2 This file is part of GNUnet
3 (C) 2004-2013 Christian Grothoff (and other contributing authors)
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22 * @file include/gnunet_dht_service.h
23 * @brief API to the DHT service
24 * @author Christian Grothoff
25 * @defgroup dht Distributed Hash Table
29 #ifndef GNUNET_DHT_SERVICE_H
30 #define GNUNET_DHT_SERVICE_H
32 #include "gnunet_util_lib.h"
33 #include "gnunet_block_lib.h"
34 #include "gnunet_hello_lib.h"
39 #if 0 /* keep Emacsens' auto-indent happy */
46 * Default republication frequency for stored data in the DHT.
48 #define GNUNET_DHT_DEFAULT_REPUBLISH_FREQUENCY GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_MINUTES, 60)
53 * Connection to the DHT service.
55 struct GNUNET_DHT_Handle;
58 * Handle to control a get operation.
60 struct GNUNET_DHT_GetHandle;
63 * Handle to control a find peer operation.
65 struct GNUNET_DHT_FindPeerHandle;
69 * Options for routing.
71 enum GNUNET_DHT_RouteOption
74 * Default. Do nothing special.
76 GNUNET_DHT_RO_NONE = 0,
79 * Each peer along the way should look at 'enc' (otherwise
80 * only the k-peers closest to the key should look at it).
82 GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE = 1,
85 * We should keep track of the route that the message
86 * took in the P2P network.
88 GNUNET_DHT_RO_RECORD_ROUTE = 2,
91 * This is a 'FIND-PEER' request, so approximate results are fine.
93 GNUNET_DHT_RO_FIND_PEER = 4,
96 * Possible message option for query key randomization.
98 GNUNET_DHT_RO_BART = 8,
101 * Flag given to monitors if this was the last hop for a GET/PUT.
103 GNUNET_DHT_RO_LAST_HOP = 16
108 * Initialize the connection with the DHT service.
110 * @param cfg configuration to use
111 * @param ht_len size of the internal hash table to use for
112 * processing multiple GET/FIND requests in parallel
113 * @return NULL on error
115 struct GNUNET_DHT_Handle *
116 GNUNET_DHT_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
117 unsigned int ht_len);
121 * Shutdown connection with the DHT service.
123 * @param handle connection to shut down
126 GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle);
129 /* *************** Standard API: get and put ******************* */
133 * Opaque handle to cancel a PUT operation.
135 struct GNUNET_DHT_PutHandle;
139 * Type of a PUT continuation. You must not call
140 * #GNUNET_DHT_disconnect in this continuation.
143 * @param success #GNUNET_OK if the PUT was transmitted,
144 * #GNUNET_NO on timeout,
145 * #GNUNET_SYSERR on disconnect from service
146 * after the PUT message was transmitted
147 * (so we don't know if it was received or not)
149 typedef void (*GNUNET_DHT_PutContinuation)(void *cls,
154 * Perform a PUT operation storing data in the DHT.
156 * @param handle handle to DHT service
157 * @param key the key to store under
158 * @param desired_replication_level estimate of how many
159 * nearest peers this request should reach
160 * @param options routing options for this message
161 * @param type type of the value
162 * @param size number of bytes in @a data; must be less than 64k
163 * @param data the data to store
164 * @param exp desired expiration time for the value
165 * @param timeout how long to wait for transmission of this request
166 * @param cont continuation to call when done (transmitting request to service)
167 * You must not call #GNUNET_DHT_disconnect in this continuation
168 * @param cont_cls closure for @a cont
169 * @return handle to cancel the "PUT" operation, NULL on error
172 struct GNUNET_DHT_PutHandle *
173 GNUNET_DHT_put (struct GNUNET_DHT_Handle *handle,
174 const struct GNUNET_HashCode *key,
175 uint32_t desired_replication_level,
176 enum GNUNET_DHT_RouteOption options,
177 enum GNUNET_BLOCK_Type type,
178 size_t size, const void *data,
179 struct GNUNET_TIME_Absolute exp,
180 struct GNUNET_TIME_Relative timeout,
181 GNUNET_DHT_PutContinuation cont,
186 * Cancels a DHT PUT operation. Note that the PUT request may still
187 * go out over the network (we can't stop that); However, if the PUT
188 * has not yet been sent to the service, cancelling the PUT will stop
189 * this from happening (but there is no way for the user of this API
190 * to tell if that is the case). The only use for this API is to
191 * prevent a later call to 'cont' from #GNUNET_DHT_put (i.e. because
192 * the system is shutting down).
