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"
38 #include "gnunet_ats_service.h"
40 #define TRANSPORT_SESSION_INBOUND_STRING "<inbound>"
43 * Opaque pointer that plugins can use to distinguish specific
44 * connections to a given peer. Typically used by stateful plugins to
45 * allow the service to refer to specific streams instead of a more
46 * general notion of "some connection" to the given peer. This is
47 * useful since sometimes (i.e. for inbound TCP connections) a
48 * connection may not have an address that can be used for meaningful
49 * distinction between sessions to the same peer.
51 * Each 'struct Session' MUST start with the 'struct GNUNET_PeerIdentity'
52 * of the peer the session is for (which will be used for some error
53 * checking by the ATS code).
58 * Every 'struct Session' must begin with this header.
67 * Function that will be called whenever the plugin internally
68 * cleans up a session pointer and hence the service needs to
69 * discard all of those sessions as well. Plugins that do not
70 * use sessions can simply omit calling this function and always
71 * use NULL wherever a session pointer is needed. This function
72 * should be called BEFORE a potential "TransmitContinuation"
73 * from the "TransmitFunction".
76 * @param peer which peer was the session for
77 * @param session which session is being destroyed
80 (*GNUNET_TRANSPORT_SessionEnd) (void *cls,
81 const struct GNUNET_PeerIdentity *peer,
82 struct Session *session);
85 * Plugin tells transport service about a new inbound session
88 * @param address the address
89 * @param session the new session
90 * @param ats ats information
91 * @param ats_count number of @a ats information
94 (*GNUNET_TRANSPORT_SessionStart) (void *cls,
95 struct GNUNET_HELLO_Address *address,
96 struct Session *session,
97 const struct GNUNET_ATS_Information *ats,
101 * Function called by the transport for each received message.
102 * This function should also be called with "NULL" for the
103 * message to signal that the other peer disconnected.
106 * @param peer (claimed) identity of the other peer
107 * @param message the message, NULL if we only care about
108 * learning about the delay until we should receive again
109 * @param session identifier used for this session (NULL for plugins
110 * that do not offer bi-directional communication to the sender
111 * using the same "connection")
112 * @param sender_address binary address of the sender (if we established the
113 * connection or are otherwise sure of it; should be NULL
114 * for inbound TCP/UDP connections since it it not clear
115 * that we could establish ourselves a connection to that
116 * IP address and get the same system)
117 * @param sender_address_len number of bytes in @a sender_address
118 * @return how long the plugin should wait until receiving more data;
119 * returning #GNUNET_TIME_UNIT_FOREVER_REL means that the
120 * connection should be closed
122 typedef struct GNUNET_TIME_Relative
123 (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls,
124 const struct GNUNET_HELLO_Address *address,
125 struct Session *session,
126 const struct GNUNET_MessageHeader *message);
130 * Function that will be called to figure if an address is an loopback,
131 * LAN, WAN etc. address
134 * @param addr binary address
135 * @param addrlen length of the @a addr
136 * @return ATS Information containing the network type
138 typedef struct GNUNET_ATS_Information
139 (*GNUNET_TRANSPORT_AddressToType) (void *cls,
140 const struct sockaddr *addr,
145 * Function called when quality properties of an address change.
149 * @param address address
150 * @param address_len length of the @a address
151 * @param session session
152 * @param ats ATS information
153 * @param ats_count number entries in the @a ats array
156 (*GNUNET_TRANSPORT_UpdateAddressMetrics) (void *cls,
157 const struct GNUNET_HELLO_Address *address,
158 struct Session *session,
159 const struct GNUNET_ATS_Information *ats,
163 * Function that will be called for each address the transport
164 * is aware that it might be reachable under.
167 * @param add_remove should the address added (#GNUNET_YES) or removed (#GNUNET_NO) from the
168 * set of valid addresses?
