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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 * Method called whenever a given peer connects.
114 * @param peer peer identity this notification is about
117 (*GNUNET_CORE_ConnecTEventHandler) (void *cls,
118 const struct GNUNET_PeerIdentity *peer,
119 struct GNUNET_MQ_Handle *mq);
123 * Method called whenever a peer disconnects.
126 * @param peer peer identity this notification is about
129 (*GNUNET_CORE_DisconnecTEventHandler) (void *cls,
130 const struct GNUNET_PeerIdentity *peer,
135 * Functions with this signature are called whenever a message is
136 * received or transmitted.
138 * @param cls closure (set from #GNUNET_CORE_connect)
139 * @param peer the other peer involved (sender or receiver, NULL
140 * for loopback messages where we are both sender and receiver)
141 * @param message the actual message
142 * @return #GNUNET_OK to keep the connection open,
143 * #GNUNET_SYSERR to close connection to the peer (signal serious error)
146 (*GNUNET_CORE_MessageCallback) (void *cls,
147 const struct GNUNET_PeerIdentity *other,
148 const struct GNUNET_MessageHeader *message);
152 * Message handler. Each struct specifies how to handle on particular
153 * type of message received.
155 struct GNUNET_CORE_MessageHandler
158 * Function to call for messages of @e type.
160 GNUNET_CORE_MessageCallback callback;
163 * Type of the message this handler covers.
168 * Expected size of messages of this type. Use 0 for variable-size.
169 * If non-zero, messages of the given type will be discarded if they
170 * do not have the right size.
172 uint16_t expected_size;
178 * Function called after #GNUNET_CORE_connect has succeeded (or failed
179 * for good). Note that the private key of the peer is intentionally
180 * not exposed here; if you need it, your process should try to read
181 * the private key file directly (which should work if you are
182 * authorized...). Implementations of this function must not call
183 * #GNUNET_CORE_disconnect (other than by scheduling a new task to
187 * @param my_identity ID of this peer, NULL if we failed
190 (*GNUNET_CORE_StartupCallback) (void *cls,
191 const struct GNUNET_PeerIdentity *my_identity);
195 * Connect to the core service. Note that the connection may complete
196 * (or fail) asynchronously. This function primarily causes the given
197 * callback notification functions to be invoked whenever the
198 * specified event happens. The maximum number of queued
199 * notifications (queue length) is per client; the queue is shared
200 * across all types of notifications. So a slow client that registers
201 * for @a outbound_notify also risks missing @a inbound_notify messages.
202 * Certain events (such as connect/disconnect notifications) are not
203 * subject to queue size limitations.
205 * @param cfg configuration to use
206 * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
207 * @param init callback to call once we have successfully
208 * connected to the core service
209 * @param connects function to call on peer connect, can be NULL
210 * @param disconnects function to call on peer disconnect / timeout, can be NULL
211 * @param inbound_notify function to call for all inbound messages, can be NULL
212 * note that the core is allowed to drop notifications about inbound
213 * messages if the client does not process them fast enough (for this
214 * notification type, a bounded queue is used)
215 * @param inbound_hdr_only set to #GNUNET_YES if @a inbound_notify will only read the
216 * `struct GNUNET_MessageHeader` and hence we do not need to give it the full message;
217 * can be used to improve efficiency, ignored if inbound_notify is NULL
218 * note that the core is allowed to drop notifications about inbound
219 * messages if the client does not process them fast enough (for this
220 * notification type, a bounded queue is used)
221 * @param outbound_notify function to call for all outbound messages, can be NULL;
222 * note that the core is allowed to drop notifications about outbound
223 * messages if the client does not process them fast enough (for this
224 * notification type, a bounded queue is used)
225 * @param outbound_hdr_only set to #GNUNET_YES if @a outbound_notify will only read the
226 * `struct GNUNET_MessageHeader` and hence we do not need to give it the full message
227 * can be used to improve efficiency, ignored if outbound_notify is NULL
228 * note that the core is allowed to drop notifications about outbound
229 * messages if the client does not process them fast enough (for this
230 * notification type, a bounded queue is used)
231 * @param handlers callbacks for messages we care about, NULL-terminated
232 * note that the core is allowed to drop notifications about inbound
233 * messages if the client does not process them fast enough (for this
234 * notification type, a bounded queue is used)
235 * @return handle to the core service (only useful for disconnect until @a init is called),
236 * NULL on error (in this case, init is never called)
238 struct GNUNET_CORE_Handle *
239 GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
241 GNUNET_CORE_StartupCallback init,
242 GNUNET_CORE_ConnectEventHandler connects,
243 GNUNET_CORE_DisconnectEventHandler disconnects,
244 GNUNET_CORE_MessageCallback inbound_notify,
245 int inbound_hdr_only,
246 GNUNET_CORE_MessageCallback outbound_notify,
247 int outbound_hdr_only,
248 const struct GNUNET_CORE_MessageHandler *handlers);
252 * Connect to the core service. Note that the connection may complete
253 * (or fail) asynchronously. This function primarily causes the given
254 * callback notification functions to be invoked whenever the
255 * specified event happens. The maximum number of queued
256 * notifications (queue length) is per client; the queue is shared
257 * across all types of notifications. So a slow client that registers
258 * for @a outbound_notify also risks missing @a inbound_notify messages.