194 * @param ph put operation to cancel ('cont' will no longer be called)
197 GNUNET_DHT_put_cancel (struct GNUNET_DHT_PutHandle *ph);
201 * Iterator called on each result obtained for a DHT
202 * operation that expects a reply
205 * @param exp when will this value expire
206 * @param key key of the result
207 * @param get_path peers on reply path (or NULL if not recorded)
208 * [0] = datastore's first neighbor, [length - 1] = local peer
209 * @param get_path_length number of entries in @a get_path
210 * @param put_path peers on the PUT path (or NULL if not recorded)
211 * [0] = origin, [length - 1] = datastore
212 * @param put_path_length number of entries in @a put_path
213 * @param type type of the result
214 * @param size number of bytes in @a data
215 * @param data pointer to the result data
217 typedef void (*GNUNET_DHT_GetIterator) (void *cls,
218 struct GNUNET_TIME_Absolute exp,
219 const struct GNUNET_HashCode *key,
220 const struct GNUNET_PeerIdentity *get_path,
221 unsigned int get_path_length,
222 const struct GNUNET_PeerIdentity *put_path,
223 unsigned int put_path_length,
224 enum GNUNET_BLOCK_Type type,
225 size_t size, const void *data);
229 * Perform an asynchronous GET operation on the DHT identified. See
230 * also #GNUNET_BLOCK_evaluate.
232 * @param handle handle to the DHT service
233 * @param type expected type of the response object
234 * @param key the key to look up
235 * @param desired_replication_level estimate of how many
236 nearest peers this request should reach
237 * @param options routing options for this message
238 * @param xquery extended query data (can be NULL, depending on type)
239 * @param xquery_size number of bytes in @a xquery
240 * @param iter function to call on each result
241 * @param iter_cls closure for @a iter
243 * @return handle to stop the async get
245 struct GNUNET_DHT_GetHandle *
246 GNUNET_DHT_get_start (struct GNUNET_DHT_Handle *handle,
247 enum GNUNET_BLOCK_Type type,
248 const struct GNUNET_HashCode *key,
249 uint32_t desired_replication_level,
250 enum GNUNET_DHT_RouteOption options,
251 const void *xquery, size_t xquery_size,
252 GNUNET_DHT_GetIterator iter, void *iter_cls);
256 * Tell the DHT not to return any of the following known results
259 * @param get_handle get operation for which results should be filtered
260 * @param num_results number of results to be blocked that are
261 * provided in this call (size of the @a results array)
262 * @param results array of hash codes over the 'data' of the results
266 GNUNET_DHT_get_filter_known_results (struct GNUNET_DHT_GetHandle *get_handle,
267 unsigned int num_results,
268 const struct GNUNET_HashCode *results);
271 * Stop async DHT-get. Frees associated resources.
273 * @param get_handle GET operation to stop.
275 * On return get_handle will no longer be valid, caller
276 * must not use again!!!
279 GNUNET_DHT_get_stop (struct GNUNET_DHT_GetHandle *get_handle);
282 /* *************** Extended API: monitor ******************* */
285 * Handle to monitor requests
287 struct GNUNET_DHT_MonitorHandle;
290 * Callback called on each GET request going through the DHT.
292 * @param cls Closure.
293 * @param options Options, for instance RecordRoute, DemultiplexEverywhere.
294 * @param type The type of data in the request.
