summaryrefslogtreecommitdiffstats
path: root/src/device.c
blob: bb12310aab46e6428213fc6ceb6cd46ef7b16473 (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
989
990
991
992
993
994
995
996
997
998
999
/*
	usbmuxd - iPhone/iPod Touch USB multiplex server daemon

Copyright (C) 2009	Hector Martin "marcan" <hector@marcansoft.com>
Copyright (C) 2014  Mikkel Kamstrup Erlandsen <mikkel.kamstrup@xamarin.com>

This program 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 2 or version 3.

This program 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 this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

*/

#define _BSD_SOURCE

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <sys/time.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <inttypes.h>
#include <pthread.h>
#include "device.h"
#include "client.h"
#include "preflight.h"
#include "usb.h"
#include "log.h"

int next_device_id;

#define DEV_MRU 65536

#define CONN_INBUF_SIZE		262144
#define CONN_OUTBUF_SIZE	65536

#define ACK_TIMEOUT 30

enum mux_protocol {
	MUX_PROTO_VERSION = 0,
	MUX_PROTO_CONTROL = 1,
	MUX_PROTO_SETUP = 2,
	MUX_PROTO_TCP = IPPROTO_TCP,
};

enum mux_dev_state {
	MUXDEV_INIT,	// sent version packet
	MUXDEV_ACTIVE,	// received version packet, active
	MUXDEV_DEAD		// dead
};

enum mux_conn_state {
	CONN_CONNECTING,	// SYN
	CONN_CONNECTED,		// SYN/SYNACK/ACK -> active
	CONN_REFUSED,		// RST received during SYN
	CONN_DYING,			// RST received
	CONN_DEAD			// being freed; used to prevent infinite recursion between client<->device freeing
};

struct mux_header
{
	uint32_t protocol;
	uint32_t length;
	uint32_t magic;
	uint16_t tx_seq;
	uint16_t rx_seq;
};

struct version_header
{
	uint32_t major;
	uint32_t minor;
	uint32_t padding;
};

struct mux_device;

#define CONN_ACK_PENDING 1

struct mux_connection
{
	struct mux_device *dev;
	struct mux_client *client;
	enum mux_conn_state state;
	uint16_t sport, dport;
	uint32_t tx_seq, tx_ack, tx_acked, tx_win;
	uint32_t rx_seq, rx_recvd, rx_ack, rx_win;
	uint32_t max_payload;
	uint32_t sendable;
	int flags;
	unsigned char *ib_buf;
	uint32_t ib_size;
	uint32_t ib_capacity;
	unsigned char *ob_buf;
	uint32_t ob_capacity;
	short events;
	uint64_t last_ack_time;
};

struct mux_device
{
	struct usb_device *usbdev;
	int id;
	enum mux_dev_state state;
	int visible;
	struct collection connections;
	uint16_t next_sport;
	unsigned char *pktbuf;
	uint32_t pktlen;
	void *preflight_cb_data;
	int version;
	uint16_t rx_seq;
	uint16_t tx_seq;
};

static struct collection device_list;
pthread_mutex_t device_list_mutex;

static struct mux_device* get_mux_device_for_id(int device_id)
{
  struct mux_device *dev = NULL;
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *cdev, &device_list) {
		if(cdev->id == device_id) {
			dev = cdev;
			break;
		}
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);

	return dev;
}

static struct mux_connection* get_mux_connection(int device_id, struct mux_client *client)
{
	struct mux_connection *conn = NULL;
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *dev, &device_list) {
		if(dev->id == device_id) {
			FOREACH(struct mux_connection *lconn, &dev->connections) {
				if(lconn->client == client) {
					conn = lconn;
					break;
				}
			} ENDFOREACH
			break;
		}
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);

	return conn;
}

static int get_next_device_id(void)
{
	while(1) {
		int ok = 1;
		pthread_mutex_lock(&device_list_mutex);
		FOREACH(struct mux_device *dev, &device_list) {
			if(dev->id == next_device_id) {
				next_device_id++;
				ok = 0;
				break;
			}
		} ENDFOREACH
		pthread_mutex_unlock(&device_list_mutex);
		if(ok)
			return next_device_id++;
	}
}

