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21 * @author Christian Grothoff
23 * @file include/gnunet_core_service.h
24 * Core service; the main API for encrypted P2P communications
26 * @defgroup core Core service
27 * Encrypted direct communication between peers
29 * @see [Documentation](https://gnunet.org/gnunet-core-subsystem)
33 #ifndef GNUNET_CORE_SERVICE_H
34 #define GNUNET_CORE_SERVICE_H
39 #if 0 /* keep Emacsens' auto-indent happy */
44 #include "gnunet_util_lib.h"
45 #include "gnunet_transport_service.h"
48 * Version number of GNUnet-core API.
50 #define GNUNET_CORE_VERSION 0x00000001
55 enum GNUNET_CORE_Priority
59 * Lowest priority, i.e. background traffic (i.e. fs)
61 GNUNET_CORE_PRIO_BACKGROUND = 0,
64 * Normal traffic (i.e. cadet/dv relay, DHT)
66 GNUNET_CORE_PRIO_BEST_EFFORT = 1,
69 * Urgent traffic (local peer, i.e. conversation).
71 GNUNET_CORE_PRIO_URGENT = 2,
74 * Highest priority, control traffic (i.e. NSE, Core/Cadet KX).
76 GNUNET_CORE_PRIO_CRITICAL_CONTROL = 3
83 * Opaque handle to the service.
85 struct GNUNET_CORE_Handle;
89 * Method called whenever a given peer connects.
92 * @param peer peer identity this notification is about
95 (*GNUNET_CORE_ConnectEventHandler) (void *cls,
96 const struct GNUNET_PeerIdentity *peer);
100 * Method called whenever a peer disconnects.
103 * @param peer peer identity this notification is about
106 (*GNUNET_CORE_DisconnectEventHandler) (void *cls,
107 const struct GNUNET_PeerIdentity *peer);
111 * Functions with this signature are called whenever a message is
112 * received or transmitted.
114 * @param cls closure (set from #GNUNET_CORE_connect)
115 * @param peer the other peer involved (sender or receiver, NULL
116 * for loopback messages where we are both sender and receiver)
117 * @param message the actual message
118 * @return #GNUNET_OK to keep the connection open,
119 * #GNUNET_SYSERR to close connection to the peer (signal serious error)
122 (*GNUNET_CORE_MessageCallback) (void *cls,
123 const struct GNUNET_PeerIdentity *other,
124 const struct GNUNET_MessageHeader *message);
128 * Message handler. Each struct specifies how to handle on particular
129 * type of message received.
131 struct GNUNET_CORE_MessageHandler
134 * Function to call for messages of @e type.
136 GNUNET_CORE_MessageCallback callback;
139 * Type of the message this handler covers.
144 * Expected size of messages of this type. Use 0 for variable-size.
145 * If non-zero, messages of the given type will be discarded if they
146 * do not have the right size.
148 uint16_t expected_size;
154 * Function called after #GNUNET_CORE_connect has succeeded (or failed
155 * for good). Note that the private key of the peer is intentionally
156 * not exposed here; if you need it, your process should try to read
157 * the private key file directly (which should work if you are
158 * authorized...). Implementations of this function must not call
159 * #GNUNET_CORE_disconnect (other than by scheduling a new task to
163 * @param my_identity ID of this peer, NULL if we failed
166 (*GNUNET_CORE_StartupCallback) (void *cls,
167 const struct GNUNET_PeerIdentity *my_identity);
171 * Connect to the core service. Note that the connection may complete
172 * (or fail) asynchronously. This function primarily causes the given
173 * callback notification functions to be invoked whenever the
174 * specified event happens. The maximum number of queued
175 * notifications (queue length) is per client; the queue is shared
176 * across all types of notifications. So a slow client that registers
177 * for @a outbound_notify also risks missing @a inbound_notify messages.
178 * Certain events (such as connect/disconnect notifications) are not
179 * subject to queue size limitations.
