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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,
97 struct GNUNET_MQ_Handle *mq);
101 * Method called whenever a peer disconnects.
104 * @param peer peer identity this notification is about
107 (*GNUNET_CORE_DisconnectEventHandler) (void *cls,
108 const struct GNUNET_PeerIdentity *peer,
113 * Functions with this signature are called whenever a message is
114 * received or transmitted.
116 * @param cls closure (set from #GNUNET_CORE_connect)
117 * @param peer the other peer involved (sender or receiver, NULL
118 * for loopback messages where we are both sender and receiver)
119 * @param message the actual message
120 * @return #GNUNET_OK to keep the connection open,
121 * #GNUNET_SYSERR to close connection to the peer (signal serious error)
124 (*GNUNET_CORE_MessageCallback) (void *cls,
125 const struct GNUNET_PeerIdentity *other,
126 const struct GNUNET_MessageHeader *message);
130 * Message handler. Each struct specifies how to handle on particular
131 * type of message received.
133 struct GNUNET_CORE_MessageHandler
136 * Function to call for messages of @e type.
138 GNUNET_CORE_MessageCallback callback;
141 * Type of the message this handler covers.
146 * Expected size of messages of this type. Use 0 for variable-size.
147 * If non-zero, messages of the given type will be discarded if they
148 * do not have the right size.
150 uint16_t expected_size;
156 * Function called after #GNUNET_CORE_connect has succeeded (or failed
157 * for good). Note that the private key of the peer is intentionally
158 * not exposed here; if you need it, your process should try to read
159 * the private key file directly (which should work if you are
160 * authorized...). Implementations of this function must not call
161 * #GNUNET_CORE_disconnect (other than by scheduling a new task to
165 * @param my_identity ID of this peer, NULL if we failed
168 (*GNUNET_CORE_StartupCallback) (void *cls,
169 const struct GNUNET_PeerIdentity *my_identity);
173 * Connect to the core service. Note that the connection may complete
174 * (or fail) asynchronously. This function primarily causes the given
175 * callback notification functions to be invoked whenever the
176 * specified event happens. The maximum number of queued
177 * notifications (queue length) is per client; the queue is shared
178 * across all types of notifications. So a slow client that registers
179 * for @a outbound_notify also risks missing @a inbound_notify messages.
180 * Certain events (such as connect/disconnect notifications) are not
181 * subject to queue size limitations.
183 * @param cfg configuration to use
184 * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
185 * @param init callback to call once we have successfully
186 * connected to the core service
187 * @param connects function to call on peer connect, can be NULL
188 * @param disconnects function to call on peer disconnect / timeout, can be NULL
189 * @param handlers callbacks for messages we care about, NULL-terminated
190 * note that the core is allowed to drop notifications about inbound
191 * messages if the client does not process them fast enough (for this
192 * notification type, a bounded queue is used)
193 * @return handle to the core service (only useful for disconnect until @a init is called),
194 * NULL on error (in this case, init is never called)
196 struct GNUNET_CORE_Handle *
197 GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
199 GNUNET_CORE_StartupCallback init,
200 GNUNET_CORE_ConnectEventHandler connects,
201 GNUNET_CORE_DisconnectEventHandler disconnects,
202 const struct GNUNET_MQ_MessageHandler *handlers);
206 * Disconnect from the core service.
208 * @param handle connection to core to disconnect
211 GNUNET_CORE_disconnect (struct GNUNET_CORE_Handle *handle);
215 * Inquire with CORE what options should be set for a message
216 * so that it is transmitted with the given @a priority and
217 * the given @a cork value.
219 * @param cork desired corking
220 * @param priority desired message priority
221 * @param[out] flags set to `flags` value for #GNUNET_MQ_set_options()
222 * @return `extra` argument to give to #GNUNET_MQ_set_options()
225 GNUNET_CORE_get_mq_options (int cork,
226 enum GNUNET_CORE_Priority priority,
231 * Obtain the message queue for a connected peer.
