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
7 by the Free Software Foundation; either version 3, or (at your
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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 name name of the transport that generated the address
127 * @param addr one of the addresses of the host, NULL for the last address
128 * the specific address format depends on the transport
129 * @param addrlen length of the address
130 * @param expires when should this address automatically expire?
132 typedef void (*GNUNET_TRANSPORT_AddressNotification) (void *cls,
141 * Function that will be called whenever the plugin receives data over
142 * the network and wants to determine how long it should wait until
143 * the next time it reads from the given peer. Note that some plugins
144 * (such as UDP) may not be able to wait (for a particular peer), so
145 * the waiting part is optional. Plugins that can wait should call
146 * this function, sleep the given amount of time, and call it again
147 * (with zero bytes read) UNTIL it returns zero and only then read.
150 * @param peer which peer did we read data from
151 * @param amount_recved number of bytes read (can be zero)
152 * @return how long to wait until reading more from this peer
153 * (to enforce inbound quotas)
155 typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_TrafficReport) (void *cls,
157 GNUNET_PeerIdentity *peer,
158 size_t amount_recved);
161 * Function called whenever the plugin has to notify ATS about costs for using this transport
163 * The cost will be passed as struct GNUNET_TRANSPORT_ATS_Cost_Information[]
164 * This array is 0-terminated, so the last element will be a pair:
165 * ((cost->cost_type==GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR) && cost->cost_value==0))
169 * @param addr peer address
170 * @param addrlen address length
171 * @param cost pointer to the first element of struct GNUNET_TRANSPORT_ATS_Cost_Information[]
173 typedef void (*GNUNET_TRANSPORT_CostReport) (void *cls,
174 const struct GNUNET_PeerIdentity *peer,
177 struct GNUNET_TRANSPORT_ATS_Information * cost);
180 * The transport service will pass a pointer to a struct
181 * of this type as the first and only argument to the
182 * entry point of each transport plugin.
184 struct GNUNET_TRANSPORT_PluginEnvironment
187 * Configuration to use.
189 const struct GNUNET_CONFIGURATION_Handle *cfg;
192 * Identity of this peer.
194 const struct GNUNET_PeerIdentity *my_identity;
197 * Pointer (!) to our HELLO message. Note that the address
198 * referred to "*our_hello" might change over time.
200 struct GNUNET_HELLO_Message *const*our_hello;
203 * Closure for the various callbacks.
208 * Handle for reporting statistics.
210 struct GNUNET_STATISTICS_Handle *stats;
213 * Function that should be called by the transport plugin
214 * whenever a message is received.
216 GNUNET_TRANSPORT_PluginReceiveCallback receive;
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 * Inform service about traffic received, get information
227 * about when we might be willing to receive more.
229 GNUNET_TRANSPORT_TrafficReport traffic_report;
232 * Function that must be called by the plugin when a non-NULL
233 * session handle stops being valid (is destroyed).
235 GNUNET_TRANSPORT_SessionEnd session_end;
238 * Inform service about costs for using this transport plugin
240 GNUNET_TRANSPORT_CostReport cost_report;
243 * What is the maximum number of connections that this transport
244 * should allow? Transports that do not have sessions (such as
245 * UDP) can ignore this value.
247 uint32_t max_connections;
253 * Function called by the GNUNET_TRANSPORT_TransmitFunction
257 * @param target who was the recipient of the message?
258 * @param result GNUNET_OK on success
259 * GNUNET_SYSERR if the target disconnected;
260 * disconnect will ALSO be signalled using
261 * the ReceiveCallback.
264 (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
265 const struct GNUNET_PeerIdentity *
270 * Function that can be used by the transport service to transmit
271 * a message using the plugin. Note that in the case of a
272 * peer disconnecting, the continuation MUST be called
273 * prior to the disconnect notification itself. This function
274 * will be called with this peer's HELLO message to initiate
275 * a fresh connection to another peer.
