/* This file is part of GNUnet Copyright (C) 2004-2013, 2016 GNUnet e.V. GNUnet is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see . */ /** * @author Christian Grothoff * * @file * API to the DHT service * * @defgroup dht DHT service * Distributed Hash Table * * @see [Documentation](https://gnunet.org/developer-handbook-dht) * * @{ */ #ifndef GNUNET_DHT_SERVICE_H #define GNUNET_DHT_SERVICE_H #include "gnunet_util_lib.h" #include "gnunet_block_lib.h" #include "gnunet_hello_lib.h" #ifdef __cplusplus extern "C" { #if 0 /* keep Emacsens' auto-indent happy */ } #endif #endif /** * Default republication frequency for stored data in the DHT. */ #define GNUNET_DHT_DEFAULT_REPUBLISH_FREQUENCY GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_MINUTES, 60) /** * Connection to the DHT service. */ struct GNUNET_DHT_Handle; /** * Handle to control a get operation. */ struct GNUNET_DHT_GetHandle; /** * Handle to control a find peer operation. */ struct GNUNET_DHT_FindPeerHandle; /** * Options for routing. */ enum GNUNET_DHT_RouteOption { /** * Default. Do nothing special. */ GNUNET_DHT_RO_NONE = 0, /** * Each peer along the way should look at 'enc' (otherwise * only the k-peers closest to the key should look at it). */ GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE = 1, /** * We should keep track of the route that the message * took in the P2P network. */ GNUNET_DHT_RO_RECORD_ROUTE = 2, /** * This is a 'FIND-PEER' request, so approximate results are fine. */ GNUNET_DHT_RO_FIND_PEER = 4, /** * Possible message option for query key randomization. */ GNUNET_DHT_RO_BART = 8, /** * Flag given to monitors if this was the last hop for a GET/PUT. */ GNUNET_DHT_RO_LAST_HOP = 16 }; /** * Initialize the connection with the DHT service. * * @param cfg configuration to use * @param ht_len size of the internal hash table to use for * processing multiple GET/FIND requests in parallel * @return NULL on error */ struct GNUNET_DHT_Handle * GNUNET_DHT_connect (const struct GNUNET_CONFIGURATION_Handle *cfg, unsigned int ht_len); /** * Shutdown connection with the DHT service. * * @param handle connection to shut down */ void GNUNET_DHT_disconnect (struct GNUNET_DHT_Handle *handle); /* *************** Standard API: get and put ******************* */ /** * Opaque handle to cancel a PUT operation. */ struct GNUNET_DHT_PutHandle; /** * Perform a PUT operation storing data in the DHT. * * @param handle handle to DHT service * @param key the key to store under * @param desired_replication_level estimate of how many * nearest peers this request should reach * @param options routing options for this message * @param type type of the value * @param size number of bytes in @a data; must be less than 64k * @param data the data to store * @param exp desired expiration time for the value * @param cont continuation to call when done (transmitting request to service) * You must not call #GNUNET_DHT_disconnect in this continuation * @param cont_cls closure for @a cont * @return handle to cancel the "PUT" operation, NULL on error * (size too big) */ struct GNUNET_DHT_PutHandle * GNUNET_DHT_put (struct GNUNET_DHT_Handle *handle, const struct GNUNET_HashCode *key, uint32_t desired_replication_level, enum GNUNET_DHT_RouteOption options, enum GNUNET_BLOCK_Type type, size_t size, const void *data, struct GNUNET_TIME_Absolute exp, GNUNET_SCHEDULER_TaskCallback cont, void *cont_cls); /** * Cancels a DHT PUT operation. Note that the PUT request may still * go out over the network (we can't stop that); However, if the PUT * has not yet been sent to the service, cancelling the PUT will stop * this from happening (but there is no way for the user of this API * to tell if that is the case). The only use for this API is to * prevent a later call to 'cont' from #GNUNET_DHT_put (i.e. because * the system is shutting down). * * @param ph put operation to cancel ('cont' will no longer be called) */ void GNUNET_DHT_put_cancel (struct GNUNET_DHT_PutHandle *ph); /** * Iterator called on each result obtained for a DHT * operation that expects a reply * * @param cls closure * @param exp when will this value expire * @param key key of the result * @param get_path peers on reply path (or NULL if not recorded) * [0] = datastore's first neighbor, [length - 1] = local peer * @param get_path_length number of entries in @a get_path * @param put_path peers on the PUT path (or NULL if not recorded) * [0] = origin, [length - 1] = datastore * @param put_path_length number of entries in @a put_path * @param type type of the result * @param size number of bytes in @a data * @param data pointer to the result data */ typedef void (*GNUNET_DHT_GetIterator) (void *cls, struct GNUNET_TIME_Absolute exp, const struct GNUNET_HashCode *key, const struct GNUNET_PeerIdentity *get_path, unsigned int get_path_length, const struct GNUNET_PeerIdentity *put_path, unsigned int put_path_length, enum GNUNET_BLOCK_Type type, size_t size, const void *data); /** * Perform an asynchronous GET operation on the DHT identified. See * also #GNUNET_BLOCK_evaluate. * * @param handle handle to the DHT service * @param type expected type of the response object * @param key the key to look up * @param desired_replication_level