2 This file is part of GNUnet
3 (C) 2009 Christian Grothoff (and other contributing authors)
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6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 2, or (at your
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13 General Public License for more details.
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22 * @file transport/plugin_transport.h
23 * @brief API for the transport services. This header
24 * specifies the struct that is given to the plugin's entry
25 * method and the other struct that must be returned.
26 * Note that the destructors of transport plugins will
27 * be given the value returned by the constructor
28 * and is expected to return a NULL pointer.
31 * - consider moving DATA message (latency measurement)
32 * to service; avoids encapsulation overheads and
33 * would enable latency measurements for non-bidi
37 * @author Christian Grothoff
39 #ifndef PLUGIN_TRANSPORT_H
40 #define PLUGIN_TRANSPORT_H
42 #include "gnunet_configuration_lib.h"
43 #include "gnunet_scheduler_lib.h"
44 #include "gnunet_transport_service.h"
47 * Opaque internal context for a particular peer of the transport
48 * service. Plugins will be given a pointer to this type and, if
49 * cheaply possible, should pass this pointer back to the transport
50 * service whenever additional messages from the same peer are
56 * Function called by the transport for each received message.
57 * This function should also be called with "NULL" for the
58 * message to signal that the other peer disconnected.
61 * @param plugin_context value to pass to this plugin
62 * to respond to the given peer (use is optional,
63 * but may speed up processing)
64 * @param service_context value passed to the transport-service
65 * to identify the neighbour; will be NULL on the first
66 * call for a given peer
67 * @param latency estimated latency for communicating with the
68 * given peer; should be set to GNUNET_TIME_UNIT_FOREVER_REL
69 * until the transport has seen messages transmitted in
70 * BOTH directions (and hence been able to do an actual
71 * round-trip observation); a non-FOREVER latency is also used
72 * by the transport to know that communication in both directions
73 * using this one plugin actually works
74 * @param peer (claimed) identity of the other peer
75 * @param message the message, NULL if peer was disconnected
76 * @return the new service_context that the plugin should use
77 * for future receive calls for messages from this
80 typedef struct ReadyList *
81 (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls,
85 struct GNUNET_TIME_Relative
87 const struct GNUNET_PeerIdentity
89 const struct GNUNET_MessageHeader
94 * Function that will be called if we receive a validation
95 * of an address challenge that we transmitted to another
96 * peer. Note that the validation should only be considered
97 * acceptable if the challenge matches AND if the sender
98 * address is at least a plausible address for this peer
99 * (otherwise we may be seeing a MiM attack).
102 * @param name name of the transport that generated the address
103 * @param peer who responded to our challenge
104 * @param challenge the challenge number we presumably used
105 * @param sender_addr string describing our sender address (as observed
106 * by the other peer in human-readable format)
108 typedef void (*GNUNET_TRANSPORT_ValidationNotification) (void *cls,
110 const struct GNUNET_PeerIdentity *peer,
112 const char *sender_addr);
117 * Function that will be called for each address the transport
118 * is aware that it might be reachable under.
121 * @param name name of the transport that generated the address
122 * @param addr one of the addresses of the host, NULL for the last address
123 * the specific address format depends on the transport
124 * @param addrlen length of the address
125 * @param expires when should this address automatically expire?
127 typedef void (*GNUNET_TRANSPORT_AddressNotification) (void *cls,
137 * Function that will be called for each address obtained from the HELLO.
140 * @param name name of the transport that generated the address
141 * @param addr one of the addresses of the host, NULL for the last address
142 * the specific address format depends on the transport
143 * @param addrlen length of the address
145 typedef void (*GNUNET_TRANSPORT_AddressCallback) (void *cls,
152 * Function that allows a transport to query the known
153 * network addresses for a given peer.
156 * @param timeout after how long should we time out?
157 * @param target which peer are we looking for?
158 * @param iter function to call for each known address
159 * @param iter_cls closure for iter
161 typedef void (*GNUNET_TRANSPORT_LookupAddress) (void *cls,
162 struct GNUNET_TIME_Relative
165 GNUNET_PeerIdentity * target,
166 GNUNET_TRANSPORT_AddressCallback
167 iter, void *iter_cls);
171 * The transport service will pass a pointer to a struct
172 * of this type as the first and only argument to the
173 * entry point of each transport plugin.
