summaryrefslogtreecommitdiffstats
path: root/src/peer.c
blob: 9ce5ca26b0ad6fbefb421e4c993c1335afe702cd (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
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
/*
  Copyright (c) 2012-2015, Matthias Schiffer <mschiffer@universe-factory.net>
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
       this list of conditions and the following disclaimer in the documentation
       and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/**
   \file

   Implementations of functions for peer management
*/

#include "peer.h"
#include "peer_hashtable.h"
#include "poll.h"

#include <arpa/inet.h>
#include <sys/wait.h>


/** Adds peer-specific fields to \e env */
void fastd_peer_set_shell_env(fastd_shell_env_t *env, const fastd_peer_t *peer, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *peer_addr) {
	/* both INET6_ADDRSTRLEN and IFNAMESIZE already include space for the zero termination, so there is no need to add space for the '%' here. */
	char buf[INET6_ADDRSTRLEN+IF_NAMESIZE];

	fastd_shell_env_set(env, "PEER_NAME", peer ? peer->name : NULL);

	switch(local_addr ? local_addr->sa.sa_family : AF_UNSPEC) {
	case AF_INET:
		inet_ntop(AF_INET, &local_addr->in.sin_addr, buf, sizeof(buf));
		fastd_shell_env_set(env, "LOCAL_ADDRESS", buf);

		snprintf(buf, sizeof(buf), "%u", ntohs(local_addr->in.sin_port));
		fastd_shell_env_set(env, "LOCAL_PORT", buf);

		break;

	case AF_INET6:
		inet_ntop(AF_INET6, &local_addr->in6.sin6_addr, buf, sizeof(buf));

		if (IN6_IS_ADDR_LINKLOCAL(&local_addr->in6.sin6_addr)) {
			if (if_indextoname(local_addr->in6.sin6_scope_id, buf+strlen(buf)+1))
				buf[strlen(buf)] = '%';
		}

		fastd_shell_env_set(env, "LOCAL_ADDRESS", buf);

		snprintf(buf, sizeof(buf), "%u", ntohs(local_addr->in6.sin6_port));
		fastd_shell_env_set(env, "LOCAL_PORT", buf);

		break;

	default:
		fastd_shell_env_set(env, "LOCAL_ADDRESS", NULL);
		fastd_shell_env_set(env, "LOCAL_PORT", NULL);
	}

	switch(peer_addr ? peer_addr->sa.sa_family : AF_UNSPEC) {
	case AF_INET:
		inet_ntop(AF_INET, &peer_addr->in.sin_addr, buf, sizeof(buf));
		fastd_shell_env_set(env, "PEER_ADDRESS", buf);

		snprintf(buf, sizeof(buf), "%u", ntohs(peer_addr->in.sin_port));
		fastd_shell_env_set(env, "PEER_PORT", buf);

		break;

	case AF_INET6:
		inet_ntop(AF_INET6, &peer_addr->in6.sin6_addr, buf, sizeof(buf));

		if (IN6_IS_ADDR_LINKLOCAL(&peer_addr->in6.sin6_addr)) {
			if (if_indextoname(peer_addr->in6.sin6_scope_id, buf+strlen(buf)+1))
				buf[strlen(buf)] = '%';
		}

		fastd_shell_env_set(env, "PEER_ADDRESS", buf);

		snprintf(buf, sizeof(buf), "%u", ntohs(peer_addr->in6.sin6_port));
		fastd_shell_env_set(env, "PEER_PORT", buf);

		break;

	default:
		fastd_shell_env_set(env, "PEER_ADDRESS", NULL);
		fastd_shell_env_set(env, "PEER_PORT", NULL);
	}

	conf.protocol->set_shell_env(env, peer);
}

/** Executes a shell command, providing peer-specific enviroment fields */
void fastd_peer_exec_shell_command(const fastd_shell_command_t *command, const fastd_peer_t *peer, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *peer_addr) {
	fastd_shell_env_t *env = fastd_shell_env_alloc();
	fastd_peer_set_shell_env(env, peer, local_addr, peer_addr);
	fastd_shell_command_exec(command, env);
	fastd_shell_env_free(env);
}

