aboutsummaryrefslogtreecommitdiffstats
path: root/device/send.go
blob: 21984275c7a0397fc1cca241c58d03e5caeef8d9 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
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
/* SPDX-License-Identifier: MIT
 *
 * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
 */

package device

import (
	"bytes"
	"encoding/binary"
	"net"
	"sync"
	"sync/atomic"
	"time"

	"golang.org/x/crypto/chacha20poly1305"
	"golang.org/x/net/ipv4"
	"golang.org/x/net/ipv6"
)

/* Outbound flow
 *
 * 1. TUN queue
 * 2. Routing (sequential)
 * 3. Nonce assignment (sequential)
 * 4. Encryption (parallel)
 * 5. Transmission (sequential)
 *
 * The functions in this file occur (roughly) in the order in
 * which the packets are processed.
 *
 * Locking, Producers and Consumers
 *
 * The order of packets (per peer) must be maintained,
 * but encryption of packets happen out-of-order:
 *
 * The sequential consumers will attempt to take the lock,
 * workers release lock when they have completed work (encryption) on the packet.
 *
 * If the element is inserted into the "encryption queue",
 * the content is preceded by enough "junk" to contain the transport header
 * (to allow the construction of transport messages in-place)
 */

type QueueOutboundElement struct {
	dropped int32
	sync.Mutex
	buffer  *[MaxMessageSize]byte // slice holding the packet data
	packet  []byte                // slice of "buffer" (always!)
	nonce   uint64                // nonce for encryption
	keypair *Keypair              // keypair for encryption
	peer    *Peer                 // related peer
}

func (device *Device) NewOutboundElement() *QueueOutboundElement {
	elem := device.GetOutboundElement()
	elem.dropped = AtomicFalse
	elem.buffer = device.GetMessageBuffer()
	elem.Mutex = sync.Mutex{}
	elem.nonce = 0
	elem.keypair = nil
	elem.peer = nil
	return elem
}

func (elem *QueueOutboundElement) Drop() {
	atomic.StoreInt32(&elem.dropped, AtomicTrue)
}

func (elem *QueueOutboundElement) IsDropped() bool {
	return atomic.LoadInt32(&elem.dropped) == AtomicTrue
}

func addToNonceQueue(queue chan *QueueOutboundElement, element *QueueOutboundElement, device *Device) {
	for {
		select {
		case queue <- element:
			return
		default:
			select {
			case old := <-queue:
				device.PutMessageBuffer(old.buffer)
				device.PutOutboundElement(old)
			default:
			}
		}
	}
}

func addToOutboundAndEncryptionQueues(outboundQueue chan *QueueOutboundElement, encryptionQueue chan *QueueOutboundElement, element *QueueOutboundElement) {
	select {
	case outboundQueue <- element:
		select {
		case encryptionQueue <- element:
			return
		default:
			element.Drop()
			element.peer.device.PutMessageBuffer(element.buffer)
			element.Unlock()
		}
	default:
		element.peer.device.PutMessageBuffer(element.buffer)
		element.peer.device.PutOutboundElement(element)
	}
}

/* Queues a keepalive if no packets are queued for peer
 */
func (peer *Peer) SendKeepalive() bool {
	if len(peer.queue.nonce) != 0 || peer.queue.packetInNonceQueueIsAwaitingKey.Get() || !peer.isRunning.Get() {
		return false
	}
	elem := peer.device.NewOutboundElement()
	elem.packet = nil
	select {
	case peer.queue.nonce <- elem:
		peer.device.log.Debug.Println(peer, "- Sending keepalive packet")
		return true
	default:
		peer.device.PutMessageBuffer(elem.buffer)
		peer.device.PutOutboundElement(elem)
		return false
	}
}

func (peer *Peer) SendHandshakeInitiation(isRetry bool) error {
	if !isRetry {
		atomic.StoreUint32(&peer.timers.handshakeAttempts, 0)
	}

	peer.handshake.mutex.RLock()
	if time.Since(peer.handshake.lastSentHandshake) < RekeyTimeout {
		peer.handshake.mutex.RUnlock()
		return nil
	}
	peer.handshake.mutex.RUnlock()