175 struct GNUNET_TRANSPORT_PluginEnvironment
178 * Configuration to use.
180 const struct GNUNET_CONFIGURATION_Handle *cfg;
185 struct GNUNET_SCHEDULER_Handle *sched;
190 struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded *my_public_key;
195 struct GNUNET_CRYPTO_RsaPrivateKey *my_private_key;
198 * Identity of this peer.
200 const struct GNUNET_PeerIdentity *my_identity;
203 * Closure for the various callbacks.
208 * Function that should be called by the transport plugin
209 * whenever a message is received.
211 GNUNET_TRANSPORT_PluginReceiveCallback receive;
214 * Address lookup function.
216 GNUNET_TRANSPORT_LookupAddress lookup;
219 * Function that must be called by each plugin to notify the
220 * transport service about the addresses under which the transport
221 * provided by the plugin can be reached.
223 GNUNET_TRANSPORT_AddressNotification notify_address;
226 * Function that must be called by each plugin to notify the
227 * transport service about a successful validation of an
228 * address of another peer (or at least likely successful
231 GNUNET_TRANSPORT_ValidationNotification notify_validation;
234 * What is the default quota (in terms of incoming bytes per
235 * ms) for new connections?
237 uint32_t default_quota_in;
240 * What is the maximum number of connections that this transport
241 * should allow? Transports that do not have sessions (such as
242 * UDP) can ignore this value.
244 uint32_t max_connections;
250 * Function that can be used by the transport service to validate
251 * the address of another peer. Even if
252 * we already have a connection to this peer, this function is
253 * required to establish a new one.
256 * @param target who should receive this message
257 * @param challenge challenge code to use
258 * @param timeout how long should we try to transmit these?
259 * @param addrlen length of the address
260 * @param addr the address
261 * @return GNUNET_OK on success, GNUNET_SYSERR if the address
265 (*GNUNET_TRANSPORT_ValidationFunction) (void *cls,
267 GNUNET_PeerIdentity * target,
269 struct GNUNET_TIME_Relative
270 timeout, const void *addr,
274 * Function called by the GNUNET_TRANSPORT_TransmitFunction
278 * @param service_context value passed to the transport-service
279 * to identify the neighbour
280 * @param target who was the recipient of the message?
281 * @param result GNUNET_OK on success
282 * GNUNET_SYSERR if the target disconnected;
283 * disconnect will ALSO be signalled using
284 * the ReceiveCallback.
287 (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
290 const struct GNUNET_PeerIdentity *
294 * Function that can be used by the transport service to transmit
295 * a message using the plugin. Note that in the case of a
296 * peer disconnecting, the continuation MUST be called
297 * prior to the disconnect notification itself. This function
298 * will be called with this peer's HELLO message to initiate
299 * a fresh connection to another peer.
302 * @param plugin_context value we were asked to pass to this plugin
303 * to respond to the given peer (use is optional,
304 * but may speed up processing), can be NULL
305 * @param service_context value passed to the transport-service
306 * to identify the neighbour; NULL is used to indicate
307 * an urgent message. If the urgent message can not be
308 * scheduled for immediate transmission, the plugin is to
309 * call the continuation with failure immediately
310 * @param target who should receive this message
311 * @param priority how important is the message?
312 * @param msg the message to transmit
313 * @param timeout how long to wait at most for the transmission
314 * @param cont continuation to call once the message has
315 * been transmitted (or if the transport is ready
316 * for the next transmission call; or if the
317 * peer disconnected...); can be NULL
318 * @param cont_cls closure for cont
319 * @return plugin_context that should be used next time for
320 * sending messages to the specified peer
323 (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
324 void *plugin_context,
325 struct ReadyList * service_context,
326 const struct GNUNET_PeerIdentity *
328 unsigned int priority,
329 const struct GNUNET_MessageHeader *
331 struct GNUNET_TIME_Relative timeout,
332 GNUNET_TRANSPORT_TransmitContinuation
333 cont, void *cont_cls);
337 * Function that can be called to force a disconnect from the
338 * specified neighbour. This should also cancel all previously
339 * scheduled transmissions. Obviously the transmission may have been
340 * partially completed already, which is OK. The plugin is supposed
341 * to close the connection (if applicable) and no longer call the
342 * transmit continuation(s).