static int send_packet(struct mux_device *dev, enum mux_protocol proto, void *header, const void *data, int length)
{
	unsigned char *buffer;
	int hdrlen;
	int res;

	switch(proto) {
		case MUX_PROTO_VERSION:
			hdrlen = sizeof(struct version_header);
			break;
		case MUX_PROTO_SETUP:
			hdrlen = 0;
			break;
		case MUX_PROTO_TCP:
			hdrlen = sizeof(struct tcphdr);
			break;
		default:
			usbmuxd_log(LL_ERROR, "Invalid protocol %d for outgoing packet (dev %d hdr %p data %p len %d)", proto, dev->id, header, data, length);
			return -1;
	}
	usbmuxd_log(LL_SPEW, "send_packet(%d, 0x%x, %p, %p, %d)", dev->id, proto, header, data, length);

	int mux_header_size = ((dev->version < 2) ? 8 : sizeof(struct mux_header));

	int total = mux_header_size + hdrlen + length;

	if(total > USB_MTU) {
		usbmuxd_log(LL_ERROR, "Tried to send packet larger than USB MTU (hdr %d data %d total %d) to device %d", hdrlen, length, total, dev->id);
		return -1;
	}

	buffer = malloc(total);
	struct mux_header *mhdr = (struct mux_header *)buffer;
	mhdr->protocol = htonl(proto);
	mhdr->length = htonl(total);
	if (dev->version >= 2) {
		mhdr->magic = htonl(0xfeedface);
		if (proto == MUX_PROTO_SETUP) {
			dev->tx_seq = 0;
			dev->rx_seq = 0xFFFF;
		}
		mhdr->tx_seq = htons(dev->tx_seq);
		mhdr->rx_seq = htons(dev->rx_seq);
		dev->tx_seq++;
	}	
	memcpy(buffer + mux_header_size, header, hdrlen);
	if(data && length)
		memcpy(buffer + mux_header_size + hdrlen, data, length);

	if((res = usb_send(dev->usbdev, buffer, total)) < 0) {
		usbmuxd_log(LL_ERROR, "usb_send failed while sending packet (len %d) to device %d: %d", total, dev->id, res);
		free(buffer);
		return res;
	}
	return total;
}

static uint16_t find_sport(struct mux_device *dev)
{
	if(collection_count(&dev->connections) >= 65535)
		return 0; //insanity

	while(1) {
		int ok = 1;
		FOREACH(struct mux_connection *conn, &dev->connections) {
			if(dev->next_sport == conn->sport) {
				dev->next_sport++;
				ok = 0;
				break;
			}
		} ENDFOREACH
		if(ok)
			return dev->next_sport++;
	}
}

static int send_anon_rst(struct mux_device *dev, uint16_t sport, uint16_t dport, uint32_t ack)
{
	struct tcphdr th;
	memset(&th, 0, sizeof(th));
	th.th_sport = htons(sport);
	th.th_dport = htons(dport);
	th.th_ack = htonl(ack);
	th.th_flags = TH_RST;
	th.th_off = sizeof(th) / 4;

	usbmuxd_log(LL_DEBUG, "[OUT] dev=%d sport=%d dport=%d flags=0x%x", dev->id, sport, dport, th.th_flags);

	int res = send_packet(dev, MUX_PROTO_TCP, &th, NULL, 0);
	return res;
}

static int send_tcp(struct mux_connection *conn, uint8_t flags, const unsigned char *data, int length)
{
	struct tcphdr th;
	memset(&th, 0, sizeof(th));
	th.th_sport = htons(conn->sport);
	th.th_dport = htons(conn->dport);
	th.th_seq = htonl(conn->tx_seq);
	th.th_ack = htonl(conn->tx_ack);
	th.th_flags = flags;
	th.th_off = sizeof(th) / 4;
	th.th_win = htons(conn->tx_win >> 8);

	usbmuxd_log(LL_DEBUG, "[OUT] dev=%d sport=%d dport=%d seq=%d ack=%d flags=0x%x window=%d[%d] len=%d",
		conn->dev->id, conn->sport, conn->dport, conn->tx_seq, conn->tx_ack, flags, conn->tx_win, conn->tx_win >> 8, length);

