-
Notifications
You must be signed in to change notification settings - Fork 4.6k
/
conn.go
1771 lines (1568 loc) · 49.8 KB
/
conn.go
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
1000
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// TLS low level connection and record layer
package qtls
import (
"bytes"
"crypto/cipher"
"crypto/subtle"
"crypto/x509"
"encoding/binary"
"errors"
"fmt"
"io"
"net"
"sync"
"sync/atomic"
"time"
)
// A Conn represents a secured connection.
// It implements the net.Conn interface.
type Conn struct {
// constant
conn net.Conn
isClient bool
phase handshakeStatus // protected by in.Mutex
// handshakeConfirmed is an atomic bool for phase == handshakeConfirmed
handshakeConfirmed int32
// confirmMutex is held by any read operation before handshakeConfirmed
confirmMutex sync.Mutex
// constant after handshake; protected by handshakeMutex
handshakeMutex sync.Mutex // handshakeMutex < in.Mutex, out.Mutex, errMutex
handshakeErr error // error resulting from handshake
connID []byte // Random connection id
clientHello []byte // ClientHello packet contents
vers uint16 // TLS version
haveVers bool // version has been negotiated
config *Config // configuration passed to constructor
// handshakeComplete is true if the connection reached application data
// and it's equivalent to phase > handshakeRunning
handshakeComplete bool
// handshakes counts the number of handshakes performed on the
// connection so far. If renegotiation is disabled then this is either
// zero or one.
handshakes int
didResume bool // whether this connection was a session resumption
cipherSuite uint16
ocspResponse []byte // stapled OCSP response
scts [][]byte // Signed certificate timestamps from server
peerCertificates []*x509.Certificate
// verifiedChains contains the certificate chains that we built, as
// opposed to the ones presented by the server.
verifiedChains [][]*x509.Certificate
// verifiedDc is set by a client who negotiates the use of a valid delegated
// credential.
verifiedDc *delegatedCredential
// serverName contains the server name indicated by the client, if any.
serverName string
// secureRenegotiation is true if the server echoed the secure
// renegotiation extension. (This is meaningless as a server because
// renegotiation is not supported in that case.)
secureRenegotiation bool
// indicates wether extended MasterSecret extension is used (see RFC7627)
useEMS bool
// clientFinishedIsFirst is true if the client sent the first Finished
// message during the most recent handshake. This is recorded because
// the first transmitted Finished message is the tls-unique
// channel-binding value.
clientFinishedIsFirst bool
// closeNotifyErr is any error from sending the alertCloseNotify record.
closeNotifyErr error
// closeNotifySent is true if the Conn attempted to send an
// alertCloseNotify record.
closeNotifySent bool
// clientFinished and serverFinished contain the Finished message sent
// by the client or server in the most recent handshake. This is
// retained to support the renegotiation extension and tls-unique
// channel-binding.
clientFinished [12]byte
serverFinished [12]byte
clientProtocol string
clientProtocolFallback bool
// ticketMaxEarlyData is the maximum bytes of 0-RTT application data
// that the client is allowed to send on the ticket it used.
ticketMaxEarlyData int64
// input/output
in, out halfConn // in.Mutex < out.Mutex
rawInput *block // raw input, right off the wire
input *block // application data waiting to be read
hand bytes.Buffer // handshake data waiting to be read
buffering bool // whether records are buffered in sendBuf
sendBuf []byte // a buffer of records waiting to be sent
// bytesSent counts the bytes of application data sent.
// packetsSent counts packets.
bytesSent int64
packetsSent int64
// warnCount counts the number of consecutive warning alerts received
// by Conn.readRecord. Protected by in.Mutex.
warnCount int
// activeCall is an atomic int32; the low bit is whether Close has
// been called. the rest of the bits are the number of goroutines
// in Conn.Write.
activeCall int32
// TLS 1.3 needs the server state until it reaches the Client Finished
hs *serverHandshakeState
// earlyDataBytes is the number of bytes of early data received so
// far. Tracked to enforce max_early_data_size.