344 * Finally, plugin MUST NOT call the services's receive function to
345 * notify the service that the connection to the specified target was
346 * closed after a getting this call.
349 * @param plugin_context value we were asked to pass to this plugin
350 * to respond to the given peer (use is optional,
351 * but may speed up processing), can be NULL (if
352 * NULL was returned from the transmit function); note
353 * that use of NULL is dangerous since then this call may
354 * cancel any session with the target peer (including
355 * HELLO validation sessions), which is likely not what
357 * @param service_context must correspond to the service context
358 * of the corresponding Transmit call; the plugin should
359 * not cancel a send call made with a different service
360 * context pointer! Never NULL.
361 * @param target peer for which the last transmission is
365 (*GNUNET_TRANSPORT_CancelFunction) (void *cls,
366 void *plugin_context,
367 struct ReadyList * service_context,
368 const struct GNUNET_PeerIdentity *
373 * Function called by the pretty printer for the resolved address for
374 * each human-readable address obtained.
377 * @param hostname one of the names for the host, NULL
378 * on the last call to the callback
380 typedef void (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
381 const char *address);
385 * Convert the transports address to a nice, human-readable
389 * @param name name of the transport that generated the address
390 * @param addr one of the addresses of the host, NULL for the last address
391 * the specific address format depends on the transport
392 * @param addrlen length of the address
393 * @param numeric should (IP) addresses be displayed in numeric form?
394 * @param timeout after how long should we give up?
395 * @param asc function to call on each string
396 * @param asc_cls closure for asc
399 (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
404 struct GNUNET_TIME_Relative
406 GNUNET_TRANSPORT_AddressStringCallback
411 * Set a quota for receiving data from the given peer; this is a
412 * per-transport limit. The transport should limit its read/select
413 * calls to stay below the quota (in terms of incoming data).
416 * @param peer the peer for whom the quota is given
417 * @param quota_in quota for receiving/sending data in bytes per ms
420 (*GNUNET_TRANSPORT_SetQuota) (void *cls,
421 const struct GNUNET_PeerIdentity * target,
426 * Another peer has suggested an address for this
427 * peer and transport plugin. Check that this could be a valid
428 * address. If so, consider adding it to the list
431 * @param addr pointer to the address
432 * @param addrlen length of addr
433 * @return GNUNET_OK if this is a plausible address for this peer
437 (*GNUNET_TRANSPORT_SuggestAddress) (void *cls,
438 const void *addr, size_t addrlen);
441 * Each plugin is required to return a pointer to a struct of this
442 * type as the return value from its entry point.
444 struct GNUNET_TRANSPORT_PluginFunctions
448 * Closure for all of the callbacks.
453 * Function used to send a single message to a particular
454 * peer using the specified address. Used to validate
457 GNUNET_TRANSPORT_ValidationFunction validate;
460 * Function that the transport service will use to transmit data to
461 * another peer. May be null for plugins that only support
462 * receiving data. After this call, the plugin call the specified
463 * continuation with success or error before notifying us about the
464 * target having disconnected.
466 GNUNET_TRANSPORT_TransmitFunction send;
469 * Function that can be used to force the plugin to disconnect
470 * from the given peer and cancel all previous transmissions
471 * (and their continuationc).
473 GNUNET_TRANSPORT_CancelFunction cancel;
476 * Function to pretty-print addresses. NOTE: this function is not
477 * yet used by transport-service, but will be used in the future
478 * once the transport-API has been completed.
480 GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
483 * Function that the transport service can use to try to enforce a
484 * quota for the number of bytes received via this transport.
485 * Transports that can not refuse incoming data (such as UDP)
486 * are free to ignore these calls.
488 GNUNET_TRANSPORT_SetQuota set_receive_quota;
491 * Function that will be called if another peer suggested that
492 * we should use a particular address (since he is reaching
493 * us at that address) for this transport.
495 GNUNET_TRANSPORT_SuggestAddress address_suggested;
498 * Relative cost of this transport compared to others. This
499 * is supposed to be a static cost estimate which determines
500 * which plugins should not even be attempted if other,
501 * cheaper transports are already working. The idea is that
502 * the costs have roughly this relationship:
504 * TCP < UDP < HTTP == HTTPS < SMTP
507 unsigned int cost_estimate;