summaryrefslogtreecommitdiff
path: root/src/include/gnunet_transport_service.h
blob: d4948e5babbc00ffcbc26a5e4ca18d512a9d036d (plain)
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
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
/*
     This file is part of GNUnet.
     (C) 2009-2014 Christian Grothoff (and other contributing authors)

     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, 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
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file include/gnunet_transport_service.h
 * @brief low-level P2P IO
 * @author Christian Grothoff
 */

#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 0x00000001


/**
 * Possible state of a neighbour.  Initially, we are #GNUNET_TRANSPORT_PS_NOT_CONNECTED.
 *
 * Then, there are two main paths. If we receive a CONNECT message, we
 * first run a check against the blacklist (#GNUNET_TRANSPORT_PS_CONNECT_RECV_BLACKLIST_INBOUND).
 * If this check is successful, 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 ALSO give that suggestion to the blacklist
 * (#GNUNET_TRANSPORT_PS_CONNECT_RECV_BLACKLIST).  Once the blacklist approves the
 * address we got from ATS, we send our CONNECT_ACK and go to
 * #GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK.  If we receive a SESSION_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 CONNECT message first.  We
 * start with #GNUNET_TRANSPORT_PS_INIT_ATS.  If we get an address, we enter
 * #GNUNET_TRANSPORT_PS_INIT_BLACKLIST and check the blacklist.  If the blacklist is OK
 * with the connection, we actually send the CONNECT message and go to
 * state #GNUNET_TRANSPORT_PS_CONNECT_SENT.  Once we receive a CONNECT_ACK, we go to
 * #GNUNET_TRANSPORT_PS_CONNECTED (and notify everyone about the new connection and send
 * back a SESSION_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 go to #GNUNET_TRANSPORT_PS_RECONNECT_BLACKLIST to check the new
 * address against the blacklist.  If the blacklist approves, we enter
 * #GNUNET_TRANSPORT_PS_RECONNECT_SENT and send a CONNECT message.  If we receive a
 * CONNECT_ACK, we go to #GNUNET_TRANSPORT_PS_CONNECTED and nobody noticed that we had
 * trouble; we also send a SESSION_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_BLACKLIST to check the
 * new address against the blacklist.  If the blacklist approves, we
 * go to #GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_CONNECT_SENT and send a
 * SESSION_CONNECT.  If we get a SESSION_ACK back, we switch the
 * primary connection to the suggested alternative from ATS, go back
 * to #GNUNET_TRANSPORT_PS_CONNECTED and send a SESSION_ACK to the other peer just to be
 * sure.  If the operation times out (or the blacklist disapproves),
 * 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 'CONNECT' 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 'CONNECT_ACK'
 * (because we have an acceptable address), we send the 'CONNECT_ACK'
 * and set the 'send_connect_ack' to 2.  If we then receive a
 * 'SESSION_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,

  /**
   * Asked to initiate connection, trying to get address approved
   * by blacklist.
   */
  GNUNET_TRANSPORT_PS_INIT_BLACKLIST,

  /**
   * Sent CONNECT message to other peer, waiting for CONNECT_ACK
   */
  GNUNET_TRANSPORT_PS_CONNECT_SENT,

  /**
   * Received a CONNECT, do a blacklist check for inbound address
   */
  GNUNET_TRANSPORT_PS_CONNECT_RECV_BLACKLIST_INBOUND,

  /**
   * Received a CONNECT, asking ATS about address suggestions.
   */
  GNUNET_TRANSPORT_PS_CONNECT_RECV_ATS,

  /**
   * Received CONNECT from other peer, got an address, checking with blacklist.
   */
  GNUNET_TRANSPORT_PS_CONNECT_RECV_BLACKLIST,

  /**
   * CONNECT request from other peer was SESSION_ACK'ed, waiting for
   * SESSION_ACK.
   */
  GNUNET_TRANSPORT_PS_CONNECT_RECV_ACK,

  /**
   * Got our CONNECT_ACK/SESSION_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,

  /**
   * Connection got into trouble, rest of the system still believes
   * it to be up; we are checking the new address against the blacklist.
   */
  GNUNET_TRANSPORT_PS_RECONNECT_BLACKLIST,

  /**
   * Sent CONNECT 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're now checking the alternative against
   * the blacklist.
   */
  GNUNET_TRANSPORT_PS_CONNECTED_SWITCHING_BLACKLIST,

