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 * Function that will be called whenever the plugin internally
86 * creates a new session and hence transport need to tell ATS.
87 * This happens when we have a inbound connection we did not
92 * @param plugin plugin
93 * @param address address
94 * @param address_len length of the @a address
95 * @param session session
96 * @param ats ATS information
97 * @param ats_count number of entries in @a ats array
100 (*GNUNET_TRANSPORT_SessionStart) (void *cls,
101 const struct GNUNET_PeerIdentity *peer,
104 uint16_t address_len,
105 struct Session *session,
106 const struct GNUNET_ATS_Information *ats,
110 * Function called by the transport for each received message.
111 * This function should also be called with "NULL" for the
112 * message to signal that the other peer disconnected.
115 * @param peer (claimed) identity of the other peer
116 * @param message the message, NULL if we only care about
117 * learning about the delay until we should receive again
118 * @param session identifier used for this session (NULL for plugins
119 * that do not offer bi-directional communication to the sender
120 * using the same "connection")
121 * @param sender_address binary address of the sender (if we established the
122 * connection or are otherwise sure of it; should be NULL
123 * for inbound TCP/UDP connections since it it not clear
124 * that we could establish ourselves a connection to that
125 * IP address and get the same system)
126 * @param sender_address_len number of bytes in @a sender_address
127 * @return how long the plugin should wait until receiving more data;
128 * returning #GNUNET_TIME_UNIT_FOREVER_REL means that the
129 * connection should be closed
131 typedef struct GNUNET_TIME_Relative
132 (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls,
133 const struct GNUNET_PeerIdentity *peer,
134 const struct GNUNET_MessageHeader *message,
135 struct Session *session,
136 const char *sender_address,
137 uint16_t sender_address_len);
141 * Function that will be called to figure if an address is an loopback,
142 * LAN, WAN etc. address
145 * @param addr binary address
146 * @param addrlen length of the @a addr
147 * @return ATS Information containing the network type
149 typedef struct GNUNET_ATS_Information
150 (*GNUNET_TRANSPORT_AddressToType) (void *cls,
151 const struct sockaddr *addr,
156 * Function called when quality properties of an address change.
160 * @param address address
161 * @param address_len length of the @a address
162 * @param session session
163 * @param ats ATS information
164 * @param ats_count number entries in the @a ats array
167 (*GNUNET_TRANSPORT_UpdateAddressMetrics) (void *cls,
168 const struct GNUNET_PeerIdentity *peer,
170 uint16_t address_len,
171 struct Session *session,
172 const struct GNUNET_ATS_Information *ats,
176 * Function that will be called for each address the transport
177 * is aware that it might be reachable under.
180 * @param add_remove should the address added (#GNUNET_YES) or removed (#GNUNET_NO) from the
181 * set of valid addresses?
182 * @param addr one of the addresses of the host
183 * the specific address format depends on the transport
184 * @param addrlen length of the @a addr
185 * @param dest_plugin plugin to use this address with
188 (*GNUNET_TRANSPORT_AddressNotification) (void *cls,
192 const char *dest_plugin);
196 * Function that will be called whenever the plugin receives data over
197 * the network and wants to determine how long it should wait until
198 * the next time it reads from the given peer. Note that some plugins
199 * (such as UDP) may not be able to wait (for a particular peer), so
200 * the waiting part is optional. Plugins that can wait should call
201 * this function, sleep the given amount of time, and call it again
202 * (with zero bytes read) UNTIL it returns zero and only then read.
205 * @param peer which peer did we read data from
206 * @param amount_recved number of bytes read (can be zero)
207 * @return how long to wait until reading more from this peer
208 * (to enforce inbound quotas); returning #GNUNET_TIME_UNIT_FOREVER_REL
209 * means that the connection should be closed
211 typedef struct GNUNET_TIME_Relative
212 (*GNUNET_TRANSPORT_TrafficReport) (void *cls,
213 const struct GNUNET_PeerIdentity *peer,
214 size_t amount_recved);
218 * Function that returns a HELLO message.