181 * @param cfg configuration to use
182 * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
183 * @param init callback to call once we have successfully
184 * connected to the core service
185 * @param connects function to call on peer connect, can be NULL
186 * @param disconnects function to call on peer disconnect / timeout, can be NULL
187 * @param inbound_notify function to call for all inbound messages, can be NULL
188 * note that the core is allowed to drop notifications about inbound
189 * messages if the client does not process them fast enough (for this
190 * notification type, a bounded queue is used)
191 * @param inbound_hdr_only set to #GNUNET_YES if @a inbound_notify will only read the
192 * `struct GNUNET_MessageHeader` and hence we do not need to give it the full message;
193 * can be used to improve efficiency, ignored if inbound_notify is NULL
194 * note that the core is allowed to drop notifications about inbound
195 * messages if the client does not process them fast enough (for this
196 * notification type, a bounded queue is used)
197 * @param outbound_notify function to call for all outbound messages, can be NULL;
198 * note that the core is allowed to drop notifications about outbound
199 * messages if the client does not process them fast enough (for this
200 * notification type, a bounded queue is used)
201 * @param outbound_hdr_only set to #GNUNET_YES if @a outbound_notify will only read the
202 * `struct GNUNET_MessageHeader` and hence we do not need to give it the full message
203 * can be used to improve efficiency, ignored if outbound_notify is NULL
204 * note that the core is allowed to drop notifications about outbound
205 * messages if the client does not process them fast enough (for this
206 * notification type, a bounded queue is used)
207 * @param handlers callbacks for messages we care about, NULL-terminated
208 * note that the core is allowed to drop notifications about inbound
209 * messages if the client does not process them fast enough (for this
210 * notification type, a bounded queue is used)
211 * @return handle to the core service (only useful for disconnect until @a init is called),
212 * NULL on error (in this case, init is never called)
214 struct GNUNET_CORE_Handle *
215 GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
217 GNUNET_CORE_StartupCallback init,
218 GNUNET_CORE_ConnectEventHandler connects,
219 GNUNET_CORE_DisconnectEventHandler disconnects,
220 GNUNET_CORE_MessageCallback inbound_notify,
221 int inbound_hdr_only,
222 GNUNET_CORE_MessageCallback outbound_notify,
223 int outbound_hdr_only,
224 const struct GNUNET_CORE_MessageHandler *handlers);
228 * Disconnect from the core service. This function can only
229 * be called *after* all pending #GNUNET_CORE_notify_transmit_ready
230 * requests have been explicitly cancelled.
232 * @param handle connection to core to disconnect
235 GNUNET_CORE_disconnect (struct GNUNET_CORE_Handle *handle);
239 * Handle for a transmission request.
241 struct GNUNET_CORE_TransmitHandle;
245 * Ask the core to call @a notify once it is ready to transmit the
246 * given number of bytes to the specified @a target. Must only be
247 * called after a connection to the respective peer has been
248 * established (and the client has been informed about this). You may
249 * have one request of this type pending for each connected peer at
250 * any time. If a peer disconnects, the application MUST call
251 * #GNUNET_CORE_notify_transmit_ready_cancel() on the respective
252 * transmission request, if one such request is pending.
254 * @param handle connection to core service
255 * @param cork is corking allowed for this transmission?
256 * @param priority how important is the message?
257 * @param maxdelay how long can the message wait? Only effective if @a cork is #GNUNET_YES
258 * @param target who should receive the message, never NULL (can be this peer's identity for loopback)
259 * @param notify_size how many bytes of buffer space does @a notify want?
260 * @param notify function to call when buffer space is available;
261 * will be called with NULL on timeout; clients MUST cancel
262 * all pending transmission requests DURING the disconnect
264 * @param notify_cls closure for @a notify
265 * @return non-NULL if the notify callback was queued,
266 * NULL if we can not even queue the request (request already pending);
267 * if NULL is returned, @a notify will NOT be called.
269 struct GNUNET_CORE_TransmitHandle *
270 GNUNET_CORE_notify_transmit_ready (struct GNUNET_CORE_Handle *handle,
272 enum GNUNET_CORE_Priority priority,
273 struct GNUNET_TIME_Relative maxdelay,
274 const struct GNUNET_PeerIdentity *target,
276 GNUNET_CONNECTION_TransmitReadyNotify notify,
281 * Cancel the specified transmission-ready notification.
283 * @param th handle that was returned by #GNUNET_CORE_notify_transmit_ready().
286 GNUNET_CORE_notify_transmit_ready_cancel (struct GNUNET_CORE_TransmitHandle *th);
290 * Handle to a CORE monitoring operation.
292 struct GNUNET_CORE_MonitorHandle;
296 * State machine for our P2P encryption handshake. Everyone starts in
297 * #GNUNET_CORE_KX_STATE_DOWN, if we receive the other peer's key
298 * (other peer initiated) we start in state
299 * #GNUNET_CORE_KX_STATE_KEY_RECEIVED (since we will immediately send
300 * our own); otherwise we start in #GNUNET_CORE_KX_STATE_KEY_SENT. If
301 * we get back a PONG from within either state, we move up to
302 * #GNUNET_CORE_KX_STATE_UP (the PONG will always be sent back
303 * encrypted with the key we sent to the other peer). Eventually,
304 * we will try to rekey, for this we will enter
305 * #GNUNET_CORE_KX_STATE_REKEY_SENT until the rekey operation is
306 * confirmed by a PONG from the other peer.
