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"
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 destoyed
80 (*GNUNET_TRANSPORT_SessionEnd) (void *cls,
81 const struct GNUNET_PeerIdentity *peer,
82 struct Session *session);
86 * Function that will be called whenever the plugin internally
87 * creates a new session and hence transport need to tell ATS.
88 * This happens when we have a inbound connection we did not
93 * @param plugin plugin
94 * @param address address
95 * @param address_len length of the @a address
96 * @param session session
97 * @param ats ATS information
98 * @param ats_count number of entries in @a ats array
101 (*GNUNET_TRANSPORT_SessionStart) (void *cls,
102 const struct GNUNET_PeerIdentity *peer,
105 uint16_t address_len,
106 struct Session *session,
107 const struct GNUNET_ATS_Information *ats,
112 * Function called by the transport for each received message.
113 * This function should also be called with "NULL" for the
114 * message to signal that the other peer disconnected.
117 * @param peer (claimed) identity of the other peer
118 * @param message the message, NULL if we only care about
119 * learning about the delay until we should receive again
120 * @param session identifier used for this session (NULL for plugins
121 * that do not offer bi-directional communication to the sender
122 * using the same "connection")
123 * @param sender_address binary address of the sender (if we established the
124 * connection or are otherwise sure of it; should be NULL
125 * for inbound TCP/UDP connections since it it not clear
126 * that we could establish ourselves a connection to that
127 * IP address and get the same system)
128 * @param sender_address_len number of bytes in @a sender_address
129 * @return how long the plugin should wait until receiving more data;
130 * returning #GNUNET_TIME_UNIT_FOREVER_REL means that the
131 * connection should be closed
133 typedef struct GNUNET_TIME_Relative
134 (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls,
135 const struct GNUNET_PeerIdentity *peer,
136 const struct GNUNET_MessageHeader *message,
137 struct Session *session,
138 const char *sender_address,
139 uint16_t sender_address_len);
143 * Function that will be called to figure if an address is an loopback,
144 * LAN, WAN etc. address
147 * @param addr binary address
148 * @param addrlen length of the @a addr
149 * @return ATS Information containing the network type
151 typedef struct GNUNET_ATS_Information
152 (*GNUNET_TRANSPORT_AddressToType) (void *cls,
153 const struct sockaddr *addr,
158 * Function called when quality properties of an address change.
162 * @param address address
163 * @param address_len length of the @a address
164 * @param session session
165 * @param ats ATS information
166 * @param ats_count number entries in the @a ats array
169 (*GNUNET_TRANSPORT_UpdateAddressMetrics) (void *cls,
170 const struct GNUNET_PeerIdentity *peer,
172 uint16_t address_len,
173 struct Session *session,
174 const struct GNUNET_ATS_Information *ats,
178 * Function that will be called for each address the transport
179 * is aware that it might be reachable under.
182 * @param add_remove should the address added (#GNUNET_YES) or removed (#GNUNET_NO) from the
183 * set of valid addresses?
184 * @param addr one of the addresses of the host
185 * the specific address format depends on the transport
186 * @param addrlen length of the @a addr
187 * @param dest_plugin plugin to use this address with
190 (*GNUNET_TRANSPORT_AddressNotification) (void *cls,
194 const char *dest_plugin);
198 * Function that will be called whenever the plugin receives data over
199 * the network and wants to determine how long it should wait until
200 * the next time it reads from the given peer. Note that some plugins
201 * (such as UDP) may not be able to wait (for a particular peer), so
202 * the waiting part is optional. Plugins that can wait should call
203 * this function, sleep the given amount of time, and call it again
204 * (with zero bytes read) UNTIL it returns zero and only then read.
207 * @param peer which peer did we read data from
208 * @param amount_recved number of bytes read (can be zero)
209 * @return how long to wait until reading more from this peer
210 * (to enforce inbound quotas); returning #GNUNET_TIME_UNIT_FOREVER_REL
211 * means that the connection should be closed
213 typedef struct GNUNET_TIME_Relative
214 (*GNUNET_TRANSPORT_TrafficReport) (void *cls,
215 const struct GNUNET_PeerIdentity *peer,
216 size_t amount_recved);
220 * Function that returns a HELLO message.
222 typedef const struct GNUNET_MessageHeader *
223 (*GNUNET_TRANSPORT_GetHelloCallback) (void);
227 * The transport service will pass a pointer to a struct
228 * of this type as the first and only argument to the
229 * entry point of each transport plugin.