295 * @param hop_count Hop count so far.
296 * @param path_length number of entries in @a path (or 0 if not recorded).
297 * @param path peers on the GET path (or NULL if not recorded).
298 * @param desired_replication_level Desired replication level.
299 * @param key Key of the requested data.
301 typedef void (*GNUNET_DHT_MonitorGetCB) (void *cls,
302 enum GNUNET_DHT_RouteOption options,
303 enum GNUNET_BLOCK_Type type,
305 uint32_t desired_replication_level,
306 unsigned int path_length,
307 const struct GNUNET_PeerIdentity *path,
308 const struct GNUNET_HashCode * key);
311 * Callback called on each GET reply going through the DHT.
313 * @param cls Closure.
314 * @param type The type of data in the result.
315 * @param get_path Peers on GET path (or NULL if not recorded).
316 * @param get_path_length number of entries in @a get_path.
317 * @param put_path peers on the PUT path (or NULL if not recorded).
318 * @param put_path_length number of entries in @a get_path.
319 * @param exp Expiration time of the data.
320 * @param key Key of the data.
321 * @param data Pointer to the result data.
322 * @param size Number of bytes in @a data.
324 typedef void (*GNUNET_DHT_MonitorGetRespCB) (void *cls,
325 enum GNUNET_BLOCK_Type type,
326 const struct GNUNET_PeerIdentity *get_path,
327 unsigned int get_path_length,
328 const struct GNUNET_PeerIdentity *put_path,
329 unsigned int put_path_length,
330 struct GNUNET_TIME_Absolute exp,
331 const struct GNUNET_HashCode *key,
336 * Callback called on each PUT request going through the DHT.
338 * @param cls Closure.
339 * @param options Options, for instance RecordRoute, DemultiplexEverywhere.
340 * @param type The type of data in the request.
341 * @param hop_count Hop count so far.
342 * @param path_length number of entries in @a path (or 0 if not recorded).
343 * @param path peers on the PUT path (or NULL if not recorded).
344 * @param desired_replication_level Desired replication level.
345 * @param exp Expiration time of the data.
346 * @param key Key under which data is to be stored.
347 * @param data Pointer to the data carried.
348 * @param size Number of bytes in data.
350 typedef void (*GNUNET_DHT_MonitorPutCB) (void *cls,
351 enum GNUNET_DHT_RouteOption options,
352 enum GNUNET_BLOCK_Type type,
354 uint32_t desired_replication_level,
355 unsigned int path_length,
356 const struct GNUNET_PeerIdentity *path,
357 struct GNUNET_TIME_Absolute exp,
358 const struct GNUNET_HashCode *key,
363 * Start monitoring the local DHT service.
365 * @param handle Handle to the DHT service.
366 * @param type Type of blocks that are of interest.
367 * @param key Key of data of interest, NULL for all.
368 * @param get_cb Callback to process monitored get messages.
369 * @param get_resp_cb Callback to process monitored get response messages.
370 * @param put_cb Callback to process monitored put messages.
371 * @param cb_cls Closure for callbacks
372 * @return Handle to stop monitoring.
374 struct GNUNET_DHT_MonitorHandle *
375 GNUNET_DHT_monitor_start (struct GNUNET_DHT_Handle *handle,
376 enum GNUNET_BLOCK_Type type,
377 const struct GNUNET_HashCode *key,
378 GNUNET_DHT_MonitorGetCB get_cb,
379 GNUNET_DHT_MonitorGetRespCB get_resp_cb,
380 GNUNET_DHT_MonitorPutCB put_cb,
386 * On return handle will no longer be valid, caller must not use again!!!
388 * @param handle The handle to the monitor request returned by monitor_start.
391 GNUNET_DHT_monitor_stop (struct GNUNET_DHT_MonitorHandle *handle);
394 #if 0 /* keep Emacsens' auto-indent happy */
401 /** @} */ /* end of group dht */
405 /* gnunet_dht_service.h */