/
handshake_server.go
2190 lines (1902 loc) · 67.4 KB
/
handshake_server.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 2009 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.
package runner
import (
"bytes"
"crypto"
"crypto/ecdsa"
"crypto/ed25519"
"crypto/elliptic"
"crypto/rsa"
"crypto/subtle"
"crypto/x509"
"errors"
"fmt"
"io"
"math/big"
"time"
)
// serverHandshakeState contains details of a server handshake in progress.
// It's discarded once the handshake has completed.
type serverHandshakeState struct {
c *Conn
clientHello *clientHelloMsg
hello *serverHelloMsg
suite *cipherSuite
ellipticOk bool
ecdsaOk bool
sessionState *sessionState
finishedHash finishedHash
masterSecret []byte
certsFromClient [][]byte
cert *Certificate
finishedBytes []byte
}
// serverHandshake performs a TLS handshake as a server.
func (c *Conn) serverHandshake() error {
config := c.config
// If this is the first server handshake, we generate a random key to
// encrypt the tickets with.
config.serverInitOnce.Do(config.serverInit)
c.sendHandshakeSeq = 0
c.recvHandshakeSeq = 0
hs := serverHandshakeState{
c: c,
}
if err := hs.readClientHello(); err != nil {
return err
}
if c.vers >= VersionTLS13 {
if err := hs.doTLS13Handshake(); err != nil {
return err
}
} else {
isResume, err := hs.processClientHello()
if err != nil {
return err
}
// For an overview of TLS handshaking, see https://tools.ietf.org/html/rfc5246#section-7.3
if isResume {
// The client has included a session ticket and so we do an abbreviated handshake.
if err := hs.doResumeHandshake(); err != nil {
return err
}
if err := hs.establishKeys(); err != nil {
return err
}
if c.config.Bugs.RenewTicketOnResume {
if err := hs.sendSessionTicket(); err != nil {
return err
}
}
if err := hs.sendFinished(c.firstFinished[:], isResume); err != nil {
return err
}
// Most retransmits are triggered by a timeout, but the final
// leg of the handshake is retransmited upon re-receiving a
// Finished.
if err := c.simulatePacketLoss(func() {
c.sendHandshakeSeq--
c.writeRecord(recordTypeHandshake, hs.finishedBytes)
c.flushHandshake()
}); err != nil {
return err
}
if err := hs.readFinished(nil, isResume); err != nil {
return err
}
c.didResume = true
} else {
// The client didn't include a session ticket, or it wasn't
// valid so we do a full handshake.
if err := hs.doFullHandshake(); err != nil {
return err
}
if err := hs.establishKeys(); err != nil {
return err
}
if err := hs.readFinished(c.firstFinished[:], isResume); err != nil {
return err
}
if c.config.Bugs.AlertBeforeFalseStartTest != 0 {
c.sendAlert(c.config.Bugs.AlertBeforeFalseStartTest)
}
if c.config.Bugs.ExpectFalseStart {
if err := c.readRecord(recordTypeApplicationData); err != nil {
return fmt.Errorf("tls: peer did not false start: %s", err)
}
}
if err := hs.sendSessionTicket(); err != nil {
return err
}
if err := hs.sendFinished(nil, isResume); err != nil {
return err
}
}
c.exporterSecret = hs.masterSecret
}
c.handshakeComplete = true
copy(c.clientRandom[:], hs.clientHello.random)
copy(c.serverRandom[:], hs.hello.random)
return nil
}
// readClientHello reads a ClientHello message from the client and determines
// the protocol version.
func (hs *serverHandshakeState) readClientHello() error {
config := hs.c.config
c := hs.c
if err := c.simulatePacketLoss(nil); err != nil {
return err
}
msg, err := c.readHandshake()
if err != nil {
return err
}
var ok bool
hs.clientHello, ok = msg.(*clientHelloMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(hs.clientHello, msg)
}
if size := config.Bugs.RequireClientHelloSize; size != 0 && len(hs.clientHello.raw) != size {
return fmt.Errorf("tls: ClientHello record size is %d, but expected %d", len(hs.clientHello.raw), size)
}
if c.isDTLS && !config.Bugs.SkipHelloVerifyRequest {
// Per RFC 6347, the version field in HelloVerifyRequest SHOULD
// be always DTLS 1.0
helloVerifyRequest := &helloVerifyRequestMsg{
vers: VersionDTLS10,
cookie: make([]byte, 32),
}
if _, err := io.ReadFull(c.config.rand(), helloVerifyRequest.cookie); err != nil {
c.sendAlert(alertInternalError)
return errors.New("dtls: short read from Rand: " + err.Error())
}
c.writeRecord(recordTypeHandshake, helloVerifyRequest.marshal())
c.flushHandshake()
if err := c.simulatePacketLoss(nil); err != nil {
return err
}
msg, err := c.readHandshake()
if err != nil {
return err
}
newClientHello, ok := msg.(*clientHelloMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(hs.clientHello, msg)
}
if !bytes.Equal(newClientHello.cookie, helloVerifyRequest.cookie) {
return errors.New("dtls: invalid cookie")
}
// Apart from the cookie, the two ClientHellos must
// match. Note that clientHello.equal compares the
// serialization, so we make a copy.
