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22 * @author Christian Grothoff
25 * API of the transport service towards the communicator processes.
27 * @defgroup transport TRANSPORT service
28 * Low-level communication with other peers
30 * @see [Documentation](https://gnunet.org/transport-service)
35 #ifndef GNUNET_TRANSPORT_COMMUNICATION_SERVICE_H
36 #define GNUNET_TRANSPORT_COMMUNICATION_SERVICE_H
40 #if 0 /* keep Emacsens' auto-indent happy */
45 #include "gnunet_util_lib.h"
46 #include "gnunet_nt_lib.h"
49 * Version number of the transport communication API.
51 #define GNUNET_TRANSPORT_COMMUNICATION_VERSION 0x00000000
55 * Function called by the transport service to initialize a
56 * message queue given address information about another peer.
57 * If and when the communication channel is established, the
58 * communicator must call #GNUNET_TRANSPORT_communicator_mq_add()
59 * to notify the service that the channel is now up. It is
60 * the responsibility of the communicator to manage sane
61 * retries and timeouts for any @a peer/@a address combination
62 * provided by the transport service. Timeouts and retries
63 * do not need to be signalled to the transport service.
66 * @param peer identity of the other peer
67 * @param address where to send the message, human-readable
68 * communicator-specific format, 0-terminated, UTF-8
69 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the provided address is
72 typedef int (*GNUNET_TRANSPORT_CommunicatorMqInit) (
74 const struct GNUNET_PeerIdentity *peer,
79 * Opaque handle to the transport service for communicators.
81 struct GNUNET_TRANSPORT_CommunicatorHandle;
85 * What characteristics does this communicator have?
87 * FIXME: may want to distinguish bi-directional as well,
88 * should we define a bit for that? Needed in DV logic (handle_dv_learn)!
90 enum GNUNET_TRANSPORT_CommunicatorCharacteristics
94 * Characteristics are unknown (i.e. DV).
96 GNUNET_TRANSPORT_CC_UNKNOWN = 0,
99 * Transmission is reliabile (with ACKs), i.e. TCP/HTTP/HTTPS.
101 GNUNET_TRANSPORT_CC_RELIABLE = 1,
104 * Transmission is unreliable (i.e. UDP)
106 GNUNET_TRANSPORT_CC_UNRELIABLE = 2
112 * Function called when the transport service has received a
113 * backchannel message for this communicator (!) via a different
116 * Typically used to receive messages of type
117 * #GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_FC_LIMITS or
118 * #GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_KX_CONFIRMATION
119 * as well as communicator-specific messages to assist with
123 * @param sender which peer sent the notification
126 typedef void (*GNUNET_TRANSPORT_CommunicatorNotify) (
128 const struct GNUNET_PeerIdentity *sender,
129 const struct GNUNET_MessageHeader *msg);
133 * Connect to the transport service.
135 * @param cfg configuration to use
136 * @param config_section section of the configuration to use for options
137 * @param addr_prefix address prefix for addresses supported by this
138 * communicator, could be NULL for incoming-only communicators
139 * @param cc what characteristics does the communicator have?
140 * @param mq_init function to call to initialize a message queue given
141 * the address of another peer, can be NULL if the
142 * communicator only supports receiving messages
143 * @param mq_init_cls closure for @a mq_init
144 * @param notify_cb function to pass backchannel messages to communicator
145 * @param notify_cb_cls closure for @a notify_cb
146 * @return NULL on error
148 struct GNUNET_TRANSPORT_CommunicatorHandle *
149 GNUNET_TRANSPORT_communicator_connect (
150 const struct GNUNET_CONFIGURATION_Handle *cfg,
151 const char *config_section_name,
152 const char *addr_prefix,
153 enum GNUNET_TRANSPORT_CommunicatorCharacteristics cc,
154 GNUNET_TRANSPORT_CommunicatorMqInit mq_init,
156 GNUNET_TRANSPORT_CommunicatorNotify notify_cb,
157 void *notify_cb_cls);
161 * Disconnect from the transport service.
163 * @param ch handle returned from connect
166 GNUNET_TRANSPORT_communicator_disconnect (
167 struct GNUNET_TRANSPORT_CommunicatorHandle *ch);
170 /* ************************* Receiving *************************** */
173 * Function called to notify communicator that we have received
174 * and processed the message. Used for flow control (if supported
175 * by the communicator).
178 * @param success #GNUNET_SYSERR on failure (try to disconnect/reset connection)
179 * #GNUNET_OK on success
181 typedef void (*GNUNET_TRANSPORT_MessageCompletedCallback) (void *cls,
186 * Notify transport service that the communicator has received
189 * @param handle connection to transport service
190 * @param sender presumed sender of the message (details to be checked
192 * @param msg the message
193 * @param expected_addr_validity how long does the communicator believe it
194 * will continue to be able to receive messages from the same address
195 * on which it received this message?
