2 This file is part of GNUnet
3 (C) 2009, 2010 Christian Grothoff (and other contributing authors)
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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. This function
75 * should be called BEFORE a potential "TransmitContinuation"
76 * from the "TransmitFunction".
79 * @param peer which peer was the session for
80 * @param session which session is being destoyed
82 typedef void (*GNUNET_TRANSPORT_SessionEnd) (void *cls,
83 const struct GNUNET_PeerIdentity *peer,
84 struct Session *session);
88 * Function called by the transport for each received message.
89 * This function should also be called with "NULL" for the
90 * message to signal that the other peer disconnected.
93 * @param peer (claimed) identity of the other peer
94 * @param message the message, NULL if we only care about
95 * learning about the delay until we should receive again -- FIXME!
96 * @param distance in overlay hops; use 1 unless DV (or 0 if message == NULL)
97 * @param session identifier used for this session (NULL for plugins
98 * that do not offer bi-directional communication to the sender
99 * using the same "connection")
100 * @param sender_address binary address of the sender (if we established the
101 * connection or are otherwise sure of it; should be NULL
102 * for inbound TCP/UDP connections since it it not clear
103 * that we could establish ourselves a connection to that
104 * IP address and get the same system)
105 * @param sender_address_len number of bytes in sender_address
106 * @return how long the plugin should wait until receiving more data
107 * (plugins that do not support this, can ignore the return value)
109 typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls,
111 GNUNET_PeerIdentity *
114 GNUNET_MessageHeader *
116 const struct GNUNET_TRANSPORT_ATS_Information *ats,
118 struct Session *session,
119 const char *sender_address,
120 uint16_t sender_address_len);
124 * Function that will be called for each address the transport
125 * is aware that it might be reachable under.
128 * @param add_remove should the address added (YES) or removed (NO) from the
129 * set of valid addresses?
130 * @param addr one of the addresses of the host
131 * the specific address format depends on the transport
132 * @param addrlen length of the address
134 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);
162 * Function called whenever the plugin has to notify ATS about costs for using this transport
164 * The cost will be passed as struct GNUNET_TRANSPORT_ATS_Cost_Information[]
165 * This array is 0-terminated, so the last element will be a pair:
166 * ((cost->cost_type==GNUNET_TRANSPORT_ATS_ARRAY_TERMINATOR) && cost->cost_value==0))
170 * @param addr peer address
171 * @param addrlen address length
172 * @param cost pointer to the first element of struct GNUNET_TRANSPORT_ATS_Cost_Information[]
174 typedef void (*GNUNET_TRANSPORT_CostReport) (void *cls,
175 const struct GNUNET_PeerIdentity *peer,
178 struct GNUNET_TRANSPORT_ATS_Information * cost);
182 * Function that returns a HELLO message.
184 typedef const struct GNUNET_MessageHeader * (*GNUNET_TRANSPORT_GetHelloCallback)(void);
188 * The transport service will pass a pointer to a struct
189 * of this type as the first and only argument to the
190 * entry point of each transport plugin.
192 struct GNUNET_TRANSPORT_PluginEnvironment
195 * Configuration to use.
197 const struct GNUNET_CONFIGURATION_Handle *cfg;
200 * Identity of this peer.
202 const struct GNUNET_PeerIdentity *my_identity;
205 * Closure for the various callbacks.
210 * Handle for reporting statistics.
212 struct GNUNET_STATISTICS_Handle *stats;
215 * Function that should be called by the transport plugin
216 * whenever a message is received.
218 GNUNET_TRANSPORT_PluginReceiveCallback receive;
222 * Function that returns our HELLO.
224 GNUNET_TRANSPORT_GetHelloCallback get_our_hello;
227 * Function that must be called by each plugin to notify the
228 * transport service about the addresses under which the transport
229 * provided by the plugin can be reached.
231 GNUNET_TRANSPORT_AddressNotification notify_address;
234 * Function that must be called by the plugin when a non-NULL
235 * session handle stops being valid (is destroyed).
237 GNUNET_TRANSPORT_SessionEnd session_end;
240 * Inform service about costs for using this transport plugin
242 GNUNET_TRANSPORT_CostReport cost_report;
245 * What is the maximum number of connections that this transport
246 * should allow? Transports that do not have sessions (such as
247 * UDP) can ignore this value.
249 uint32_t max_connections;
255 * Function called by the GNUNET_TRANSPORT_TransmitFunction
256 * upon "completion". In the case that a peer disconnects,
257 * this function must be called for each pending request
258 * (with a 'failure' indication) AFTER notifying the service
259 * about the disconnect event (so that the service won't try
260 * to transmit more messages, believing the connection still
264 * @param target who was the recipient of the message?
265 * @param result GNUNET_OK on success
266 * GNUNET_SYSERR if the target disconnected;
267 * disconnect will ALSO be signalled using
268 * the ReceiveCallback.
271 (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
272 const struct GNUNET_PeerIdentity *
277 * Function that can be used by the transport service to transmit
278 * a message using the plugin. Note that in the case of a
279 * peer disconnecting, the continuation MUST be called
280 * prior to the disconnect notification itself. This function
281 * will be called with this peer's HELLO message to initiate
282 * a fresh connection to another peer.