	peer.handshake.mutex.Lock()
	if time.Since(peer.handshake.lastSentHandshake) < RekeyTimeout {
		peer.handshake.mutex.Unlock()
		return nil
	}
	peer.handshake.lastSentHandshake = time.Now()
	peer.handshake.mutex.Unlock()

	peer.device.log.Debug.Println(peer, "- Sending handshake initiation")

	msg, err := peer.device.CreateMessageInitiation(peer)
	if err != nil {
		peer.device.log.Error.Println(peer, "- Failed to create initiation message:", err)
		return err
	}

	var buff [MessageInitiationSize]byte
	writer := bytes.NewBuffer(buff[:0])
	binary.Write(writer, binary.LittleEndian, msg)
	packet := writer.Bytes()
	peer.cookieGenerator.AddMacs(packet)

	peer.timersAnyAuthenticatedPacketTraversal()
	peer.timersAnyAuthenticatedPacketSent()

	err = peer.SendBuffer(packet)
	if err != nil {
		peer.device.log.Error.Println(peer, "- Failed to send handshake initiation", err)
	}
	peer.timersHandshakeInitiated()

	return err
}

func (peer *Peer) SendHandshakeResponse() error {
	peer.handshake.mutex.Lock()
	peer.handshake.lastSentHandshake = time.Now()
	peer.handshake.mutex.Unlock()

	peer.device.log.Debug.Println(peer, "- Sending handshake response")

	response, err := peer.device.CreateMessageResponse(peer)
	if err != nil {
		peer.device.log.Error.Println(peer, "- Failed to create response message:", err)
		return err
	}

	var buff [MessageResponseSize]byte
	writer := bytes.NewBuffer(buff[:0])
	binary.Write(writer, binary.LittleEndian, response)
	packet := writer.Bytes()
	peer.cookieGenerator.AddMacs(packet)

	err = peer.BeginSymmetricSession()
	if err != nil {
		peer.device.log.Error.Println(peer, "- Failed to derive keypair:", err)
		return err
	}

	peer.timersSessionDerived()
	peer.timersAnyAuthenticatedPacketTraversal()
	peer.timersAnyAuthenticatedPacketSent()

	err = peer.SendBuffer(packet)
	if err != nil {
		peer.device.log.Error.Println(peer, "- Failed to send handshake response", err)
	}
	return err
}

func (device *Device) SendHandshakeCookie(initiatingElem *QueueHandshakeElement) error {

	device.log.Debug.Println("Sending cookie response for denied handshake message for", initiatingElem.endpoint.DstToString())

	sender := binary.LittleEndian.Uint32(initiatingElem.packet[4:8])
	reply, err := device.cookieChecker.CreateReply(initiatingElem.packet, sender, initiatingElem.endpoint.DstToBytes())
	if err != nil {
		device.log.Error.Println("Failed to create cookie reply:", err)
		return err
	}

	var buff [MessageCookieReplySize]byte
	writer := bytes.NewBuffer(buff[:0])
	binary.Write(writer, binary.LittleEndian, reply)
	device.net.bind.Send(writer.Bytes(), initiatingElem.endpoint)
	if err != nil {
		device.log.Error.Println("Failed to send cookie reply:", err)
	}
	return err
}

func (peer *Peer) keepKeyFreshSending() {
	keypair := peer.keypairs.Current()
	if keypair == nil {
		return
	}
	nonce := atomic.LoadUint64(&keypair.sendNonce)
	if nonce > RekeyAfterMessages || (keypair.isInitiator && time.Since(keypair.created) > RekeyAfterTime) {
		peer.SendHandshakeInitiation(false)
	}
}

/* Reads packets from the TUN and inserts
 * into nonce queue for peer
 *
 * Obs. Single instance per TUN device
 */
func (device *Device) RoutineReadFromTUN() {

	logDebug := device.log.Debug
	logError := device.log.Error

	defer func() {
		logDebug.Println("Routine: TUN reader - stopped")
		device.state.stopping.Done()
	}()

	logDebug.Println("Routine: TUN reader - started")
	device.state.starting.Done()

	var elem *QueueOutboundElement

	for {
		if elem != nil {
			device.PutMessageBuffer(elem.buffer)
			device.PutOutboundElement(elem)
		}
		elem = device.NewOutboundElement()