233 * @param h the core handle
234 * @param pid the identity of the peer
235 * @return NULL if @a pid is not connected
237 struct GNUNET_MQ_Handle *
238 GNUNET_CORE_get_mq (const struct GNUNET_CORE_Handle *h,
239 const struct GNUNET_PeerIdentity *pid);
243 * Handle for a transmission request.
245 struct GNUNET_CORE_TransmitHandle;
249 * Ask the core to call @a notify once it is ready to transmit the
250 * given number of bytes to the specified @a target. Must only be
251 * called after a connection to the respective peer has been
252 * established (and the client has been informed about this). You may
253 * have one request of this type pending for each connected peer at
254 * any time. If a peer disconnects, the application MUST call
255 * #GNUNET_CORE_notify_transmit_ready_cancel() on the respective
256 * transmission request, if one such request is pending.
258 * @param handle connection to core service
259 * @param cork is corking allowed for this transmission?
260 * @param priority how important is the message?
261 * @param maxdelay how long can the message wait? Only effective if @a cork is #GNUNET_YES
262 * @param target who should receive the message, never NULL (can be this peer's identity for loopback)
263 * @param notify_size how many bytes of buffer space does @a notify want?
264 * @param notify function to call when buffer space is available;
265 * will be called with NULL on timeout; clients MUST cancel
266 * all pending transmission requests DURING the disconnect
268 * @param notify_cls closure for @a notify
269 * @return non-NULL if the notify callback was queued,
270 * NULL if we can not even queue the request (request already pending);
271 * if NULL is returned, @a notify will NOT be called.
273 struct GNUNET_CORE_TransmitHandle *
274 GNUNET_CORE_notify_transmit_ready (struct GNUNET_CORE_Handle *handle,
276 enum GNUNET_CORE_Priority priority,
277 struct GNUNET_TIME_Relative maxdelay,
278 const struct GNUNET_PeerIdentity *target,
280 GNUNET_CONNECTION_TransmitReadyNotify notify,
285 * Cancel the specified transmission-ready notification.
287 * @param th handle that was returned by #GNUNET_CORE_notify_transmit_ready().
290 GNUNET_CORE_notify_transmit_ready_cancel (struct GNUNET_CORE_TransmitHandle *th);
294 * Handle to a CORE monitoring operation.
296 struct GNUNET_CORE_MonitorHandle;
300 * State machine for our P2P encryption handshake. Everyone starts in
301 * #GNUNET_CORE_KX_STATE_DOWN, if we receive the other peer's key
302 * (other peer initiated) we start in state
303 * #GNUNET_CORE_KX_STATE_KEY_RECEIVED (since we will immediately send
304 * our own); otherwise we start in #GNUNET_CORE_KX_STATE_KEY_SENT. If
305 * we get back a PONG from within either state, we move up to
306 * #GNUNET_CORE_KX_STATE_UP (the PONG will always be sent back
307 * encrypted with the key we sent to the other peer). Eventually,
308 * we will try to rekey, for this we will enter
309 * #GNUNET_CORE_KX_STATE_REKEY_SENT until the rekey operation is
310 * confirmed by a PONG from the other peer.
312 enum GNUNET_CORE_KxState
317 GNUNET_CORE_KX_STATE_DOWN,
320 * We've sent our session key.
322 GNUNET_CORE_KX_STATE_KEY_SENT,
325 * We've received the other peers session key.
327 GNUNET_CORE_KX_STATE_KEY_RECEIVED,
330 * The other peer has confirmed our session key + PING with a PONG
331 * message encrypted with his session key (which we got). Key
334 GNUNET_CORE_KX_STATE_UP,
337 * We're rekeying (or had a timeout), so we have sent the other peer
338 * our new ephemeral key, but we did not get a matching PONG yet.