/** Executes the on-establish command for a peer */
static inline void on_establish(const fastd_peer_t *peer) {
	fastd_peer_exec_shell_command(&conf.on_establish, peer, &peer->local_address, &peer->address);
}

/** Executes the on-disestablish command for a peer */
static inline void on_disestablish(const fastd_peer_t *peer) {
	fastd_peer_exec_shell_command(&conf.on_disestablish, peer, &peer->local_address, &peer->address);
}

/** Compares two peers by their peer ID */
static int peer_id_cmp(fastd_peer_t *const *a, fastd_peer_t *const *b) {
	if ((*a)->id == (*b)->id)
		return 0;
	else if ((*a)->id < (*b)->id)
		return -1;
	else
		return 1;
}

/** Finds the entry for a peer with a specified ID in the array \e ctx.peers */
static fastd_peer_t ** peer_p_find_by_id(uint64_t id) {
	fastd_peer_t key = {.id = id};
	fastd_peer_t *const keyp = &key;

	return VECTOR_BSEARCH(&keyp, ctx.peers, peer_id_cmp);
}

/** Finds the index of a peer with a specified ID in the array \e ctx.peers */
static size_t peer_index_find_by_id(uint64_t id) {
	fastd_peer_t **ret = peer_p_find_by_id(id);

	if (!ret)
		exit_bug("peer_index_find_by_id: not found");

	return ret - VECTOR_DATA(ctx.peers);

}

/** Finds the index of a peer in the array \e ctx.peers */
static inline size_t peer_index(fastd_peer_t *peer) {
	return peer_index_find_by_id(peer->id);
}

/** Finds a peer with a specified ID */
fastd_peer_t * fastd_peer_find_by_id(uint64_t id) {
	fastd_peer_t **ret = peer_p_find_by_id(id);

	if (ret)
		return *ret;
	else
		return NULL;

}

/** Closes and frees the dynamic socket of the peer with a specified ID */
static void free_socket_by_id(size_t i) {
	fastd_peer_t *peer = VECTOR_INDEX(ctx.peers, i);

	if (!peer->sock)
		return;

	if (fastd_peer_is_socket_dynamic(peer)) {
		if (peer->sock->peer != peer)
			exit_bug("dynamic peer socket mismatch");

		fastd_socket_close(peer->sock);
		free(peer->sock);

		peer->sock = NULL;
		fastd_poll_set_fd_peer(i);
	}
	else {
		peer->sock = NULL;
	}
}

/** Closes and frees a peer's dynamic socket */
static inline void free_socket(fastd_peer_t *peer) {
	free_socket_by_id(peer_index(peer));
}

/** Checks if a peer group has any contraints which might cause connection attempts to be rejected */
static inline bool has_group_config_constraints(const fastd_peer_group_t *group) {
	for (; group; group = group->parent) {
		if (group->max_connections >= 0)
			return true;
	}

	return false;
}

/**
   Resets a peer's socket

   If the peer's old socket is dynamic, it is closed. Then either a new dynamic socket is opened
   or a default socket is used.
*/
void fastd_peer_reset_socket(fastd_peer_t *peer) {
	size_t i = peer_index(peer);

	if (peer->address.sa.sa_family == AF_UNSPEC) {
		free_socket_by_id(i);
		return;
	}

	if (!fastd_peer_is_socket_dynamic(peer))
		return;

	pr_debug("resetting socket for peer %P", peer);

	free_socket_by_id(i);

	switch (peer->address.sa.sa_family) {
	case AF_INET:
		if (ctx.sock_default_v4)
			peer->sock = ctx.sock_default_v4;
		else
			peer->sock = fastd_socket_open(peer, AF_INET);
		break;

	case AF_INET6:
		if (ctx.sock_default_v6)
			peer->sock = ctx.sock_default_v6;
		else
			peer->sock = fastd_socket_open(peer, AF_INET6);
	}

	if (!peer->sock || !fastd_peer_is_socket_dynamic(peer))
		return;