259 * Certain events (such as connect/disconnect notifications) are not
260 * subject to queue size limitations.
262 * @param cfg configuration to use
263 * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
264 * @param init callback to call once we have successfully
265 * connected to the core service
266 * @param connects function to call on peer connect, can be NULL
267 * @param disconnects function to call on peer disconnect / timeout, can be NULL
268 * @param handlers callbacks for messages we care about, NULL-terminated
269 * note that the core is allowed to drop notifications about inbound
270 * messages if the client does not process them fast enough (for this
271 * notification type, a bounded queue is used)
272 * @return handle to the core service (only useful for disconnect until @a init is called),
273 * NULL on error (in this case, init is never called)
275 struct GNUNET_CORE_Handle *
276 GNUNET_CORE_connecT (const struct GNUNET_CONFIGURATION_Handle *cfg,
278 GNUNET_CORE_StartupCallback init,
279 GNUNET_CORE_ConnecTEventHandler connects,
280 GNUNET_CORE_DisconnecTEventHandler disconnects,
281 const struct GNUNET_MQ_MessageHandler *handlers);
285 * Disconnect from the core service. This function can only
286 * be called *after* all pending #GNUNET_CORE_notify_transmit_ready
287 * requests have been explicitly cancelled.
289 * @param handle connection to core to disconnect
292 GNUNET_CORE_disconnect (struct GNUNET_CORE_Handle *handle);
296 * Handle for a transmission request.
298 struct GNUNET_CORE_TransmitHandle;
302 * Ask the core to call @a notify once it is ready to transmit the
303 * given number of bytes to the specified @a target. Must only be
304 * called after a connection to the respective peer has been
305 * established (and the client has been informed about this). You may
306 * have one request of this type pending for each connected peer at
307 * any time. If a peer disconnects, the application MUST call
308 * #GNUNET_CORE_notify_transmit_ready_cancel() on the respective
309 * transmission request, if one such request is pending.
311 * @param handle connection to core service
312 * @param cork is corking allowed for this transmission?
313 * @param priority how important is the message?
314 * @param maxdelay how long can the message wait? Only effective if @a cork is #GNUNET_YES
315 * @param target who should receive the message, never NULL (can be this peer's identity for loopback)
316 * @param notify_size how many bytes of buffer space does @a notify want?
317 * @param notify function to call when buffer space is available;
318 * will be called with NULL on timeout; clients MUST cancel
319 * all pending transmission requests DURING the disconnect
321 * @param notify_cls closure for @a notify
322 * @return non-NULL if the notify callback was queued,
323 * NULL if we can not even queue the request (request already pending);
324 * if NULL is returned, @a notify will NOT be called.
326 struct GNUNET_CORE_TransmitHandle *
327 GNUNET_CORE_notify_transmit_ready (struct GNUNET_CORE_Handle *handle,
329 enum GNUNET_CORE_Priority priority,
330 struct GNUNET_TIME_Relative maxdelay,
331 const struct GNUNET_PeerIdentity *target,
333 GNUNET_CONNECTION_TransmitReadyNotify notify,
338 * Cancel the specified transmission-ready notification.
340 * @param th handle that was returned by #GNUNET_CORE_notify_transmit_ready().
343 GNUNET_CORE_notify_transmit_ready_cancel (struct GNUNET_CORE_TransmitHandle *th);
347 * Handle to a CORE monitoring operation.
349 struct GNUNET_CORE_MonitorHandle;
353 * State machine for our P2P encryption handshake. Everyone starts in
354 * #GNUNET_CORE_KX_STATE_DOWN, if we receive the other peer's key
355 * (other peer initiated) we start in state
356 * #GNUNET_CORE_KX_STATE_KEY_RECEIVED (since we will immediately send
357 * our own); otherwise we start in #GNUNET_CORE_KX_STATE_KEY_SENT. If
358 * we get back a PONG from within either state, we move up to
359 * #GNUNET_CORE_KX_STATE_UP (the PONG will always be sent back
360 * encrypted with the key we sent to the other peer). Eventually,
361 * we will try to rekey, for this we will enter
362 * #GNUNET_CORE_KX_STATE_REKEY_SENT until the rekey operation is
363 * confirmed by a PONG from the other peer.