196 * @param cb function to call once handling the message is done, NULL if
197 * flow control is not supported by this communicator
198 * @param cb_cls closure for @a cb
199 * @return #GNUNET_OK if all is well, #GNUNET_NO if the message was
200 * immediately dropped due to memory limitations (communicator
201 * should try to apply back pressure),
202 * #GNUNET_SYSERR if the message could not be delivered because
203 * the tranport service is not yet up
206 GNUNET_TRANSPORT_communicator_receive (
207 struct GNUNET_TRANSPORT_CommunicatorHandle *handle,
208 const struct GNUNET_PeerIdentity *sender,
209 const struct GNUNET_MessageHeader *msg,
210 struct GNUNET_TIME_Relative expected_addr_validity,
211 GNUNET_TRANSPORT_MessageCompletedCallback cb,
215 /* ************************* Discovery *************************** */
218 * Handle returned to identify the internal data structure the transport
219 * API has created to manage a message queue to a particular peer.
221 struct GNUNET_TRANSPORT_QueueHandle;
225 * Possible states of a connection.
227 enum GNUNET_TRANSPORT_ConnectionStatus
231 * Connection is down.
233 GNUNET_TRANSPORT_CS_DOWN = -1,
236 * this is an outbound connection (transport initiated)
238 GNUNET_TRANSPORT_CS_OUTBOUND = 0,
241 * this is an inbound connection (communicator initiated)
243 GNUNET_TRANSPORT_CS_INBOUND = 1
248 * Notify transport service that a MQ became available due to an
249 * "inbound" connection or because the communicator discovered the
250 * presence of another peer.
252 * @param ch connection to transport service
253 * @param peer peer with which we can now communicate
254 * @param address address in human-readable format, 0-terminated, UTF-8
255 * @param mtu maximum message size supported by queue, 0 if
256 * sending is not supported, SIZE_MAX for no MTU
257 * @param nt which network type does the @a address belong to?
258 * @param cs what is the connection status of the queue?
259 * @param mq message queue of the @a peer
260 * @return API handle identifying the new MQ
262 struct GNUNET_TRANSPORT_QueueHandle *
263 GNUNET_TRANSPORT_communicator_mq_add (
264 struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
265 const struct GNUNET_PeerIdentity *peer,
268 enum GNUNET_NetworkType nt,
269 enum GNUNET_TRANSPORT_ConnectionStatus cs,
270 struct GNUNET_MQ_Handle *mq);
274 * Notify transport service that an MQ became unavailable due to a
275 * disconnect or timeout.
277 * @param qh handle for the queue that must be invalidated
280 GNUNET_TRANSPORT_communicator_mq_del (struct GNUNET_TRANSPORT_QueueHandle *qh);
284 * Internal representation of an address a communicator is
285 * currently providing for the transport service.
287 struct GNUNET_TRANSPORT_AddressIdentifier;
291 * Notify transport service about an address that this communicator
292 * provides for this peer.
294 * @param ch connection to transport service
295 * @param address our address in human-readable format, 0-terminated, UTF-8
296 * @param nt which network type does the address belong to?
297 * @param expiration when does the communicator forsee this address expiring?
299 struct GNUNET_TRANSPORT_AddressIdentifier *
300 GNUNET_TRANSPORT_communicator_address_add (
301 struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
303 enum GNUNET_NetworkType nt,
304 struct GNUNET_TIME_Relative expiration);
308 * Notify transport service about an address that this communicator
309 * no longer provides for this peer.
311 * @param ai address that is no longer provided
314 GNUNET_TRANSPORT_communicator_address_remove (
315 struct GNUNET_TRANSPORT_AddressIdentifier *ai);
319 * The communicator asks the transport service to route a message via
320 * a different path to another communicator service at another peer.
321 * This must only be done for special control traffic (as there is no
322 * flow control for this API), such as acknowledgements, and generally
323 * only be done if the communicator is uni-directional (i.e. cannot
324 * send the message back itself).
326 * While backchannel messages are signed and encrypted, communicators
327 * must protect against replay attacks when using this backchannel
330 * @param ch handle of this communicator
331 * @param pid peer to send the message to
332 * @param comm name of the communicator to send the message to
333 * @param header header of the message to transmit and pass via the
334 * notify-API to @a pid's communicator @a comm
337 GNUNET_TRANSPORT_communicator_notify (
338 struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
339 const struct GNUNET_PeerIdentity *pid,
341 const struct GNUNET_MessageHeader *header);
344 #if 0 /* keep Emacsens' auto-indent happy */
351 /* ifndef GNUNET_TRANSPORT_COMMUNICATOR_SERVICE_H */
354 /** @} */ /* end of group */
356 /* end of gnunet_transport_communicator_service.h */