	fastd_poll_set_fd_peer(i);
}

/**
   Schedules a handshake after the given delay

   @param peer	the peer
   @param delay	the delay in milliseconds
*/
void fastd_peer_schedule_handshake(fastd_peer_t *peer, int delay) {
	fastd_peer_unschedule_handshake(peer);

	peer->next_handshake = ctx.now + delay;

	fastd_dlist_head_t *list;
	for (list = &ctx.handshake_queue; list->next; list = list->next) {
		fastd_peer_t *entry = container_of(list->next, fastd_peer_t, handshake_entry);

		if (entry->next_handshake > peer->next_handshake)
			break;
	}

	fastd_dlist_insert(list, &peer->handshake_entry);
}

/** Checks if the peer group \e group1 lies in \e group2 */
static inline bool is_group_in(const fastd_peer_group_t *group1, const fastd_peer_group_t *group2) {
	while (group1) {
		if (group1 == group2)
			return true;

		group1 = group1->parent;
	}

	return false;
}

/** Checks if a peer lies in a peer group */
static bool is_peer_in_group(const fastd_peer_t *peer, const fastd_peer_group_t *group) {
	return is_group_in(peer->group, group);
}

/**
   Resets a peer (internal function)

   Disestablished the current connection with the peer (if any) and drops any scheduled handshake.

   After a call to reset_peer a peer must be deleted by delete_peer or re-initialized by setup_peer.
*/
static void reset_peer(fastd_peer_t *peer) {
	if (fastd_peer_is_established(peer)) {
		on_disestablish(peer);
		pr_info("connection with %P disestablished.", peer);
	}

	free_socket(peer);

	conf.protocol->reset_peer_state(peer);

	size_t i, deleted = 0;
	for (i = 0; i < VECTOR_LEN(ctx.eth_addrs); i++) {
		if (VECTOR_INDEX(ctx.eth_addrs, i).peer == peer) {
			deleted++;
		}
		else if (deleted) {
			VECTOR_INDEX(ctx.eth_addrs, i-deleted) = VECTOR_INDEX(ctx.eth_addrs, i);
		}
	}

	VECTOR_RESIZE(ctx.eth_addrs, VECTOR_LEN(ctx.eth_addrs)-deleted);

	fastd_peer_unschedule_handshake(peer);

	fastd_peer_hashtable_remove(peer);

	memset(&peer->stats, 0, sizeof(peer->stats));

	peer->address.sa.sa_family = AF_UNSPEC;
	peer->local_address.sa.sa_family = AF_UNSPEC;
	peer->state = STATE_INACTIVE;
}

/**
   Starts the first handshake with a newly setup peer

   If a peer group has a peer limit the handshakes will be delayed between 0 and 3 seconds
   make the choice of peers random (it will be biased by the latency, which might or might not be
   what a user wants)
*/
static void init_handshake(fastd_peer_t *peer) {
	unsigned delay = 0;
	if (has_group_config_constraints(peer->group))
		delay = fastd_rand(0, 3000);

	peer->state = STATE_HANDSHAKE;

	fastd_peer_schedule_handshake(peer, delay);
}

/** Handles an asynchronous DNS resolve response */
void fastd_peer_handle_resolve(fastd_peer_t *peer, fastd_remote_t *remote, size_t n_addresses, const fastd_peer_address_t *addresses) {
	free(remote->addresses);
	remote->addresses = fastd_new_array(n_addresses, fastd_peer_address_t);
	memcpy(remote->addresses, addresses, n_addresses*sizeof(fastd_peer_address_t));

	remote->n_addresses = n_addresses;
	remote->current_address = 0;

	if (peer->state == STATE_RESOLVING)
		init_handshake(peer);
}

/** Initializes a peer */
static void setup_peer(fastd_peer_t *peer) {
	if (VECTOR_LEN(peer->remotes) == 0) {
		peer->next_remote = -1;
	}
	else {
		size_t i;
		for (i = 0; i < VECTOR_LEN(peer->remotes); i++) {
			fastd_remote_t *remote = &VECTOR_INDEX(peer->remotes, i);

			remote->last_resolve_timeout = ctx.now;

			if (!remote->hostname) {
				remote->n_addresses = 1;
				remote->addresses = &remote->address;
			}
		}

		peer->next_remote = 0;
	}

	peer->last_handshake_timeout = ctx.now;
	peer->last_handshake_address.sa.sa_family = AF_UNSPEC;

	peer->last_handshake_response_timeout = ctx.now;
	peer->last_handshake_response_address.sa.sa_family = AF_UNSPEC;

	peer->establish_handshake_timeout = ctx.now;

