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.
48 * Each 'struct Session' MUST start with the 'struct GNUNET_PeerIdentity'
49 * of the peer the session is for (which will be used for some error
50 * checking by the ATS code).
55 * Every 'struct Session' must begin with this header.
63 * Function that will be called whenever the plugin internally
64 * cleans up a session pointer and hence the service needs to
65 * discard all of those sessions as well. Plugins that do not
66 * use sessions can simply omit calling this function and always
67 * use NULL wherever a session pointer is needed. This function
68 * should be called BEFORE a potential "TransmitContinuation"
69 * from the "TransmitFunction".
72 * @param peer which peer was the session for
73 * @param session which session is being destoyed
75 typedef void (*GNUNET_TRANSPORT_SessionEnd) (void *cls,
76 const struct GNUNET_PeerIdentity *
77 peer, struct Session * session);
81 * Function called by the transport for each received message.
82 * This function should also be called with "NULL" for the
83 * message to signal that the other peer disconnected.
86 * @param peer (claimed) identity of the other peer
87 * @param message the message, NULL if we only care about
88 * learning about the delay until we should receive again
89 * @param session identifier used for this session (NULL for plugins
90 * that do not offer bi-directional communication to the sender
91 * using the same "connection")
92 * @param sender_address binary address of the sender (if we established the
93 * connection or are otherwise sure of it; should be NULL
94 * for inbound TCP/UDP connections since it it not clear
95 * that we could establish ourselves a connection to that
96 * IP address and get the same system)
97 * @param sender_address_len number of bytes in sender_address
98 * @return how long the plugin should wait until receiving more data
99 * (plugins that do not support this, can ignore the return value)
102 GNUNET_TIME_Relative (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls,
103 const struct GNUNET_PeerIdentity *peer,
104 const struct GNUNET_MessageHeader *message,
105 struct Session *session,
106 const char *sender_address,
107 uint16_t sender_address_len);
111 * Function that will be called to figure if an address is an loopback,
112 * LAN, WAN etc. address
115 * @param addr binary address
116 * @param addrlen length of the address
117 * @return ATS Information containing the network type
119 typedef struct GNUNET_ATS_Information
120 (*GNUNET_TRANSPORT_AddressToType) (void *cls,
121 const struct sockaddr *addr,
126 * Function called when quality properties of an address change.
130 * @param address address
131 * @param address_len length of the address
132 * @param session session
133 * @param ats ATS information
134 * @param ats_count number of ATS information contained
137 (*GNUNET_TRANSPORT_UpdateAddressMetrics) (void *cls,
138 const struct GNUNET_PeerIdentity *peer,
140 uint16_t address_len,
141 struct Session *session,
142 const struct GNUNET_ATS_Information *ats,
146 * Function that will be called for each address the transport
147 * is aware that it might be reachable under.
150 * @param add_remove should the address added (YES) or removed (NO) from the
151 * set of valid addresses?
152 * @param addr one of the addresses of the host
153 * the specific address format depends on the transport
154 * @param addrlen length of the address
155 * @param dest_plugin plugin to use this address with
157 typedef void (*GNUNET_TRANSPORT_AddressNotification) (void *cls, int add_remove,
160 const char *dest_plugin);
164 * Function that will be called whenever the plugin receives data over
165 * the network and wants to determine how long it should wait until
166 * the next time it reads from the given peer. Note that some plugins
167 * (such as UDP) may not be able to wait (for a particular peer), so
168 * the waiting part is optional. Plugins that can wait should call
169 * this function, sleep the given amount of time, and call it again
170 * (with zero bytes read) UNTIL it returns zero and only then read.
173 * @param peer which peer did we read data from
174 * @param amount_recved number of bytes read (can be zero)
175 * @return how long to wait until reading more from this peer
176 * (to enforce inbound quotas)
178 typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_TrafficReport) (void
189 * Function that returns a HELLO message.
191 typedef const struct GNUNET_MessageHeader *
192 (*GNUNET_TRANSPORT_GetHelloCallback) (void);
196 * The transport service will pass a pointer to a struct
197 * of this type as the first and only argument to the
198 * entry point of each transport plugin.
200 struct GNUNET_TRANSPORT_PluginEnvironment
203 * Configuration to use.
205 const struct GNUNET_CONFIGURATION_Handle *cfg;
208 * Identity of this peer.