	int res = send_packet(conn->dev, MUX_PROTO_TCP, &th, data, length);
	if(res >= 0) {
		conn->tx_acked = conn->tx_ack;
		conn->last_ack_time = mstime64();
		conn->flags &= ~CONN_ACK_PENDING;
	}
	return res;
}

static void connection_teardown(struct mux_connection *conn)
{
	int res;
	if(conn->state == CONN_DEAD)
		return;
	usbmuxd_log(LL_DEBUG, "connection_teardown dev %d sport %d dport %d", conn->dev->id, conn->sport, conn->dport);
	if(conn->dev->state != MUXDEV_DEAD && conn->state != CONN_DYING && conn->state != CONN_REFUSED) {
		res = send_tcp(conn, TH_RST, NULL, 0);
		if(res < 0)
			usbmuxd_log(LL_ERROR, "Error sending TCP RST to device %d (%d->%d)", conn->dev->id, conn->sport, conn->dport);
	}
	if(conn->client) {
		if(conn->state == CONN_REFUSED || conn->state == CONN_CONNECTING) {
			client_notify_connect(conn->client, RESULT_CONNREFUSED);
		} else {
			conn->state = CONN_DEAD;
			client_close(conn->client);
		}
	}
	if(conn->ib_buf)
		free(conn->ib_buf);
	if(conn->ob_buf)
		free(conn->ob_buf);
	collection_remove(&conn->dev->connections, conn);
	free(conn);
}

int device_start_connect(int device_id, uint16_t dport, struct mux_client *client)
{
	struct mux_device *dev = get_mux_device_for_id(device_id);
	if(!dev) {
		usbmuxd_log(LL_WARNING, "Attempted to connect to nonexistent device %d", device_id);
		return -RESULT_BADDEV;
	}

	uint16_t sport = find_sport(dev);
	if(!sport) {
		usbmuxd_log(LL_WARNING, "Unable to allocate port for device %d", device_id);
		return -RESULT_BADDEV;
	}

	struct mux_connection *conn;
	conn = malloc(sizeof(struct mux_connection));
	memset(conn, 0, sizeof(struct mux_connection));

	conn->dev = dev;
	conn->client = client;
	conn->state = CONN_CONNECTING;
	conn->sport = sport;
	conn->dport = dport;
	conn->tx_seq = 0;
	conn->tx_ack = 0;
	conn->tx_acked = 0;
	conn->tx_win = 131072;
	conn->rx_recvd = 0;
	conn->flags = 0;
	conn->max_payload = USB_MTU - sizeof(struct mux_header) - sizeof(struct tcphdr);

	conn->ob_buf = malloc(CONN_OUTBUF_SIZE);
	conn->ob_capacity = CONN_OUTBUF_SIZE;
	conn->ib_buf = malloc(CONN_INBUF_SIZE);
	conn->ib_capacity = CONN_INBUF_SIZE;
	conn->ib_size = 0;

	int res;

	res = send_tcp(conn, TH_SYN, NULL, 0);
	if(res < 0) {
		usbmuxd_log(LL_ERROR, "Error sending TCP SYN to device %d (%d->%d)", dev->id, sport, dport);
		free(conn);
		return -RESULT_CONNREFUSED; //bleh
	}
	collection_add(&dev->connections, conn);
	return 0;
}

/**
 * Examine the state of a connection's buffers and
 * update all connection flags and masks accordingly.
 * Does not do I/O.
 *
 * @param conn The connection to update.
 */
static void update_connection(struct mux_connection *conn)
{
	uint32_t sent = conn->tx_seq - conn->rx_ack;

	if(conn->rx_win > sent)
		conn->sendable = conn->rx_win - sent;
	else
		conn->sendable = 0;

	if(conn->sendable > conn->ob_capacity)
		conn->sendable = conn->ob_capacity;
	if(conn->sendable > conn->max_payload)
		conn->sendable = conn->max_payload;

	if(conn->sendable > 0)
		conn->events |= POLLIN;
	else
		conn->events &= ~POLLIN;

	if(conn->ib_size)
		conn->events |= POLLOUT;
	else
		conn->events &= ~POLLOUT;

	if(conn->tx_acked != conn->tx_ack)
		conn->flags |= CONN_ACK_PENDING;
	else
		conn->flags &= ~CONN_ACK_PENDING;

