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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
93 * Characteristics are unknown (i.e. DV).
95 GNUNET_TRANSPORT_CC_UNKNOWN = 0,
98 * Transmission is reliabile (with ACKs), i.e. TCP/HTTP/HTTPS.
100 GNUNET_TRANSPORT_CC_RELIABLE = 1,
103 * Transmission is unreliable (i.e. UDP)
105 GNUNET_TRANSPORT_CC_UNRELIABLE = 2
110 * Function called when the transport service has received a
111 * backchannel message for this communicator (!) via a different
114 * Typically used to receive messages of type
115 * #GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_FC_LIMITS or
116 * #GNUNET_MESSAGE_TYPE_TRANSPORT_COMMUNICATOR_KX_CONFIRMATION
117 * as well as communicator-specific messages to assist with
121 * @param sender which peer sent the notification
124 typedef void (*GNUNET_TRANSPORT_CommunicatorNotify) (
126 const struct GNUNET_PeerIdentity *sender,
127 const struct GNUNET_MessageHeader *msg);
131 * Connect to the transport service.
133 * @param cfg configuration to use
134 * @param config_section section of the configuration to use for options
135 * @param addr_prefix address prefix for addresses supported by this
136 * communicator, could be NULL for incoming-only communicators
137 * @param cc what characteristics does the communicator have?
138 * @param mq_init function to call to initialize a message queue given
139 * the address of another peer, can be NULL if the
140 * communicator only supports receiving messages
141 * @param mq_init_cls closure for @a mq_init
142 * @param notify_cb function to pass backchannel messages to communicator
143 * @param notify_cb_cls closure for @a notify_cb
144 * @return NULL on error
146 struct GNUNET_TRANSPORT_CommunicatorHandle *
147 GNUNET_TRANSPORT_communicator_connect (
148 const struct GNUNET_CONFIGURATION_Handle *cfg,
149 const char *config_section_name,
150 const char *addr_prefix,
151 enum GNUNET_TRANSPORT_CommunicatorCharacteristics cc,
152 GNUNET_TRANSPORT_CommunicatorMqInit mq_init,
154 GNUNET_TRANSPORT_CommunicatorNotify notify_cb,
155 void *notify_cb_cls);
159 * Disconnect from the transport service.
161 * @param ch handle returned from connect
164 GNUNET_TRANSPORT_communicator_disconnect (
165 struct GNUNET_TRANSPORT_CommunicatorHandle *ch);
168 /* ************************* Receiving *************************** */
171 * Function called to notify communicator that we have received
172 * and processed the message. Used for flow control (if supported
173 * by the communicator).
176 * @param success #GNUNET_SYSERR on failure (try to disconnect/reset connection)
177 * #GNUNET_OK on success
179 typedef void (*GNUNET_TRANSPORT_MessageCompletedCallback) (void *cls,
184 * Notify transport service that the communicator has received
187 * @param handle connection to transport service
188 * @param sender presumed sender of the message (details to be checked
190 * @param msg the message
191 * @param expected_addr_validity how long does the communicator believe it
192 * will continue to be able to receive messages from the same address
193 * on which it received this message?
194 * @param cb function to call once handling the message is done, NULL if
195 * flow control is not supported by this communicator
196 * @param cb_cls closure for @a cb
197 * @return #GNUNET_OK if all is well, #GNUNET_NO if the message was
198 * immediately dropped due to memory limitations (communicator
199 * should try to apply back pressure),
200 * #GNUNET_SYSERR if the message could not be delivered because
201 * the tranport service is not yet up
204 GNUNET_TRANSPORT_communicator_receive (
205 struct GNUNET_TRANSPORT_CommunicatorHandle *handle,
206 const struct GNUNET_PeerIdentity *sender,
207 const struct GNUNET_MessageHeader *msg,
208 struct GNUNET_TIME_Relative expected_addr_validity,
209 GNUNET_TRANSPORT_MessageCompletedCallback cb,
213 /* ************************* Discovery *************************** */
216 * Handle returned to identify the internal data structure the transport
217 * API has created to manage a message queue to a particular peer.
