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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 #include "gnunet-service-cadet-new_connection.h"
28 #include "gnunet-service-cadet-new_tunnels.h"
29 #include "gnunet-service-cadet-new_peer.h"
30 #include "gnunet-service-cadet-new_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);
162 * Notify @a path that it is no longer used for connection @a cc which
163 * ended at the path's offset @a off.
165 * @param path the path to forget the @a cc
166 * @param off the offset where the @a cc ended
167 * @param cc the connection to forget
170 GCPP_del_connection (struct CadetPeerPath *path,
172 struct CadetConnection *cc)
174 struct CadetPeerPathEntry *entry;
176 LOG (GNUNET_ERROR_TYPE_DEBUG,
177 "Removing connection %s to path %s at offset %u\n",
181 GNUNET_assert (off < path->entries_length);
182 entry = path->entries[off];
183 GNUNET_assert (cc == entry->cc);
189 * This path is no longer needed, free resources.
191 * @param path path resources to free
194 path_destroy (struct CadetPeerPath *path)
196 LOG (GNUNET_ERROR_TYPE_DEBUG,
197 "Destroying path %s\n",
199 for (unsigned int i=0;i<path->entries_length;i++)
201 struct CadetPeerPathEntry *entry = path->entries[i];
203 if (NULL != entry->cc)
205 struct CadetTConnection *ct;
207 ct = GCC_get_ct (entry->cc);
209 GCT_connection_lost (ct);
210 GCC_destroy_without_tunnel (entry->cc);
214 GNUNET_free (path->entries);
220 * The owning peer of this path is no longer interested in maintaining
221 * it, so the path should be discarded or shortened (in case a
222 * previous peer on the path finds the path desirable).
224 * @param path the path that is being released
227 GCPP_release (struct CadetPeerPath *path)
229 struct CadetPeerPathEntry *entry;
231 LOG (GNUNET_ERROR_TYPE_DEBUG,
232 "Owner releases path %s\n",
235 entry = path->entries[path->entries_length - 1];
238 /* cut 'off' end of path */
239 GCP_path_entry_remove (entry->peer,
241 path->entries_length - 1);
242 path->entries_length--; /* We don't bother shrinking the 'entries' array,
243 as it's probably not worth it. */
245 if (0 == path->entries_length)
248 /* see if new peer at the end likes this path any better */
249 entry = path->entries[path->entries_length - 1];
250 path->hn = GCP_attach_path (entry->peer,
252 path->entries_length - 1,
254 if (NULL != path->hn)
255 return; /* yep, got attached, we are done. */
258 /* nobody wants us, discard the path */
264 * Updates the score for an entry on the path based
265 * on our experiences with using @a path.
267 * @param path the path to update
268 * @param off offset of the entry to update
269 * @param delta change in the score to apply
272 GCPP_update_score (struct CadetPeerPath *path,
276 struct CadetPeerPathEntry *entry;
278 GNUNET_assert (off < path->entries_length);
279 entry = path->entries[off];
281 /* Add delta, with checks for overflows */
284 if (delta + entry->score < entry->score)
285 entry->score = INT_MAX;
287 entry->score += delta;
291 if (delta + entry->score > entry->score)
292 entry->score = INT_MIN;
294 entry->score += delta;
296 recalculate_path_desirability (path);
301 * Closure for #find_peer_at() and #check_match().
303 struct CheckMatchContext
307 * Set to a matching path, if any.
309 struct CadetPeerPath *match;
312 * Array the combined paths.
314 struct CadetPeer **cpath;
317 * How long is the @e cpath array?
319 unsigned int cpath_length;
325 * Check if the given path is identical on all of the
326 * hops until @a off, and not longer than @a off. If the
327 * @a path matches, store it in `match`.
329 * @param cls the `struct CheckMatchContext` to check against
330 * @param path the path to check
331 * @param off offset to check at
332 * @return #GNUNET_YES (continue to iterate), or if found #GNUNET_NO
335 check_match (void *cls,
336 struct CadetPeerPath *path,
339 struct CheckMatchContext *cm_ctx = cls;
341 GNUNET_assert (path->entries_length > off);
342 if ( (path->entries_length != off + 1) &&
343 (off + 1 != cm_ctx->cpath_length) )
345 LOG (GNUNET_ERROR_TYPE_DEBUG,
346 "check_match missmatch because path %s is too long (%u vs. %u vs. %u)\n",
348 path->entries_length,
350 cm_ctx->cpath_length);
351 return GNUNET_YES; /* too long, goes somewhere else already, thus cannot be useful */
353 for (unsigned int i=0;i<off;i++)
354 if (cm_ctx->cpath[i] !=
355 GCPP_get_peer_at_offset (path,
358 LOG (GNUNET_ERROR_TYPE_DEBUG,
359 "check_match path %s missmatches at offset %u\n",
362 return GNUNET_YES; /* missmatch, ignore */
364 LOG (GNUNET_ERROR_TYPE_DEBUG,
365 "check_match found match with path %s\n",
367 cm_ctx->match = path;
368 return GNUNET_NO; /* match, we are done! */
373 * Extend path @a path by the @a num_peers from the @a peers
374 * array, assuming the owners past the current owner want it.