	usbmuxd_log(LL_SPEW, "update_connection: sendable %d, events %d, flags %d", conn->sendable, conn->events, conn->flags);
	client_set_events(conn->client, conn->events);
}

static int send_tcp_ack(struct mux_connection *conn)
{
	if(send_tcp(conn, TH_ACK, NULL, 0) < 0) {
		usbmuxd_log(LL_ERROR, "Error sending TCP ACK (%d->%d)", conn->sport, conn->dport);
		connection_teardown(conn);
    return -1;
	}

  update_connection(conn);

  return 0;
}

/**
 * Flush input and output buffers for a client connection.
 *
 * @param device_id Numeric id for the device.
 * @param client The client to flush buffers for.
 * @param events event mask for the client. POLLOUT means that
 *   the client is ready to receive data, POLLIN that it has
 *   data to be read (and send along to the device).
 */
void device_client_process(int device_id, struct mux_client *client, short events)
{
	struct mux_connection *conn = get_mux_connection(device_id, client);

	if(!conn) {
		usbmuxd_log(LL_WARNING, "Could not find connection for device %d client %p", device_id, client);
		return;
	}
	usbmuxd_log(LL_SPEW, "device_client_process (%d)", events);

	int res;
	int size;
	if((events & POLLOUT) && conn->ib_size > 0) {
		// Client is ready to receive data, send what we have
		// in the client's connection buffer (if there is any)
		size = client_write(conn->client, conn->ib_buf, conn->ib_size);
		if(size <= 0) {
			usbmuxd_log(LL_DEBUG, "error writing to client (%d)", size);
			connection_teardown(conn);
			return;
		}
		conn->tx_ack += size;
		if(size == (int)conn->ib_size) {
			conn->ib_size = 0;
		} else {
			conn->ib_size -= size;
			memmove(conn->ib_buf, conn->ib_buf + size, conn->ib_size);
		}
	}
	if((events & POLLIN) && conn->sendable > 0) {
		// There is inbound trafic on the client socket,
		// convert it to tcp and send to the device
		// (if the device's input buffer is not full)
		size = client_read(conn->client, conn->ob_buf, conn->sendable);
		if(size <= 0) {
			if (size < 0) {
				usbmuxd_log(LL_DEBUG, "error reading from client (%d)", size);
			}
			connection_teardown(conn);
			return;
		}
		res = send_tcp(conn, TH_ACK, conn->ob_buf, size);
		if(res < 0) {
			connection_teardown(conn);
			return;
		}
		conn->tx_seq += size;
	}

	update_connection(conn);
}

/**
 * Copy a payload to a connection's in-buffer and
 * set the POLLOUT event mask on the connection so
 * the next main_loop iteration will dispatch the
 * buffer if the connection socket is writable.
 *
 * Connection buffers are flushed in the
 * device_client_process() function.
 *
 * @param conn The connection to add incoming data to.
 * @param payload Payload to prepare for writing.
 *   The payload will be copied immediately so you are
 *   free to alter or free the payload buffer when this
 *   function returns.
 * @param payload_length number of bytes to copy from from
 *   the payload.
 */
static void connection_device_input(struct mux_connection *conn, unsigned char *payload, uint32_t payload_length)
{
	if((conn->ib_size + payload_length) > conn->ib_capacity) {
		usbmuxd_log(LL_ERROR, "Input buffer overflow on device %d connection %d->%d (space=%d, payload=%d)", conn->dev->id, conn->sport, conn->dport, conn->ib_capacity-conn->ib_size, payload_length);
		connection_teardown(conn);
		return;
	}
	memcpy(conn->ib_buf + conn->ib_size, payload, payload_length);
	conn->ib_size += payload_length;
	conn->rx_recvd += payload_length;
	update_connection(conn);
}

void device_abort_connect(int device_id, struct mux_client *client)
{
  struct mux_connection *conn = get_mux_connection(device_id, client);
	if (conn) {
		connection_teardown(conn);
	} else {
		usbmuxd_log(LL_WARNING, "Attempted to abort for nonexistent connection for device %d", device_id);
	}
}