		// read packet

		offset := MessageTransportHeaderSize
		size, err := device.tun.device.Read(elem.buffer[:], offset)

		if err != nil {
			if !device.isClosed.Get() {
				logError.Println("Failed to read packet from TUN device:", err)
				device.Close()
			}
			device.PutMessageBuffer(elem.buffer)
			device.PutOutboundElement(elem)
			return
		}

		if size == 0 || size > MaxContentSize {
			continue
		}

		elem.packet = elem.buffer[offset : offset+size]

		// lookup peer

		var peer *Peer
		switch elem.packet[0] >> 4 {
		case ipv4.Version:
			if len(elem.packet) < ipv4.HeaderLen {
				continue
			}
			dst := elem.packet[IPv4offsetDst : IPv4offsetDst+net.IPv4len]
			peer = device.allowedips.LookupIPv4(dst)

		case ipv6.Version:
			if len(elem.packet) < ipv6.HeaderLen {
				continue
			}
			dst := elem.packet[IPv6offsetDst : IPv6offsetDst+net.IPv6len]
			peer = device.allowedips.LookupIPv6(dst)

		default:
			logDebug.Println("Received packet with unknown IP version")
		}

		if peer == nil {
			continue
		}

		// insert into nonce/pre-handshake queue

		if peer.isRunning.Get() {
			if peer.queue.packetInNonceQueueIsAwaitingKey.Get() {
				peer.SendHandshakeInitiation(false)
			}
			addToNonceQueue(peer.queue.nonce, elem, device)
			elem = nil
		}
	}
}

func (peer *Peer) FlushNonceQueue() {
	select {
	case peer.signals.flushNonceQueue <- struct{}{}:
	default:
	}
}

/* Queues packets when there is no handshake.
 * Then assigns nonces to packets sequentially
 * and creates "work" structs for workers
 *
 * Obs. A single instance per peer
 */
func (peer *Peer) RoutineNonce() {
	var keypair *Keypair

	device := peer.device
	logDebug := device.log.Debug

	flush := func() {
		for {
			select {
			case elem := <-peer.queue.nonce:
				device.PutMessageBuffer(elem.buffer)
				device.PutOutboundElement(elem)
			default:
				return
			}
		}
	}

	defer func() {
		flush()
		logDebug.Println(peer, "- Routine: nonce worker - stopped")
		peer.queue.packetInNonceQueueIsAwaitingKey.Set(false)
		peer.routines.stopping.Done()
	}()

	peer.routines.starting.Done()
	logDebug.Println(peer, "- Routine: nonce worker - started")

	for {
	NextPacket:
		peer.queue.packetInNonceQueueIsAwaitingKey.Set(false)

		select {
		case <-peer.routines.stop:
			return

		case <-peer.signals.flushNonceQueue:
			flush()
			goto NextPacket

		case elem, ok := <-peer.queue.nonce:

			if !ok {
				return
			}

			// make sure to always pick the newest key

			for {

				// check validity of newest key pair

				keypair = peer.keypairs.Current()
				if keypair != nil && keypair.sendNonce < RejectAfterMessages {
					if time.Since(keypair.created) < RejectAfterTime {
						break
					}
				}
				peer.queue.packetInNonceQueueIsAwaitingKey.Set(true)

				// no suitable key pair, request for new handshake

				select {
				case <-peer.signals.newKeypairArrived:
				default:
				}

				peer.SendHandshakeInitiation(false)

				// wait for key to be established

				logDebug.Println(peer, "- Awaiting keypair")

				select {
				case <-peer.signals.newKeypairArrived:
					logDebug.Println(peer, "- Obtained awaited keypair")

				case <-peer.signals.flushNonceQueue:
					device.PutMessageBuffer(elem.buffer)
					device.PutOutboundElement(elem)
					flush()
					goto NextPacket

				case <-peer.routines.stop:
					device.PutMessageBuffer(elem.buffer)
					device.PutOutboundElement(elem)
					return
				}
			}
			peer.queue.packetInNonceQueueIsAwaitingKey.Set(false)

			// populate work element

			elem.peer = peer
			elem.nonce = atomic.AddUint64(&keypair.sendNonce, 1) - 1

			// double check in case of race condition added by future code

			if elem.nonce >= RejectAfterMessages {
				atomic.StoreUint64(&keypair.sendNonce, RejectAfterMessages)
				device.PutMessageBuffer(elem.buffer)
				device.PutOutboundElement(elem)
				goto NextPacket
			}

			elem.keypair = keypair
			elem.dropped = AtomicFalse
			elem.Lock()