210 const struct GNUNET_PeerIdentity *my_identity;
213 * Closure for the various callbacks.
218 * Handle for reporting statistics.
220 struct GNUNET_STATISTICS_Handle *stats;
223 * Function that should be called by the transport plugin
224 * whenever a message is received. If this field is "NULL",
225 * the plugin should load in 'stub' mode and NOT fully
226 * initialize and instead only return an API with the
227 * 'address_pretty_printer', 'address_to_string' and
228 * 'string_to_address' functions.
230 GNUNET_TRANSPORT_PluginReceiveCallback receive;
234 * Function that returns our HELLO.
236 GNUNET_TRANSPORT_GetHelloCallback get_our_hello;
239 * Function that must be called by each plugin to notify the
240 * transport service about the addresses under which the transport
241 * provided by the plugin can be reached.
243 GNUNET_TRANSPORT_AddressNotification notify_address;
246 * Function that must be called by the plugin when a non-NULL
247 * session handle stops being valid (is destroyed).
249 GNUNET_TRANSPORT_SessionEnd session_end;
252 * Function that will be called to figure if an address is an loopback,
253 * LAN, WAN etc. address
255 GNUNET_TRANSPORT_AddressToType get_address_type;
258 * Function that will be called to figure if an address is an loopback,
259 * LAN, WAN etc. address
261 GNUNET_TRANSPORT_UpdateAddressMetrics update_address_metrics;
265 * What is the maximum number of connections that this transport
266 * should allow? Transports that do not have sessions (such as
267 * UDP) can ignore this value.
269 uint32_t max_connections;
275 * Function called by the GNUNET_TRANSPORT_TransmitFunction
276 * upon "completion". In the case that a peer disconnects,
277 * this function must be called for each pending request
278 * (with a 'failure' indication) AFTER notifying the service
279 * about the disconnect event (so that the service won't try
280 * to transmit more messages, believing the connection still
284 * @param target who was the recipient of the message?
285 * @param result GNUNET_OK on success
286 * GNUNET_SYSERR if the target disconnected;
287 * disconnect will ALSO be signalled using
288 * the ReceiveCallback.
289 * @param size_payload bytes of payload from transport service in message
290 * @param size_on_wire bytes required on wire for transmission,
291 * 0 if result == GNUNET_SYSERR
293 typedef void (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
295 GNUNET_PeerIdentity *
299 size_t size_on_wire);
302 * The new send function with just the session and no address
304 * Function that can be used by the transport service to transmit
305 * a message using the plugin. Note that in the case of a
306 * peer disconnecting, the continuation MUST be called
307 * prior to the disconnect notification itself. This function
308 * will be called with this peer's HELLO message to initiate
309 * a fresh connection to another peer.
312 * @param session which session must be used
313 * @param msgbuf the message to transmit
314 * @param msgbuf_size number of bytes in 'msgbuf'
315 * @param priority how important is the message (most plugins will
316 * ignore message priority and just FIFO)
317 * @param timeout how long to wait at most for the transmission (does not
318 * require plugins to discard the message after the timeout,
319 * just advisory for the desired delay; most plugins will ignore
321 * @param cont continuation to call once the message has
322 * been transmitted (or if the transport is ready
323 * for the next transmission call; or if the
324 * peer disconnected...); can be NULL
325 * @param cont_cls closure for cont
326 * @return number of bytes used (on the physical network, with overheads);
327 * -1 on hard errors (i.e. address invalid); 0 is a legal value
328 * and does NOT mean that the message was not transmitted (DV)
330 typedef ssize_t (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
331 struct Session *session,
332 const char *msgbuf, size_t msgbuf_size,
333 unsigned int priority,
334 struct GNUNET_TIME_Relative to,
335 GNUNET_TRANSPORT_TransmitContinuation cont,
340 * Function that can be called to force a disconnect from the
341 * specified neighbour. This should also cancel all previously
342 * scheduled transmissions. Obviously the transmission may have been
343 * partially completed already, which is OK. The plugin is supposed
344 * to close the connection (if applicable) and no longer call the
345 * transmit continuation(s).
347 * Finally, plugin MUST NOT call the services's receive function to
348 * notify the service that the connection to the specified target was
349 * closed after a getting this call.
352 * @param target peer for which the last transmission is
355 typedef void (*GNUNET_TRANSPORT_DisconnectFunction) (void *cls,
357 GNUNET_PeerIdentity *
362 * Function called by the pretty printer for the resolved address for
363 * each human-readable address obtained.