169 * @param address the address to add or remove
172 (*GNUNET_TRANSPORT_AddressNotification) (void *cls, int add_remove,
173 const struct GNUNET_HELLO_Address *address);
177 * Function that will be called whenever the plugin receives data over
178 * the network and wants to determine how long it should wait until
179 * the next time it reads from the given peer. Note that some plugins
180 * (such as UDP) may not be able to wait (for a particular peer), so
181 * the waiting part is optional. Plugins that can wait should call
182 * this function, sleep the given amount of time, and call it again
183 * (with zero bytes read) UNTIL it returns zero and only then read.
186 * @param peer which peer did we read data from
187 * @param amount_recved number of bytes read (can be zero)
188 * @return how long to wait until reading more from this peer
189 * (to enforce inbound quotas); returning #GNUNET_TIME_UNIT_FOREVER_REL
190 * means that the connection should be closed
192 typedef struct GNUNET_TIME_Relative
193 (*GNUNET_TRANSPORT_TrafficReport) (void *cls,
194 const struct GNUNET_PeerIdentity *peer,
195 size_t amount_recved);
199 * Function that returns a HELLO message.
201 typedef const struct GNUNET_MessageHeader *
202 (*GNUNET_TRANSPORT_GetHelloCallback) (void);
206 * The transport service will pass a pointer to a struct
207 * of this type as the first and only argument to the
208 * entry point of each transport plugin.
210 struct GNUNET_TRANSPORT_PluginEnvironment
213 * Configuration to use.
215 const struct GNUNET_CONFIGURATION_Handle *cfg;
218 * Identity of this peer.
220 const struct GNUNET_PeerIdentity *my_identity;
223 * Closure for the various callbacks.
228 * Handle for reporting statistics.
230 struct GNUNET_STATISTICS_Handle *stats;
233 * Function that should be called by the transport plugin
234 * whenever a message is received. If this field is "NULL",
235 * the plugin should load in 'stub' mode and NOT fully
236 * initialize and instead only return an API with the
237 * 'address_pretty_printer', 'address_to_string' and
238 * 'string_to_address' functions.
240 GNUNET_TRANSPORT_PluginReceiveCallback receive;
243 * Function that returns our HELLO.
245 GNUNET_TRANSPORT_GetHelloCallback get_our_hello;
248 * Function that must be called by each plugin to notify the
249 * transport service about the addresses under which the transport
250 * provided by the plugin can be reached.
252 GNUNET_TRANSPORT_AddressNotification notify_address;
255 * Function that must be called by the plugin when a non-NULL
256 * session handle stops being valid (is destroyed).
258 GNUNET_TRANSPORT_SessionEnd session_end;
261 * Function called by the plugin when a new (incoming) session was created
262 * not explicitly created using the the get_session function
264 GNUNET_TRANSPORT_SessionStart session_start;
267 * Function that will be called to figure if an address is an loopback,
268 * LAN, WAN etc. address
270 GNUNET_TRANSPORT_AddressToType get_address_type;
273 * Function that will be called to figure if an address is an loopback,
274 * LAN, WAN etc. address
276 GNUNET_TRANSPORT_UpdateAddressMetrics update_address_metrics;
280 * What is the maximum number of connections that this transport
281 * should allow? Transports that do not have sessions (such as
282 * UDP) can ignore this value.
284 uint32_t max_connections;
290 * Function called by the #GNUNET_TRANSPORT_TransmitFunction
291 * upon "completion". In the case that a peer disconnects,
292 * this function must be called for each pending request
293 * (with a 'failure' indication) AFTER notifying the service
294 * about the disconnect event (so that the service won't try
295 * to transmit more messages, believing the connection still
299 * @param target who was the recipient of the message?
300 * @param result #GNUNET_OK on success
301 * #GNUNET_SYSERR if the target disconnected;
302 * disconnect will ALSO be signalled using
303 * the ReceiveCallback.
304 * @param size_payload bytes of payload from transport service in message
305 * @param size_on_wire bytes required on wire for transmission,
306 * 0 if result == #GNUNET_SYSERR
309 (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
310 const struct GNUNET_PeerIdentity *target,
313 size_t size_on_wire);
317 * The new send function with just the session and no address
319 * Function that can be used by the transport service to transmit
320 * a message using the plugin. Note that in the case of a
321 * peer disconnecting, the continuation MUST be called
322 * prior to the disconnect notification itself. This function
323 * will be called with this peer's HELLO message to initiate
324 * a fresh connection to another peer.
