
736 * @param off offset to return, must be smaller than path length
737 * @return the peer at offset @a off
740 GCPP_get_peer_at_offset (struct CadetPeerPath *path,
743 GNUNET_assert (off < path->entries_length);
744 return path->entries[off]->peer;
749 * Convert a path to a human-readable string.
751 * @param path path to convert
752 * @return string, to be freed by caller (unlike other *_2s APIs!)
755 GCPP_2s (struct CadetPeerPath *path)
757 static char buf[2048];
759 const unsigned int max_plen = (sizeof(buf) - 16) / 5 - 2; /* 5 characters per entry */
762 for (unsigned int i = 0;
763 i < path->entries_length;
766 if ( (path->entries_length > max_plen) &&
767 (i == max_plen / 2) )
768 off += GNUNET_snprintf (&buf[off],
771 if ( (path->entries_length > max_plen) &&
772 (i > max_plen / 2) &&
773 (i < path->entries_length - max_plen / 2) )
775 off += GNUNET_snprintf (&buf[off],
778 GNUNET_i2s (GCP_get_id (GCPP_get_peer_at_offset (path,
780 (i == path->entries_length -1) ? "" : "-");
782 GNUNET_snprintf (&buf[off],
790 /* end of gnunet-service-cadet-new_paths.c */