summaryrefslogtreecommitdiff
path: root/src/include/gnunet_transport_service.h
blob: d291609a8a9941dfe1aa90ffa8222580141c98c7 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
/*
     This file is part of GNUnet.
     Copyright (C) 2009-2016 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Affero General Public License for more details.
*/

/**
 * @author Christian Grothoff
 *
 * @file
 * Low-level P2P IO
 *
 * @defgroup transport  Transport service
 * Low-level P2P IO
 *
 * @see [Documentation](https://gnunet.org/transport-service)
 *
 * @{
 */

#ifndef GNUNET_TRANSPORT_SERVICE_H
#define GNUNET_TRANSPORT_SERVICE_H

#ifdef __cplusplus
extern "C"
{
#if 0                           /* keep Emacsens' auto-indent happy */
}
#endif
#endif

#include "gnunet_util_lib.h"
#include "gnunet_ats_service.h"

/**
 * Version number of the transport API.
 */
#define GNUNET_TRANSPORT_VERSION 0x00000003


/* *************************** HELLO *************************** */

/**
 * Handle for a #GNUNET_TRANSPORT_offer_hello operation
 */
struct GNUNET_TRANSPORT_OfferHelloHandle;


/**
 * Offer the transport service the HELLO of another peer.  Note that
 * the transport service may just ignore this message if the HELLO is
 * malformed or useless due to our local configuration.
 *
 * @param cfg configuration
 * @param hello the hello message
 * @param cont continuation to call when HELLO has been sent,
 *      tc reason #GNUNET_SCHEDULER_REASON_TIMEOUT for fail
 *      tc reasong #GNUNET_SCHEDULER_REASON_READ_READY for success
 * @param cont_cls closure for @a cont
 * @return a `struct GNUNET_TRANSPORT_OfferHelloHandle` handle or NULL on failure,
 *      in case of failure @a cont will not be called
 *
 */
struct GNUNET_TRANSPORT_OfferHelloHandle *
GNUNET_TRANSPORT_offer_hello (const struct GNUNET_CONFIGURATION_Handle *cfg,
                              const struct GNUNET_MessageHeader *hello,
                              GNUNET_SCHEDULER_TaskCallback cont,
                              void *cont_cls);


/**
 * Cancel the request to transport to offer the HELLO message
 *
 * @param ohh the `struct GNUNET_TRANSPORT_OfferHelloHandle` to cancel
 */
void
GNUNET_TRANSPORT_offer_hello_cancel (struct GNUNET_TRANSPORT_OfferHelloHandle *ohh);


/* *********************** Address to String ******************* */

/**
 * Handle to cancel a pending address lookup.
 */
struct GNUNET_TRANSPORT_AddressToStringContext;


/**
 * Function to call with a textual representation of an address.  This
 * function will be called several times with different possible
 * textual representations, and a last time with @a address being NULL
 * to signal the end of the iteration.  Note that @a address NULL
 * always is the last call, regardless of the value in @a res.
 *
 * @param cls closure
 * @param address NULL on end of iteration,
 *        otherwise 0-terminated printable UTF-8 string,
 *        in particular an empty string if @a res is #GNUNET_NO
 * @param res result of the address to string conversion:
 *        if #GNUNET_OK: conversion successful
 *        if #GNUNET_NO: address was invalid (or not supported)
 *        if #GNUNET_SYSERR: communication error (IPC error)
 */
typedef void
(*GNUNET_TRANSPORT_AddressToStringCallback) (void *cls,
                                             const char *address,
                                             int res);


