2 This file is part of GNUnet
3 (C) 2009, 2010 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
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
8 option) any later version.
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11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
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17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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22 * @file transport/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"
38 #include "transport_selection.h"
42 * Opaque pointer that plugins can use to distinguish specific
43 * connections to a given peer. Typically used by stateful plugins to
44 * allow the service to refer to specific streams instead of a more
45 * general notion of "some connection" to the given peer. This is
46 * useful since sometimes (i.e. for inbound TCP connections) a
47 * connection may not have an address that can be used for meaningful
48 * distinction between sessions to the same peer.
53 * Every 'struct Session' must begin with this header.
59 * Cached signature for PONG generation for the session. Do not use
62 struct GNUNET_CRYPTO_RsaSignature pong_signature;
65 * Expiration time for signature. Do not use in the plugin!
67 struct GNUNET_TIME_Absolute pong_sig_expires;
72 * Function that will be called whenever the plugin internally
73 * cleans up a session pointer and hence the service needs to
74 * discard all of those sessions as well. Plugins that do not
75 * use sessions can simply omit calling this function and always
76 * use NULL wherever a session pointer is needed.
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 *
117 struct Session *session,
118 const char *sender_address,
119 uint16_t sender_address_len);
123 * Function that will be called for each address the transport
124 * is aware that it might be reachable under.
127 * @param name name of the transport that generated the address
128 * @param addr one of the addresses of the host, NULL for the last address
129 * the specific address format depends on the transport
130 * @param addrlen length of the address
131 * @param expires when should this address automatically expire?
133 typedef void (*GNUNET_TRANSPORT_AddressNotification) (void *cls,
142 * Function that will be called whenever the plugin receives data over
143 * the network and wants to determine how long it should wait until
144 * the next time it reads from the given peer. Note that some plugins
145 * (such as UDP) may not be able to wait (for a particular peer), so
146 * the waiting part is optional. Plugins that can wait should call
147 * this function, sleep the given amount of time, and call it again
148 * (with zero bytes read) UNTIL it returns zero and only then read.
151 * @param peer which peer did we read data from
152 * @param amount_recved number of bytes read (can be zero)
153 * @return how long to wait until reading more from this peer
154 * (to enforce inbound quotas)
156 typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_TrafficReport) (void *cls,
158 GNUNET_PeerIdentity *peer,
159 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_ATS_Cost_Information[]
165 * This array is 0-terminated, so the last element will be a pair:
166 * ((cost->cost_type==GNUNET_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_ATS_Cost_Information[]
174 typedef void (*GNUNET_TRANSPORT_CostReport) (void *cls,
175 const struct GNUNET_PeerIdentity *peer,
178 struct GNUNET_ATS_Information * cost);
181 * The transport service will pass a pointer to a struct
182 * of this type as the first and only argument to the
183 * entry point of each transport plugin.
185 struct GNUNET_TRANSPORT_PluginEnvironment
188 * Configuration to use.
190 const struct GNUNET_CONFIGURATION_Handle *cfg;
193 * Identity of this peer.
195 const struct GNUNET_PeerIdentity *my_identity;
198 * Pointer (!) to our HELLO message. Note that the address
199 * referred to "*our_hello" might change over time.
201 struct GNUNET_HELLO_Message *const*our_hello;
204 * Closure for the various callbacks.
209 * Handle for reporting statistics.
211 struct GNUNET_STATISTICS_Handle *stats;
214 * Function that should be called by the transport plugin
215 * whenever a message is received.
217 GNUNET_TRANSPORT_PluginReceiveCallback receive;
220 * Function that must be called by each plugin to notify the
221 * transport service about the addresses under which the transport
222 * provided by the plugin can be reached.
224 GNUNET_TRANSPORT_AddressNotification notify_address;
227 * Inform service about traffic received, get information
228 * about when we might be willing to receive more.
230 GNUNET_TRANSPORT_TrafficReport traffic_report;
233 * Function that must be called by the plugin when a non-NULL
234 * session handle stops being valid (is destroyed).
236 GNUNET_TRANSPORT_SessionEnd session_end;
239 * Inform service about costs for using this transport plugin
241 GNUNET_TRANSPORT_CostReport cost_report;
244 * What is the maximum number of connections that this transport
245 * should allow? Transports that do not have sessions (such as
246 * UDP) can ignore this value.
248 uint32_t max_connections;
254 * Function called by the GNUNET_TRANSPORT_TransmitFunction
258 * @param target who was the recipient of the message?
259 * @param result GNUNET_OK on success
260 * GNUNET_SYSERR if the target disconnected;
261 * disconnect will ALSO be signalled using
262 * the ReceiveCallback.
265 (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
266 const struct GNUNET_PeerIdentity *
271 * Function that can be used by the transport service to transmit
272 * a message using the plugin. Note that in the case of a
273 * peer disconnecting, the continuation MUST be called
274 * prior to the disconnect notification itself. This function
275 * will be called with this peer's HELLO message to initiate
276 * a fresh connection to another peer.
