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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)
79 /* FIXME: update path desirability! */
80 GNUNET_break (0); // not implemented
85 * Return how much we like keeping the path. This is an aggregate
86 * score based on various factors, including the age of the path
87 * (older == better), and the value of this path to all of its ajacent
88 * peers. For example, long paths that end at a peer that we have no
89 * shorter way to reach are very desirable, while long paths that end
90 * at a peer for which we have a shorter way as well are much less
91 * desirable. Higher values indicate more valuable paths. The
92 * returned value should be used to decide which paths to remember.
94 * @param path path to return the length for
95 * @return desirability of the path, larger is more desirable
97 GNUNET_CONTAINER_HeapCostType
98 GCPP_get_desirability (const struct CadetPeerPath *path)
100 return path->desirability;
105 * Return connection to @a destination using @a path, or return
106 * NULL if no such connection exists.
108 * @param path path to traverse
109 * @param destination destination node to get to, must be on path
110 * @param off offset of @a destination on @a path
111 * @return NULL if we have no existing connection
112 * otherwise connection from us to @a destination via @a path
114 struct CadetConnection *
115 GCPP_get_connection (struct CadetPeerPath *path,
116 struct CadetPeer *destination,
119 struct CadetPeerPathEntry *entry;
121 GNUNET_assert (off < path->entries_length);
122 entry = path->entries[off];
123 GNUNET_assert (entry->peer == destination);
129 * Notify @a path that it is used for connection @a cc
130 * which ends at the path's offset @a off.
132 * @param path the path to remember the @a cc
133 * @param off the offset where the @a cc ends
134 * @param cc the connection to remember
137 GCPP_add_connection (struct CadetPeerPath *path,
139 struct CadetConnection *cc)
141 struct CadetPeerPathEntry *entry;
143 LOG (GNUNET_ERROR_TYPE_DEBUG,
144 "Adding connection %s to path %s at offset %u\n",
148 GNUNET_assert (off < path->entries_length);
149 entry = path->entries[off];
150 GNUNET_assert (NULL == entry->cc);
157 * Notify @a path that it is no longer used for connection @a cc which
158 * ended at the path's offset @a off.
160 * @param path the path to forget the @a cc
161 * @param off the offset where the @a cc ended
162 * @param cc the connection to forget
165 GCPP_del_connection (struct CadetPeerPath *path,
167 struct CadetConnection *cc)
169 struct CadetPeerPathEntry *entry;
171 LOG (GNUNET_ERROR_TYPE_DEBUG,
172 "Removing connection %s to path %s at offset %u\n",
176 GNUNET_assert (off < path->entries_length);
177 entry = path->entries[off];
178 GNUNET_assert (cc == entry->cc);
184 * This path is no longer needed, free resources.
186 * @param path path resources to free
189 path_destroy (struct CadetPeerPath *path)
191 LOG (GNUNET_ERROR_TYPE_DEBUG,
192 "Destroying path %s\n",
194 for (unsigned int i=0;i<path->entries_length;i++)
196 struct CadetPeerPathEntry *entry = path->entries[i];
198 if (NULL != entry->cc)
200 struct CadetTConnection *ct;
202 ct = GCC_get_ct (entry->cc);
204 GCT_connection_lost (ct);
205 GCC_destroy_without_tunnel (entry->cc);
209 GNUNET_free (path->entries);
215 * The owning peer of this path is no longer interested in maintaining
216 * it, so the path should be discarded or shortened (in case a
217 * previous peer on the path finds the path desirable).
219 * @param path the path that is being released
222 GCPP_release (struct CadetPeerPath *path)
224 struct CadetPeerPathEntry *entry;
226 LOG (GNUNET_ERROR_TYPE_DEBUG,
227 "Owner releases path %s\n",
230 entry = path->entries[path->entries_length - 1];
233 /* cut 'off' end of path */
234 GCP_path_entry_remove (entry->peer,
236 path->entries_length - 1);
237 path->entries_length--; /* We don't bother shrinking the 'entries' array,
238 as it's probably not worth it. */
240 if (0 == path->entries_length)
243 /* see if new peer at the end likes this path any better */
244 entry = path->entries[path->entries_length - 1];
245 path->hn = GCP_attach_path (entry->peer,
247 path->entries_length - 1,
249 if (NULL != path->hn)
250 return; /* yep, got attached, we are done. */
253 /* nobody wants us, discard the path */
259 * Updates the score for an entry on the path based
260 * on our experiences with using @a path.