#ifdef WITH_DYNAMIC_PEERS
	peer->verify_timeout = ctx.now;
	peer->verify_valid_timeout = ctx.now;
#endif

	if (!fastd_peer_is_enabled(peer))
		/* Keep the peer in STATE_INACTIVE */
		return;

	fastd_remote_t *next_remote = fastd_peer_get_next_remote(peer);
	if (next_remote) {
		next_remote->current_address = 0;

		if (next_remote->hostname) {
			peer->state = STATE_RESOLVING;
			fastd_resolve_peer(peer, next_remote);
			fastd_peer_schedule_handshake_default(peer);
		}
		else  {
			init_handshake(peer);
		}
	}
	else {
		peer->state = STATE_PASSIVE;
	}
}

/**
   Frees a peer

   If the peer has already been added to the peer list,
   use fastd_peer_delete() instead.
*/
void fastd_peer_free(fastd_peer_t *peer) {
	free(peer->key);

	size_t i;
	for (i = 0; i < VECTOR_LEN(peer->remotes); i++) {
		fastd_remote_t *remote = &VECTOR_INDEX(peer->remotes, i);

		if (remote->hostname) {
			free(remote->addresses);
			free(remote->hostname);
		}
	}

	VECTOR_FREE(peer->remotes);

	free(peer->name);
	free(peer);
}

/** Deletes a peer */
static void delete_peer(fastd_peer_t *peer) {
	if (fastd_peer_is_dynamic(peer) || peer->config_source_dir)
		pr_verbose("deleting peer %P", peer);

	size_t i = peer_index(peer);
	VECTOR_DELETE(ctx.peers, i);
	fastd_poll_delete_peer(i);

	conf.protocol->free_peer_state(peer);

	fastd_peer_free(peer);
}


/** Checks if two fastd_peer_address_t are equal */
bool fastd_peer_address_equal(const fastd_peer_address_t *addr1, const fastd_peer_address_t *addr2) {
	if (addr1->sa.sa_family != addr2->sa.sa_family)
		return false;

	switch (addr1->sa.sa_family) {
	case AF_UNSPEC:
		break;

	case AF_INET:
		if (addr1->in.sin_addr.s_addr != addr2->in.sin_addr.s_addr)
			return false;
		if (addr1->in.sin_port != addr2->in.sin_port)
			return false;
		break;

	case AF_INET6:
		if (!IN6_ARE_ADDR_EQUAL(&addr1->in6.sin6_addr, &addr2->in6.sin6_addr))
			return false;
		if (addr1->in6.sin6_port != addr2->in6.sin6_port)
			return false;
		if (IN6_IS_ADDR_LINKLOCAL(&addr1->in6.sin6_addr)) {
			if (addr1->in6.sin6_scope_id != addr2->in6.sin6_scope_id)
				return false;
		}
	}

	return true;
}

/** If \e addr is a v4-mapped IPv6 address, it is converted to an IPv4 address */
void fastd_peer_address_simplify(fastd_peer_address_t *addr) {
	if (addr->sa.sa_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&addr->in6.sin6_addr)) {
		struct sockaddr_in6 mapped = addr->in6;

		memset(addr, 0, sizeof(fastd_peer_address_t));
		addr->in.sin_family = AF_INET;
		addr->in.sin_port = mapped.sin6_port;
		memcpy(&addr->in.sin_addr.s_addr, &mapped.sin6_addr.s6_addr[12], 4);
	}
}