308 enum GNUNET_CORE_KxState
313 GNUNET_CORE_KX_STATE_DOWN,
316 * We've sent our session key.
318 GNUNET_CORE_KX_STATE_KEY_SENT,
321 * We've received the other peers session key.
323 GNUNET_CORE_KX_STATE_KEY_RECEIVED,
326 * The other peer has confirmed our session key + PING with a PONG
327 * message encrypted with his session key (which we got). Key
330 GNUNET_CORE_KX_STATE_UP,
333 * We're rekeying (or had a timeout), so we have sent the other peer
334 * our new ephemeral key, but we did not get a matching PONG yet.
335 * This is equivalent to being #GNUNET_CORE_KX_STATE_KEY_RECEIVED,
336 * except that the session is marked as 'up' with sessions (as we
337 * don't want to drop and re-establish P2P connections simply due to
340 GNUNET_CORE_KX_STATE_REKEY_SENT,
343 * Last state of a KX (when it is being terminated). Set
344 * just before CORE frees the internal state for this peer.
346 GNUNET_CORE_KX_PEER_DISCONNECT,
349 * This is not a state in a peer's state machine, but a special
350 * value used with the #GNUNET_CORE_MonitorCallback to indicate
351 * that we finished the initial iteration over the peers.
353 GNUNET_CORE_KX_ITERATION_FINISHED,
356 * This is not a state in a peer's state machine, but a special
357 * value used with the #GNUNET_CORE_MonitorCallback to indicate
358 * that we lost the connection to the CORE service (and will try
359 * to reconnect). If this happens, most likely the CORE service
360 * crashed and thus all connection state should be assumed lost.
362 GNUNET_CORE_KX_CORE_DISCONNECT
368 * Function called by the monitor callback whenever
369 * a peer's connection status changes.
372 * @param pid identity of the peer this update is about
373 * @param state current key exchange state of the peer
374 * @param timeout when does the current state expire
377 (*GNUNET_CORE_MonitorCallback)(void *cls,
378 const struct GNUNET_PeerIdentity *pid,
379 enum GNUNET_CORE_KxState state,
380 struct GNUNET_TIME_Absolute timeout);
384 * Monitor connectivity and KX status of all peers known to CORE.
385 * Calls @a peer_cb with the current status for each connected peer,
386 * and then once with NULL to indicate that all peers that are
387 * currently active have been handled. After that, the iteration
388 * continues until it is cancelled. Normal users of the CORE API are
389 * not expected to use this function. It is different in that it
390 * truly lists all connections (including those where the KX is in
391 * progress), not just those relevant to the application. This
392 * function is used by special applications for diagnostics.
394 * @param cfg configuration handle
395 * @param peer_cb function to call with the peer information
396 * @param peer_cb_cls closure for @a peer_cb
397 * @return NULL on error
399 struct GNUNET_CORE_MonitorHandle *
400 GNUNET_CORE_monitor_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
401 GNUNET_CORE_MonitorCallback peer_cb,
406 * Stop monitoring CORE activity.
408 * @param mh monitor to stop
411 GNUNET_CORE_monitor_stop (struct GNUNET_CORE_MonitorHandle *mh);
415 * Check if the given peer is currently connected. This function is for special
416 * cirumstances (GNUNET_TESTBED uses it), normal users of the CORE API are
417 * expected to track which peers are connected based on the connect/disconnect
418 * callbacks from #GNUNET_CORE_connect. This function is NOT part of the
419 * 'versioned', 'official' API. This function returns
420 * synchronously after looking in the CORE API cache.
422 * @param h the core handle
423 * @param pid the identity of the peer to check if it has been connected to us
424 * @return #GNUNET_YES if the peer is connected to us; #GNUNET_NO if not
427 GNUNET_CORE_is_peer_connected_sync (const struct GNUNET_CORE_Handle *h,
428 const struct GNUNET_PeerIdentity *pid);
432 * Create a message queue for sending messages to a peer with CORE.
433 * Messages may only be queued with #GNUNET_MQ_send once the init callback has
434 * been called for the given handle.
435 * There must only be one queue per peer for each core handle.
436 * The message queue can only be used to transmit messages,
437 * not to receive them.
439 * @param h the core handle
440 * @param target the target peer for this queue, may not be NULL
441 * @return a message queue for sending messages over the core handle
444 struct GNUNET_MQ_Handle *
445 GNUNET_CORE_mq_create (struct GNUNET_CORE_Handle *h,
446 const struct GNUNET_PeerIdentity *target);
449 #if 0 /* keep Emacsens' auto-indent happy */
456 /* ifndef GNUNET_CORE_SERVICE_H */
459 /** @} */ /* end of group core */
461 /* end of gnunet_core_service.h */