/**
 * Convert a binary address into a human readable address.
 *
 * @param cfg configuration to use
 * @param address address to convert (binary format)
 * @param numeric should (IP) addresses be displayed in numeric form
 *                (otherwise do reverse DNS lookup)
 * @param timeout how long is the lookup allowed to take at most
 * @param aluc function to call with the results
 * @param aluc_cls closure for @a aluc
 * @return handle to cancel the operation, NULL on error
 */
struct GNUNET_TRANSPORT_AddressToStringContext *
GNUNET_TRANSPORT_address_to_string (const struct GNUNET_CONFIGURATION_Handle *cfg,
                                    const struct GNUNET_HELLO_Address *address,
                                    int numeric,
                                    struct GNUNET_TIME_Relative timeout,
                                    GNUNET_TRANSPORT_AddressToStringCallback aluc,
                                    void *aluc_cls);


/**
 * Cancel request for address conversion.
 *
 * @param alc the context handle
 */
void
GNUNET_TRANSPORT_address_to_string_cancel (struct GNUNET_TRANSPORT_AddressToStringContext *alc);


/* *********************** Monitoring ************************** */


/**
 * Possible state of a neighbour.  Initially, we are #GNUNET_TRANSPORT_PS_NOT_CONNECTED.
 *
 * Then, there are two main paths. If we receive a SYN message, we give
 * the inbound address to ATS. After the check we ask ATS for a suggestion
 * (#GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS). If ATS makes a suggestion, we
 * send our SYN_ACK and go to #GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK.
 * If we receive a ACK, we go to #GNUNET_TRANSPORT_PS_CONNECTED
 * (and notify everyone about the new connection). If the operation times out,
 * we go to #GNUNET_TRANSPORT_PS_DISCONNECT.
 *
 * The other case is where we transmit a SYN message first.  We
 * start with #GNUNET_TRANSPORT_PS_INIT_ATS.  If we get an address, we send
 * the SYN message and go to state #GNUNET_TRANSPORT_PS_CONNECT_SENT.
 * Once we receive a SYN_ACK, we go to #GNUNET_TRANSPORT_PS_CONNECTED
 * (and notify everyone about the new connection and send
 * back a ACK).  If the operation times out, we go to
 * #GNUNET_TRANSPORT_PS_DISCONNECT.
 *
 * If the session is in trouble (i.e. transport-level disconnect or
 * timeout), we go to #GNUNET_TRANSPORT_PS_RECONNECT_ATS where we ask ATS for a new
 * address (we don't notify anyone about the disconnect yet).  Once we
 * have a new address, we enter #GNUNET_TRANSPORT_PS_RECONNECT_SENT and send a
 * SYN message.  If we receive a
 * SYN_ACK, we go to #GNUNET_TRANSPORT_PS_CONNECTED and nobody noticed that we had
 * trouble; we also send a ACK at this time just in case.  If
 * the operation times out, we go to #GNUNET_TRANSPORT_PS_DISCONNECT (and notify everyone
 * about the lost connection).
 *
 * If ATS decides to switch addresses while we have a normal
 * connection, we go to #GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_SYN_SENT
 * and send a SESSION_CONNECT.  If we get a ACK back, we switch the
 * primary connection to the suggested alternative from ATS, go back
 * to #GNUNET_TRANSPORT_PS_CONNECTED and send a ACK to the other peer just to be
 * sure.  If the operation times out
 * we go to #GNUNET_TRANSPORT_PS_CONNECTED (and notify ATS that the given alternative
 * address is "invalid").
 *
 * Once a session is in #GNUNET_TRANSPORT_PS_DISCONNECT, it is cleaned up and then goes
 * to (#GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED).  If we receive an explicit disconnect
 * request, we can go from any state to #GNUNET_TRANSPORT_PS_DISCONNECT, possibly after
 * generating disconnect notifications.
 *
 * Note that it is quite possible that while we are in any of these
 * states, we could receive a 'SYN' request from the other peer.
 * We then enter a 'weird' state where we pursue our own primary state
 * machine (as described above), but with the 'send_connect_ack' flag
 * set to 1.  If our state machine allows us to send a 'SYN_ACK'
 * (because we have an acceptable address), we send the 'SYN_ACK'
 * and set the 'send_connect_ack' to 2.  If we then receive a
 * 'ACK', we go to #GNUNET_TRANSPORT_PS_CONNECTED (and reset 'send_connect_ack'
 * to 0).
 *
 */
enum GNUNET_TRANSPORT_PeerState
{
  /**
   * Fresh peer or completely disconnected
   */
  GNUNET_TRANSPORT_PS_NOT_CONNECTED = 0,