278 * @param target who should receive this message
279 * @param msgbuf the message to transmit
280 * @param msgbuf_size number of bytes in 'msgbuf'
281 * @param priority how important is the message (most plugins will
282 * ignore message priority and just FIFO)
283 * @param timeout how long to wait at most for the transmission (does not
284 * require plugins to discard the message after the timeout,
285 * just advisory for the desired delay; most plugins will ignore
287 * @param session which session must be used (or NULL for "any")
288 * @param addr the address to use (can be NULL if the plugin
289 * is "on its own" (i.e. re-use existing TCP connection))
290 * @param addrlen length of the address in bytes
291 * @param force_address GNUNET_YES if the plugin MUST use the given address,
292 * GNUNET_NO means the plugin may use any other address and
293 * GNUNET_SYSERR means that only reliable existing
294 * bi-directional connections should be used (regardless
296 * @param cont continuation to call once the message has
297 * been transmitted (or if the transport is ready
298 * for the next transmission call; or if the
299 * peer disconnected...); can be NULL
300 * @param cont_cls closure for cont
301 * @return number of bytes used (on the physical network, with overheads);
302 * -1 on hard errors (i.e. address invalid); 0 is a legal value
303 * and does NOT mean that the message was not transmitted (DV)
306 (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
307 const struct GNUNET_PeerIdentity *
312 struct GNUNET_TIME_Relative timeout,
313 struct Session *session,
317 GNUNET_TRANSPORT_TransmitContinuation
318 cont, void *cont_cls);
322 * Function that can be called to force a disconnect from the
323 * specified neighbour. This should also cancel all previously
324 * scheduled transmissions. Obviously the transmission may have been
325 * partially completed already, which is OK. The plugin is supposed
326 * to close the connection (if applicable) and no longer call the
327 * transmit continuation(s).
329 * Finally, plugin MUST NOT call the services's receive function to
330 * notify the service that the connection to the specified target was
331 * closed after a getting this call.
334 * @param target peer for which the last transmission is
338 (*GNUNET_TRANSPORT_DisconnectFunction) (void *cls,
339 const struct GNUNET_PeerIdentity *
344 * Function called by the pretty printer for the resolved address for
345 * each human-readable address obtained.
348 * @param hostname one of the names for the host, NULL
349 * on the last call to the callback
351 typedef void (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
352 const char *address);
356 * Convert the transports address to a nice, human-readable
360 * @param name name of the transport that generated the address
361 * @param addr one of the addresses of the host, NULL for the last address
362 * the specific address format depends on the transport
363 * @param addrlen length of the address
364 * @param numeric should (IP) addresses be displayed in numeric form?
365 * @param timeout after how long should we give up?
366 * @param asc function to call on each string
367 * @param asc_cls closure for asc
370 (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
375 struct GNUNET_TIME_Relative
377 GNUNET_TRANSPORT_AddressStringCallback
382 * Another peer has suggested an address for this peer and transport
383 * plugin. Check that this could be a valid address. This function
384 * is not expected to 'validate' the address in the sense of trying to
385 * connect to it but simply to see if the binary format is technically
386 * legal for establishing a connection to this peer (and make sure that
387 * the address really corresponds to our network connection/settings
388 * and not some potential man-in-the-middle).
390 * @param addr pointer to the address
391 * @param addrlen length of addr
392 * @return GNUNET_OK if this is a plausible address for this peer
393 * and transport, GNUNET_SYSERR if not
396 (*GNUNET_TRANSPORT_CheckAddress) (void *cls,
397 const void *addr, size_t addrlen);
401 * Function called for a quick conversion of the binary address to
402 * a numeric address. Note that the caller must not free the
403 * address and that the next call to this function is allowed
404 * to override the address again.
407 * @param addr binary address
408 * @param addr_len length of the address
409 * @return string representing the same address
411 typedef const char* (*GNUNET_TRANSPORT_AddressToString) (void *cls,
417 * Each plugin is required to return a pointer to a struct of this
418 * type as the return value from its entry point.
420 struct GNUNET_TRANSPORT_PluginFunctions
424 * Closure for all of the callbacks.
429 * Function that the transport service will use to transmit data to
430 * another peer. May be NULL for plugins that only support
431 * receiving data. After this call, the plugin call the specified
432 * continuation with success or error before notifying us about the
433 * target having disconnected.
435 GNUNET_TRANSPORT_TransmitFunction send;
438 * Function that can be used to force the plugin to disconnect from
439 * the given peer and cancel all previous transmissions (and their
440 * continuations). Note that if the transport does not have
441 * sessions / persistent connections (for example, UDP), this
442 * function may very well do nothing.
444 GNUNET_TRANSPORT_DisconnectFunction disconnect;
447 * Function to pretty-print addresses. NOTE: this function is not
448 * yet used by transport-service, but will be used in the future
449 * once the transport-API has been completed.
451 GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
454 * Function that will be called to check if a binary address
455 * for this plugin is well-formed and corresponds to an
456 * address for THIS peer (as per our configuration). Naturally,
457 * if absolutely necessary, plugins can be a bit conservative in
458 * their answer, but in general plugins should make sure that the
459 * address does not redirect traffic to a 3rd party that might
460 * try to man-in-the-middle our traffic.
462 GNUNET_TRANSPORT_CheckAddress check_address;
465 * Function that will be called to convert a binary address
466 * to a string (numeric conversion only).
468 GNUNET_TRANSPORT_AddressToString address_to_string;