// We don't keep track of rejected 0-RTT data since there's no need
// to ever buffer it. in.Mutex.
earlyDataBytes int64
// binder is the value of the PSK binder that was validated to
// accept the 0-RTT data. Exposed as ConnectionState.Unique0RTTToken.
binder []byte
tmp [16]byte
}
type handshakeStatus int
const (
handshakeRunning handshakeStatus = iota
discardingEarlyData
readingEarlyData
waitingClientFinished
readingClientFinished
handshakeConfirmed
)
// Access to net.Conn methods.
// Cannot just embed net.Conn because that would
// export the struct field too.
// LocalAddr returns the local network address.
func (c *Conn) LocalAddr() net.Addr {
return c.conn.LocalAddr()
}
// RemoteAddr returns the remote network address.
func (c *Conn) RemoteAddr() net.Addr {
return c.conn.RemoteAddr()
}
// SetDeadline sets the read and write deadlines associated with the connection.
// A zero value for t means Read and Write will not time out.
// After a Write has timed out, the TLS state is corrupt and all future writes will return the same error.
func (c *Conn) SetDeadline(t time.Time) error {
return c.conn.SetDeadline(t)
}
// SetReadDeadline sets the read deadline on the underlying connection.
// A zero value for t means Read will not time out.
func (c *Conn) SetReadDeadline(t time.Time) error {
return c.conn.SetReadDeadline(t)
}
// SetWriteDeadline sets the write deadline on the underlying connection.
// A zero value for t means Write will not time out.
// After a Write has timed out, the TLS state is corrupt and all future writes will return the same error.
func (c *Conn) SetWriteDeadline(t time.Time) error {
return c.conn.SetWriteDeadline(t)
}
// A halfConn represents one direction of the record layer
// connection, either sending or receiving.
type halfConn struct {
sync.Mutex
err error // first permanent error
version uint16 // protocol version
cipher interface{} // cipher algorithm
mac macFunction
seq [8]byte // 64-bit sequence number
bfree *block // list of free blocks
additionalData [13]byte // to avoid allocs; interface method args escape
nextCipher interface{} // next encryption state
nextMac macFunction // next MAC algorithm
// used to save allocating a new buffer for each MAC.
inDigestBuf, outDigestBuf []byte
setKeyCallback func(suite *CipherSuite, trafficSecret []byte)
traceErr func(error)
}
func (hc *halfConn) setErrorLocked(err error) error {
hc.err = err
if hc.traceErr != nil {
hc.traceErr(err)
}
return err
}
// prepareCipherSpec sets the encryption and MAC states
// that a subsequent changeCipherSpec will use.
func (hc *halfConn) prepareCipherSpec(version uint16, cipher interface{}, mac macFunction) {
hc.version = version
hc.nextCipher = cipher
hc.nextMac = mac
}
// changeCipherSpec changes the encryption and MAC states
// to the ones previously passed to prepareCipherSpec.
func (hc *halfConn) changeCipherSpec() error {
if hc.nextCipher == nil {
return alertInternalError
}
hc.cipher = hc.nextCipher
hc.mac = hc.nextMac
hc.nextCipher = nil
hc.nextMac = nil
for i := range hc.seq {
hc.seq[i] = 0
}
return nil
}
func (hc *halfConn) exportKey(suite *cipherSuite, trafficSecret []byte) {
if hc.setKeyCallback != nil {
hc.setKeyCallback(&CipherSuite{*suite}, trafficSecret)
}
}
func (hc *halfConn) setKey(version uint16, suite *cipherSuite, trafficSecret []byte) {
if hc.setKeyCallback != nil {
return
}
hc.version = version
hash := hashForSuite(suite)
key := hkdfExpandLabel(hash, trafficSecret, nil, "key", suite.keyLen)
iv := hkdfExpandLabel(hash, trafficSecret, nil, "iv", suite.ivLen)
hc.cipher = suite.aead(key, iv)
for i := range hc.seq {
hc.seq[i] = 0
}
}
// incSeq increments the sequence number.
func (hc *halfConn) incSeq() {
for i := 7; i >= 0; i-- {
hc.seq[i]++
if hc.seq[i] != 0 {
return
}
}
// Not allowed to let sequence number wrap.