static void device_version_input(struct mux_device *dev, struct version_header *vh)
{
	if(dev->state != MUXDEV_INIT) {
		usbmuxd_log(LL_WARNING, "Version packet from already initialized device %d", dev->id);
		return;
	}
	vh->major = ntohl(vh->major);
	vh->minor = ntohl(vh->minor);
	if(vh->major != 2 && vh->major != 1) {
		usbmuxd_log(LL_ERROR, "Device %d has unknown version %d.%d", dev->id, vh->major, vh->minor);
		pthread_mutex_lock(&device_list_mutex);
		collection_remove(&device_list, dev);
		pthread_mutex_unlock(&device_list_mutex);
		free(dev);
		return;
	}
	dev->version = vh->major;

	if (dev->version >= 2) {
		send_packet(dev, MUX_PROTO_SETUP, NULL, "\x07", 1);
	}

	usbmuxd_log(LL_NOTICE, "Connected to v%d.%d device %d on location 0x%x with serial number %s", dev->version, vh->minor, dev->id, usb_get_location(dev->usbdev), usb_get_serial(dev->usbdev));
	dev->state = MUXDEV_ACTIVE;
	collection_init(&dev->connections);
	struct device_info info;
	info.id = dev->id;
	info.location = usb_get_location(dev->usbdev);
	info.serial = usb_get_serial(dev->usbdev);
	info.pid = usb_get_pid(dev->usbdev);
	preflight_worker_device_add(&info);
}

static void device_control_input(struct mux_device *dev, unsigned char *payload, uint32_t payload_length)
{
	if (payload_length > 0) {
		switch (payload[0]) {
		case 3:
			if (payload_length > 1) {
				char* buf = malloc(payload_length);
				strncpy(buf, (char*)payload+1, payload_length-1);
				buf[payload_length-1] = '\0';
				usbmuxd_log(LL_ERROR, "%s: ERROR: %s", __func__, buf);
				free(buf);
			} else {
				usbmuxd_log(LL_ERROR, "%s: Error occured, but empty error message", __func__);
			}
			break;
		case 7:
			if (payload_length > 1) {
				char* buf = malloc(payload_length);
				strncpy(buf, (char*)payload+1, payload_length-1);
				buf[payload_length-1] = '\0';
				usbmuxd_log(LL_INFO, "%s: %s", __func__, buf);
				free(buf);
			}
			break;
		default:
			break;
		}
	} else {
		usbmuxd_log(LL_WARNING, "%s: got a type 1 packet without payload", __func__);
	}
}

/**
 * Handle an incoming TCP packet from the device.
 *
 * @param dev The device handle TCP input on.
 * @param th Pointer to the TCP header struct.
 * @param payload Payload data.
 * @param payload_length Number of bytes in payload.
 */
static void device_tcp_input(struct mux_device *dev, struct tcphdr *th, unsigned char *payload, uint32_t payload_length)
{
	uint16_t sport = ntohs(th->th_dport);
	uint16_t dport = ntohs(th->th_sport);
	struct mux_connection *conn = NULL;

	usbmuxd_log(LL_DEBUG, "[IN] dev=%d sport=%d dport=%d seq=%d ack=%d flags=0x%x window=%d[%d] len=%d",
		dev->id, dport, sport, ntohl(th->th_seq), ntohl(th->th_ack), th->th_flags, ntohs(th->th_win) << 8, ntohs(th->th_win), payload_length);

	if(dev->state != MUXDEV_ACTIVE) {
		usbmuxd_log(LL_ERROR, "Received TCP packet from device %d but the device isn't active yet, discarding", dev->id);
		return;
	}

	// Find the connection on this device that has the right sport and dport
	FOREACH(struct mux_connection *lconn, &dev->connections) {
		if(lconn->sport == sport && lconn->dport == dport) {
			conn = lconn;
			break;
		}
	} ENDFOREACH

	if(!conn) {
		if(!(th->th_flags & TH_RST)) {
			usbmuxd_log(LL_INFO, "No connection for device %d incoming packet %d->%d", dev->id, dport, sport);
			if(send_anon_rst(dev, sport, dport, ntohl(th->th_seq)) < 0)
				usbmuxd_log(LL_ERROR, "Error sending TCP RST to device %d (%d->%d)", conn->dev->id, sport, dport);
		}
		return;
	}

	conn->rx_seq = ntohl(th->th_seq);
	conn->rx_ack = ntohl(th->th_ack);
	conn->rx_win = ntohs(th->th_win) << 8;