219 struct GNUNET_TRANSPORT_QueueHandle;
223 * Possible states of a connection.
225 enum GNUNET_TRANSPORT_ConnectionStatus
228 * Connection is down.
230 GNUNET_TRANSPORT_CS_DOWN = -1,
233 * this is an outbound connection (transport initiated)
235 GNUNET_TRANSPORT_CS_OUTBOUND = 0,
238 * this is an inbound connection (communicator initiated)
240 GNUNET_TRANSPORT_CS_INBOUND = 1
245 * Notify transport service that a MQ became available due to an
246 * "inbound" connection or because the communicator discovered the
247 * presence of another peer.
249 * @param ch connection to transport service
250 * @param peer peer with which we can now communicate
251 * @param address address in human-readable format, 0-terminated, UTF-8
252 * @param mtu maximum message size supported by queue, 0 if
253 * sending is not supported, SIZE_MAX for no MTU
254 * @param nt which network type does the @a address belong to?
255 * @param cs what is the connection status of the queue?
256 * @param mq message queue of the @a peer
257 * @return API handle identifying the new MQ
259 struct GNUNET_TRANSPORT_QueueHandle *
260 GNUNET_TRANSPORT_communicator_mq_add (
261 struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
262 const struct GNUNET_PeerIdentity *peer,
265 enum GNUNET_NetworkType nt,
266 enum GNUNET_TRANSPORT_ConnectionStatus cs,
267 struct GNUNET_MQ_Handle *mq);
271 * Notify transport service that an MQ became unavailable due to a
272 * disconnect or timeout.
274 * @param qh handle for the queue that must be invalidated
277 GNUNET_TRANSPORT_communicator_mq_del (struct GNUNET_TRANSPORT_QueueHandle *qh);
281 * Internal representation of an address a communicator is
282 * currently providing for the transport service.
284 struct GNUNET_TRANSPORT_AddressIdentifier;
288 * Notify transport service about an address that this communicator
289 * provides for this peer.
291 * @param ch connection to transport service
292 * @param address our address in human-readable format, 0-terminated, UTF-8
293 * @param nt which network type does the address belong to?
294 * @param expiration when does the communicator forsee this address expiring?
296 struct GNUNET_TRANSPORT_AddressIdentifier *
297 GNUNET_TRANSPORT_communicator_address_add (
298 struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
300 enum GNUNET_NetworkType nt,
301 struct GNUNET_TIME_Relative expiration);
305 * Notify transport service about an address that this communicator
306 * no longer provides for this peer.
308 * @param ai address that is no longer provided
311 GNUNET_TRANSPORT_communicator_address_remove (
312 struct GNUNET_TRANSPORT_AddressIdentifier *ai);
316 * The communicator asks the transport service to route a message via
317 * a different path to another communicator service at another peer.
318 * This must only be done for special control traffic (as there is no
319 * flow control for this API), such as acknowledgements, and generally
320 * only be done if the communicator is uni-directional (i.e. cannot
321 * send the message back itself).
323 * While backchannel messages are signed and encrypted, communicators
324 * must protect against replay attacks when using this backchannel
327 * @param ch handle of this communicator
328 * @param pid peer to send the message to
329 * @param comm name of the communicator to send the message to
330 * @param header header of the message to transmit and pass via the
331 * notify-API to @a pid's communicator @a comm
334 GNUNET_TRANSPORT_communicator_notify (
335 struct GNUNET_TRANSPORT_CommunicatorHandle *ch,
336 const struct GNUNET_PeerIdentity *pid,
338 const struct GNUNET_MessageHeader *header);
341 #if 0 /* keep Emacsens' auto-indent happy */
348 /* ifndef GNUNET_TRANSPORT_COMMUNICATOR_SERVICE_H */
351 /** @} */ /* end of group */
353 /* end of gnunet_transport_communicator_service.h */