339 * This is equivalent to being #GNUNET_CORE_KX_STATE_KEY_RECEIVED,
340 * except that the session is marked as 'up' with sessions (as we
341 * don't want to drop and re-establish P2P connections simply due to
344 GNUNET_CORE_KX_STATE_REKEY_SENT,
347 * Last state of a KX (when it is being terminated). Set
348 * just before CORE frees the internal state for this peer.
350 GNUNET_CORE_KX_PEER_DISCONNECT,
353 * This is not a state in a peer's state machine, but a special
354 * value used with the #GNUNET_CORE_MonitorCallback to indicate
355 * that we finished the initial iteration over the peers.
357 GNUNET_CORE_KX_ITERATION_FINISHED,
360 * This is not a state in a peer's state machine, but a special
361 * value used with the #GNUNET_CORE_MonitorCallback to indicate
362 * that we lost the connection to the CORE service (and will try
363 * to reconnect). If this happens, most likely the CORE service
364 * crashed and thus all connection state should be assumed lost.
366 GNUNET_CORE_KX_CORE_DISCONNECT
372 * Function called by the monitor callback whenever
373 * a peer's connection status changes.
376 * @param pid identity of the peer this update is about
377 * @param state current key exchange state of the peer
378 * @param timeout when does the current state expire
381 (*GNUNET_CORE_MonitorCallback)(void *cls,
382 const struct GNUNET_PeerIdentity *pid,
383 enum GNUNET_CORE_KxState state,
384 struct GNUNET_TIME_Absolute timeout);
388 * Monitor connectivity and KX status of all peers known to CORE.
389 * Calls @a peer_cb with the current status for each connected peer,
390 * and then once with NULL to indicate that all peers that are
391 * currently active have been handled. After that, the iteration
392 * continues until it is cancelled. Normal users of the CORE API are
393 * not expected to use this function. It is different in that it
394 * truly lists all connections (including those where the KX is in
395 * progress), not just those relevant to the application. This
396 * function is used by special applications for diagnostics.
398 * @param cfg configuration handle
399 * @param peer_cb function to call with the peer information
400 * @param peer_cb_cls closure for @a peer_cb
401 * @return NULL on error
403 struct GNUNET_CORE_MonitorHandle *
404 GNUNET_CORE_monitor_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
405 GNUNET_CORE_MonitorCallback peer_cb,
410 * Stop monitoring CORE activity.
412 * @param mh monitor to stop
415 GNUNET_CORE_monitor_stop (struct GNUNET_CORE_MonitorHandle *mh);
419 * Check if the given peer is currently connected. This function is for special
420 * cirumstances (GNUNET_TESTBED uses it), normal users of the CORE API are
421 * expected to track which peers are connected based on the connect/disconnect
422 * callbacks from #GNUNET_CORE_connect. This function is NOT part of the
423 * 'versioned', 'official' API. This function returns
424 * synchronously after looking in the CORE API cache.
426 * @param h the core handle
427 * @param pid the identity of the peer to check if it has been connected to us
428 * @return #GNUNET_YES if the peer is connected to us; #GNUNET_NO if not
431 GNUNET_CORE_is_peer_connected_sync (const struct GNUNET_CORE_Handle *h,
432 const struct GNUNET_PeerIdentity *pid);
436 * Create a message queue for sending messages to a peer with CORE.
437 * Messages may only be queued with #GNUNET_MQ_send once the init callback has
438 * been called for the given handle.
439 * There must only be one queue per peer for each core handle.
440 * The message queue can only be used to transmit messages,
441 * not to receive them.
443 * @param h the core handle
444 * @param target the target peer for this queue, may not be NULL
445 * @return a message queue for sending messages over the core handle
448 struct GNUNET_MQ_Handle *
449 GNUNET_CORE_mq_create (struct GNUNET_CORE_Handle *h,
450 const struct GNUNET_PeerIdentity *target);
453 #if 0 /* keep Emacsens' auto-indent happy */
460 /* ifndef GNUNET_CORE_SERVICE_H */
463 /** @} */ /* end of group core */
465 /* end of gnunet_core_service.h */