376 * @param path path to extend
377 * @param peers list of peers beyond the end of @a path
378 * @param num_peers length of the @a peers array
379 * @param force force attachment, even if we have other
383 extend_path (struct CadetPeerPath *path,
384 struct CadetPeer **peers,
385 unsigned int num_peers,
388 unsigned int old_len = path->entries_length;
389 struct GNUNET_CONTAINER_HeapNode *hn;
393 GNUNET_array_grow (path->entries,
394 path->entries_length,
395 old_len + num_peers);
396 for (i=num_peers-1;i >= 0;i--)
398 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
400 path->entries[old_len + i] = entry;
401 entry->peer = peers[i];
404 for (i=num_peers-1;i >= 0;i--)
406 struct CadetPeerPathEntry *entry = path->entries[old_len + i];
408 GCP_path_entry_add (entry->peer,
413 /* If we extend an existing path, detach it from the
414 old owner and re-attach to the new one */
416 for (i=num_peers-1;i>=0;i--)
418 struct CadetPeerPathEntry *entry = path->entries[old_len + i];
420 path->entries_length = old_len + i + 1;
421 recalculate_path_desirability (path);
422 hn = GCP_attach_path (peers[i],
424 old_len + (unsigned int) i,
428 GCP_path_entry_remove (entry->peer,
432 path->entries[old_len + i] = NULL;
436 /* none of the peers is interested in this path;
438 GNUNET_array_grow (path->entries,
439 path->entries_length,
443 GCP_detach_path (path->entries[old_len-1]->peer,
447 LOG (GNUNET_ERROR_TYPE_DEBUG,
448 "Extended path %s\n",
454 * Create a peer path based on the result of a DHT lookup. If we
455 * already know this path, or one that is longer, simply return NULL.
456 * Otherwise, we try to extend an existing path, or create a new one
459 * @param get_path path of the get request
460 * @param get_path_length lenght of @a get_path
461 * @param put_path path of the put request
462 * @param put_path_length length of the @a put_path
463 * @return a path through the network
466 GCPP_try_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
467 unsigned int get_path_length,
468 const struct GNUNET_PeerIdentity *put_path,
469 unsigned int put_path_length)
471 struct CadetPeer *cpath[get_path_length + put_path_length];
472 struct CheckMatchContext cm_ctx;
473 struct CadetPeerPath *path;
474 struct GNUNET_CONTAINER_HeapNode *hn;
477 unsigned int total_len;
479 /* precompute 'cpath' so we can avoid doing the lookups lots of times */
481 total_len = get_path_length + put_path_length;
482 for (unsigned int off=0;off<total_len;off++)
484 const struct GNUNET_PeerIdentity *pid;
486 pid = (off < get_path_length)
487 ? &get_path[get_path_length - off]
488 : &put_path[get_path_length + put_path_length - off];
489 cpath[off - skip] = GCP_get (pid,
491 /* Check that no peer is twice on the path */
492 for (unsigned int i=0;i<off;i++)
494 if (cpath[i] == cpath[off])
503 /* First figure out if this path is a subset of an existing path, an
504 extension of an existing path, or a new path. */
505 cm_ctx.cpath_length = total_len;
506 cm_ctx.cpath = cpath;
508 for (i=total_len-1;i>=0;i--)
510 GCP_iterate_paths_at (cpath[i],
514 if (NULL != cm_ctx.match)
516 if (i == total_len - 1)
518 /* Existing path includes this one, nothing to do! */
519 LOG (GNUNET_ERROR_TYPE_DEBUG,
520 "Path discovered from DHT is already known\n");
523 if (cm_ctx.match->entries_length == i + 1)
525 /* Existing path ends in the middle of new path, extend it! */
526 LOG (GNUNET_ERROR_TYPE_DEBUG,
527 "Trying to extend existing path %s by additional links discovered from DHT\n",
528 GCPP_2s (cm_ctx.match));
529 extend_path (cm_ctx.match,
538 /* No match at all, create completely new path */
539 path = GNUNET_new (struct CadetPeerPath);
540 path->entries_length = total_len;
541 path->entries = GNUNET_new_array (path->entries_length,
542 struct CadetPeerPathEntry *);
543 for (i=path->entries_length-1;i>=0;i--)
545 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
547 path->entries[i] = entry;
548 entry->peer = cpath[i];
551 for (i=path->entries_length-1;i>=0;i--)
553 struct CadetPeerPathEntry *entry = path->entries[i];
555 GCP_path_entry_add (entry->peer,
560 /* Finally, try to attach it */
562 for (i=total_len-1;i>=0;i--)
564 struct CadetPeerPathEntry *entry = path->entries[i];
566 path->entries_length = i + 1;
567 recalculate_path_desirability (path);
568 hn = GCP_attach_path (cpath[i],
574 GCP_path_entry_remove (entry->peer,
578 path->entries[i] = NULL;
582 /* None of the peers on the path care about it. */
583 LOG (GNUNET_ERROR_TYPE_DEBUG,
584 "Path discovered from DHT is not interesting to us\n");
585 GNUNET_free (path->entries);
590 /* Shrink path to actual useful length */
591 GNUNET_array_grow (path->entries,
592 path->entries_length,
594 LOG (GNUNET_ERROR_TYPE_DEBUG,
595 "Created new path %s based on information from DHT\n",
601 * We got an incoming connection, obtain the corresponding path.
