2 This file is part of GNUnet
3 (C) 2009, 2010 Christian Grothoff (and other contributing authors)
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6 it under the terms of the GNU General Public License as published
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22 * @file include/gnunet_transport_plugin.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.
29 * @author Christian Grothoff
31 #ifndef PLUGIN_TRANSPORT_H
32 #define PLUGIN_TRANSPORT_H
34 #include "gnunet_configuration_lib.h"
35 #include "gnunet_scheduler_lib.h"
36 #include "gnunet_statistics_service.h"
37 #include "gnunet_transport_service.h"
40 * Opaque pointer that plugins can use to distinguish specific
41 * connections to a given peer. Typically used by stateful plugins to
42 * allow the service to refer to specific streams instead of a more
43 * general notion of "some connection" to the given peer. This is
44 * useful since sometimes (i.e. for inbound TCP connections) a
45 * connection may not have an address that can be used for meaningful
46 * distinction between sessions to the same peer.
51 * Every 'struct Session' must begin with this header.
57 * Cached signature for PONG generation for the session. Do not use
60 struct GNUNET_CRYPTO_RsaSignature pong_signature;
63 * Expiration time for signature. Do not use in the plugin!
65 struct GNUNET_TIME_Absolute pong_sig_expires;
70 * Function that will be called whenever the plugin internally
71 * cleans up a session pointer and hence the service needs to
72 * discard all of those sessions as well. Plugins that do not
73 * use sessions can simply omit calling this function and always
74 * use NULL wherever a session pointer is needed.
77 * @param peer which peer was the session for
78 * @param session which session is being destoyed
80 typedef void (*GNUNET_TRANSPORT_SessionEnd) (void *cls,
81 const struct GNUNET_PeerIdentity *peer,
82 struct Session *session);
86 * Function called by the transport for each received message.
87 * This function should also be called with "NULL" for the
88 * message to signal that the other peer disconnected.
91 * @param peer (claimed) identity of the other peer
92 * @param message the message, NULL if we only care about
93 * learning about the delay until we should receive again -- FIXME!
94 * @param distance in overlay hops; use 1 unless DV (or 0 if message == NULL)
95 * @param session identifier used for this session (NULL for plugins
96 * that do not offer bi-directional communication to the sender
97 * using the same "connection")
98 * @param sender_address binary address of the sender (if we established the
99 * connection or are otherwise sure of it; should be NULL
100 * for inbound TCP/UDP connections since it it not clear
101 * that we could establish ourselves a connection to that
102 * IP address and get the same system)
103 * @param sender_address_len number of bytes in sender_address
104 * @return how long the plugin should wait until receiving more data
105 * (plugins that do not support this, can ignore the return value)
107 typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls,
109 GNUNET_PeerIdentity *
112 GNUNET_MessageHeader *
114 const struct GNUNET_TRANSPORT_ATS_Information *ats,
116 struct Session *session,
117 const char *sender_address,
118 uint16_t sender_address_len);
122 * Function that will be called for each address the transport
123 * is aware that it might be reachable under.
126 * @param add_remove should the address added (YES) or removed (NO) from the
127 * set of valid addresses?
128 * @param addr one of the addresses of the host
129 * the specific address format depends on the transport
130 * @param addrlen length of the address
132 typedef void (*GNUNET_TRANSPORT_AddressNotification) (void *cls,
139 * Function that will be called whenever the plugin receives data over
140 * the network and wants to determine how long it should wait until
141 * the next time it reads from the given peer. Note that some plugins
142 * (such as UDP) may not be able to wait (for a particular peer), so
143 * the waiting part is optional. Plugins that can wait should call
144 * this function, sleep the given amount of time, and call it again
145 * (with zero bytes read) UNTIL it returns zero and only then read.