/** If \e addr is an IPv4 address, it is converted to a v4-mapped IPv6 address */
void fastd_peer_address_widen(fastd_peer_address_t *addr) {
	if (addr->sa.sa_family == AF_INET) {
		struct sockaddr_in addr4 = addr->in;

		memset(addr, 0, sizeof(fastd_peer_address_t));
		addr->in6.sin6_family = AF_INET6;
		addr->in6.sin6_port = addr4.sin_port;
		addr->in6.sin6_addr.s6_addr[10] = 0xff;
		addr->in6.sin6_addr.s6_addr[11] = 0xff;
		memcpy(&addr->in6.sin6_addr.s6_addr[12], &addr4.sin_addr.s_addr, 4);
	}
}


/** Resets a peer's address to the unspecified address */
static inline void reset_peer_address(fastd_peer_t *peer) {
	if (fastd_peer_is_established(peer)) {
		fastd_peer_reset(peer);
	}
	else {
		fastd_peer_hashtable_remove(peer);
		peer->address.sa.sa_family = AF_UNSPEC;
	}
}

/** Checks if an address is statically configured for a peer */
bool fastd_peer_owns_address(const fastd_peer_t *peer, const fastd_peer_address_t *addr) {
	if (fastd_peer_is_floating(peer))
		return false;

	size_t i;
	for (i = 0; i < VECTOR_LEN(peer->remotes); i++) {
		fastd_remote_t *remote = &VECTOR_INDEX(peer->remotes, i);

		if (remote->hostname)
			continue;

		if (fastd_peer_address_equal(&remote->address, addr))
			return true;
	}

	return false;
}

/** Checks if an address matches any of the configured or resolved remotes of a peer */
bool fastd_peer_matches_address(const fastd_peer_t *peer, const fastd_peer_address_t *addr) {
	if (fastd_peer_is_floating(peer))
		return true;

	size_t i, j;
	for (i = 0; i < VECTOR_LEN(peer->remotes); i++) {
		fastd_remote_t *remote = &VECTOR_INDEX(peer->remotes, i);

		for (j = 0; j < remote->n_addresses; j++) {
			if (fastd_peer_address_equal(&remote->addresses[j], addr))
				return true;
		}
	}

	return false;
}

/**
   Tries to claim an address for a peer

   Each remote address (+ port) can by used by only one peer at a time.

   If it is tried to claim an address that is currently used by another peer, the claim will fail unless
   \e force is set. The claim will fail even with \e force set if the other peer has statically configured the address
   in question.
 */
bool fastd_peer_claim_address(fastd_peer_t *new_peer, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, bool force) {
	if (remote_addr->sa.sa_family == AF_UNSPEC) {
		if (fastd_peer_is_established(new_peer))
			fastd_peer_reset(new_peer);
	}
	else {
		size_t i;
		for (i = 0; i < VECTOR_LEN(ctx.peers); i++) {
			fastd_peer_t *peer = VECTOR_INDEX(ctx.peers, i);

			if (peer == new_peer)
				continue;

			if (!fastd_peer_is_enabled(peer))
				continue;

			if (fastd_peer_owns_address(peer, remote_addr)) {
				reset_peer_address(new_peer);
				return false;
			}

			if (fastd_peer_address_equal(&peer->address, remote_addr)) {
				if (!force && fastd_peer_is_established(peer)) {
					reset_peer_address(new_peer);
					return false;
				}

				reset_peer_address(peer);
				break;
			}
		}
	}

	fastd_peer_hashtable_remove(new_peer);
	new_peer->address = *remote_addr;
	fastd_peer_hashtable_insert(new_peer);

	if (sock && sock->addr && sock != new_peer->sock) {
		free_socket(new_peer);
		new_peer->sock = sock;
	}

	if (local_addr)
		new_peer->local_address = *local_addr;

	return true;
}

/** Resets and re-initializes a peer */
void fastd_peer_reset(fastd_peer_t *peer) {
	if (peer->state != STATE_INACTIVE) {
		pr_debug("resetting peer %P", peer);
		reset_peer(peer);
	}

	setup_peer(peer);
}

/** Deletes a peer */
void fastd_peer_delete(fastd_peer_t *peer) {
	reset_peer(peer);
	delete_peer(peer);
}