262 * @param path the path to update
263 * @param off offset of the entry to update
264 * @param delta change in the score to apply
267 GCPP_update_score (struct CadetPeerPath *path,
271 struct CadetPeerPathEntry *entry;
273 GNUNET_assert (off < path->entries_length);
274 entry = path->entries[off];
276 /* Add delta, with checks for overflows */
279 if (delta + entry->score < entry->score)
280 entry->score = INT_MAX;
282 entry->score += delta;
286 if (delta + entry->score > entry->score)
287 entry->score = INT_MIN;
289 entry->score += delta;
291 recalculate_path_desirability (path);
296 * Closure for #find_peer_at() and #check_match().
298 struct CheckMatchContext
302 * Set to a matching path, if any.
304 struct CadetPeerPath *match;
307 * Array the combined paths.
309 struct CadetPeer **cpath;
312 * How long is the @e cpath array?
314 unsigned int cpath_length;
320 * Check if the given path is identical on all of the
321 * hops until @a off, and not longer than @a off. If the
322 * @a path matches, store it in `match`.
324 * @param cls the `struct CheckMatchContext` to check against
325 * @param path the path to check
326 * @param off offset to check at
327 * @return #GNUNET_YES (continue to iterate), or if found #GNUNET_NO
330 check_match (void *cls,
331 struct CadetPeerPath *path,
334 struct CheckMatchContext *cm_ctx = cls;
336 GNUNET_assert (path->entries_length > off);
337 if ( (path->entries_length != off + 1) &&
338 (off + 1 != cm_ctx->cpath_length) )
340 LOG (GNUNET_ERROR_TYPE_DEBUG,
341 "check_match missmatch because path %s is too long (%u vs. %u vs. %u)\n",
343 path->entries_length,
345 cm_ctx->cpath_length);
346 return GNUNET_YES; /* too long, goes somewhere else already, thus cannot be useful */
348 for (unsigned int i=0;i<off;i++)
349 if (cm_ctx->cpath[i] !=
350 GCPP_get_peer_at_offset (path,
353 LOG (GNUNET_ERROR_TYPE_DEBUG,
354 "check_match path %s missmatches at offset %u\n",
357 return GNUNET_YES; /* missmatch, ignore */
359 LOG (GNUNET_ERROR_TYPE_DEBUG,
360 "check_match found match with path %s\n",
362 cm_ctx->match = path;
363 return GNUNET_NO; /* match, we are done! */
368 * Extend path @a path by the @a num_peers from the @a peers
369 * array, assuming the owners past the current owner want it.
371 * @param path path to extend
372 * @param peers list of peers beyond the end of @a path
373 * @param num_peers length of the @a peers array
374 * @param force force attachment, even if we have other
378 extend_path (struct CadetPeerPath *path,
379 struct CadetPeer **peers,
380 unsigned int num_peers,
383 unsigned int old_len = path->entries_length;
384 struct GNUNET_CONTAINER_HeapNode *hn;
388 GNUNET_array_grow (path->entries,
389 path->entries_length,
390 old_len + num_peers);
391 for (i=num_peers-1;i >= 0;i--)
393 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
395 path->entries[old_len + i] = entry;
396 entry->peer = peers[i];
399 for (i=num_peers-1;i >= 0;i--)
401 struct CadetPeerPathEntry *entry = path->entries[old_len + i];
403 GCP_path_entry_add (entry->peer,
408 /* If we extend an existing path, detach it from the
409 old owner and re-attach to the new one */
411 for (i=num_peers-1;i>=0;i--)
413 struct CadetPeerPathEntry *entry = path->entries[old_len + i];
415 path->entries_length = old_len + i + 1;
416 recalculate_path_desirability (path);
417 hn = GCP_attach_path (peers[i],
419 old_len + (unsigned int) i,
423 GCP_path_entry_remove (entry->peer,
427 path->entries[old_len + i] = NULL;
431 /* none of the peers is interested in this path;
433 GNUNET_array_grow (path->entries,
434 path->entries_length,
438 GCP_detach_path (path->entries[old_len-1]->peer,
442 LOG (GNUNET_ERROR_TYPE_DEBUG,
443 "Extended path %s\n",
449 * Create a peer path based on the result of a DHT lookup. If we
450 * already know this path, or one that is longer, simply return NULL.