231 struct GNUNET_TRANSPORT_PluginEnvironment
234 * Configuration to use.
236 const struct GNUNET_CONFIGURATION_Handle *cfg;
239 * Identity of this peer.
241 const struct GNUNET_PeerIdentity *my_identity;
244 * Closure for the various callbacks.
249 * Handle for reporting statistics.
251 struct GNUNET_STATISTICS_Handle *stats;
254 * Function that should be called by the transport plugin
255 * whenever a message is received. If this field is "NULL",
256 * the plugin should load in 'stub' mode and NOT fully
257 * initialize and instead only return an API with the
258 * 'address_pretty_printer', 'address_to_string' and
259 * 'string_to_address' functions.
261 GNUNET_TRANSPORT_PluginReceiveCallback receive;
264 * Function that returns our HELLO.
266 GNUNET_TRANSPORT_GetHelloCallback get_our_hello;
269 * Function that must be called by each plugin to notify the
270 * transport service about the addresses under which the transport
271 * provided by the plugin can be reached.
273 GNUNET_TRANSPORT_AddressNotification notify_address;
276 * Function that must be called by the plugin when a non-NULL
277 * session handle stops being valid (is destroyed).
279 GNUNET_TRANSPORT_SessionEnd session_end;
282 * Function called by the plugin when a new (incoming) session was created
283 * not explicitly created using the the get_session function
285 GNUNET_TRANSPORT_SessionStart session_start;
288 * Function that will be called to figure if an address is an loopback,
289 * LAN, WAN etc. address
291 GNUNET_TRANSPORT_AddressToType get_address_type;
294 * Function that will be called to figure if an address is an loopback,
295 * LAN, WAN etc. address
297 GNUNET_TRANSPORT_UpdateAddressMetrics update_address_metrics;
301 * What is the maximum number of connections that this transport
302 * should allow? Transports that do not have sessions (such as
303 * UDP) can ignore this value.
305 uint32_t max_connections;
311 * Function called by the #GNUNET_TRANSPORT_TransmitFunction
312 * upon "completion". In the case that a peer disconnects,
313 * this function must be called for each pending request
314 * (with a 'failure' indication) AFTER notifying the service
315 * about the disconnect event (so that the service won't try
316 * to transmit more messages, believing the connection still
320 * @param target who was the recipient of the message?
321 * @param result #GNUNET_OK on success
322 * #GNUNET_SYSERR if the target disconnected;
323 * disconnect will ALSO be signalled using
324 * the ReceiveCallback.
325 * @param size_payload bytes of payload from transport service in message
326 * @param size_on_wire bytes required on wire for transmission,
327 * 0 if result == #GNUNET_SYSERR
330 (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
331 const struct GNUNET_PeerIdentity *target,
334 size_t size_on_wire);
338 * The new send function with just the session and no address
340 * Function that can be used by the transport service to transmit
341 * a message using the plugin. Note that in the case of a
342 * peer disconnecting, the continuation MUST be called
343 * prior to the disconnect notification itself. This function
344 * will be called with this peer's HELLO message to initiate
345 * a fresh connection to another peer.
348 * @param session which session must be used
349 * @param msgbuf the message to transmit
350 * @param msgbuf_size number of bytes in @a msgbuf
351 * @param priority how important is the message (most plugins will
352 * ignore message priority and just FIFO)
353 * @param to how long to wait at most for the transmission (does not
354 * require plugins to discard the message after the timeout,
355 * just advisory for the desired delay; most plugins will ignore
357 * @param cont continuation to call once the message has
358 * been transmitted (or if the transport is ready
359 * for the next transmission call; or if the
360 * peer disconnected...); can be NULL
361 * @param cont_cls closure for @a cont
362 * @return number of bytes used (on the physical network, with overheads);
363 * -1 on hard errors (i.e. address invalid); 0 is a legal value
364 * and does NOT mean that the message was not transmitted (DV)
367 (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
368 struct Session *session,
371 unsigned int priority,
372 struct GNUNET_TIME_Relative to,
373 GNUNET_TRANSPORT_TransmitContinuation cont,
378 * Function that can be called to force a disconnect from the
379 * specified neighbour for the given session only. . This should
380 * also cancel all previously scheduled transmissions for this
381 * session. Obviously the transmission may have been partially
382 * completed already, which is OK. The plugin is supposed to close
383 * the connection (if applicable).
385 * @param cls closure with the `struct Plugin`
386 * @param session session to destroy
387 * @return #GNUNET_OK on success
390 (*GNUNET_TRANSPORT_DisconnectSessionFunction) (void *cls,
391 struct Session *session);
394 * Function that is called to get the keepalive factor.