	if(th->th_flags & TH_RST) {
		char *buf = malloc(payload_length+1);
		memcpy(buf, payload, payload_length);
		if(payload_length && (buf[payload_length-1] == '\n'))
			buf[payload_length-1] = 0;
		buf[payload_length] = 0;
		usbmuxd_log(LL_DEBUG, "RST reason: %s", buf);
		free(buf);
	}

	if(conn->state == CONN_CONNECTING) {
		if(th->th_flags != (TH_SYN|TH_ACK)) {
			if(th->th_flags & TH_RST)
				conn->state = CONN_REFUSED;
			usbmuxd_log(LL_INFO, "Connection refused by device %d (%d->%d)", dev->id, sport, dport);
			connection_teardown(conn); //this also sends the notification to the client
		} else {
			conn->tx_seq++;
			conn->tx_ack++;
			conn->rx_recvd = conn->rx_seq;
			if(send_tcp(conn, TH_ACK, NULL, 0) < 0) {
				usbmuxd_log(LL_ERROR, "Error sending TCP ACK to device %d (%d->%d)", dev->id, sport, dport);
				connection_teardown(conn);
				return;
			}
			conn->state = CONN_CONNECTED;
			if(client_notify_connect(conn->client, RESULT_OK) < 0) {
				conn->client = NULL;
				connection_teardown(conn);
			}
			update_connection(conn);
		}
	} else if(conn->state == CONN_CONNECTED) {
		if(th->th_flags != TH_ACK) {
			usbmuxd_log(LL_INFO, "Connection reset by device %d (%d->%d)", dev->id, sport, dport);
			if(th->th_flags & TH_RST)
				conn->state = CONN_DYING;
			connection_teardown(conn);
		} else {
			connection_device_input(conn, payload, payload_length);

			// Device likes it best when we are prompty ACKing data
			send_tcp_ack(conn);
		}
	}
}

/**
 * Take input data from the device that has been read into a buffer
 * and dispatch it to the right protocol backend (eg. TCP).
 *
 * @param usbdev
 * @param buffer
 * @param length
 */
void device_data_input(struct usb_device *usbdev, unsigned char *buffer, uint32_t length)
{
	struct mux_device *dev = NULL;
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *tdev, &device_list) {
		if(tdev->usbdev == usbdev) {
			dev = tdev;
			break;
		}
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);
	if(!dev) {
		usbmuxd_log(LL_WARNING, "Cannot find device entry for RX input from USB device %p on location 0x%x", usbdev, usb_get_location(usbdev));
		return;
	}

	if(!length)
		return;

	// sanity check (should never happen with current USB implementation)
	if((length > USB_MRU) || (length > DEV_MRU)) {
		usbmuxd_log(LL_ERROR, "Too much data received from USB (%d), file a bug", length);
		return;
	}

	usbmuxd_log(LL_SPEW, "Mux data input for device %p: %p len %d", dev, buffer, length);

	// handle broken up transfers
	if(dev->pktlen) {
		if((length + dev->pktlen) > DEV_MRU) {
			usbmuxd_log(LL_ERROR, "Incoming split packet is too large (%d so far), dropping!", length + dev->pktlen);
			dev->pktlen = 0;
			return;
		}
        memcpy(dev->pktbuf + dev->pktlen, buffer, length);
		struct mux_header *mhdr = (struct mux_header *)dev->pktbuf;
		if((length < USB_MRU) || (ntohl(mhdr->length) == (length + dev->pktlen))) {
			buffer = dev->pktbuf;
			length += dev->pktlen;
			dev->pktlen = 0;
			usbmuxd_log(LL_SPEW, "Gathered mux data from buffer (total size: %d)", length);
		} else {
			dev->pktlen += length;
			usbmuxd_log(LL_SPEW, "Appended mux data to buffer (total size: %d)", dev->pktlen);
			return;
		}
	} else {
		struct mux_header *mhdr = (struct mux_header *)buffer;
		if((length == USB_MRU) && (length < ntohl(mhdr->length))) {
			memcpy(dev->pktbuf, buffer, length);
			dev->pktlen = length;
			usbmuxd_log(LL_SPEW, "Copied mux data to buffer (size: %d)", dev->pktlen);
			return;
		}
	}