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


/**
 * Current state of a validation process
 */
enum GNUNET_TRANSPORT_ValidationState
{
  /**
   * Undefined state
   *
   * Used for final callback indicating operation done
   */
  GNUNET_TRANSPORT_VS_NONE,

  /**
   * Fresh validation entry
   *
   * Entry was just created, no validation process was executed
   */
  GNUNET_TRANSPORT_VS_NEW,

  /**
   * Updated validation entry
   *
   * This is an update for an existing validation entry
   */
  GNUNET_TRANSPORT_VS_UPDATE,

  /**
   * Timeout for validation entry
   *
   * A timeout occured during the validation process
   */
  GNUNET_TRANSPORT_VS_TIMEOUT,

  /**
   * Validation entry is removed
   *
   * The validation entry is getting removed due to a failed validation
   */
  GNUNET_TRANSPORT_VS_REMOVE
};


/**
 * Function called by the transport for each received message.
 *
 * @param cls closure
 * @param peer (claimed) identity of the other peer
 * @param message the message
 * @param ats performance data
 * @param ats_count number of entries in @a ats
 */
typedef void
(*GNUNET_TRANSPORT_ReceiveCallback) (void *cls,
                                     const struct GNUNET_PeerIdentity *peer,
                                     const struct GNUNET_MessageHeader *message);


/**
 * Opaque handle to the service.
 */
struct GNUNET_TRANSPORT_Handle;


/**
 * Function called to notify transport users that another
 * peer connected to us.
 *
 * @param cls closure
 * @param peer the peer that connected
 * @param ats performance data
 * @param ats_count number of entries in @a ats (excluding 0-termination)
 */
typedef void
(*GNUNET_TRANSPORT_NotifyConnect) (void *cls,
                                   const struct GNUNET_PeerIdentity *peer);

/**
 * Function called to notify transport users that another
 * peer disconnected from us.
 *
 * @param cls closure
 * @param peer the peer that disconnected
 */
typedef void
(*GNUNET_TRANSPORT_NotifyDisconnect) (void *cls,
                                      const struct GNUNET_PeerIdentity *peer);


/**
 * Function to call with result of the try connect request.
 *
 *
 * @param cls closure
 * @param result #GNUNET_OK if message was transmitted to transport service
 *               #GNUNET_SYSERR if message was not transmitted to transport service
 */
typedef void
(*GNUNET_TRANSPORT_TryConnectCallback) (void *cls,
                                        const int result);


/**
 * 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 NULL to signal the end
 * of the iteration.
 *
 * @param cls closure
 * @param address NULL on error or end of iteration,
 *        otherwise 0-terminated printable UTF-8 string
 */
typedef void
(*GNUNET_TRANSPORT_AddressToStringCallback) (void *cls,
                                             const char *address);


/**
 * 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 for disconnect notification in monitor mode
 * @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);


/**
 * Function to call with validation information about a peer
 *
 * This function is called by the transport validation monitoring api to
 * indicate a change to a validation entry. The information included represent
 * the current state of the validation entry,
 *
 * If the monitoring was called with one_shot=GNUNET_YES, a final callback
 * with peer==NULL and address==NULL is executed.
 *
 * @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 for disconnect notification in monitor mode
 * @param valid_until when does this address expire
 * @param next_validation time of the next validation operation
 *
 */
typedef void
(*GNUNET_TRANSPORT_ValidationIterateCallback) (void *cls,
                                               const struct GNUNET_PeerIdentity *peer,
                                               const struct GNUNET_HELLO_Address *address,
                                               struct GNUNET_TIME_Absolute last_validation,
                                               struct GNUNET_TIME_Absolute valid_until,
                                               struct GNUNET_TIME_Absolute next_validation,
                                               enum GNUNET_TRANSPORT_ValidationState state);


/**
 * Connect to the transport service.  Note that the connection may
 * complete (or fail) asynchronously.
 *
 * @param cfg configuration to use
 * @param self our own identity (API should check that it matches
 *             the identity found by transport), or NULL (no check)
 * @param cls closure for the callbacks
 * @param rec receive function to call, or NULL
 * @param nc function to call on connect events, or NULL
 * @param nd function to call on disconnect events, or NULL
 * @return NULL on error
 */
struct GNUNET_TRANSPORT_Handle *
GNUNET_TRANSPORT_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
                          const struct GNUNET_PeerIdentity *self,
                          void *cls,
                          GNUNET_TRANSPORT_ReceiveCallback rec,
                          GNUNET_TRANSPORT_NotifyConnect nc,
                          GNUNET_TRANSPORT_NotifyDisconnect nd);