// Instead, must renegotiate before it does.
// Not likely enough to bother.
panic("TLS: sequence number wraparound")
}
// extractPadding returns, in constant time, the length of the padding to remove
// from the end of payload. It also returns a byte which is equal to 255 if the
// padding was valid and 0 otherwise. See RFC 2246, section 6.2.3.2
func extractPadding(payload []byte) (toRemove int, good byte) {
if len(payload) < 1 {
return 0, 0
}
paddingLen := payload[len(payload)-1]
t := uint(len(payload)-1) - uint(paddingLen)
// if len(payload) >= (paddingLen - 1) then the MSB of t is zero
good = byte(int32(^t) >> 31)
// The maximum possible padding length plus the actual length field
toCheck := 256
// The length of the padded data is public, so we can use an if here
if toCheck > len(payload) {
toCheck = len(payload)
}
for i := 0; i < toCheck; i++ {
t := uint(paddingLen) - uint(i)
// if i <= paddingLen then the MSB of t is zero
mask := byte(int32(^t) >> 31)
b := payload[len(payload)-1-i]
good &^= mask&paddingLen ^ mask&b
}
// We AND together the bits of good and replicate the result across
// all the bits.
good &= good << 4
good &= good << 2
good &= good << 1
good = uint8(int8(good) >> 7)
toRemove = int(paddingLen) + 1
return
}
// extractPaddingSSL30 is a replacement for extractPadding in the case that the
// protocol version is SSLv3. In this version, the contents of the padding
// are random and cannot be checked.
func extractPaddingSSL30(payload []byte) (toRemove int, good byte) {
if len(payload) < 1 {
return 0, 0
}
paddingLen := int(payload[len(payload)-1]) + 1
if paddingLen > len(payload) {
return 0, 0
}
return paddingLen, 255
}
func roundUp(a, b int) int {
return a + (b-a%b)%b
}
// cbcMode is an interface for block ciphers using cipher block chaining.
type cbcMode interface {
cipher.BlockMode
SetIV([]byte)
}
// decrypt checks and strips the mac and decrypts the data in b. Returns a
// success boolean, the number of bytes to skip from the start of the record in
// order to get the application payload, and an optional alert value.
func (hc *halfConn) decrypt(b *block) (ok bool, prefixLen int, alertValue alert) {
// pull out payload
payload := b.data[recordHeaderLen:]
macSize := 0
if hc.mac != nil {
macSize = hc.mac.Size()
}
paddingGood := byte(255)
paddingLen := 0
explicitIVLen := 0
// decrypt
if hc.cipher != nil {
switch c := hc.cipher.(type) {
case cipher.Stream:
c.XORKeyStream(payload, payload)
case aead:
explicitIVLen = c.explicitNonceLen()
if len(payload) < explicitIVLen {
return false, 0, alertBadRecordMAC
}
nonce := payload[:explicitIVLen]
payload = payload[explicitIVLen:]
if len(nonce) == 0 {
nonce = hc.seq[:]
}
var additionalData []byte
if hc.version < VersionTLS13 {
copy(hc.additionalData[:], hc.seq[:])
copy(hc.additionalData[8:], b.data[:3])
n := len(payload) - c.Overhead()
hc.additionalData[11] = byte(n >> 8)
hc.additionalData[12] = byte(n)