/** Counts how many peers in the given peer group have established a connection */
static inline size_t count_established_group_peers(const fastd_peer_group_t *group) {
	size_t i, ret = 0;
	for (i = 0; i < VECTOR_LEN(ctx.peers); i++) {
		fastd_peer_t *peer = VECTOR_INDEX(ctx.peers, i);

		if (fastd_peer_is_established(peer) && is_peer_in_group(peer, group))
			ret++;
	}

	return ret;
}

/** Checks if a peer may currently establish a connection */
bool fastd_peer_may_connect(fastd_peer_t *peer) {
	if (fastd_peer_is_established(peer))
		return true;

	const fastd_peer_group_t *group;

	for (group = peer->group; group; group = group->parent) {
		if (group->max_connections < 0)
			continue;

		if (count_established_group_peers(group) >= (size_t)group->max_connections)
			return false;
	}

	return true;
}

/** Checks if two peer configurations are equivalent (exept for the name) */
static inline bool peer_configs_equal(const fastd_peer_t *peer1, const fastd_peer_t *peer2) {
	if (peer1->group != peer2->group)
		return false;

	if (peer1->floating != peer2->floating)
		return false;

	if (VECTOR_LEN(peer1->remotes) != VECTOR_LEN(peer2->remotes))
		return false;

	size_t i;
	for (i = 0; i < VECTOR_LEN(peer1->remotes); i++) {
		const fastd_remote_t *remote1 = &VECTOR_INDEX(peer1->remotes, i), *remote2 = &VECTOR_INDEX(peer2->remotes, i);

		if (!fastd_peer_address_equal(&remote1->address, &remote2->address))
			return false;

		if (!strequal(remote1->hostname, remote2->hostname))
			return false;
	}

	return true;
}

/** Adds a new peer */
bool fastd_peer_add(fastd_peer_t *peer) {
	if (!peer->key) {
		pr_warn("no valid key configured for peer %P", peer);
		goto error;
	}

	fastd_peer_t *other = conf.protocol->find_peer(peer->key);
	if (other) {
		if (peer->config_state != CONFIG_NEW)
			exit_bug("tried to replace with active peer");

		switch (other->config_state) {
		case CONFIG_NEW:
		case CONFIG_DISABLED:
			pr_warn("duplicate key used by peers %P and %P, disabling both", peer, other);
			other->config_state = CONFIG_DISABLED;
			goto error;

		case CONFIG_STATIC:
			if (!strequal(other->name, peer->name))
				pr_verbose("peer %P has been renamed to %P", other, peer);

			if (peer_configs_equal(other, peer)) {
				free(other->name);
				other->name = peer->name;
				peer->name = NULL;

				fastd_peer_free(peer);

				pr_verbose("peer %P is unchanged", other);
				other->config_state = CONFIG_NEW;

				return true;
			}
			else {
				pr_verbose("peer %P has changed", peer);
			}

			fastd_peer_delete(other);
			break;

#ifdef WITH_DYNAMIC_PEERS
		case CONFIG_DYNAMIC:
			pr_verbose("dynamic peer %P is now configured as %P", other, peer);
			fastd_peer_delete(other);
#endif
		}
	}

	peer->id = ctx.next_peer_id++;

	VECTOR_ADD(ctx.peers, peer);
	fastd_poll_add_peer();

	conf.protocol->init_peer_state(peer);

	if (fastd_peer_is_dynamic(peer) || peer->config_source_dir)
		pr_verbose("adding peer %P", peer);

	return true;

  error:
	fastd_peer_free(peer);
	return false;
}

/** Prints a debug message when no handshake could be sent because the current remote didn't resolve successfully */
static inline void no_valid_address_debug(const fastd_peer_t *peer) {
	pr_debug("not sending a handshake to %P (no valid address resolved)", peer);
}