327 * @param session which session must be used
328 * @param msgbuf the message to transmit
329 * @param msgbuf_size number of bytes in @a msgbuf
330 * @param priority how important is the message (most plugins will
331 * ignore message priority and just FIFO)
332 * @param to how long to wait at most for the transmission (does not
333 * require plugins to discard the message after the timeout,
334 * just advisory for the desired delay; most plugins will ignore
336 * @param cont continuation to call once the message has
337 * been transmitted (or if the transport is ready
338 * for the next transmission call; or if the
339 * peer disconnected...); can be NULL
340 * @param cont_cls closure for @a cont
341 * @return number of bytes used (on the physical network, with overheads);
342 * -1 on hard errors (i.e. address invalid); 0 is a legal value
343 * and does NOT mean that the message was not transmitted (DV)
346 (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
347 struct Session *session,
350 unsigned int priority,
351 struct GNUNET_TIME_Relative to,
352 GNUNET_TRANSPORT_TransmitContinuation cont,
357 * Function that can be called to force a disconnect from the
358 * specified neighbour for the given session only. . This should
359 * also cancel all previously scheduled transmissions for this
360 * session. Obviously the transmission may have been partially
361 * completed already, which is OK. The plugin is supposed to close
362 * the connection (if applicable).
364 * @param cls closure with the `struct Plugin`
365 * @param session session to destroy
366 * @return #GNUNET_OK on success
369 (*GNUNET_TRANSPORT_DisconnectSessionFunction) (void *cls,
370 struct Session *session);
373 * Function that is called to get the keepalive factor.
374 * GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT is divided by this number to
375 * calculate the interval between keepalive packets.
377 * @param cls closure with the `struct Plugin`
378 * @return keepalive factor
381 (*GNUNET_TRANSPORT_QueryKeepaliveFactorFunction) (void *cls);
385 * Function that can be called to force a disconnect from the
386 * specified neighbour. This should also cancel all previously
387 * scheduled transmissions. Obviously the transmission may have been
388 * partially completed already, which is OK. The plugin is supposed
389 * to close the connection (if applicable) and no longer call the
390 * transmit continuation(s).
393 * @param target peer for which the last transmission is
397 (*GNUNET_TRANSPORT_DisconnectPeerFunction) (void *cls,
398 const struct GNUNET_PeerIdentity *target);
402 * Function called by the pretty printer for the resolved address for
403 * each human-readable address obtained.
406 * @param address one of the names for the host, NULL
407 * on the last call to the callback
410 (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
411 const char *address);
415 * Convert the transports address to a nice, human-readable
419 * @param type name of the transport that generated the address
420 * @param addr one of the addresses of the host, NULL for the last address
421 * the specific address format depends on the transport
422 * @param addrlen length of the @a addr
423 * @param numeric should (IP) addresses be displayed in numeric form?
424 * @param timeout after how long should we give up?
425 * @param asc function to call on each string
426 * @param asc_cls closure for @a asc
429 (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
434 struct GNUNET_TIME_Relative timeout,
435 GNUNET_TRANSPORT_AddressStringCallback asc,
440 * Another peer has suggested an address for this peer and transport
441 * plugin. Check that this could be a valid address. This function
442 * is not expected to 'validate' the address in the sense of trying to
443 * connect to it but simply to see if the binary format is technically
444 * legal for establishing a connection to this peer (and make sure that
445 * the address really corresponds to our network connection/settings
446 * and not some potential man-in-the-middle).