365 enum GNUNET_CORE_KxState
370 GNUNET_CORE_KX_STATE_DOWN,
373 * We've sent our session key.
375 GNUNET_CORE_KX_STATE_KEY_SENT,
378 * We've received the other peers session key.
380 GNUNET_CORE_KX_STATE_KEY_RECEIVED,
383 * The other peer has confirmed our session key + PING with a PONG
384 * message encrypted with his session key (which we got). Key
387 GNUNET_CORE_KX_STATE_UP,
390 * We're rekeying (or had a timeout), so we have sent the other peer
391 * our new ephemeral key, but we did not get a matching PONG yet.
392 * This is equivalent to being #GNUNET_CORE_KX_STATE_KEY_RECEIVED,
393 * except that the session is marked as 'up' with sessions (as we
394 * don't want to drop and re-establish P2P connections simply due to
397 GNUNET_CORE_KX_STATE_REKEY_SENT,
400 * Last state of a KX (when it is being terminated). Set
401 * just before CORE frees the internal state for this peer.
403 GNUNET_CORE_KX_PEER_DISCONNECT,
406 * This is not a state in a peer's state machine, but a special
407 * value used with the #GNUNET_CORE_MonitorCallback to indicate
408 * that we finished the initial iteration over the peers.
410 GNUNET_CORE_KX_ITERATION_FINISHED,
413 * This is not a state in a peer's state machine, but a special
414 * value used with the #GNUNET_CORE_MonitorCallback to indicate
415 * that we lost the connection to the CORE service (and will try
416 * to reconnect). If this happens, most likely the CORE service
417 * crashed and thus all connection state should be assumed lost.
419 GNUNET_CORE_KX_CORE_DISCONNECT
425 * Function called by the monitor callback whenever
426 * a peer's connection status changes.
429 * @param pid identity of the peer this update is about
430 * @param state current key exchange state of the peer
431 * @param timeout when does the current state expire
434 (*GNUNET_CORE_MonitorCallback)(void *cls,
435 const struct GNUNET_PeerIdentity *pid,
436 enum GNUNET_CORE_KxState state,
437 struct GNUNET_TIME_Absolute timeout);
441 * Monitor connectivity and KX status of all peers known to CORE.
442 * Calls @a peer_cb with the current status for each connected peer,
443 * and then once with NULL to indicate that all peers that are
444 * currently active have been handled. After that, the iteration
445 * continues until it is cancelled. Normal users of the CORE API are
446 * not expected to use this function. It is different in that it
447 * truly lists all connections (including those where the KX is in
448 * progress), not just those relevant to the application. This
449 * function is used by special applications for diagnostics.
451 * @param cfg configuration handle
452 * @param peer_cb function to call with the peer information
453 * @param peer_cb_cls closure for @a peer_cb
454 * @return NULL on error
456 struct GNUNET_CORE_MonitorHandle *
457 GNUNET_CORE_monitor_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
458 GNUNET_CORE_MonitorCallback peer_cb,
463 * Stop monitoring CORE activity.
465 * @param mh monitor to stop
468 GNUNET_CORE_monitor_stop (struct GNUNET_CORE_MonitorHandle *mh);
472 * Check if the given peer is currently connected. This function is for special
473 * cirumstances (GNUNET_TESTBED uses it), normal users of the CORE API are
474 * expected to track which peers are connected based on the connect/disconnect
475 * callbacks from #GNUNET_CORE_connect. This function is NOT part of the
476 * 'versioned', 'official' API. This function returns
477 * synchronously after looking in the CORE API cache.
479 * @param h the core handle
480 * @param pid the identity of the peer to check if it has been connected to us
481 * @return #GNUNET_YES if the peer is connected to us; #GNUNET_NO if not
484 GNUNET_CORE_is_peer_connected_sync (const struct GNUNET_CORE_Handle *h,
485 const struct GNUNET_PeerIdentity *pid);
489 * Create a message queue for sending messages to a peer with CORE.
490 * Messages may only be queued with #GNUNET_MQ_send once the init callback has
491 * been called for the given handle.
492 * There must only be one queue per peer for each core handle.
493 * The message queue can only be used to transmit messages,
494 * not to receive them.
496 * @param h the core handle
497 * @param target the target peer for this queue, may not be NULL
498 * @return a message queue for sending messages over the core handle
501 struct GNUNET_MQ_Handle *
502 GNUNET_CORE_mq_create (struct GNUNET_CORE_Handle *h,
503 const struct GNUNET_PeerIdentity *target);
506 #if 0 /* keep Emacsens' auto-indent happy */
513 /* ifndef GNUNET_CORE_SERVICE_H */
516 /** @} */ /* end of group core */
518 /* end of gnunet_core_service.h */