603 * @param path_length number of segments on the @a path
604 * @param pids path through the network, in reverse order (we are at the end at index @a path_length)
605 * @return corresponding path object
607 struct CadetPeerPath *
608 GCPP_get_path_from_route (unsigned int path_length,
609 const struct GNUNET_PeerIdentity *pids)
611 struct CheckMatchContext cm_ctx;
612 struct CadetPeer *cpath[path_length];
613 struct CadetPeerPath *path;
615 /* precompute inverted 'cpath' so we can avoid doing the lookups and
616 have the correct order */
617 for (unsigned int off=0;off<path_length;off++)
618 cpath[off] = GCP_get (&pids[path_length - 1 - off],
621 /* First figure out if this path is a subset of an existing path, an
622 extension of an existing path, or a new path. */
623 cm_ctx.cpath = cpath;
624 cm_ctx.cpath_length = path_length;
626 for (int i=path_length-1;i>=0;i--)
628 GCP_iterate_paths_at (cpath[i],
632 if (NULL != cm_ctx.match)
634 if (i == path_length - 1)
636 /* Existing path includes this one, return the match! */
637 LOG (GNUNET_ERROR_TYPE_DEBUG,
638 "Returning existing path %s as inverse for incoming connection\n",
639 GCPP_2s (cm_ctx.match));
642 if (cm_ctx.match->entries_length == i + 1)
644 /* Existing path ends in the middle of new path, extend it! */
645 LOG (GNUNET_ERROR_TYPE_DEBUG,
646 "Extending existing path %s to create inverse for incoming connection\n",
647 GCPP_2s (cm_ctx.match));
648 extend_path (cm_ctx.match,
652 /* Check that extension was successful */
653 GNUNET_assert (cm_ctx.match->entries_length == path_length);
656 /* Eh, we found a match but couldn't use it? Something is wrong. */
661 /* No match at all, create completely new path */
662 path = GNUNET_new (struct CadetPeerPath);
663 path->entries_length = path_length;
664 path->entries = GNUNET_new_array (path->entries_length,
665 struct CadetPeerPathEntry *);
666 for (int i=path_length-1;i>=0;i--)
668 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
670 path->entries[i] = entry;
671 entry->peer = cpath[i];
674 for (int i=path_length-1;i>=0;i--)
676 struct CadetPeerPathEntry *entry = path->entries[i];
678 GCP_path_entry_add (entry->peer,
682 recalculate_path_desirability (path);
683 LOG (GNUNET_ERROR_TYPE_DEBUG,
684 "Created new path %s to create inverse for incoming connection\n",
686 path->hn = GCP_attach_path (cpath[path_length - 1],
695 * Return the length of the path. Excludes one end of the
696 * path, so the loopback path has length 0.
698 * @param path path to return the length for
699 * @return number of peers on the path
702 GCPP_get_length (struct CadetPeerPath *path)
704 return path->entries_length;
709 * Find peer's offset on path.
711 * @param path path to search
712 * @param cp peer to look for
713 * @return offset of @a cp on @a path, or UINT_MAX if not found
716 GCPP_find_peer (struct CadetPeerPath *path,
717 struct CadetPeer *cp)
719 for (unsigned int off = 0;
720 off < path->entries_length;
722 if (cp == GCPP_get_peer_at_offset (path,
730 * Obtain the peer at offset @a off in @a path.
732 * @param path peer path to inspect
733 * @param off offset to return, must be smaller than path length
734 * @return the peer at offset @a off
737 GCPP_get_peer_at_offset (struct CadetPeerPath *path,
740 GNUNET_assert (off < path->entries_length);
741 return path->entries[off]->peer;
746 * Convert a path to a human-readable string.
748 * @param path path to convert
749 * @return string, to be freed by caller (unlike other *_2s APIs!)
752 GCPP_2s (struct CadetPeerPath *path)
754 static char buf[2048];
756 const unsigned int max_plen = (sizeof(buf) - 16) / 5 - 2; /* 5 characters per entry */
759 for (unsigned int i = 0;
760 i < path->entries_length;
763 if ( (path->entries_length > max_plen) &&
764 (i == max_plen / 2) )
765 off += GNUNET_snprintf (&buf[off],
768 if ( (path->entries_length > max_plen) &&
769 (i > max_plen / 2) &&
770 (i < path->entries_length - max_plen / 2) )
772 off += GNUNET_snprintf (&buf[off],
775 GNUNET_i2s (GCP_get_id (GCPP_get_peer_at_offset (path,
777 (i == path->entries_length -1) ? "" : "-");
779 GNUNET_snprintf (&buf[off],
787 /* end of gnunet-service-cadet-new_paths.c */