148 * @param peer which peer did we read data from
149 * @param amount_recved number of bytes read (can be zero)
150 * @return how long to wait until reading more from this peer
151 * (to enforce inbound quotas)
153 typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_TrafficReport) (void *cls,
155 GNUNET_PeerIdentity *peer,
156 size_t amount_recved);
159 * Function called whenever the plugin has to notify ATS about costs for using this transport
161 * The cost will be passed as struct GNUNET_TRANSPORT_ATS_Cost_Information[]
162 * This array is 0-terminated, so the last element will be a pair:
163 * ((cost->cost_type==GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR) && cost->cost_value==0))
167 * @param addr peer address
168 * @param addrlen address length
169 * @param cost pointer to the first element of struct GNUNET_TRANSPORT_ATS_Cost_Information[]
171 typedef void (*GNUNET_TRANSPORT_CostReport) (void *cls,
172 const struct GNUNET_PeerIdentity *peer,
175 struct GNUNET_TRANSPORT_ATS_Information * cost);
178 * The transport service will pass a pointer to a struct
179 * of this type as the first and only argument to the
180 * entry point of each transport plugin.
182 struct GNUNET_TRANSPORT_PluginEnvironment
185 * Configuration to use.
187 const struct GNUNET_CONFIGURATION_Handle *cfg;
190 * Identity of this peer.
192 const struct GNUNET_PeerIdentity *my_identity;
195 * Pointer (!) to our HELLO message. Note that the address
196 * referred to "*our_hello" might change over time.
198 struct GNUNET_HELLO_Message *const*our_hello;
201 * Closure for the various callbacks.
206 * Handle for reporting statistics.
208 struct GNUNET_STATISTICS_Handle *stats;
211 * Function that should be called by the transport plugin
212 * whenever a message is received.
214 GNUNET_TRANSPORT_PluginReceiveCallback receive;
217 * Function that must be called by each plugin to notify the
218 * transport service about the addresses under which the transport
219 * provided by the plugin can be reached.
221 GNUNET_TRANSPORT_AddressNotification notify_address;
224 * Inform service about traffic received, get information
225 * about when we might be willing to receive more.
227 GNUNET_TRANSPORT_TrafficReport traffic_report;
230 * Function that must be called by the plugin when a non-NULL
231 * session handle stops being valid (is destroyed).
233 GNUNET_TRANSPORT_SessionEnd session_end;
236 * Inform service about costs for using this transport plugin
238 GNUNET_TRANSPORT_CostReport cost_report;
241 * What is the maximum number of connections that this transport
242 * should allow? Transports that do not have sessions (such as
243 * UDP) can ignore this value.
245 uint32_t max_connections;
251 * Function called by the GNUNET_TRANSPORT_TransmitFunction
252 * upon "completion". In the case that a peer disconnects,
253 * this function must be called for each pending request
254 * (with a 'failure' indication) AFTER notifying the service
255 * about the disconnect event (so that the service won't try
256 * to transmit more messages, believing the connection still
260 * @param target who was the recipient of the message?
261 * @param result GNUNET_OK on success
262 * GNUNET_SYSERR if the target disconnected;
263 * disconnect will ALSO be signalled using
264 * the ReceiveCallback.
267 (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
268 const struct GNUNET_PeerIdentity *
273 * Function that can be used by the transport service to transmit
274 * a message using the plugin. Note that in the case of a
275 * peer disconnecting, the continuation MUST be called
276 * prior to the disconnect notification itself. This function
277 * will be called with this peer's HELLO message to initiate
278 * a fresh connection to another peer.
281 * @param target who should receive this message
282 * @param msgbuf the message to transmit
283 * @param msgbuf_size number of bytes in 'msgbuf'
284 * @param priority how important is the message (most plugins will
285 * ignore message priority and just FIFO)
286 * @param timeout how long to wait at most for the transmission (does not
287 * require plugins to discard the message after the timeout,
288 * just advisory for the desired delay; most plugins will ignore
290 * @param session which session must be used (or NULL for "any")
291 * @param addr the address to use (can be NULL if the plugin
292 * is "on its own" (i.e. re-use existing TCP connection))
293 * @param addrlen length of the address in bytes
294 * @param force_address GNUNET_YES if the plugin MUST use the given address,
295 * GNUNET_NO means the plugin may use any other address and
296 * GNUNET_SYSERR means that only reliable existing
297 * bi-directional connections should be used (regardless
299 * @param cont continuation to call once the message has
300 * been transmitted (or if the transport is ready
301 * for the next transmission call; or if the
302 * peer disconnected...); can be NULL
303 * @param cont_cls closure for cont
304 * @return number of bytes used (on the physical network, with overheads);
305 * -1 on hard errors (i.e. address invalid); 0 is a legal value
306 * and does NOT mean that the message was not transmitted (DV)
309 (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
310 const struct GNUNET_PeerIdentity *
315 struct GNUNET_TIME_Relative timeout,
316 struct Session *session,
320 GNUNET_TRANSPORT_TransmitContinuation
321 cont, void *cont_cls);
325 * Function that can be called to force a disconnect from the
326 * specified neighbour. This should also cancel all previously
327 * scheduled transmissions. Obviously the transmission may have been
328 * partially completed already, which is OK. The plugin is supposed
329 * to close the connection (if applicable) and no longer call the
330 * transmit continuation(s).