285 * @param target who should receive this message
286 * @param msgbuf the message to transmit
287 * @param msgbuf_size number of bytes in 'msgbuf'
288 * @param priority how important is the message (most plugins will
289 * ignore message priority and just FIFO)
290 * @param timeout how long to wait at most for the transmission (does not
291 * require plugins to discard the message after the timeout,
292 * just advisory for the desired delay; most plugins will ignore
294 * @param session which session must be used (or NULL for "any")
295 * @param addr the address to use (can be NULL if the plugin
296 * is "on its own" (i.e. re-use existing TCP connection))
297 * @param addrlen length of the address in bytes
298 * @param force_address GNUNET_YES if the plugin MUST use the given address,
299 * GNUNET_NO means the plugin may use any other address and
300 * GNUNET_SYSERR means that only reliable existing
301 * bi-directional connections should be used (regardless
303 * @param cont continuation to call once the message has
304 * been transmitted (or if the transport is ready
305 * for the next transmission call; or if the
306 * peer disconnected...); can be NULL
307 * @param cont_cls closure for cont
308 * @return number of bytes used (on the physical network, with overheads);
309 * -1 on hard errors (i.e. address invalid); 0 is a legal value
310 * and does NOT mean that the message was not transmitted (DV)
313 (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
314 const struct GNUNET_PeerIdentity *
319 struct GNUNET_TIME_Relative timeout,
320 struct Session *session,
324 GNUNET_TRANSPORT_TransmitContinuation
325 cont, void *cont_cls);
329 * Function that can be called to force a disconnect from the
330 * specified neighbour. This should also cancel all previously
331 * scheduled transmissions. Obviously the transmission may have been
332 * partially completed already, which is OK. The plugin is supposed
333 * to close the connection (if applicable) and no longer call the
334 * transmit continuation(s).
336 * Finally, plugin MUST NOT call the services's receive function to
337 * notify the service that the connection to the specified target was
338 * closed after a getting this call.
341 * @param target peer for which the last transmission is
345 (*GNUNET_TRANSPORT_DisconnectFunction) (void *cls,
346 const struct GNUNET_PeerIdentity *
351 * Function called by the pretty printer for the resolved address for
352 * each human-readable address obtained.
355 * @param hostname one of the names for the host, NULL
356 * on the last call to the callback
358 typedef void (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
359 const char *address);
363 * Convert the transports address to a nice, human-readable
367 * @param name name of the transport that generated the address
368 * @param addr one of the addresses of the host, NULL for the last address
369 * the specific address format depends on the transport
370 * @param addrlen length of the address
371 * @param numeric should (IP) addresses be displayed in numeric form?
372 * @param timeout after how long should we give up?
373 * @param asc function to call on each string
374 * @param asc_cls closure for asc
377 (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
382 struct GNUNET_TIME_Relative
384 GNUNET_TRANSPORT_AddressStringCallback
389 * Another peer has suggested an address for this peer and transport
390 * plugin. Check that this could be a valid address. This function
391 * is not expected to 'validate' the address in the sense of trying to
392 * connect to it but simply to see if the binary format is technically
393 * legal for establishing a connection to this peer (and make sure that
394 * the address really corresponds to our network connection/settings
395 * and not some potential man-in-the-middle).
397 * @param addr pointer to the address
398 * @param addrlen length of addr
399 * @return GNUNET_OK if this is a plausible address for this peer
400 * and transport, GNUNET_SYSERR if not
403 (*GNUNET_TRANSPORT_CheckAddress) (void *cls,
404 const void *addr, size_t addrlen);
408 * Function called for a quick conversion of the binary address to
409 * a numeric address. Note that the caller must not free the
410 * address and that the next call to this function is allowed
411 * to override the address again.
414 * @param addr binary address
415 * @param addr_len length of the address
416 * @return string representing the same address
418 typedef const char* (*GNUNET_TRANSPORT_AddressToString) (void *cls,
424 * Each plugin is required to return a pointer to a struct of this
425 * type as the return value from its entry point.
427 struct GNUNET_TRANSPORT_PluginFunctions
431 * Closure for all of the callbacks.
436 * Function that the transport service will use to transmit data to
437 * another peer. May be NULL for plugins that only support
438 * receiving data. After this call, the plugin call the specified
439 * continuation with success or error before notifying us about the
440 * target having disconnected.
442 GNUNET_TRANSPORT_TransmitFunction send;
445 * Function that can be used to force the plugin to disconnect from
446 * the given peer and cancel all previous transmissions (and their
449 GNUNET_TRANSPORT_DisconnectFunction disconnect;
452 * Function to pretty-print addresses. NOTE: this function is not
453 * yet used by transport-service, but will be used in the future
454 * once the transport-API has been completed.
456 GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
459 * Function that will be called to check if a binary address
460 * for this plugin is well-formed and corresponds to an
461 * address for THIS peer (as per our configuration). Naturally,
462 * if absolutely necessary, plugins can be a bit conservative in
463 * their answer, but in general plugins should make sure that the
464 * address does not redirect traffic to a 3rd party that might
465 * try to man-in-the-middle our traffic.
467 GNUNET_TRANSPORT_CheckAddress check_address;
470 * Function that will be called to convert a binary address
471 * to a string (numeric conversion only).
473 GNUNET_TRANSPORT_AddressToString address_to_string;