estimate of how many nearest peers this request should reach * @param options routing options for this message * @param xquery extended query data (can be NULL, depending on type) * @param xquery_size number of bytes in @a xquery * @param iter function to call on each result * @param iter_cls closure for @a iter * @return handle to stop the async get */ struct GNUNET_DHT_GetHandle * GNUNET_DHT_get_start (struct GNUNET_DHT_Handle *handle, enum GNUNET_BLOCK_Type type, const struct GNUNET_HashCode *key, uint32_t desired_replication_level, enum GNUNET_DHT_RouteOption options, const void *xquery, size_t xquery_size, GNUNET_DHT_GetIterator iter, void *iter_cls); /** * Tell the DHT not to return any of the following known results * to this client. * * @param get_handle get operation for which results should be filtered * @param num_results number of results to be blocked that are * provided in this call (size of the @a results array) * @param results array of hash codes over the `data` of the results * to be blocked */ void GNUNET_DHT_get_filter_known_results (struct GNUNET_DHT_GetHandle *get_handle, unsigned int num_results, const struct GNUNET_HashCode *results); /** * Stop async DHT-get. Frees associated resources. * * @param get_handle GET operation to stop. */ void GNUNET_DHT_get_stop (struct GNUNET_DHT_GetHandle *get_handle); /* *************** Extended API: monitor ******************* */ /** * Handle to monitor requests */ struct GNUNET_DHT_MonitorHandle; /** * Callback called on each GET request going through the DHT. * * @param cls Closure. * @param options Options, for instance RecordRoute, DemultiplexEverywhere. * @param type The type of data in the request. * @param hop_count Hop count so far. * @param path_length number of entries in @a path (or 0 if not recorded). * @param path peers on the GET path (or NULL if not recorded). * @param desired_replication_level Desired replication level. * @param key Key of the requested data. */ typedef void (*GNUNET_DHT_MonitorGetCB) (void *cls, enum GNUNET_DHT_RouteOption options, enum GNUNET_BLOCK_Type type, uint32_t hop_count, uint32_t desired_replication_level, unsigned int path_length, const struct GNUNET_PeerIdentity *path, const struct GNUNET_HashCode *key); /** * Callback called on each GET reply going through the DHT. * * @param cls Closure. * @param type The type of data in the result. * @param get_path Peers on GET path (or NULL if not recorded). * @param get_path_length number of entries in @a get_path. * @param put_path peers on the PUT path (or NULL if not recorded). * @param put_path_length number of entries in @a get_path. * @param exp Expiration time of the data. * @param key Key of the data. * @param data Pointer to the result data. * @param size Number of bytes in @a data. */ typedef void (*GNUNET_DHT_MonitorGetRespCB) (void *cls, enum GNUNET_BLOCK_Type type, const struct GNUNET_PeerIdentity *get_path, unsigned int get_path_length, const struct GNUNET_PeerIdentity *put_path, unsigned int put_path_length, struct GNUNET_TIME_Absolute exp, const struct GNUNET_HashCode *key, const void *data, size_t size); /** * Callback called on each PUT request going through the DHT. * * @param cls Closure. * @param options Options, for instance RecordRoute, DemultiplexEverywhere. * @param type The type of data in the request. * @param hop_count Hop count so far. * @param path_length number of entries in @a path (or 0 if not recorded). * @param path peers on the PUT path (or NULL if not recorded). * @param desired_replication_level Desired replication level. * @param exp Expiration time of the data. * @param key Key under which data is to be stored. * @param data Pointer to the data carried. * @param size Number of bytes in @a data. */ typedef void (*GNUNET_DHT_MonitorPutCB) (void *cls, enum GNUNET_DHT_RouteOption options, enum GNUNET_BLOCK_Type type, uint32_t hop_count, uint32_t desired_replication_level, unsigned int path_length, const struct GNUNET_PeerIdentity *path, struct GNUNET_TIME_Absolute exp, const struct GNUNET_HashCode *key, const void *data, size_t size); /** * Start monitoring the local DHT service. * * @param handle Handle to the DHT service. * @param type Type of blocks that are of interest. * @param key Key of data of interest, NULL for all. * @param get_cb Callback to process monitored get messages. * @param get_resp_cb Callback to process monitored get response messages. * @param put_cb Callback to process monitored put messages. * @param cb_cls Closure for callbacks * @return Handle to stop monitoring. */ struct GNUNET_DHT_MonitorHandle * GNUNET_DHT_monitor_start (struct GNUNET_DHT_Handle *handle, enum GNUNET_BLOCK_Type type, const struct GNUNET_HashCode *key, GNUNET_DHT_MonitorGetCB get_cb, GNUNET_DHT_MonitorGetRespCB get_resp_cb, GNUNET_DHT_MonitorPutCB put_cb, void *cb_cls); /** * Stop monitoring. * On return handle will no longer be valid, caller must not use it anymore. * * @param handle The handle to the monitor request returned by * #GNUNET_DHT_monitor_start(). */ void GNUNET_DHT_monitor_stop (struct GNUNET_DHT_MonitorHandle *handle); #if 0 /* keep Emacsens' auto-indent happy */ { #endif #ifdef __cplusplus } #endif #endif /** @} */ /* end of group dht */