/** Sends a new handshake to the current address of the given remote of a peer */
static void send_handshake(fastd_peer_t *peer, fastd_remote_t *next_remote) {
	if (!fastd_peer_is_established(peer)) {
		if (!next_remote->n_addresses) {
			no_valid_address_debug(peer);
			return;
		}

		fastd_peer_claim_address(peer, NULL, NULL, &next_remote->addresses[next_remote->current_address], false);
		fastd_peer_reset_socket(peer);
	}

	if (!peer->sock)
		return;

	if (peer->address.sa.sa_family == AF_UNSPEC) {
		no_valid_address_debug(peer);
		return;
	}

	if (!fastd_timed_out(peer->last_handshake_timeout)
	    && fastd_peer_address_equal(&peer->address, &peer->last_handshake_address)) {
		pr_debug("not sending a handshake to %P as we sent one a short time ago", peer);
		return;
	}

	peer->last_handshake_timeout = ctx.now + MIN_HANDSHAKE_INTERVAL;
	peer->last_handshake_address = peer->address;
	conf.protocol->handshake_init(peer->sock, &peer->local_address, &peer->address, peer);
}

/** Sends a handshake to one peer, if a scheduled handshake is due */
void fastd_peer_handle_handshake_queue(void) {
	if (!ctx.handshake_queue.next)
		return;

	fastd_peer_t *peer = container_of(ctx.handshake_queue.next, fastd_peer_t, handshake_entry);
	if (!fastd_timed_out(peer->next_handshake))
		return;

	fastd_peer_schedule_handshake_default(peer);

	if (!fastd_peer_may_connect(peer)) {
		if (peer->next_remote != -1) {
			pr_debug("temporarily disabling handshakes with %P", peer);
			peer->next_remote = -1;
		}

		return;
	}

	fastd_remote_t *next_remote = fastd_peer_get_next_remote(peer);

	if (next_remote || fastd_peer_is_established(peer)) {
		send_handshake(peer, next_remote);

		if (fastd_peer_is_established(peer))
			return;

		peer->state = STATE_HANDSHAKE;

		if (++next_remote->current_address < next_remote->n_addresses)
			return;

		peer->next_remote++;
	}

	if (peer->next_remote < 0 || (size_t)peer->next_remote >= VECTOR_LEN(peer->remotes))
		peer->next_remote = 0;

	next_remote = fastd_peer_get_next_remote(peer);
	next_remote->current_address = 0;

	if (next_remote->hostname)
		fastd_resolve_peer(peer, next_remote);
}

/** Marks a peer as established */
void fastd_peer_set_established(fastd_peer_t *peer) {
	if (fastd_peer_is_established(peer))
		return;

	peer->state = STATE_ESTABLISHED;
	peer->established = ctx.now;
	on_establish(peer);
	pr_info("connection with %P established.", peer);
}

/** Compares two MAC addresses */
static inline int eth_addr_cmp(const fastd_eth_addr_t *addr1, const fastd_eth_addr_t *addr2) {
	return memcmp(addr1->data, addr2->data, ETH_ALEN);
}

/** Compares two fastd_peer_eth_addr_t entries by their MAC addresses */
static int peer_eth_addr_cmp(const fastd_peer_eth_addr_t *addr1, const fastd_peer_eth_addr_t *addr2) {
	return eth_addr_cmp(&addr1->addr, &addr2->addr);
}

/** Adds a MAC address to the sorted list of addresses associated with a peer (or updates the timeout of an existing entry) */
void fastd_peer_eth_addr_add(fastd_peer_t *peer, fastd_eth_addr_t addr) {
	int min = 0, max = VECTOR_LEN(ctx.eth_addrs);

	if (peer && !fastd_peer_is_established(peer))
		exit_bug("tried to learn ethernet address on non-established peer");

	while (max > min) {
		int cur = (min+max)/2;
		int cmp = eth_addr_cmp(&addr, &VECTOR_INDEX(ctx.eth_addrs, cur).addr);

		if (cmp == 0) {
			VECTOR_INDEX(ctx.eth_addrs, cur).peer = peer;
			VECTOR_INDEX(ctx.eth_addrs, cur).timeout = ctx.now + ETH_ADDR_STALE_TIME;
			return; /* We're done here. */
		}
		else if (cmp < 0) {
			max = cur;
		}
		else {
			min = cur+1;
		}
	}