additionalData = hc.additionalData[:]
} else {
if len(payload) > int((1<<14)+256) {
return false, 0, alertRecordOverflow
}
// Check AD header, see 5.2 of RFC8446
additionalData = make([]byte, 5)
additionalData[0] = byte(recordTypeApplicationData)
binary.BigEndian.PutUint16(additionalData[1:], VersionTLS12)
binary.BigEndian.PutUint16(additionalData[3:], uint16(len(payload)))
}
var err error
payload, err = c.Open(payload[:0], nonce, payload, additionalData)
if err != nil {
return false, 0, alertBadRecordMAC
}
b.resize(recordHeaderLen + explicitIVLen + len(payload))
case cbcMode:
blockSize := c.BlockSize()
if hc.version >= VersionTLS11 {
explicitIVLen = blockSize
}
if len(payload)%blockSize != 0 || len(payload) < roundUp(explicitIVLen+macSize+1, blockSize) {
return false, 0, alertBadRecordMAC
}
if explicitIVLen > 0 {
c.SetIV(payload[:explicitIVLen])
payload = payload[explicitIVLen:]
}
c.CryptBlocks(payload, payload)
if hc.version == VersionSSL30 {
paddingLen, paddingGood = extractPaddingSSL30(payload)
} else {
paddingLen, paddingGood = extractPadding(payload)
// To protect against CBC padding oracles like Lucky13, the data
// past paddingLen (which is secret) is passed to the MAC
// function as extra data, to be fed into the HMAC after
// computing the digest. This makes the MAC constant time as
// long as the digest computation is constant time and does not
// affect the subsequent write.
}
default:
panic("unknown cipher type")
}
}
// check, strip mac
if hc.mac != nil {
if len(payload) < macSize {
return false, 0, alertBadRecordMAC
}
// strip mac off payload, b.data
n := len(payload) - macSize - paddingLen
n = subtle.ConstantTimeSelect(int(uint32(n)>>31), 0, n) // if n < 0 { n = 0 }
b.data[3] = byte(n >> 8)
b.data[4] = byte(n)
remoteMAC := payload[n : n+macSize]
localMAC := hc.mac.MAC(hc.inDigestBuf, hc.seq[0:], b.data[:recordHeaderLen], payload[:n], payload[n+macSize:])
if subtle.ConstantTimeCompare(localMAC, remoteMAC) != 1 || paddingGood != 255 {
return false, 0, alertBadRecordMAC
}
hc.inDigestBuf = localMAC
b.resize(recordHeaderLen + explicitIVLen + n)
}
hc.incSeq()
return true, recordHeaderLen + explicitIVLen, 0
}
// padToBlockSize calculates the needed padding block, if any, for a payload.
// On exit, prefix aliases payload and extends to the end of the last full
// block of payload. finalBlock is a fresh slice which contains the contents of
// any suffix of payload as well as the needed padding to make finalBlock a
// full block.
func padToBlockSize(payload []byte, blockSize int) (prefix, finalBlock []byte) {
overrun := len(payload) % blockSize
paddingLen := blockSize - overrun
prefix = payload[:len(payload)-overrun]
finalBlock = make([]byte, blockSize)
copy(finalBlock, payload[len(payload)-overrun:])
for i := overrun; i < blockSize; i++ {
finalBlock[i] = byte(paddingLen - 1)
}
return
}
// encrypt encrypts and macs the data in b.