279 * @param target who should receive this message
280 * @param msgbuf the message to transmit
281 * @param msgbuf_size number of bytes in 'msgbuf'
282 * @param priority how important is the message (most plugins will
283 * ignore message priority and just FIFO)
284 * @param timeout how long to wait at most for the transmission (does not
285 * require plugins to discard the message after the timeout,
286 * just advisory for the desired delay; most plugins will ignore
288 * @param session which session must be used (or NULL for "any")
289 * @param addr the address to use (can be NULL if the plugin
290 * is "on its own" (i.e. re-use existing TCP connection))
291 * @param addrlen length of the address in bytes
292 * @param force_address GNUNET_YES if the plugin MUST use the given address,
293 * GNUNET_NO means the plugin may use any other address and
294 * GNUNET_SYSERR means that only reliable existing
295 * bi-directional connections should be used (regardless
297 * @param cont continuation to call once the message has
298 * been transmitted (or if the transport is ready
299 * for the next transmission call; or if the
300 * peer disconnected...); can be NULL
301 * @param cont_cls closure for cont
302 * @return number of bytes used (on the physical network, with overheads);
303 * -1 on hard errors (i.e. address invalid); 0 is a legal value
304 * and does NOT mean that the message was not transmitted (DV)
307 (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
308 const struct GNUNET_PeerIdentity *
313 struct GNUNET_TIME_Relative timeout,
314 struct Session *session,
318 GNUNET_TRANSPORT_TransmitContinuation
319 cont, void *cont_cls);
323 * Function that can be called to force a disconnect from the
324 * specified neighbour. This should also cancel all previously
325 * scheduled transmissions. Obviously the transmission may have been
326 * partially completed already, which is OK. The plugin is supposed
327 * to close the connection (if applicable) and no longer call the
328 * transmit continuation(s).
330 * Finally, plugin MUST NOT call the services's receive function to
331 * notify the service that the connection to the specified target was
332 * closed after a getting this call.
335 * @param target peer for which the last transmission is
339 (*GNUNET_TRANSPORT_DisconnectFunction) (void *cls,
340 const struct GNUNET_PeerIdentity *
345 * Function called by the pretty printer for the resolved address for
346 * each human-readable address obtained.
349 * @param hostname one of the names for the host, NULL
350 * on the last call to the callback
352 typedef void (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
353 const char *address);
357 * Convert the transports address to a nice, human-readable
361 * @param name name of the transport that generated the address
362 * @param addr one of the addresses of the host, NULL for the last address
363 * the specific address format depends on the transport
364 * @param addrlen length of the address
365 * @param numeric should (IP) addresses be displayed in numeric form?
366 * @param timeout after how long should we give up?
367 * @param asc function to call on each string
368 * @param asc_cls closure for asc
371 (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
376 struct GNUNET_TIME_Relative
378 GNUNET_TRANSPORT_AddressStringCallback
383 * Another peer has suggested an address for this peer and transport
384 * plugin. Check that this could be a valid address. This function
385 * is not expected to 'validate' the address in the sense of trying to
386 * connect to it but simply to see if the binary format is technically
387 * legal for establishing a connection to this peer (and make sure that
388 * the address really corresponds to our network connection/settings
389 * and not some potential man-in-the-middle).
391 * @param addr pointer to the address
392 * @param addrlen length of addr
393 * @return GNUNET_OK if this is a plausible address for this peer
394 * and transport, GNUNET_SYSERR if not
397 (*GNUNET_TRANSPORT_CheckAddress) (void *cls,
398 const void *addr, size_t addrlen);
402 * Function called for a quick conversion of the binary address to
403 * a numeric address. Note that the caller must not free the
404 * address and that the next call to this function is allowed
405 * to override the address again.
408 * @param addr binary address
409 * @param addr_len length of the address
410 * @return string representing the same address
412 typedef const char* (*GNUNET_TRANSPORT_AddressToString) (void *cls,
418 * Each plugin is required to return a pointer to a struct of this
419 * type as the return value from its entry point.
421 struct GNUNET_TRANSPORT_PluginFunctions
425 * Closure for all of the callbacks.
430 * Function that the transport service will use to transmit data to
431 * another peer. May be NULL for plugins that only support
432 * receiving data. After this call, the plugin call the specified
433 * continuation with success or error before notifying us about the
434 * target having disconnected.
436 GNUNET_TRANSPORT_TransmitFunction send;
439 * Function that can be used to force the plugin to disconnect from
440 * the given peer and cancel all previous transmissions (and their
441 * continuations). Note that if the transport does not have
442 * sessions / persistent connections (for example, UDP), this
443 * function may very well do nothing.
445 GNUNET_TRANSPORT_DisconnectFunction disconnect;
448 * Function to pretty-print addresses. NOTE: this function is not
449 * yet used by transport-service, but will be used in the future
450 * once the transport-API has been completed.
452 GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
455 * Function that will be called to check if a binary address
456 * for this plugin is well-formed and corresponds to an
457 * address for THIS peer (as per our configuration). Naturally,
458 * if absolutely necessary, plugins can be a bit conservative in
459 * their answer, but in general plugins should make sure that the
460 * address does not redirect traffic to a 3rd party that might
461 * try to man-in-the-middle our traffic.
463 GNUNET_TRANSPORT_CheckAddress check_address;
466 * Function that will be called to convert a binary address
467 * to a string (numeric conversion only).
469 GNUNET_TRANSPORT_AddressToString address_to_string;