  /**
   * Asked to initiate connection, trying to get address from ATS
   */
  GNUNET_TRANSPORT_PS_INIT_ATS,

  /**
   * Sent SYN message to other peer, waiting for SYN_ACK
   */
  GNUNET_TRANSPORT_PS_SYN_SENT,

  /**
   * Received a SYN, asking ATS about address suggestions.
   */
  GNUNET_TRANSPORT_PS_SYN_RECV_ATS,

  /**
   * SYN request from other peer was SYN_ACK'ed, waiting for ACK.
   */
  GNUNET_TRANSPORT_PS_SYN_RECV_ACK,

  /**
   * Got our SYN_ACK/ACK, connection is up.
   */
  GNUNET_TRANSPORT_PS_CONNECTED,

  /**
   * Connection got into trouble, rest of the system still believes
   * it to be up, but we're getting a new address from ATS.
   */
  GNUNET_TRANSPORT_PS_RECONNECT_ATS,

  /**
   * Sent SYN over new address (either by ATS telling us to switch
   * addresses or from RECONNECT_ATS); if this fails, we need to tell
   * the rest of the system about a disconnect.
   */
  GNUNET_TRANSPORT_PS_RECONNECT_SENT,

  /**
   * We have some primary connection, but ATS suggested we switch
   * to some alternative; we now sent a SYN message for the
   * alternative session to the other peer and waiting for a
   * SYN_ACK to make this our primary connection.
   */
  GNUNET_TRANSPORT_PS_SWITCH_SYN_SENT,

  /**
   * Disconnect in progress (we're sending the DISCONNECT message to the
   * other peer; after that is finished, the state will be cleaned up).
   */
  GNUNET_TRANSPORT_PS_DISCONNECT,

  /**
   * We're finished with the disconnect; and are cleaning up the state
   * now!  We put the struct into this state when we are really in the
   * task that calls 'free' on it and are about to remove the record
   * from the map.  We should never find a 'struct NeighbourMapEntry'
   * in this state in the map.  Accessing a 'struct NeighbourMapEntry'
   * in this state virtually always means using memory that has been
   * freed (the exception being the cleanup code in #free_neighbour()).
   */
  GNUNET_TRANSPORT_PS_DISCONNECT_FINISHED
};


/**
 * Convert a transport state to a human readable string.
 *
 * @param state the state
 */
const char *
GNUNET_TRANSPORT_ps2s (enum GNUNET_TRANSPORT_PeerState state);


/**
 * Check if a state is defined as connected
 *
 * @param state the state value
 * @return #GNUNET_YES or #GNUNET_NO
 */
int
GNUNET_TRANSPORT_is_connected (enum GNUNET_TRANSPORT_PeerState state);


/**
 * Handle for a #GNUNET_TRANSPORT_monitor_peers operation.
 */
struct GNUNET_TRANSPORT_PeerMonitoringContext;


/**
 * Function to call with information about a peer
 *
 * If one_shot was set to #GNUNET_YES to iterate over all peers once,
 * a final call with NULL for peer and address will follow when done.
 * In this case state and timeout do not contain valid values.
 *
 * The #GNUNET_TRANSPORT_monitor_peers_cancel() call MUST not be called from
 * within this function!
 *
 *
 * @param cls closure
 * @param peer peer this update is about,
 *      NULL if this is the final last callback for a iteration operation
 * @param address address, NULL if this is the final callback for iteration op
 * @param state current state this peer is in
 * @param state_timeout timeout for the current state of the peer
 */
typedef void
(*GNUNET_TRANSPORT_PeerIterateCallback) (void *cls,
                                         const struct GNUNET_PeerIdentity *peer,
                                         const struct GNUNET_HELLO_Address *address,
                                         enum GNUNET_TRANSPORT_PeerState state,
                                         struct GNUNET_TIME_Absolute state_timeout);