/**
 * Disconnect from the transport service.
 *
 * @param handle handle returned from connect
 */
void
GNUNET_TRANSPORT_disconnect (struct GNUNET_TRANSPORT_Handle *handle);


/**
 * Opaque handle for a transmission-ready request.
 */
struct GNUNET_TRANSPORT_TryConnectHandle;


/**
 * Ask the transport service to establish a connection to
 * the given peer.
 *
 * @param handle connection to transport service
 * @param target who we should try to connect to
 * @param cb callback to be called when request was transmitted to transport
 *         service
 * @param cb_cls closure for the callback @a cb
 * @return a `struct GNUNET_TRANSPORT_TryConnectHandle` handle or
 *         NULL on failure (@a cb will not be called)
 */
struct GNUNET_TRANSPORT_TryConnectHandle *
GNUNET_TRANSPORT_try_connect (struct GNUNET_TRANSPORT_Handle *handle,
                              const struct GNUNET_PeerIdentity *target,
                              GNUNET_TRANSPORT_TryConnectCallback cb,
                              void *cb_cls);


/**
 * Cancel the request to transport to try a connect
 * Callback will not be called
 *
 * @param tch GNUNET_TRANSPORT_TryConnectHandle handle to cancel
 */
void
GNUNET_TRANSPORT_try_connect_cancel (struct GNUNET_TRANSPORT_TryConnectHandle *tch);


/**
 * Opaque handle for a transmission-ready request.
 */
struct GNUNET_TRANSPORT_TransmitHandle;


/**
 * Function called to notify a client about the connection begin ready
 * to queue more data.  @a buf will be NULL and @a size zero if the
 * connection was closed for writing in the meantime.
 *
 * @param cls closure
 * @param size number of bytes available in @a buf
 * @param buf where the callee should write the message
 * @return number of bytes written to @a buf
 */
typedef size_t
(*GNUNET_TRANSPORT_TransmitReadyNotify) (void *cls,
                                         size_t size,
                                         void *buf);


/**
 * Check if we could queue a message of the given size for
 * transmission.  The transport service will take both its internal
 * buffers and bandwidth limits imposed by the other peer into
 * consideration when answering this query.
 *
 * @param handle connection to transport service
 * @param target who should receive the message
 * @param size how big is the message we want to transmit?
 * @param timeout after how long should we give up (and call
 *        notify with buf NULL and size 0)?
 * @param notify function to call when we are ready to
 *        send such a message
 * @param notify_cls closure for @a notify
 * @return NULL if someone else is already waiting to be notified
 *         non-NULL if the notify callback was queued (can be used to cancel
 *         using GNUNET_TRANSPORT_notify_transmit_ready_cancel)
 */
struct GNUNET_TRANSPORT_TransmitHandle *
GNUNET_TRANSPORT_notify_transmit_ready (struct GNUNET_TRANSPORT_Handle *handle,
                                        const struct GNUNET_PeerIdentity *target,
                                        size_t size,
                                        struct GNUNET_TIME_Relative timeout,
                                        GNUNET_TRANSPORT_TransmitReadyNotify notify,
                                        void *notify_cls);


/**
 * Cancel the specified transmission-ready notification.
 *
 * @param th handle of the transmission notification request to cancel
 */
void
GNUNET_TRANSPORT_notify_transmit_ready_cancel (struct GNUNET_TRANSPORT_TransmitHandle *th);


/**
 * Function called whenever there is an update to the
 * HELLO of this peer.
 *
 * @param cls closure
 * @param hello our updated HELLO
 */
typedef void
(*GNUNET_TRANSPORT_HelloUpdateCallback) (void *cls,
                                         const struct GNUNET_MessageHeader *hello);


/**
 * Handle to cancel a #GNUNET_TRANSPORT_get_hello() operation.
 */
struct GNUNET_TRANSPORT_GetHelloHandle;


/**
 * Checks if a given peer is connected to us
 *
 * @param handle connection to transport service
 * @param peer the peer to check
 * @return #GNUNET_YES (connected) or #GNUNET_NO (disconnected)
 */
int
GNUNET_TRANSPORT_check_peer_connected (struct GNUNET_TRANSPORT_Handle *handle,
                                       const struct GNUNET_PeerIdentity *peer);