395 * GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT is divided by this number to
396 * calculate the interval between keepalive packets.
398 * @param cls closure with the `struct Plugin`
399 * @return keepalive factor
402 (*GNUNET_TRANSPORT_QueryKeepaliveFactorFunction) (void *cls);
406 * Function that can be called to force a disconnect from the
407 * specified neighbour. This should also cancel all previously
408 * scheduled transmissions. Obviously the transmission may have been
409 * partially completed already, which is OK. The plugin is supposed
410 * to close the connection (if applicable) and no longer call the
411 * transmit continuation(s).
414 * @param target peer for which the last transmission is
418 (*GNUNET_TRANSPORT_DisconnectPeerFunction) (void *cls,
419 const struct GNUNET_PeerIdentity *target);
423 * Function called by the pretty printer for the resolved address for
424 * each human-readable address obtained.
427 * @param address one of the names for the host, NULL
428 * on the last call to the callback
431 (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
432 const char *address);
436 * Convert the transports address to a nice, human-readable
440 * @param type name of the transport that generated the address
441 * @param addr one of the addresses of the host, NULL for the last address
442 * the specific address format depends on the transport
443 * @param addrlen length of the @a addr
444 * @param numeric should (IP) addresses be displayed in numeric form?
445 * @param timeout after how long should we give up?
446 * @param asc function to call on each string
447 * @param asc_cls closure for @a asc
450 (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
455 struct GNUNET_TIME_Relative timeout,
456 GNUNET_TRANSPORT_AddressStringCallback asc,
461 * Another peer has suggested an address for this peer and transport
462 * plugin. Check that this could be a valid address. This function
463 * is not expected to 'validate' the address in the sense of trying to
464 * connect to it but simply to see if the binary format is technically
465 * legal for establishing a connection to this peer (and make sure that
466 * the address really corresponds to our network connection/settings
467 * and not some potential man-in-the-middle).
469 * @param addr pointer to the address
470 * @param addrlen length of @a addr
471 * @return #GNUNET_OK if this is a plausible address for this peer
472 * and transport, #GNUNET_SYSERR if not
475 (*GNUNET_TRANSPORT_CheckAddress) (void *cls,
481 * Create a new session to transmit data to the target
482 * This session will used to send data to this peer and the plugin will
483 * notify us by calling the env->session_end function
485 * @param cls the plugin
486 * @param address the hello address
487 * @return the session if the address is valid, NULL otherwise
489 typedef struct Session *
490 (*GNUNET_TRANSPORT_CreateSession) (void *cls,
491 const struct GNUNET_HELLO_Address *address);
495 * Function called for a quick conversion of the binary address to
496 * a numeric address. Note that the caller must not free the
497 * address and that the next call to this function is allowed
498 * to override the address again.
501 * @param addr binary address
502 * @param addr_len length of the @a addr
503 * @return string representing the same address
506 (*GNUNET_TRANSPORT_AddressToString) (void *cls,
512 * Function called to convert a string address to
515 * @param cls closure (`struct Plugin*`)
516 * @param addr string address
517 * @param addrlen length of the @a addr including \0 termination
518 * @param buf location to store the buffer
519 * If the function returns #GNUNET_SYSERR, its contents are undefined.
520 * @param added length of created address
521 * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
524 (*GNUNET_TRANSPORT_StringToAddress) (void *cls,
532 * Function to obtain the network type for a session
534 * @param cls closure ('struct Plugin*')
535 * @param session the session
536 * @return the network type
538 typedef enum GNUNET_ATS_Network_Type
539 (*GNUNET_TRANSPORT_GetNetworkType) (void *cls,
540 struct Session *session);
544 * Each plugin is required to return a pointer to a struct of this
545 * type as the return value from its entry point.
547 struct GNUNET_TRANSPORT_PluginFunctions
551 * Closure for all of the callbacks.
556 * Function that the transport service will use to transmit data to
557 * another peer. May be NULL for plugins that only support
558 * receiving data. After this call, the plugin call the specified
559 * continuation with success or error before notifying us about the
560 * target having disconnected.
562 GNUNET_TRANSPORT_TransmitFunction send;
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_DisconnectPeerFunction disconnect_peer;
572 * Function that can be used to force the plugin to disconnect from
573 * the given peer and cancel all previous transmissions (and their
576 GNUNET_TRANSPORT_DisconnectSessionFunction disconnect_session;
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;