func (hc *halfConn) encrypt(b *block, explicitIVLen int) (bool, alert) {
// mac
if hc.mac != nil {
mac := hc.mac.MAC(hc.outDigestBuf, hc.seq[0:], b.data[:recordHeaderLen], b.data[recordHeaderLen+explicitIVLen:], nil)
n := len(b.data)
b.resize(n + len(mac))
copy(b.data[n:], mac)
hc.outDigestBuf = mac
}
payload := b.data[recordHeaderLen:]
// encrypt
if hc.cipher != nil {
switch c := hc.cipher.(type) {
case cipher.Stream:
c.XORKeyStream(payload, payload)
case aead:
// explicitIVLen is always 0 for TLS1.3
payloadLen := len(b.data) - recordHeaderLen - explicitIVLen
payloadOffset := recordHeaderLen + explicitIVLen
nonce := b.data[recordHeaderLen : recordHeaderLen+explicitIVLen]
if len(nonce) == 0 {
nonce = hc.seq[:]
}
var additionalData []byte
if hc.version < VersionTLS13 {
// make room in a buffer for payload + MAC
b.resize(len(b.data) + c.Overhead())
payload = b.data[payloadOffset : payloadOffset+payloadLen]
copy(hc.additionalData[:], hc.seq[:])
copy(hc.additionalData[8:], b.data[:3])
binary.BigEndian.PutUint16(hc.additionalData[11:], uint16(payloadLen))
additionalData = hc.additionalData[:]
} else {
// make room in a buffer for TLSCiphertext.encrypted_record:
// payload + MAC + extra data if needed
b.resize(len(b.data) + c.Overhead() + 1)
payload = b.data[payloadOffset : payloadOffset+payloadLen+1]
// 1 byte of content type is appended to payload and encrypted
payload[len(payload)-1] = b.data[0]
// opaque_type
b.data[0] = byte(recordTypeApplicationData)
// Add AD header, see 5.2 of RFC8446
additionalData = make([]byte, 5)
additionalData[0] = b.data[0]
binary.BigEndian.PutUint16(additionalData[1:], VersionTLS12)
binary.BigEndian.PutUint16(additionalData[3:], uint16(len(payload)+c.Overhead()))
}
c.Seal(payload[:0], nonce, payload, additionalData)
case cbcMode:
blockSize := c.BlockSize()
if explicitIVLen > 0 {
c.SetIV(payload[:explicitIVLen])
payload = payload[explicitIVLen:]
}
prefix, finalBlock := padToBlockSize(payload, blockSize)
b.resize(recordHeaderLen + explicitIVLen + len(prefix) + len(finalBlock))
c.CryptBlocks(b.data[recordHeaderLen+explicitIVLen:], prefix)
c.CryptBlocks(b.data[recordHeaderLen+explicitIVLen+len(prefix):], finalBlock)
default:
panic("unknown cipher type")
}
}
// update length to include MAC and any block padding needed.
n := len(b.data) - recordHeaderLen
b.data[3] = byte(n >> 8)
b.data[4] = byte(n)
hc.incSeq()
return true, 0
}
// A block is a simple data buffer.
type block struct {
data []byte
off int // index for Read
link *block
}
// resize resizes block to be n bytes, growing if necessary.
func (b *block) resize(n int) {
if n > cap(b.data) {
b.reserve(n)
}
b.data = b.data[0:n]
}
// reserve makes sure that block contains a capacity of at least n bytes.
func (b *block) reserve(n int) {
if cap(b.data) >= n {
return
}
m := cap(b.data)
if m == 0 {
m = 1024
}
for m < n {
m *= 2
}
data := make([]byte, len(b.data), m)
copy(data, b.data)
b.data = data
}
// readFromUntil reads from r into b until b contains at least n bytes
// or else returns an error.
func (b *block) readFromUntil(r io.Reader, n int) error {
// quick case
if len(b.data) >= n {
return nil
}
// read until have enough.
b.reserve(n)
for {
m, err := r.Read(b.data[len(b.data):cap(b.data)])
b.data = b.data[0 : len(b.data)+m]
if len(b.data) >= n {
// TODO(bradfitz,agl): slightly suspicious
// that we're throwing away r.Read's err here.
break
}
if err != nil {
return err
}
}
return nil
}
func (b *block) Read(p []byte) (n int, err error) {
n = copy(p, b.data[b.off:])
b.off += n
if b.off >= len(b.data) {
err = io.EOF
}
return
}
// newBlock allocates a new block, from hc's free list if possible.
func (hc *halfConn) newBlock() *block {
b := hc.bfree
if b == nil {
return new(block)
}
hc.bfree = b.link
b.link = nil
b.resize(0)
return b
}
// freeBlock returns a block to hc's free list.