448 * @param addr pointer to the address
449 * @param addrlen length of @a addr
450 * @return #GNUNET_OK if this is a plausible address for this peer
451 * and transport, #GNUNET_SYSERR if not
454 (*GNUNET_TRANSPORT_CheckAddress) (void *cls,
460 * Create a new session to transmit data to the target
461 * This session will used to send data to this peer and the plugin will
462 * notify us by calling the env->session_end function
464 * @param cls the plugin
465 * @param address the hello address
466 * @return the session if the address is valid, NULL otherwise
468 typedef struct Session *
469 (*GNUNET_TRANSPORT_CreateSession) (void *cls,
470 const struct GNUNET_HELLO_Address *address);
474 * Function that will be called whenever the transport service wants to
475 * notify the plugin that a session is still active and in use and
476 * therefore the session timeout for this session has to be updated
479 * @param peer which peer was the session for
480 * @param session which session is being updated
483 (*GNUNET_TRANSPORT_UpdateSessionTimeout) (void *cls,
484 const struct GNUNET_PeerIdentity *peer,
485 struct Session *session);
488 * Function called for a quick conversion of the binary address to
489 * a numeric address. Note that the caller must not free the
490 * address and that the next call to this function is allowed
491 * to override the address again.
494 * @param addr binary address
495 * @param addr_len length of the @a addr
496 * @return string representing the same address
499 (*GNUNET_TRANSPORT_AddressToString) (void *cls,
505 * Function called to convert a string address to
508 * @param cls closure (`struct Plugin*`)
509 * @param addr string address
510 * @param addrlen length of the @a addr including \0 termination
511 * @param buf location to store the buffer
512 * If the function returns #GNUNET_SYSERR, its contents are undefined.
513 * @param added length of created address
514 * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
517 (*GNUNET_TRANSPORT_StringToAddress) (void *cls,
525 * Function to obtain the network type for a session
527 * @param cls closure ('struct Plugin*')
528 * @param session the session
529 * @return the network type
531 typedef enum GNUNET_ATS_Network_Type
532 (*GNUNET_TRANSPORT_GetNetworkType) (void *cls,
533 struct Session *session);
537 * Each plugin is required to return a pointer to a struct of this
538 * type as the return value from its entry point.
540 struct GNUNET_TRANSPORT_PluginFunctions
544 * Closure for all of the callbacks.
549 * Function that the transport service will use to transmit data to
550 * another peer. May be NULL for plugins that only support
551 * receiving data. After this call, the plugin call the specified
552 * continuation with success or error before notifying us about the
553 * target having disconnected.
555 GNUNET_TRANSPORT_TransmitFunction send;
558 * Function that can be used to force the plugin to disconnect from
559 * the given peer and cancel all previous transmissions (and their
562 GNUNET_TRANSPORT_DisconnectPeerFunction disconnect_peer;
565 * Function that can be used to force the plugin to disconnect from
566 * the given peer and cancel all previous transmissions (and their
569 GNUNET_TRANSPORT_DisconnectSessionFunction disconnect_session;
572 * Function that will be called whenever the transport service wants to
573 * notify the plugin that a session is still active and in use and
574 * therefore the session timeout for this session has to be updated
576 GNUNET_TRANSPORT_UpdateSessionTimeout update_session_timeout;
579 * Function that is used to query keepalive factor.
580 * GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT is divided by this number to
581 * calculate the interval between keepalive packets.
583 GNUNET_TRANSPORT_QueryKeepaliveFactorFunction query_keepalive_factor;
586 * Function to pretty-print addresses. NOTE: this function is not
587 * yet used by transport-service, but will be used in the future
588 * once the transport-API has been completed.
590 GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
593 * Function that will be called to check if a binary address
594 * for this plugin is well-formed and corresponds to an
595 * address for THIS peer (as per our configuration). Naturally,
596 * if absolutely necessary, plugins can be a bit conservative in
597 * their answer, but in general plugins should make sure that the
598 * address does not redirect traffic to a 3rd party that might
599 * try to man-in-the-middle our traffic.
601 GNUNET_TRANSPORT_CheckAddress check_address;
604 * Function that will be called to convert a binary address
605 * to a string (numeric conversion only).
607 GNUNET_TRANSPORT_AddressToString address_to_string;
610 * Function that will be called to convert a string address
611 * to binary (numeric conversion only).
613 GNUNET_TRANSPORT_StringToAddress string_to_address;
616 * Function that will be called tell the plugin to create a session
619 GNUNET_TRANSPORT_CreateSession get_session;
622 * Function to obtain the network type for a session
624 GNUNET_TRANSPORT_GetNetworkType get_network;