/**
 * Set transport metrics for a peer and a direction
 *
 * @param handle transport handle
 * @param peer the peer to set the metric for
 * @param inbound set inbound direction (#GNUNET_YES or #GNUNET_NO)
 * @param outbound set outbound direction (#GNUNET_YES or #GNUNET_NO)
 * @param ats the metric as ATS information
 * @param ats_count the number of metrics
 *
 * Supported ATS values:
 * #GNUNET_ATS_QUALITY_NET_DELAY  (value in ms)
 * #GNUNET_ATS_QUALITY_NET_DISTANCE (value in count(hops))
 *
 * Example
 * To enforce a delay of 10 ms for peer p1 in sending direction use:
 *
 * struct GNUNET_ATS_Information ats;
 * ats.type = ntohl (GNUNET_ATS_QUALITY_NET_DELAY);
 * ats.value = ntohl (10);
 * GNUNET_TRANSPORT_set_traffic_metric (th, p1, TM_SEND, &ats, 1);
 *
 * Note:
 * Delay restrictions in receiving direction will be enforced with
 * 1 message delay.
 */
void
GNUNET_TRANSPORT_set_traffic_metric (struct GNUNET_TRANSPORT_Handle *handle,
				     const struct GNUNET_PeerIdentity *peer,
				     int inbound,
				     int outbound,
				     const struct GNUNET_ATS_Information *ats,
				     size_t ats_count);


/**
 * Obtain updates on changes to the HELLO message for this peer. The callback
 * given in this function is never called synchronously.
 *
 * @param handle connection to transport service
 * @param rec function to call with the HELLO
 * @param rec_cls closure for @a rec
 * @return handle to cancel the operation
 */
struct GNUNET_TRANSPORT_GetHelloHandle *
GNUNET_TRANSPORT_get_hello (struct GNUNET_TRANSPORT_Handle *handle,
                            GNUNET_TRANSPORT_HelloUpdateCallback rec,
                            void *rec_cls);


/**
 * Stop receiving updates about changes to our HELLO message.
 *
 * @param ghh handle to cancel
 */
void
GNUNET_TRANSPORT_get_hello_cancel (struct GNUNET_TRANSPORT_GetHelloHandle *ghh);


/**
 * 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 handle connection to transport service
 * @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 cls closure for continuation
 * @return a GNUNET_TRANSPORT_OfferHelloHandle handle or NULL on failure,
 *      in case of failure cont will not be called
 *
 */
struct GNUNET_TRANSPORT_OfferHelloHandle *
GNUNET_TRANSPORT_offer_hello (struct GNUNET_TRANSPORT_Handle *handle,
                              const struct GNUNET_MessageHeader *hello,
                              GNUNET_SCHEDULER_Task cont, void *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);


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


/**
 * 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 pic the context handle
 */
void
GNUNET_TRANSPORT_address_to_string_cancel (struct GNUNET_TRANSPORT_AddressToStringContext *pic);


/**
 * 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);


/**
 * Convert validation state to human-readable string.
 *
 * @param state the state value
 * @return corresponding string
 */
const char *
GNUNET_TRANSPORT_vs2s (enum GNUNET_TRANSPORT_ValidationState state);


/**
 * 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 timeout how long is the lookup allowed to take at most
 * @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,
                                struct GNUNET_TIME_Relative timeout,
                                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);


/**
 * Return information about pending address validation operations for a specific
 * or all peers
 *
 * @param cfg configuration to use
 * @param peer a specific peer identity to obtain validation entries for,
 *      NULL for all peers
 * @param one_shot #GNUNET_YES to return all entries and then end (with NULL+NULL),
 *                 #GNUNET_NO to monitor validation entries continuously
 * @param timeout how long is the lookup allowed to take at most
 * @param validation_callback function to call with the results
 * @param validation_callback_cls closure for @a validation_callback
 */
struct GNUNET_TRANSPORT_ValidationMonitoringContext *
GNUNET_TRANSPORT_monitor_validation_entries (const struct GNUNET_CONFIGURATION_Handle *cfg,
                                             const struct GNUNET_PeerIdentity *peer,
                                             int one_shot,
                                             struct GNUNET_TIME_Relative timeout,
                                             GNUNET_TRANSPORT_ValidationIterateCallback validation_callback,
                                             void *validation_callback_cls);


/**
 * Return information about all current pending validation operations
 *
 * @param vic handle for the request to cancel
 */
void
GNUNET_TRANSPORT_monitor_validation_entries_cancel (struct GNUNET_TRANSPORT_ValidationMonitoringContext *vic);


/**
 * 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);



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

/* ifndef GNUNET_TRANSPORT_SERVICE_H */
#endif
/* end of gnunet_transport_service.h */