// The protocol is such that each side only has a block or two on
// its free list at a time, so there's no need to worry about
// trimming the list, etc.
func (hc *halfConn) freeBlock(b *block) {
b.link = hc.bfree
hc.bfree = b
}
// splitBlock splits a block after the first n bytes,
// returning a block with those n bytes and a
// block with the remainder. the latter may be nil.
func (hc *halfConn) splitBlock(b *block, n int) (*block, *block) {
if len(b.data) <= n {
return b, nil
}
bb := hc.newBlock()
bb.resize(len(b.data) - n)
copy(bb.data, b.data[n:])
b.data = b.data[0:n]
return b, bb
}
// RecordHeaderError results when a TLS record header is invalid.
type RecordHeaderError struct {
// Msg contains a human readable string that describes the error.
Msg string
// RecordHeader contains the five bytes of TLS record header that
// triggered the error.
RecordHeader [5]byte
}
func (e RecordHeaderError) Error() string { return "tls: " + e.Msg }
func (c *Conn) newRecordHeaderError(msg string) (err RecordHeaderError) {
err.Msg = msg
copy(err.RecordHeader[:], c.rawInput.data)
return err
}
// readRecord reads the next TLS record from the connection
// and updates the record layer state.
// c.in.Mutex <= L; c.input == nil.
// c.input can still be nil after a call, retry if so.
func (c *Conn) readRecord(want recordType) error {
// Caller must be in sync with connection:
// handshake data if handshake not yet completed,
// else application data.
switch want {
default:
c.sendAlert(alertInternalError)
return c.in.setErrorLocked(errors.New("tls: unknown record type requested"))
case recordTypeHandshake, recordTypeChangeCipherSpec:
if c.phase != handshakeRunning && c.phase != readingClientFinished {
c.sendAlert(alertInternalError)
return c.in.setErrorLocked(errors.New("tls: handshake or ChangeCipherSpec requested while not in handshake"))
}
case recordTypeApplicationData:
if c.phase == handshakeRunning || c.phase == readingClientFinished {
c.sendAlert(alertInternalError)
return c.in.setErrorLocked(errors.New("tls: application data record requested while in handshake"))
}
}
Again:
if c.rawInput == nil {
c.rawInput = c.in.newBlock()
}
b := c.rawInput
// Read header, payload.
if err := b.readFromUntil(c.conn, recordHeaderLen); err != nil {
// RFC suggests that EOF without an alertCloseNotify is
// an error, but popular web sites seem to do this,
// so we can't make it an error.
// if err == io.EOF {
// err = io.ErrUnexpectedEOF
// }
if e, ok := err.(net.Error); !ok || !e.Temporary() {
c.in.setErrorLocked(err)
}
return err
}
typ := recordType(b.data[0])
// No valid TLS record has a type of 0x80, however SSLv2 handshakes
// start with a uint16 length where the MSB is set and the first record
// is always < 256 bytes long. Therefore typ == 0x80 strongly suggests
// an SSLv2 client.
if want == recordTypeHandshake && typ == 0x80 {
c.sendAlert(alertProtocolVersion)
return c.in.setErrorLocked(c.newRecordHeaderError("unsupported SSLv2 handshake received"))
}
vers := uint16(b.data[1])<<8 | uint16(b.data[2])
n := int(b.data[3])<<8 | int(b.data[4])
if n > maxCiphertext {
c.sendAlert(alertRecordOverflow)
msg := fmt.Sprintf("oversized record received with length %d", n)
return c.in.setErrorLocked(c.newRecordHeaderError(msg))
}
if !c.haveVers {
// First message, be extra suspicious: this might not be a TLS
// client. Bail out before reading a full 'body', if possible.