366 * @param hostname one of the names for the host, NULL
367 * on the last call to the callback
369 typedef void (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
370 const char *address);
374 * Convert the transports address to a nice, human-readable
378 * @param name name of the transport that generated the address
379 * @param addr one of the addresses of the host, NULL for the last address
380 * the specific address format depends on the transport
381 * @param addrlen length of the address
382 * @param numeric should (IP) addresses be displayed in numeric form?
383 * @param timeout after how long should we give up?
384 * @param asc function to call on each string
385 * @param asc_cls closure for asc
387 typedef void (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
395 GNUNET_TRANSPORT_AddressStringCallback
400 * Another peer has suggested an address for this peer and transport
401 * plugin. Check that this could be a valid address. This function
402 * is not expected to 'validate' the address in the sense of trying to
403 * connect to it but simply to see if the binary format is technically
404 * legal for establishing a connection to this peer (and make sure that
405 * the address really corresponds to our network connection/settings
406 * and not some potential man-in-the-middle).
408 * @param addr pointer to the address
409 * @param addrlen length of addr
410 * @return GNUNET_OK if this is a plausible address for this peer
411 * and transport, GNUNET_SYSERR if not
413 typedef int (*GNUNET_TRANSPORT_CheckAddress) (void *cls, const void *addr,
417 * Create a new session to transmit data to the target
418 * This session will used to send data to this peer and the plugin will
419 * notify us by calling the env->session_end function
421 * @param cls the plugin
422 * @param target the neighbour id
423 * @param addr pointer to the address
424 * @param addrlen length of addr
425 * @return the session if the address is valid, NULL otherwise
427 typedef struct Session * (*GNUNET_TRANSPORT_CreateSession) (void *cls,
428 const struct GNUNET_HELLO_Address *address);
432 * Function called for a quick conversion of the binary address to
433 * a numeric address. Note that the caller must not free the
434 * address and that the next call to this function is allowed
435 * to override the address again.
438 * @param addr binary address
439 * @param addr_len length of the address
440 * @return string representing the same address
442 typedef const char *(*GNUNET_TRANSPORT_AddressToString) (void *cls,
447 * Function called to convert a string address to
450 * @param cls closure ('struct Plugin*')
451 * @param addr string address
452 * @param addrlen length of the address including \0 termination
453 * @param buf location to store the buffer
454 * If the function returns GNUNET_SYSERR, its contents are undefined.
455 * @param added length of created address
456 * @return GNUNET_OK on success, GNUNET_SYSERR on failure
458 typedef int (*GNUNET_TRANSPORT_StringToAddress) (void *cls,
466 * Each plugin is required to return a pointer to a struct of this
467 * type as the return value from its entry point.
469 struct GNUNET_TRANSPORT_PluginFunctions
473 * Closure for all of the callbacks.
478 * Function that the transport service will use to transmit data to
479 * another peer. May be NULL for plugins that only support
480 * receiving data. After this call, the plugin call the specified
481 * continuation with success or error before notifying us about the
482 * target having disconnected.
484 GNUNET_TRANSPORT_TransmitFunction send;
487 * Function that can be used to force the plugin to disconnect from
488 * the given peer and cancel all previous transmissions (and their
491 GNUNET_TRANSPORT_DisconnectFunction disconnect;
494 * Function to pretty-print addresses. NOTE: this function is not
495 * yet used by transport-service, but will be used in the future
496 * once the transport-API has been completed.
498 GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
501 * Function that will be called to check if a binary address
502 * for this plugin is well-formed and corresponds to an
503 * address for THIS peer (as per our configuration). Naturally,
504 * if absolutely necessary, plugins can be a bit conservative in
505 * their answer, but in general plugins should make sure that the
506 * address does not redirect traffic to a 3rd party that might
507 * try to man-in-the-middle our traffic.
509 GNUNET_TRANSPORT_CheckAddress check_address;
512 * Function that will be called to convert a binary address
513 * to a string (numeric conversion only).
515 GNUNET_TRANSPORT_AddressToString address_to_string;
518 * Function that will be called to convert a string address
519 * to binary (numeric conversion only).
521 GNUNET_TRANSPORT_StringToAddress string_to_address;
524 * Function that will be called tell the plugin to create a session
527 GNUNET_TRANSPORT_CreateSession get_session;