/**
 * Return information about a specific peer or all peers currently known to
 * transport service once or in monitoring mode. To obtain information about
 * a specific peer, a peer identity can be passed. To obtain information about
 * all peers currently known to transport service, NULL can be passed as peer
 * identity.
 *
 * For each peer, the callback is called with information about the address used
 * to communicate with this peer, the state this peer is currently in and the
 * the current timeout for this state.
 *
 * Upon completion, the #GNUNET_TRANSPORT_PeerIterateCallback is called one
 * more time with `NULL`. After this, the operation must no longer be
 * explicitly canceled.
 *
 * The #GNUNET_TRANSPORT_monitor_peers_cancel call MUST not be called in the
 * the peer_callback!
 *
 * @param cfg configuration to use
 * @param peer a specific peer identity to obtain information for,
 *      NULL for all peers
 * @param one_shot #GNUNET_YES to return the current state and then end (with NULL+NULL),
 *                 #GNUNET_NO to monitor peers continuously
 * @param peer_callback function to call with the results
 * @param peer_callback_cls closure for @a peer_callback
 */
struct GNUNET_TRANSPORT_PeerMonitoringContext *
GNUNET_TRANSPORT_monitor_peers (const struct GNUNET_CONFIGURATION_Handle *cfg,
                                const struct GNUNET_PeerIdentity *peer,
                                int one_shot,
                                GNUNET_TRANSPORT_PeerIterateCallback peer_callback,
                                void *peer_callback_cls);


/**
 * Cancel request to monitor peers
 *
 * @param pic handle for the request to cancel
 */
void
GNUNET_TRANSPORT_monitor_peers_cancel (struct GNUNET_TRANSPORT_PeerMonitoringContext *pic);


/* *********************** Blacklisting ************************ */

/**
 * Handle for blacklisting peers.
 */
struct GNUNET_TRANSPORT_Blacklist;


/**
 * Function that decides if a connection is acceptable or not.
 *
 * @param cls closure
 * @param pid peer to approve or disapproave
 * @return #GNUNET_OK if the connection is allowed, #GNUNET_SYSERR if not
 */
typedef int
(*GNUNET_TRANSPORT_BlacklistCallback) (void *cls,
                                       const struct GNUNET_PeerIdentity *pid);


/**
 * Install a blacklist callback.  The service will be queried for all
 * existing connections as well as any fresh connections to check if
 * they are permitted.  If the blacklisting callback is unregistered,
 * all hosts that were denied in the past will automatically be
 * whitelisted again.  Cancelling the blacklist handle is also the
 * only way to re-enable connections from peers that were previously
 * blacklisted.
 *
 * @param cfg configuration to use
 * @param cb callback to invoke to check if connections are allowed
 * @param cb_cls closure for @a cb
 * @return NULL on error, otherwise handle for cancellation
 */
struct GNUNET_TRANSPORT_Blacklist *
GNUNET_TRANSPORT_blacklist (const struct GNUNET_CONFIGURATION_Handle *cfg,
                            GNUNET_TRANSPORT_BlacklistCallback cb,
                            void *cb_cls);


/**
 * Abort the blacklist.  Note that this function is the only way for
 * removing a peer from the blacklist.
 *
 * @param br handle of the request that is to be cancelled
 */
void
GNUNET_TRANSPORT_blacklist_cancel (struct GNUNET_TRANSPORT_Blacklist *br);


/**
 * Handle for a plugin session state monitor.
 */
struct GNUNET_TRANSPORT_PluginMonitor;

/**
 * Abstract representation of a plugin's session.
 * Corresponds to the `struct GNUNET_ATS_Session` within the TRANSPORT service.
 */
struct GNUNET_TRANSPORT_PluginSession;


/**
 * Possible states of a session in a plugin.
 */
enum GNUNET_TRANSPORT_SessionState
{