// The current max version is 3.3 so if the version is >= 16.0,
// it's probably not real.
if (typ != recordTypeAlert && typ != want) || vers >= 0x1000 {
c.sendAlert(alertUnexpectedMessage)
return c.in.setErrorLocked(c.newRecordHeaderError("first record does not look like a TLS handshake"))
}
}
if err := b.readFromUntil(c.conn, recordHeaderLen+n); err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
if e, ok := err.(net.Error); !ok || !e.Temporary() {
c.in.setErrorLocked(err)
}
return err
}
// Process message.
b, c.rawInput = c.in.splitBlock(b, recordHeaderLen+n)
// TLS 1.3 middlebox compatibility: skip over unencrypted CCS.
if c.vers >= VersionTLS13 && typ == recordTypeChangeCipherSpec && c.phase != handshakeConfirmed {
if len(b.data) != 6 || b.data[5] != 1 {
c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
}
c.in.freeBlock(b)
return c.in.err
}
peekedAlert := peekAlert(b) // peek at a possible alert before decryption
ok, off, alertValue := c.in.decrypt(b)
switch {
case !ok && c.phase == discardingEarlyData:
// If the client said that it's sending early data and we did not
// accept it, we are expected to fail decryption.
c.in.freeBlock(b)
return nil
case ok && c.phase == discardingEarlyData:
c.phase = waitingClientFinished
case !ok:
c.in.traceErr, c.out.traceErr = nil, nil // not that interesting
c.in.freeBlock(b)
err := c.sendAlert(alertValue)
// If decryption failed because the message is an unencrypted
// alert, return a more meaningful error message
if alertValue == alertBadRecordMAC && peekedAlert != nil {
err = peekedAlert
}
return c.in.setErrorLocked(err)
}
b.off = off
data := b.data[b.off:]
if (c.vers < VersionTLS13 && len(data) > maxPlaintext) || len(data) > maxPlaintext+1 {
c.in.freeBlock(b)
return c.in.setErrorLocked(c.sendAlert(alertRecordOverflow))
}
// After checking the plaintext length, remove 1.3 padding and
// extract the real content type.
// See https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-5.4.
if c.vers >= VersionTLS13 {
i := len(data) - 1
for i >= 0 {
if data[i] != 0 {
break
}
i--
}
if i < 0 {
c.in.freeBlock(b)
return c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
}
typ = recordType(data[i])
data = data[:i]
b.resize(b.off + i) // shrinks, guaranteed not to reallocate
}
if typ != recordTypeAlert && len(data) > 0 {
// this is a valid non-alert message: reset the count of alerts
c.warnCount = 0
}
switch typ {
default:
c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
case recordTypeAlert:
if len(data) != 2 {
c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
break
}
if alert(data[1]) == alertCloseNotify {
c.in.setErrorLocked(io.EOF)
break
}
switch data[0] {
case alertLevelWarning:
// drop on the floor
c.in.freeBlock(b)
c.warnCount++
if c.warnCount > maxWarnAlertCount {
c.sendAlert(alertUnexpectedMessage)
return c.in.setErrorLocked(errors.New("tls: too many warn alerts"))
}
goto Again
case alertLevelError:
c.in.setErrorLocked(&net.OpError{Op: "remote error", Err: alert(data[1])})
default:
c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
}
case recordTypeChangeCipherSpec:
if typ != want || len(data) != 1 || data[0] != 1 || c.vers >= VersionTLS13 {
c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
break
}
// Handshake messages are not allowed to fragment across the CCS
if c.hand.Len() > 0 {
c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
break
}
// Handshake messages are not allowed to fragment across the CCS
if c.hand.Len() > 0 {
c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
break
}
err := c.in.changeCipherSpec()
if err != nil {
c.in.setErrorLocked(c.sendAlert(err.(alert)))
}
case recordTypeApplicationData:
if typ != want || c.phase == waitingClientFinished {
c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
break
}
if c.phase == readingEarlyData {
c.earlyDataBytes += int64(len(b.data) - b.off)
if c.earlyDataBytes > c.ticketMaxEarlyData {
return c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
}
}
c.input = b
b = nil
case recordTypeHandshake:
// TODO(rsc): Should at least pick off connection close.