220 typedef const struct GNUNET_MessageHeader *
221 (*GNUNET_TRANSPORT_GetHelloCallback) (void);
225 * The transport service will pass a pointer to a struct
226 * of this type as the first and only argument to the
227 * entry point of each transport plugin.
229 struct GNUNET_TRANSPORT_PluginEnvironment
232 * Configuration to use.
234 const struct GNUNET_CONFIGURATION_Handle *cfg;
237 * Identity of this peer.
239 const struct GNUNET_PeerIdentity *my_identity;
242 * Closure for the various callbacks.
247 * Handle for reporting statistics.
249 struct GNUNET_STATISTICS_Handle *stats;
252 * Function that should be called by the transport plugin
253 * whenever a message is received. If this field is "NULL",
254 * the plugin should load in 'stub' mode and NOT fully
255 * initialize and instead only return an API with the
256 * 'address_pretty_printer', 'address_to_string' and
257 * 'string_to_address' functions.
259 GNUNET_TRANSPORT_PluginReceiveCallback receive;
262 * Function that returns our HELLO.
264 GNUNET_TRANSPORT_GetHelloCallback get_our_hello;
267 * Function that must be called by each plugin to notify the
268 * transport service about the addresses under which the transport
269 * provided by the plugin can be reached.
271 GNUNET_TRANSPORT_AddressNotification notify_address;
274 * Function that must be called by the plugin when a non-NULL
275 * session handle stops being valid (is destroyed).
277 GNUNET_TRANSPORT_SessionEnd session_end;
280 * Function called by the plugin when a new (incoming) session was created
281 * not explicitly created using the the get_session function
283 GNUNET_TRANSPORT_SessionStart session_start;
286 * Function that will be called to figure if an address is an loopback,
287 * LAN, WAN etc. address
289 GNUNET_TRANSPORT_AddressToType get_address_type;
292 * Function that will be called to figure if an address is an loopback,
293 * LAN, WAN etc. address
295 GNUNET_TRANSPORT_UpdateAddressMetrics update_address_metrics;
299 * What is the maximum number of connections that this transport
300 * should allow? Transports that do not have sessions (such as
301 * UDP) can ignore this value.
303 uint32_t max_connections;
309 * Function called by the #GNUNET_TRANSPORT_TransmitFunction
310 * upon "completion". In the case that a peer disconnects,
311 * this function must be called for each pending request
312 * (with a 'failure' indication) AFTER notifying the service
313 * about the disconnect event (so that the service won't try
314 * to transmit more messages, believing the connection still
318 * @param target who was the recipient of the message?
319 * @param result #GNUNET_OK on success
320 * #GNUNET_SYSERR if the target disconnected;
321 * disconnect will ALSO be signalled using
322 * the ReceiveCallback.
323 * @param size_payload bytes of payload from transport service in message
324 * @param size_on_wire bytes required on wire for transmission,
325 * 0 if result == #GNUNET_SYSERR
328 (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
329 const struct GNUNET_PeerIdentity *target,
332 size_t size_on_wire);
336 * The new send function with just the session and no address
338 * Function that can be used by the transport service to transmit
339 * a message using the plugin. Note that in the case of a
340 * peer disconnecting, the continuation MUST be called
341 * prior to the disconnect notification itself. This function
342 * will be called with this peer's HELLO message to initiate
343 * a fresh connection to another peer.
