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3 Copyright (C) 2009-2017 GNUnet e.V.
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18 SPDX-License-Identifier: AGPL3.0-or-later
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
38 #if 0 /* keep Emacsens' auto-indent happy */
43 #include "gnunet_util_lib.h"
44 #include "gnunet_transport_service.h"
47 * Version number of GNUnet-core API.
49 #define GNUNET_CORE_VERSION 0x00000001
53 * Opaque handle to the service.
55 struct GNUNET_CORE_Handle;
59 * Method called whenever a given peer connects.
62 * @param peer peer identity this notification is about
63 * @return closure associated with @a peer. given to mq callbacks and
64 * #GNUNET_CORE_DisconnectEventHandler
66 typedef void *(*GNUNET_CORE_ConnectEventHandler) (
68 const struct GNUNET_PeerIdentity *peer,
69 struct GNUNET_MQ_Handle *mq);
73 * Method called whenever a peer disconnects.
76 * @param peer peer identity this notification is about
77 * @param peer_cls closure associated with peer. given in
78 * #GNUNET_CORE_ConnectEventHandler
80 typedef void (*GNUNET_CORE_DisconnectEventHandler) (
82 const struct GNUNET_PeerIdentity *peer,
87 * Function called after #GNUNET_CORE_connect has succeeded (or failed
88 * for good). Note that the private key of the peer is intentionally
89 * not exposed here; if you need it, your process should try to read
90 * the private key file directly (which should work if you are
91 * authorized...). Implementations of this function must not call
92 * #GNUNET_CORE_disconnect (other than by scheduling a new task to
96 * @param my_identity ID of this peer, NULL if we failed
98 typedef void (*GNUNET_CORE_StartupCallback) (
100 const struct GNUNET_PeerIdentity *my_identity);
104 * Connect to the core service. Note that the connection may complete
105 * (or fail) asynchronously. This function primarily causes the given
106 * callback notification functions to be invoked whenever the
107 * specified event happens. The maximum number of queued
108 * notifications (queue length) is per client; the queue is shared
109 * across all types of notifications. So a slow client that registers
110 * for @a outbound_notify also risks missing @a inbound_notify messages.
111 * Certain events (such as connect/disconnect notifications) are not
112 * subject to queue size limitations.
114 * @param cfg configuration to use
115 * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
116 * @param init callback to call once we have successfully
117 * connected to the core service
118 * @param connects function to call on peer connect, can be NULL
119 * @param disconnects function to call on peer disconnect / timeout, can be NULL
120 * @param handlers callbacks for messages we care about, NULL-terminated
121 * note that the core is allowed to drop notifications about inbound
122 * messages if the client does not process them fast enough (for this
123 * notification type, a bounded queue is used)
124 * @return handle to the core service (only useful for disconnect until @a init is called),
125 * NULL on error (in this case, init is never called)
127 struct GNUNET_CORE_Handle *
128 GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
130 GNUNET_CORE_StartupCallback init,
131 GNUNET_CORE_ConnectEventHandler connects,
132 GNUNET_CORE_DisconnectEventHandler disconnects,
133 const struct GNUNET_MQ_MessageHandler *handlers);
137 * Disconnect from the core service.
139 * @param handle connection to core to disconnect
142 GNUNET_CORE_disconnect (struct GNUNET_CORE_Handle *handle);
146 * Obtain the message queue for a connected peer.
148 * @param h the core handle
149 * @param pid the identity of the peer
150 * @return NULL if @a pid is not connected
152 struct GNUNET_MQ_Handle *
153 GNUNET_CORE_get_mq (const struct GNUNET_CORE_Handle *h,
154 const struct GNUNET_PeerIdentity *pid);
158 * Handle to a CORE monitoring operation.
160 struct GNUNET_CORE_MonitorHandle;
164 * State machine for our P2P encryption handshake. Everyone starts in
165 * #GNUNET_CORE_KX_STATE_DOWN, if we receive the other peer's key
166 * (other peer initiated) we start in state
167 * #GNUNET_CORE_KX_STATE_KEY_RECEIVED (since we will immediately send
168 * our own); otherwise we start in #GNUNET_CORE_KX_STATE_KEY_SENT. If
169 * we get back a PONG from within either state, we move up to
170 * #GNUNET_CORE_KX_STATE_UP (the PONG will always be sent back
171 * encrypted with the key we sent to the other peer). Eventually,
172 * we will try to rekey, for this we will enter
173 * #GNUNET_CORE_KX_STATE_REKEY_SENT until the rekey operation is
174 * confirmed by a PONG from the other peer.
176 enum GNUNET_CORE_KxState
181 GNUNET_CORE_KX_STATE_DOWN = 0,
184 * We've sent our session key.