	struct mux_header *mhdr = (struct mux_header *)buffer;
	int mux_header_size = ((dev->version < 2) ? 8 : sizeof(struct mux_header));
	if(ntohl(mhdr->length) != length) {
		usbmuxd_log(LL_ERROR, "Incoming packet size mismatch (dev %d, expected %d, got %d)", dev->id, ntohl(mhdr->length), length);
		return;
	}

	struct tcphdr *th;
	unsigned char *payload;
	uint32_t payload_length;

	if (dev->version >= 2) {
		dev->rx_seq = ntohs(mhdr->rx_seq);
	}

	switch(ntohl(mhdr->protocol)) {
		case MUX_PROTO_VERSION:
			if(length < (mux_header_size + sizeof(struct version_header))) {
				usbmuxd_log(LL_ERROR, "Incoming version packet is too small (%d)", length);
				return;
			}
			device_version_input(dev, (struct version_header *)((char*)mhdr+mux_header_size));
			break;
		case MUX_PROTO_CONTROL:
			payload = (unsigned char *)(mhdr+1);
			payload_length = length - mux_header_size;
			device_control_input(dev, payload, payload_length);
			break;
		case MUX_PROTO_TCP:
			if(length < (mux_header_size + sizeof(struct tcphdr))) {
				usbmuxd_log(LL_ERROR, "Incoming TCP packet is too small (%d)", length);
				return;
			}
			th = (struct tcphdr *)((char*)mhdr+mux_header_size);
			payload = (unsigned char *)(th+1);
			payload_length = length - sizeof(struct tcphdr) - mux_header_size;
			device_tcp_input(dev, th, payload, payload_length);
			break;
		default:
			usbmuxd_log(LL_ERROR, "Incoming packet for device %d has unknown protocol 0x%x)", dev->id, ntohl(mhdr->protocol));
			break;
	}

}

int device_add(struct usb_device *usbdev)
{
	int res;
	int id = get_next_device_id();
	struct mux_device *dev;
	usbmuxd_log(LL_NOTICE, "Connecting to new device on location 0x%x as ID %d", usb_get_location(usbdev), id);
	dev = malloc(sizeof(struct mux_device));
	dev->id = id;
	dev->usbdev = usbdev;
	dev->state = MUXDEV_INIT;
	dev->visible = 0;
	dev->next_sport = 1;
	dev->pktbuf = malloc(DEV_MRU);
	dev->pktlen = 0;
	dev->preflight_cb_data = NULL;
	dev->version = 0;
	struct version_header vh;
	vh.major = htonl(1);
	vh.minor = htonl(0);
	vh.padding = 0;
	if((res = send_packet(dev, MUX_PROTO_VERSION, &vh, NULL, 0)) < 0) {
		usbmuxd_log(LL_ERROR, "Error sending version request packet to device %d", id);
		free(dev);
		return res;
	}
	pthread_mutex_lock(&device_list_mutex);
	collection_add(&device_list, dev);
	pthread_mutex_unlock(&device_list_mutex);
	return 0;
}

void device_remove(struct usb_device *usbdev)
{
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *dev, &device_list) {
		if(dev->usbdev == usbdev) {
			usbmuxd_log(LL_NOTICE, "Removed device %d on location 0x%x", dev->id, usb_get_location(usbdev));
			if(dev->state == MUXDEV_ACTIVE) {
				dev->state = MUXDEV_DEAD;
				FOREACH(struct mux_connection *conn, &dev->connections) {
					connection_teardown(conn);
				} ENDFOREACH
				client_device_remove(dev->id);
				collection_free(&dev->connections);
			}
			if (dev->preflight_cb_data) {
				preflight_device_remove_cb(dev->preflight_cb_data);
			}
			collection_remove(&device_list, dev);
			pthread_mutex_unlock(&device_list_mutex);
			free(dev->pktbuf);
			free(dev);
			return;
		}
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);

	usbmuxd_log(LL_WARNING, "Cannot find device entry while removing USB device %p on location 0x%x", usbdev, usb_get_location(usbdev));
}

void device_set_visible(int device_id)
{
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *dev, &device_list) {
		if(dev->id == device_id) {
			dev->visible = 1;
			break;
		}
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);
}

void device_set_preflight_cb_data(int device_id, void* data)
{
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *dev, &device_list) {
		if(dev->id == device_id) {
			dev->preflight_cb_data = data;
			break;
		}
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);
}

int device_get_count(int include_hidden)
{
	int count = 0;
	struct collection dev_list = {NULL, 0};
	pthread_mutex_lock(&device_list_mutex);
	collection_copy(&dev_list, &device_list);
	pthread_mutex_unlock(&device_list_mutex);