346 * @param session which session must be used
347 * @param msgbuf the message to transmit
348 * @param msgbuf_size number of bytes in @a msgbuf
349 * @param priority how important is the message (most plugins will
350 * ignore message priority and just FIFO)
351 * @param to how long to wait at most for the transmission (does not
352 * require plugins to discard the message after the timeout,
353 * just advisory for the desired delay; most plugins will ignore
355 * @param cont continuation to call once the message has
356 * been transmitted (or if the transport is ready
357 * for the next transmission call; or if the
358 * peer disconnected...); can be NULL
359 * @param cont_cls closure for @a cont
360 * @return number of bytes used (on the physical network, with overheads);
361 * -1 on hard errors (i.e. address invalid); 0 is a legal value
362 * and does NOT mean that the message was not transmitted (DV)
365 (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
366 struct Session *session,
369 unsigned int priority,
370 struct GNUNET_TIME_Relative to,
371 GNUNET_TRANSPORT_TransmitContinuation cont,
376 * Function that can be called to force a disconnect from the
377 * specified neighbour for the given session only. . This should
378 * also cancel all previously scheduled transmissions for this
379 * session. Obviously the transmission may have been partially
380 * completed already, which is OK. The plugin is supposed to close
381 * the connection (if applicable).
383 * @param cls closure with the `struct Plugin`
384 * @param session session to destroy
385 * @return #GNUNET_OK on success
388 (*GNUNET_TRANSPORT_DisconnectSessionFunction) (void *cls,
389 struct Session *session);
392 * Function that is called to get the keepalive factor.
393 * GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT is divided by this number to
394 * calculate the interval between keepalive packets.
396 * @param cls closure with the `struct Plugin`
397 * @return keepalive factor
400 (*GNUNET_TRANSPORT_QueryKeepaliveFactorFunction) (void *cls);
404 * Function that can be called to force a disconnect from the
405 * specified neighbour. This should also cancel all previously
406 * scheduled transmissions. Obviously the transmission may have been
407 * partially completed already, which is OK. The plugin is supposed
408 * to close the connection (if applicable) and no longer call the
409 * transmit continuation(s).
412 * @param target peer for which the last transmission is
416 (*GNUNET_TRANSPORT_DisconnectPeerFunction) (void *cls,
417 const struct GNUNET_PeerIdentity *target);
421 * Function called by the pretty printer for the resolved address for
422 * each human-readable address obtained.
425 * @param address one of the names for the host, NULL
426 * on the last call to the callback
429 (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
430 const char *address);
434 * Convert the transports address to a nice, human-readable
438 * @param type name of the transport that generated the address
439 * @param addr one of the addresses of the host, NULL for the last address
440 * the specific address format depends on the transport
441 * @param addrlen length of the @a addr
442 * @param numeric should (IP) addresses be displayed in numeric form?
443 * @param timeout after how long should we give up?
444 * @param asc function to call on each string
445 * @param asc_cls closure for @a asc
448 (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
453 struct GNUNET_TIME_Relative timeout,
454 GNUNET_TRANSPORT_AddressStringCallback asc,
459 * Another peer has suggested an address for this peer and transport
460 * plugin. Check that this could be a valid address. This function
461 * is not expected to 'validate' the address in the sense of trying to
462 * connect to it but simply to see if the binary format is technically
463 * legal for establishing a connection to this peer (and make sure that
464 * the address really corresponds to our network connection/settings
465 * and not some potential man-in-the-middle).
467 * @param addr pointer to the address
468 * @param addrlen length of @a addr
469 * @return #GNUNET_OK if this is a plausible address for this peer
470 * and transport, #GNUNET_SYSERR if not
473 (*GNUNET_TRANSPORT_CheckAddress) (void *cls,
479 * Create a new session to transmit data to the target
480 * This session will used to send data to this peer and the plugin will
481 * notify us by calling the env->session_end function
483 * @param cls the plugin
484 * @param address the hello address
485 * @return the session if the address is valid, NULL otherwise
487 typedef struct Session *
488 (*GNUNET_TRANSPORT_CreateSession) (void *cls,
489 const struct GNUNET_HELLO_Address *address);
493 * Function that will be called whenever the transport service wants to
494 * notify the plugin that a session is still active and in use and
495 * therefore the session timeout for this session has to be updated
498 * @param peer which peer was the session for
499 * @param session which session is being updated
502 (*GNUNET_TRANSPORT_UpdateSessionTimeout) (void *cls,
503 const struct GNUNET_PeerIdentity *peer,
504 struct Session *session);
507 * Function called for a quick conversion of the binary address to
508 * a numeric address. Note that the caller must not free the
509 * address and that the next call to this function is allowed
510 * to override the address again.