332 * Finally, plugin MUST NOT call the services's receive function to
333 * notify the service that the connection to the specified target was
334 * closed after a getting this call.
337 * @param target peer for which the last transmission is
341 (*GNUNET_TRANSPORT_DisconnectFunction) (void *cls,
342 const struct GNUNET_PeerIdentity *
347 * Function called by the pretty printer for the resolved address for
348 * each human-readable address obtained.
351 * @param hostname one of the names for the host, NULL
352 * on the last call to the callback
354 typedef void (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
355 const char *address);
359 * Convert the transports address to a nice, human-readable
363 * @param name name of the transport that generated the address
364 * @param addr one of the addresses of the host, NULL for the last address
365 * the specific address format depends on the transport
366 * @param addrlen length of the address
367 * @param numeric should (IP) addresses be displayed in numeric form?
368 * @param timeout after how long should we give up?
369 * @param asc function to call on each string
370 * @param asc_cls closure for asc
373 (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
378 struct GNUNET_TIME_Relative
380 GNUNET_TRANSPORT_AddressStringCallback
385 * Another peer has suggested an address for this peer and transport
386 * plugin. Check that this could be a valid address. This function
387 * is not expected to 'validate' the address in the sense of trying to
388 * connect to it but simply to see if the binary format is technically
389 * legal for establishing a connection to this peer (and make sure that
390 * the address really corresponds to our network connection/settings
391 * and not some potential man-in-the-middle).
393 * @param addr pointer to the address
394 * @param addrlen length of addr
395 * @return GNUNET_OK if this is a plausible address for this peer
396 * and transport, GNUNET_SYSERR if not
399 (*GNUNET_TRANSPORT_CheckAddress) (void *cls,
400 const void *addr, size_t addrlen);
404 * Function called for a quick conversion of the binary address to
405 * a numeric address. Note that the caller must not free the
406 * address and that the next call to this function is allowed
407 * to override the address again.
410 * @param addr binary address
411 * @param addr_len length of the address
412 * @return string representing the same address
414 typedef const char* (*GNUNET_TRANSPORT_AddressToString) (void *cls,
420 * Each plugin is required to return a pointer to a struct of this
421 * type as the return value from its entry point.
423 struct GNUNET_TRANSPORT_PluginFunctions
427 * Closure for all of the callbacks.
432 * Function that the transport service will use to transmit data to
433 * another peer. May be NULL for plugins that only support
434 * receiving data. After this call, the plugin call the specified
435 * continuation with success or error before notifying us about the
436 * target having disconnected.
438 GNUNET_TRANSPORT_TransmitFunction send;
441 * Function that can be used to force the plugin to disconnect from
442 * the given peer and cancel all previous transmissions (and their
443 * continuations). Note that if the transport does not have
444 * sessions / persistent connections (for example, UDP), this
445 * function may very well do nothing.
447 GNUNET_TRANSPORT_DisconnectFunction disconnect;
450 * Function to pretty-print addresses. NOTE: this function is not
451 * yet used by transport-service, but will be used in the future
452 * once the transport-API has been completed.
454 GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
457 * Function that will be called to check if a binary address
458 * for this plugin is well-formed and corresponds to an
459 * address for THIS peer (as per our configuration). Naturally,
460 * if absolutely necessary, plugins can be a bit conservative in
461 * their answer, but in general plugins should make sure that the
462 * address does not redirect traffic to a 3rd party that might
463 * try to man-in-the-middle our traffic.
465 GNUNET_TRANSPORT_CheckAddress check_address;
468 * Function that will be called to convert a binary address
469 * to a string (numeric conversion only).
471 GNUNET_TRANSPORT_AddressToString address_to_string;