451 * Otherwise, we try to extend an existing path, or create a new one
454 * @param get_path path of the get request
455 * @param get_path_length lenght of @a get_path
456 * @param put_path path of the put request
457 * @param put_path_length length of the @a put_path
458 * @return a path through the network
461 GCPP_try_path_from_dht (const struct GNUNET_PeerIdentity *get_path,
462 unsigned int get_path_length,
463 const struct GNUNET_PeerIdentity *put_path,
464 unsigned int put_path_length)
466 struct CadetPeer *cpath[get_path_length + put_path_length];
467 struct CheckMatchContext cm_ctx;
468 struct CadetPeerPath *path;
469 struct GNUNET_CONTAINER_HeapNode *hn;
472 unsigned int total_len;
474 /* precompute 'cpath' so we can avoid doing the lookups lots of times */
476 total_len = get_path_length + put_path_length;
477 for (unsigned int off=0;off<total_len;off++)
479 const struct GNUNET_PeerIdentity *pid;
481 pid = (off < get_path_length)
482 ? &get_path[get_path_length - off]
483 : &put_path[get_path_length + put_path_length - off];
484 cpath[off - skip] = GCP_get (pid,
486 /* Check that no peer is twice on the path */
487 for (unsigned int i=0;i<off;i++)
489 if (cpath[i] == cpath[off])
498 /* First figure out if this path is a subset of an existing path, an
499 extension of an existing path, or a new path. */
500 cm_ctx.cpath_length = total_len;
501 cm_ctx.cpath = cpath;
503 for (i=total_len-1;i>=0;i--)
505 GCP_iterate_paths_at (cpath[i],
509 if (NULL != cm_ctx.match)
511 if (i == total_len - 1)
513 /* Existing path includes this one, nothing to do! */
514 LOG (GNUNET_ERROR_TYPE_DEBUG,
515 "Path discovered from DHT is already known\n");
518 if (cm_ctx.match->entries_length == i + 1)
520 /* Existing path ends in the middle of new path, extend it! */
521 LOG (GNUNET_ERROR_TYPE_DEBUG,
522 "Trying to extend existing path %s by additional links discovered from DHT\n",
523 GCPP_2s (cm_ctx.match));
524 extend_path (cm_ctx.match,
533 /* No match at all, create completely new path */
534 path = GNUNET_new (struct CadetPeerPath);
535 path->entries_length = total_len;
536 path->entries = GNUNET_new_array (path->entries_length,
537 struct CadetPeerPathEntry *);
538 for (i=path->entries_length-1;i>=0;i--)
540 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
542 path->entries[i] = entry;
543 entry->peer = cpath[i];
546 for (i=path->entries_length-1;i>=0;i--)
548 struct CadetPeerPathEntry *entry = path->entries[i];
550 GCP_path_entry_add (entry->peer,
555 /* Finally, try to attach it */
557 for (i=total_len-1;i>=0;i--)
559 struct CadetPeerPathEntry *entry = path->entries[i];
561 path->entries_length = i + 1;
562 recalculate_path_desirability (path);
563 hn = GCP_attach_path (cpath[i],
569 GCP_path_entry_remove (entry->peer,
573 path->entries[i] = NULL;
577 /* None of the peers on the path care about it. */
578 LOG (GNUNET_ERROR_TYPE_DEBUG,
579 "Path discovered from DHT is not interesting to us\n");
580 GNUNET_free (path->entries);
585 /* Shrink path to actual useful length */
586 GNUNET_array_grow (path->entries,
587 path->entries_length,
589 LOG (GNUNET_ERROR_TYPE_DEBUG,
590 "Created new path %s based on information from DHT\n",
596 * We got an incoming connection, obtain the corresponding path.