	VECTOR_INSERT(ctx.eth_addrs, ((fastd_peer_eth_addr_t) {addr, peer, ctx.now + ETH_ADDR_STALE_TIME}), min);

	if (peer)
		pr_debug("learned new MAC address %E on peer %P", &addr, peer);
	else
		pr_debug("learned new local MAC address %E", &addr);
}

/** Finds the peer that is associated with a given MAC address */
bool fastd_peer_find_by_eth_addr(const fastd_eth_addr_t addr, fastd_peer_t **peer) {
	const fastd_peer_eth_addr_t key = {.addr = addr};
	fastd_peer_eth_addr_t *peer_eth_addr = VECTOR_BSEARCH(&key, ctx.eth_addrs, peer_eth_addr_cmp);

	if (!peer_eth_addr)
		return false;

	*peer = peer_eth_addr->peer;
	return true;
}

/**
   Performs maintenance tasks for a peer

   \li If no data was received from the peer for some time, it is reset.
   \li If no data was sent to the peer for some time, a keepalive is sent.
 */
static bool maintain_peer(fastd_peer_t *peer) {
	if (fastd_peer_is_dynamic(peer) || fastd_peer_is_established(peer)) {
		/* check for peer timeout */
		if (fastd_timed_out(peer->timeout)) {
#ifdef WITH_DYNAMIC_PEERS
			if (fastd_peer_is_dynamic(peer) &&
			    fastd_timed_out(peer->verify_timeout) &&
			    fastd_timed_out(peer->verify_valid_timeout)) {
				fastd_peer_delete(peer);
				return false;
			}
#endif

			if (fastd_peer_is_established(peer))
				fastd_peer_reset(peer);
			return true;
		}

		/* check for keepalive timeout */
		if (!fastd_peer_is_established(peer))
			return true;

		if (!fastd_timed_out(peer->keepalive_timeout))
			return true;

		pr_debug2("sending keepalive to %P", peer);
		conf.protocol->send(peer, fastd_buffer_alloc(0, conf.min_encrypt_head_space, conf.min_encrypt_tail_space));
	}

	return true;
}

/** Removes all time-outed MAC addresses from \e ctx.eth_addrs */
static void eth_addr_cleanup(void) {
	size_t i, deleted = 0;

	for (i = 0; i < VECTOR_LEN(ctx.eth_addrs); i++) {
		if (fastd_timed_out(VECTOR_INDEX(ctx.eth_addrs, i).timeout)) {
			deleted++;
			pr_debug("MAC address %E not seen for more than %u seconds, removing",
				 &VECTOR_INDEX(ctx.eth_addrs, i).addr, ETH_ADDR_STALE_TIME/1000);
		}
		else if (deleted) {
			VECTOR_INDEX(ctx.eth_addrs, i-deleted) = VECTOR_INDEX(ctx.eth_addrs, i);
		}
	}

	VECTOR_RESIZE(ctx.eth_addrs, VECTOR_LEN(ctx.eth_addrs)-deleted);
}

/** Performs periodic maintenance tasks for peers */
void fastd_peer_maintenance(void) {
	size_t i;
	for (i = 0; i < VECTOR_LEN(ctx.peers);) {
		fastd_peer_t *peer = VECTOR_INDEX(ctx.peers, i);

		if (maintain_peer(peer))
			i++;
	}

	eth_addr_cleanup();
}

/** Resets all peers */
void fastd_peer_reset_all(void) {
	size_t i;
	for (i = 0; i < VECTOR_LEN(ctx.peers);) {
		fastd_peer_t *peer = VECTOR_INDEX(ctx.peers, i);

		if (fastd_peer_is_dynamic(peer)) {
			fastd_peer_delete(peer);
		}
		else {
			fastd_peer_reset(peer);
			i++;
		}
	}
}