// If early data was being read, a Finished message is expected
// instead of (early) application data. Other post-handshake
// messages include HelloRequest and NewSessionTicket.
if typ != want && want != recordTypeApplicationData {
return c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
}
c.hand.Write(data)
}
if b != nil {
c.in.freeBlock(b)
}
return c.in.err
}
// peekAlert looks at a message to spot an unencrypted alert. It must be
// called before decryption to avoid a side channel, and its result must
// only be used if decryption fails, to avoid false positives.
func peekAlert(b *block) error {
if len(b.data) < 7 {
return nil
}
if recordType(b.data[0]) != recordTypeAlert {
return nil
}
return &net.OpError{Op: "remote error", Err: alert(b.data[6])}
}
// sendAlert sends a TLS alert message.
// c.out.Mutex <= L.
func (c *Conn) sendAlertLocked(err alert) error {
switch err {
case alertNoRenegotiation, alertCloseNotify:
c.tmp[0] = alertLevelWarning
default:
c.tmp[0] = alertLevelError
}
c.tmp[1] = byte(err)
_, writeErr := c.writeRecordLocked(recordTypeAlert, c.tmp[0:2])
if err == alertCloseNotify {
// closeNotify is a special case in that it isn't an error.
return writeErr
}
return c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err})
}
// sendAlert sends a TLS alert message.
// L < c.out.Mutex.
func (c *Conn) sendAlert(err alert) error {
if c.config.AlternativeRecordLayer != nil {
return nil
}
c.out.Lock()
defer c.out.Unlock()
return c.sendAlertLocked(err)
}
const (
// tcpMSSEstimate is a conservative estimate of the TCP maximum segment
// size (MSS). A constant is used, rather than querying the kernel for
// the actual MSS, to avoid complexity. The value here is the IPv6
// minimum MTU (1280 bytes) minus the overhead of an IPv6 header (40
// bytes) and a TCP header with timestamps (32 bytes).
tcpMSSEstimate = 1208
// recordSizeBoostThreshold is the number of bytes of application data
// sent after which the TLS record size will be increased to the
// maximum.
recordSizeBoostThreshold = 128 * 1024
)
// maxPayloadSizeForWrite returns the maximum TLS payload size to use for the
// next application data record. There is the following trade-off:
//
// - For latency-sensitive applications, such as web browsing, each TLS
// record should fit in one TCP segment.
// - For throughput-sensitive applications, such as large file transfers,
// larger TLS records better amortize framing and encryption overheads.
//
// A simple heuristic that works well in practice is to use small records for
// the first 1MB of data, then use larger records for subsequent data, and
// reset back to smaller records after the connection becomes idle. See "High
// Performance Web Networking", Chapter 4, or:
// https://www.igvita.com/2013/10/24/optimizing-tls-record-size-and-buffering-latency/
//
// In the interests of simplicity and determinism, this code does not attempt
// to reset the record size once the connection is idle, however.
//
// c.out.Mutex <= L.
func (c *Conn) maxPayloadSizeForWrite(typ recordType, explicitIVLen int) int {
if c.config.DynamicRecordSizingDisabled || typ != recordTypeApplicationData {
return maxPlaintext
}
if c.bytesSent >= recordSizeBoostThreshold {
return maxPlaintext
}
// Subtract TLS overheads to get the maximum payload size.
macSize := 0
if c.out.mac != nil {
macSize = c.out.mac.Size()
}
payloadBytes := tcpMSSEstimate - recordHeaderLen - explicitIVLen
if c.out.cipher != nil {
switch ciph := c.out.cipher.(type) {
case cipher.Stream:
payloadBytes -= macSize
case cipher.AEAD:
payloadBytes -= ciph.Overhead()
if c.vers >= VersionTLS13 {
payloadBytes -= 1 // ContentType
}
case cbcMode:
blockSize := ciph.BlockSize()
// The payload must fit in a multiple of blockSize, with
// room for at least one padding byte.