  /**
   * The session was created (first call for each session object).
   */
  GNUNET_TRANSPORT_SS_INIT,

  /**
   * Initial session handshake is in progress.
   */
  GNUNET_TRANSPORT_SS_HANDSHAKE,

  /**
   * Session is fully UP.
   */
  GNUNET_TRANSPORT_SS_UP,

  /**
   * This is just an update about the session,
   * the state did not change.
   */
  GNUNET_TRANSPORT_SS_UPDATE,

  /**
   * Session is being torn down and about to disappear.
   * Last call for each session object.
   */
  GNUNET_TRANSPORT_SS_DONE

};


/**
 * Information about a plugin's session.
 */
struct GNUNET_TRANSPORT_SessionInfo
{

  /**
   * New state of the session.
   */
  enum GNUNET_TRANSPORT_SessionState state;

  /**
   * #GNUNET_YES if this is an inbound connection,
   * #GNUNET_NO if this is an outbound connection,
   * #GNUNET_SYSERR if connections of this plugin
   *             are so fundamentally bidirectional
   *             that they have no 'initiator'
   */
  int is_inbound;

  /**
   * Number of messages pending transmission for this session.
   */
  uint32_t num_msg_pending;

  /**
   * Number of bytes pending transmission for this session.
   */
  uint32_t num_bytes_pending;

  /**
   * Until when does this plugin refuse to receive to manage
   * staying within the inbound quota?  ZERO if receive is
   * active.
   */
  struct GNUNET_TIME_Absolute receive_delay;

  /**
   * At what time will this session timeout (unless activity
   * happens)?
   */
  struct GNUNET_TIME_Absolute session_timeout;

  /**
   * Address used by the session.  Can be NULL if none is available.
   */
  const struct GNUNET_HELLO_Address *address;
};


/**
 * Function called by the plugin with information about the
 * current sessions managed by the plugin (for monitoring).
 *
 * @param cls closure
 * @param session session handle this information is about,
 *        NULL to indicate that we are "in sync" (initial
 *        iteration complete)
 * @param session_ctx storage location where the application
 *        can store data; will point to NULL on #GNUNET_TRANSPORT_SS_INIT,
 *        and must be reset to NULL on #GNUNET_TRANSPORT_SS_DONE
 * @param info information about the state of the session,
 *        NULL if @a session is also NULL and we are
 *        merely signalling that the initial iteration is over;
 *        NULL with @a session being non-NULL if the monitor
 *        was being cancelled while sessions were active
 */
typedef void
(*GNUNET_TRANSPORT_SessionMonitorCallback) (void *cls,
                                            struct GNUNET_TRANSPORT_PluginSession *session,
                                            void **session_ctx,
                                            const struct GNUNET_TRANSPORT_SessionInfo *info);


/**
 * Install a plugin session state monitor callback.  The callback
 * will be notified whenever the session changes.
 *
 * @param cfg configuration to use
 * @param cb callback to invoke on events
 * @param cb_cls closure for @a cb
 * @return NULL on error, otherwise handle for cancellation
 */
struct GNUNET_TRANSPORT_PluginMonitor *
GNUNET_TRANSPORT_monitor_plugins (const struct GNUNET_CONFIGURATION_Handle *cfg,
                                  GNUNET_TRANSPORT_SessionMonitorCallback cb,
                                  void *cb_cls);


/**
 * Cancel monitoring the plugin session state.  The callback will be
 * called once for each session that is up with the "info" argument
 * being NULL (this is just to enable client-side cleanup).
 *
 * @param pm handle of the request that is to be cancelled
 */
void
GNUNET_TRANSPORT_monitor_plugins_cancel (struct GNUNET_TRANSPORT_PluginMonitor *pm);



#if 0                           /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif

/* ifndef GNUNET_TRANSPORT_SERVICE_H */
#endif

/** @} */  /* end of group */

/* end of gnunet_transport_service.h */