			// add to parallel and sequential queue
			addToOutboundAndEncryptionQueues(peer.queue.outbound, device.queue.encryption, elem)
		}
	}
}

/* Encrypts the elements in the queue
 * and marks them for sequential consumption (by releasing the mutex)
 *
 * Obs. One instance per core
 */
func (device *Device) RoutineEncryption() {

	var nonce [chacha20poly1305.NonceSize]byte

	logDebug := device.log.Debug

	defer func() {
		for {
			select {
			case elem, ok := <-device.queue.encryption:
				if ok && !elem.IsDropped() {
					elem.Drop()
					device.PutMessageBuffer(elem.buffer)
					elem.Unlock()
				}
			default:
				goto out
			}
		}
	out:
		logDebug.Println("Routine: encryption worker - stopped")
		device.state.stopping.Done()
	}()

	logDebug.Println("Routine: encryption worker - started")
	device.state.starting.Done()

	for {

		// fetch next element

		select {
		case <-device.signals.stop:
			return

		case elem, ok := <-device.queue.encryption:

			if !ok {
				return
			}

			// check if dropped

			if elem.IsDropped() {
				continue
			}

			// populate header fields

			header := elem.buffer[:MessageTransportHeaderSize]

			fieldType := header[0:4]
			fieldReceiver := header[4:8]
			fieldNonce := header[8:16]

			binary.LittleEndian.PutUint32(fieldType, MessageTransportType)
			binary.LittleEndian.PutUint32(fieldReceiver, elem.keypair.remoteIndex)
			binary.LittleEndian.PutUint64(fieldNonce, elem.nonce)

			// pad content to multiple of 16

			mtu := int(atomic.LoadInt32(&device.tun.mtu))
			lastUnit := len(elem.packet) % mtu
			paddedSize := (lastUnit + PaddingMultiple - 1) & ^(PaddingMultiple - 1)
			if paddedSize > mtu {
				paddedSize = mtu
			}
			for i := len(elem.packet); i < paddedSize; i++ {
				elem.packet = append(elem.packet, 0)
			}

			// encrypt content and release to consumer

			binary.LittleEndian.PutUint64(nonce[4:], elem.nonce)
			elem.packet = elem.keypair.send.Seal(
				header,
				nonce[:],
				elem.packet,
				nil,
			)
			elem.Unlock()
		}
	}
}

/* Sequentially reads packets from queue and sends to endpoint
 *
 * Obs. Single instance per peer.
 * The routine terminates then the outbound queue is closed.
 */
func (peer *Peer) RoutineSequentialSender() {

	device := peer.device

	logDebug := device.log.Debug
	logError := device.log.Error

	defer func() {
		for {
			select {
			case elem, ok := <-peer.queue.outbound:
				if ok {
					if !elem.IsDropped() {
						device.PutMessageBuffer(elem.buffer)
						elem.Drop()
					}
					device.PutOutboundElement(elem)
				}
			default:
				goto out
			}
		}
	out:
		logDebug.Println(peer, "- Routine: sequential sender - stopped")
		peer.routines.stopping.Done()
	}()

	logDebug.Println(peer, "- Routine: sequential sender - started")

	peer.routines.starting.Done()

	for {
		select {

		case <-peer.routines.stop:
			return

		case elem, ok := <-peer.queue.outbound:

			if !ok {
				return
			}

			elem.Lock()
			if elem.IsDropped() {
				device.PutOutboundElement(elem)
				continue
			}

			peer.timersAnyAuthenticatedPacketTraversal()
			peer.timersAnyAuthenticatedPacketSent()

			// send message and return buffer to pool

			length := uint64(len(elem.packet))
			err := peer.SendBuffer(elem.packet)
			if len(elem.packet) != MessageKeepaliveSize {
				peer.timersDataSent()
			}
			device.PutMessageBuffer(elem.buffer)
			device.PutOutboundElement(elem)
			if err != nil {
				logError.Println(peer, "- Failed to send data packet", err)
				continue
			}
			atomic.AddUint64(&peer.stats.txBytes, length)

			peer.keepKeyFreshSending()
		}
	}
}