186 GNUNET_CORE_KX_STATE_KEY_SENT,
189 * We've received the other peers session key.
191 GNUNET_CORE_KX_STATE_KEY_RECEIVED,
194 * The other peer has confirmed our session key + PING with a PONG
195 * message encrypted with their session key (which we got). Key
198 GNUNET_CORE_KX_STATE_UP,
201 * We're rekeying (or had a timeout), so we have sent the other peer
202 * our new ephemeral key, but we did not get a matching PONG yet.
203 * This is equivalent to being #GNUNET_CORE_KX_STATE_KEY_RECEIVED,
204 * except that the session is marked as 'up' with sessions (as we
205 * don't want to drop and re-establish P2P connections simply due to
208 GNUNET_CORE_KX_STATE_REKEY_SENT,
211 * Last state of a KX (when it is being terminated). Set
212 * just before CORE frees the internal state for this peer.
214 GNUNET_CORE_KX_PEER_DISCONNECT,
217 * This is not a state in a peer's state machine, but a special
218 * value used with the #GNUNET_CORE_MonitorCallback to indicate
219 * that we finished the initial iteration over the peers.
221 GNUNET_CORE_KX_ITERATION_FINISHED,
224 * This is not a state in a peer's state machine, but a special
225 * value used with the #GNUNET_CORE_MonitorCallback to indicate
226 * that we lost the connection to the CORE service (and will try
227 * to reconnect). If this happens, most likely the CORE service
228 * crashed and thus all connection state should be assumed lost.
230 GNUNET_CORE_KX_CORE_DISCONNECT
235 * Function called by the monitor callback whenever
236 * a peer's connection status changes.
239 * @param pid identity of the peer this update is about
240 * @param state current key exchange state of the peer
241 * @param timeout when does the current state expire
243 typedef void (*GNUNET_CORE_MonitorCallback) (
245 const struct GNUNET_PeerIdentity *pid,
246 enum GNUNET_CORE_KxState state,
247 struct GNUNET_TIME_Absolute timeout);
251 * Monitor connectivity and KX status of all peers known to CORE.
252 * Calls @a peer_cb with the current status for each connected peer,
253 * and then once with NULL to indicate that all peers that are
254 * currently active have been handled. After that, the iteration
255 * continues until it is cancelled. Normal users of the CORE API are
256 * not expected to use this function. It is different in that it
257 * truly lists all connections (including those where the KX is in
258 * progress), not just those relevant to the application. This
259 * function is used by special applications for diagnostics.
261 * @param cfg configuration handle
262 * @param peer_cb function to call with the peer information
263 * @param peer_cb_cls closure for @a peer_cb
264 * @return NULL on error
266 struct GNUNET_CORE_MonitorHandle *
267 GNUNET_CORE_monitor_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
268 GNUNET_CORE_MonitorCallback peer_cb,
273 * Stop monitoring CORE activity.
275 * @param mh monitor to stop
278 GNUNET_CORE_monitor_stop (struct GNUNET_CORE_MonitorHandle *mh);
282 * Check if the given peer is currently connected. This function is for special
283 * cirumstances (GNUNET_TESTBED uses it), normal users of the CORE API are
284 * expected to track which peers are connected based on the connect/disconnect
285 * callbacks from #GNUNET_CORE_connect. This function is NOT part of the
286 * 'versioned', 'official' API. This function returns
287 * synchronously after looking in the CORE API cache.
289 * @param h the core handle
290 * @param pid the identity of the peer to check if it has been connected to us
291 * @return #GNUNET_YES if the peer is connected to us; #GNUNET_NO if not
294 GNUNET_CORE_is_peer_connected_sync (const struct GNUNET_CORE_Handle *h,
295 const struct GNUNET_PeerIdentity *pid);
299 * Create a message queue for sending messages to a peer with CORE.
300 * Messages may only be queued with #GNUNET_MQ_send once the init callback has
301 * been called for the given handle.
302 * There must only be one queue per peer for each core handle.
303 * The message queue can only be used to transmit messages,
304 * not to receive them.
306 * @param h the core handle
307 * @param target the target peer for this queue, may not be NULL
308 * @return a message queue for sending messages over the core handle
311 struct GNUNET_MQ_Handle *
312 GNUNET_CORE_mq_create (struct GNUNET_CORE_Handle *h,
313 const struct GNUNET_PeerIdentity *target);
316 #if 0 /* keep Emacsens' auto-indent happy */
323 /* ifndef GNUNET_CORE_SERVICE_H */
326 /** @} */ /* end of group core */
328 /* end of gnunet_core_service.h */