513 * @param addr binary address
514 * @param addr_len length of the @a addr
515 * @return string representing the same address
518 (*GNUNET_TRANSPORT_AddressToString) (void *cls,
524 * Function called to convert a string address to
527 * @param cls closure (`struct Plugin*`)
528 * @param addr string address
529 * @param addrlen length of the @a addr including \0 termination
530 * @param buf location to store the buffer
531 * If the function returns #GNUNET_SYSERR, its contents are undefined.
532 * @param added length of created address
533 * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
536 (*GNUNET_TRANSPORT_StringToAddress) (void *cls,
544 * Function to obtain the network type for a session
546 * @param cls closure ('struct Plugin*')
547 * @param session the session
548 * @return the network type
550 typedef enum GNUNET_ATS_Network_Type
551 (*GNUNET_TRANSPORT_GetNetworkType) (void *cls,
552 struct Session *session);
556 * Each plugin is required to return a pointer to a struct of this
557 * type as the return value from its entry point.
559 struct GNUNET_TRANSPORT_PluginFunctions
563 * Closure for all of the callbacks.
568 * Function that the transport service will use to transmit data to
569 * another peer. May be NULL for plugins that only support
570 * receiving data. After this call, the plugin call the specified
571 * continuation with success or error before notifying us about the
572 * target having disconnected.
574 GNUNET_TRANSPORT_TransmitFunction send;
577 * Function that can be used to force the plugin to disconnect from
578 * the given peer and cancel all previous transmissions (and their
581 GNUNET_TRANSPORT_DisconnectPeerFunction disconnect_peer;
584 * Function that can be used to force the plugin to disconnect from
585 * the given peer and cancel all previous transmissions (and their
588 GNUNET_TRANSPORT_DisconnectSessionFunction disconnect_session;
591 * Function that will be called whenever the transport service wants to
592 * notify the plugin that a session is still active and in use and
593 * therefore the session timeout for this session has to be updated
595 GNUNET_TRANSPORT_UpdateSessionTimeout update_session_timeout;
598 * Function that is used to query keepalive factor.
599 * GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT is divided by this number to
600 * calculate the interval between keepalive packets.
602 GNUNET_TRANSPORT_QueryKeepaliveFactorFunction query_keepalive_factor;
605 * Function to pretty-print addresses. NOTE: this function is not
606 * yet used by transport-service, but will be used in the future
607 * once the transport-API has been completed.
609 GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
612 * Function that will be called to check if a binary address
613 * for this plugin is well-formed and corresponds to an
614 * address for THIS peer (as per our configuration). Naturally,
615 * if absolutely necessary, plugins can be a bit conservative in
616 * their answer, but in general plugins should make sure that the
617 * address does not redirect traffic to a 3rd party that might
618 * try to man-in-the-middle our traffic.
620 GNUNET_TRANSPORT_CheckAddress check_address;
623 * Function that will be called to convert a binary address
624 * to a string (numeric conversion only).
626 GNUNET_TRANSPORT_AddressToString address_to_string;
629 * Function that will be called to convert a string address
630 * to binary (numeric conversion only).
632 GNUNET_TRANSPORT_StringToAddress string_to_address;
635 * Function that will be called tell the plugin to create a session
638 GNUNET_TRANSPORT_CreateSession get_session;
641 * Function to obtain the network type for a session
643 GNUNET_TRANSPORT_GetNetworkType get_network;