	FOREACH(struct mux_device *dev, &dev_list) {
		if((dev->state == MUXDEV_ACTIVE) && (include_hidden || dev->visible))
			count++;
	} ENDFOREACH

	collection_free(&dev_list);
	return count;
}

int device_get_list(int include_hidden, struct device_info **devices)
{
	int count = 0;
	struct collection dev_list = {NULL, 0};
	pthread_mutex_lock(&device_list_mutex);
	collection_copy(&dev_list, &device_list);
	pthread_mutex_unlock(&device_list_mutex);

	*devices = malloc(sizeof(struct device_info) * dev_list.capacity);
	struct device_info *p = *devices;

	FOREACH(struct mux_device *dev, &device_list) {
		if((dev->state == MUXDEV_ACTIVE) && (include_hidden || dev->visible)) {
			p->id = dev->id;
			p->serial = usb_get_serial(dev->usbdev);
			p->location = usb_get_location(dev->usbdev);
			p->pid = usb_get_pid(dev->usbdev);
			count++;
			p++;
		}
	} ENDFOREACH

	collection_free(&dev_list);

	return count;
}

int device_get_timeout(void)
{
	uint64_t oldest = (uint64_t)-1LL;
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *dev, &device_list) {
		if(dev->state == MUXDEV_ACTIVE) {
			FOREACH(struct mux_connection *conn, &dev->connections) {
				if((conn->state == CONN_CONNECTED) && (conn->flags & CONN_ACK_PENDING) && conn->last_ack_time < oldest)
					oldest = conn->last_ack_time;
			} ENDFOREACH
		}
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);
	uint64_t ct = mstime64();
	if((int64_t)oldest == -1LL)
		return 100000; //meh
	if((ct - oldest) > ACK_TIMEOUT)
		return 0;
	return ACK_TIMEOUT - (ct - oldest);
}

void device_check_timeouts(void)
{
	uint64_t ct = mstime64();
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *dev, &device_list) {
		if(dev->state == MUXDEV_ACTIVE) {
			FOREACH(struct mux_connection *conn, &dev->connections) {
				if((conn->state == CONN_CONNECTED) && 
						(conn->flags & CONN_ACK_PENDING) && 
						(ct - conn->last_ack_time) > ACK_TIMEOUT) {
					usbmuxd_log(LL_DEBUG, "Sending ACK due to expired timeout (%" PRIu64 " -> %" PRIu64 ")", conn->last_ack_time, ct);
					send_tcp_ack(conn);
				}
			} ENDFOREACH
		}
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);
}

void device_init(void)
{
	usbmuxd_log(LL_DEBUG, "device_init");
	collection_init(&device_list);
	pthread_mutex_init(&device_list_mutex, NULL);
	next_device_id = 1;
}

void device_kill_connections(void)
{
	usbmuxd_log(LL_DEBUG, "device_kill_connections");
	FOREACH(struct mux_device *dev, &device_list) {
		if(dev->state != MUXDEV_INIT) {
			FOREACH(struct mux_connection *conn, &dev->connections) {
				connection_teardown(conn);
			} ENDFOREACH
		}
	} ENDFOREACH
	// give USB a while to send the final connection RSTs and the like
	usb_process_timeout(100);
}

void device_shutdown(void)
{
	usbmuxd_log(LL_DEBUG, "device_shutdown");
	pthread_mutex_lock(&device_list_mutex);
	FOREACH(struct mux_device *dev, &device_list) {
		FOREACH(struct mux_connection *conn, &dev->connections) {
			connection_teardown(conn);
		} ENDFOREACH
		collection_free(&dev->connections);
		collection_remove(&device_list, dev);
		free(dev);
	} ENDFOREACH
	pthread_mutex_unlock(&device_list_mutex);
	pthread_mutex_destroy(&device_list_mutex);
	collection_free(&device_list);
}