598 * @param path_length number of segments on the @a path
599 * @param pids path through the network, in reverse order (we are at the end at index @a path_length)
600 * @return corresponding path object
602 struct CadetPeerPath *
603 GCPP_get_path_from_route (unsigned int path_length,
604 const struct GNUNET_PeerIdentity *pids)
606 struct CheckMatchContext cm_ctx;
607 struct CadetPeer *cpath[path_length];
608 struct CadetPeerPath *path;
610 /* precompute inverted 'cpath' so we can avoid doing the lookups and
611 have the correct order */
612 for (unsigned int off=0;off<path_length;off++)
613 cpath[off] = GCP_get (&pids[path_length - 1 - off],
616 /* First figure out if this path is a subset of an existing path, an
617 extension of an existing path, or a new path. */
618 cm_ctx.cpath = cpath;
619 cm_ctx.cpath_length = path_length;
621 for (int i=path_length-1;i>=0;i--)
623 GCP_iterate_paths_at (cpath[i],
627 if (NULL != cm_ctx.match)
629 if (i == path_length - 1)
631 /* Existing path includes this one, return the match! */
632 LOG (GNUNET_ERROR_TYPE_DEBUG,
633 "Returning existing path %s as inverse for incoming connection\n",
634 GCPP_2s (cm_ctx.match));
637 if (cm_ctx.match->entries_length == i + 1)
639 /* Existing path ends in the middle of new path, extend it! */
640 LOG (GNUNET_ERROR_TYPE_DEBUG,
641 "Extending existing path %s to create inverse for incoming connection\n",
642 GCPP_2s (cm_ctx.match));
643 extend_path (cm_ctx.match,
647 /* Check that extension was successful */
648 GNUNET_assert (cm_ctx.match->entries_length == path_length);
651 /* Eh, we found a match but couldn't use it? Something is wrong. */
656 /* No match at all, create completely new path */
657 path = GNUNET_new (struct CadetPeerPath);
658 path->entries_length = path_length;
659 path->entries = GNUNET_new_array (path->entries_length,
660 struct CadetPeerPathEntry *);
661 for (int i=path_length-1;i>=0;i--)
663 struct CadetPeerPathEntry *entry = GNUNET_new (struct CadetPeerPathEntry);
665 path->entries[i] = entry;
666 entry->peer = cpath[i];
669 for (int i=path_length-1;i>=0;i--)
671 struct CadetPeerPathEntry *entry = path->entries[i];
673 GCP_path_entry_add (entry->peer,
677 recalculate_path_desirability (path);
678 LOG (GNUNET_ERROR_TYPE_DEBUG,
679 "Created new path %s to create inverse for incoming connection\n",
681 path->hn = GCP_attach_path (cpath[path_length - 1],
690 * Return the length of the path. Excludes one end of the
691 * path, so the loopback path has length 0.
693 * @param path path to return the length for
694 * @return number of peers on the path
697 GCPP_get_length (struct CadetPeerPath *path)
699 return path->entries_length;
704 * Find peer's offset on path.
706 * @param path path to search
707 * @param cp peer to look for
708 * @return offset of @a cp on @a path, or UINT_MAX if not found
711 GCPP_find_peer (struct CadetPeerPath *path,
712 struct CadetPeer *cp)
714 for (unsigned int off = 0;
715 off < path->entries_length;
717 if (cp == GCPP_get_peer_at_offset (path,
725 * Obtain the peer at offset @a off in @a path.
727 * @param path peer path to inspect
728 * @param off offset to return, must be smaller than path length
729 * @return the peer at offset @a off
732 GCPP_get_peer_at_offset (struct CadetPeerPath *path,
735 GNUNET_assert (off < path->entries_length);
736 return path->entries[off]->peer;
741 * Convert a path to a human-readable string.
743 * @param path path to convert
744 * @return string, to be freed by caller (unlike other *_2s APIs!)
747 GCPP_2s (struct CadetPeerPath *path)
749 static char buf[2048];
751 const unsigned int max_plen = (sizeof(buf) - 16) / 5 - 2; /* 5 characters per entry */
754 for (unsigned int i = 0;
755 i < path->entries_length;
758 if ( (path->entries_length > max_plen) &&
759 (i == max_plen / 2) )
760 off += GNUNET_snprintf (&buf[off],
763 if ( (path->entries_length > max_plen) &&
764 (i > max_plen / 2) &&
765 (i < path->entries_length - max_plen / 2) )
767 off += GNUNET_snprintf (&buf[off],
770 GNUNET_i2s (GCP_get_id (GCPP_get_peer_at_offset (path,
772 (i == path->entries_length -1) ? "" : "-");
774 GNUNET_snprintf (&buf[off],
782 /* end of gnunet-service-cadet-new_paths.c */