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22 * @file dht/gnunet-service-xdht_routing.c
23 * @brief GNUnet DHT tracking of requests for routing replies
24 * @author Supriti Singh
27 #include "gnunet-service-xdht_neighbours.h"
28 #include "gnunet-service-xdht_routing.h"
29 #include "gnunet-service-xdht.h"
33 * FIXME: Check if its better to store pointer to friend rather than storing
34 * peer identity next_hop or prev_hop.
35 * keep entries in destnation and source peer also. so when we send the trail
36 * teardown message then we don't know the source but if source gets the message
37 * then it shold remove that trail id from its finger table. But how does
38 * source know what is the desination finger ? It will whenevr contact a trail
39 * will do a lookup in routing table and if no trail id present the remove
40 * that trail of the finger and if only one trail then remove the finger.
41 * because of this use case of trail teardown I think trail compression
42 * and trail teardown should not be merged.
43 * 2. store a pointer to friendInfo in place o peer identity.
46 * Maximum number of entries in routing table.
48 #define ROUTING_TABLE_THRESHOLD 64
51 * Routing table entry .
56 * Global Unique identifier of the trail.
58 struct GNUNET_HashCode trail_id;
61 * The peer to which this request should be passed to.
63 struct GNUNET_PeerIdentity next_hop;
66 * Peer just before next hop in the trail.
68 struct GNUNET_PeerIdentity prev_hop;
72 * Routing table of the peer
74 static struct GNUNET_CONTAINER_MultiHashMap *routing_table;
77 * Update the prev. hop of the trail. Call made by trail teardown where
78 * if you are the first friend now in the trail then you need to update
81 * @return #GNUNET_OK success
82 * #GNUNET_SYSERR in case no matching entry found in routing table.
85 GDS_ROUTING_update_trail_prev_hop (const struct GNUNET_HashCode trail_id,
86 struct GNUNET_PeerIdentity prev_hop)
88 struct RoutingTrail *trail;
90 trail = GNUNET_CONTAINER_multihashmap_get (routing_table, &trail_id);
95 trail->prev_hop = prev_hop;
102 * Get the next hop for trail corresponding to trail_id
103 * @param trail_id Trail id to be searched.
104 * @return Next_hop if found
105 * NULL If next hop not found.
107 struct GNUNET_PeerIdentity *
108 GDS_ROUTING_get_next_hop (const struct GNUNET_HashCode trail_id,
109 enum GDS_ROUTING_trail_direction trail_direction)
111 struct RoutingTrail *trail;
113 trail = GNUNET_CONTAINER_multihashmap_get (routing_table, &trail_id);
118 switch (trail_direction)
120 case GDS_ROUTING_SRC_TO_DEST:
121 return &(trail->next_hop);
122 case GDS_ROUTING_DEST_TO_SRC:
123 return &(trail->prev_hop);
130 * Remove trail with trail_id
131 * @param trail_id Trail id to be removed
132 * @return #GNUNET_YES success
133 * #GNUNET_NO if entry not found.
136 GDS_ROUTING_remove_trail (const struct GNUNET_HashCode remove_trail_id)
138 struct RoutingTrail *remove_entry;
140 remove_entry = GNUNET_CONTAINER_multihashmap_get (routing_table, &remove_trail_id);
142 if (NULL == remove_entry)
145 if (GNUNET_YES == GNUNET_CONTAINER_multihashmap_remove (routing_table,
149 GNUNET_free (remove_entry);
157 * Iterate over routing table and remove entries with value as part of any trail.
160 * @param key current public key
161 * @param value value in the hash map
162 * @return #GNUNET_YES if we should continue to iterate,
165 static int remove_matching_trails (void *cls,
166 const struct GNUNET_HashCode *key,
169 struct RoutingTrail *remove_trail = cls;
170 struct GNUNET_PeerIdentity *disconnected_peer = value;
172 /* If disconnected_peer is next_hop, then send a trail teardown message through
173 * prev_hop in direction from destination to source. */
174 if (0 == GNUNET_CRYPTO_cmp_peer_identity (&remove_trail->next_hop,
177 GDS_NEIGHBOURS_send_trail_teardown (remove_trail->trail_id,
178 GDS_ROUTING_DEST_TO_SRC,
179 &remove_trail->prev_hop);
182 /* If disconnected_peer is prev_hop, then send a trail teardown through
183 * next_hop in direction from Source to Destination. */
184 if (0 == GNUNET_CRYPTO_cmp_peer_identity (&remove_trail->prev_hop,
187 GDS_NEIGHBOURS_send_trail_teardown (remove_trail->trail_id,
188 GDS_ROUTING_SRC_TO_DEST,
189 &remove_trail->next_hop);
192 GNUNET_assert (GNUNET_YES ==
193 GNUNET_CONTAINER_multihashmap_remove (routing_table,
194 &remove_trail->trail_id,
196 GNUNET_free (remove_trail);
202 * Remove every trail where peer is either next_hop or prev_hop. Also send a
203 * trail teardown message in direction of hop which is not disconnected.
204 * @param peer Peer identity. Trail containing this peer should be removed.
207 GDS_ROUTING_remove_trail_by_peer (const struct GNUNET_PeerIdentity *peer)
209 GNUNET_CONTAINER_multihashmap_iterate (routing_table, &remove_matching_trails,
215 * Add a new entry in routing table
216 * @param new_trail_id
219 * @return #GNUNET_OK success
220 * #GNUNET_SYSERR in case new_trail_id already exists in the network
221 * but with different prev_hop/next_hop
224 GDS_ROUTING_add (struct GNUNET_HashCode new_trail_id,
225 struct GNUNET_PeerIdentity prev_hop,
226 struct GNUNET_PeerIdentity next_hop)
228 struct RoutingTrail *new_entry;
230 new_entry = GNUNET_malloc (sizeof (struct RoutingTrail));
231 new_entry->trail_id = new_trail_id;
232 new_entry->next_hop = next_hop;
233 new_entry->prev_hop = prev_hop;
234 return GNUNET_CONTAINER_multihashmap_put (routing_table,
235 &new_trail_id, new_entry,
236 GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY);
241 * Check if the size of routing table has crossed threshold.
242 * @return #GNUNET_YES, if threshold crossed else #GNUNET_NO.
245 GDS_ROUTING_threshold_reached (void)
247 return (GNUNET_CONTAINER_multihashmap_size(routing_table) >
248 ROUTING_TABLE_THRESHOLD) ? GNUNET_YES:GNUNET_NO;
253 * Initialize routing subsystem.
256 GDS_ROUTING_init (void)
258 routing_table = GNUNET_CONTAINER_multihashmap_create (ROUTING_TABLE_THRESHOLD * 4 / 3,
264 * Shutdown routing subsystem.
267 GDS_ROUTING_done (void)
269 GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size (routing_table));
270 GNUNET_CONTAINER_multihashmap_destroy (routing_table);
273 /* end of gnunet-service-xdht_routing.c */