oldClientHelloCopy := *hs.clientHello
oldClientHelloCopy.raw = nil
oldClientHelloCopy.cookie = nil
newClientHelloCopy := *newClientHello
newClientHelloCopy.raw = nil
newClientHelloCopy.cookie = nil
if !oldClientHelloCopy.equal(&newClientHelloCopy) {
return errors.New("dtls: retransmitted ClientHello does not match")
}
hs.clientHello = newClientHello
}
if config.Bugs.RequireSameRenegoClientVersion && c.clientVersion != 0 {
if c.clientVersion != hs.clientHello.vers {
return fmt.Errorf("tls: client offered different version on renego")
}
}
if config.Bugs.FailIfCECPQ2Offered {
for _, offeredCurve := range hs.clientHello.supportedCurves {
if isPqGroup(offeredCurve) {
return errors.New("tls: CECPQ2 or CECPQ2b was offered")
}
}
}
if expected := config.Bugs.ExpectedKeyShares; expected != nil {
if len(expected) != len(hs.clientHello.keyShares) {
return fmt.Errorf("tls: expected %d key shares, but found %d", len(expected), len(hs.clientHello.keyShares))
}
for i, group := range expected {
if found := hs.clientHello.keyShares[i].group; found != group {
return fmt.Errorf("tls: key share #%d is for group %d, not %d", i, found, group)
}
}
}
if c.config.Bugs.ExpectPQExperimentSignal != hs.clientHello.pqExperimentSignal {
return fmt.Errorf("tls: PQ experiment signal presence (%t) was not what was expected", hs.clientHello.pqExperimentSignal)
}
c.clientVersion = hs.clientHello.vers
// Use the versions extension if supplied, otherwise use the legacy ClientHello version.
if len(hs.clientHello.supportedVersions) == 0 {
if c.isDTLS {
if hs.clientHello.vers <= VersionDTLS12 {
hs.clientHello.supportedVersions = append(hs.clientHello.supportedVersions, VersionDTLS12)
}
if hs.clientHello.vers <= VersionDTLS10 {
hs.clientHello.supportedVersions = append(hs.clientHello.supportedVersions, VersionDTLS10)
}
} else {
if hs.clientHello.vers >= VersionTLS12 {
hs.clientHello.supportedVersions = append(hs.clientHello.supportedVersions, VersionTLS12)
}
if hs.clientHello.vers >= VersionTLS11 {
hs.clientHello.supportedVersions = append(hs.clientHello.supportedVersions, VersionTLS11)
}
if hs.clientHello.vers >= VersionTLS10 {
hs.clientHello.supportedVersions = append(hs.clientHello.supportedVersions, VersionTLS10)
}
if hs.clientHello.vers >= VersionSSL30 {
hs.clientHello.supportedVersions = append(hs.clientHello.supportedVersions, VersionSSL30)
}
}
} else if config.Bugs.ExpectGREASE && !containsGREASE(hs.clientHello.supportedVersions) {
return errors.New("tls: no GREASE version value found")
}
if !c.haveVers {
if config.Bugs.NegotiateVersion != 0 {
c.wireVersion = config.Bugs.NegotiateVersion
} else {
var found bool
for _, vers := range hs.clientHello.supportedVersions {
if _, ok := config.isSupportedVersion(vers, c.isDTLS); ok {
c.wireVersion = vers
found = true
break
}
}
if !found {
c.sendAlert(alertProtocolVersion)
return errors.New("tls: client did not offer any supported protocol versions")
}
}
} else if config.Bugs.NegotiateVersionOnRenego != 0 {
c.wireVersion = config.Bugs.NegotiateVersionOnRenego
}
c.vers, ok = wireToVersion(c.wireVersion, c.isDTLS)
if !ok {
panic("Could not map wire version")
}
c.haveVers = true
clientProtocol, ok := wireToVersion(c.clientVersion, c.isDTLS)
// Reject < 1.2 ClientHellos with signature_algorithms.
if ok && clientProtocol < VersionTLS12 && len(hs.clientHello.signatureAlgorithms) > 0 {
return fmt.Errorf("tls: client included signature_algorithms before TLS 1.2")
}
// Check the client cipher list is consistent with the version.
if ok && clientProtocol < VersionTLS12 {
for _, id := range hs.clientHello.cipherSuites {
if isTLS12Cipher(id) {
return fmt.Errorf("tls: client offered TLS 1.2 cipher before TLS 1.2")
}
}
}
if config.Bugs.ExpectNoTLS12Session {
if len(hs.clientHello.sessionId) > 0 && c.vers >= VersionTLS13 {
return fmt.Errorf("tls: client offered an unexpected session ID")
}
if len(hs.clientHello.sessionTicket) > 0 {
return fmt.Errorf("tls: client offered an unexpected session ticket")
}
}
if config.Bugs.ExpectNoTLS13PSK && len(hs.clientHello.pskIdentities) > 0 {
return fmt.Errorf("tls: client offered unexpected PSK identities")
}
var scsvFound bool
for _, cipherSuite := range hs.clientHello.cipherSuites {
if cipherSuite == fallbackSCSV {
scsvFound = true
break
}
}
if !scsvFound && config.Bugs.FailIfNotFallbackSCSV {
return errors.New("tls: no fallback SCSV found when expected")
} else if scsvFound && !config.Bugs.FailIfNotFallbackSCSV {
return errors.New("tls: fallback SCSV found when not expected")
}
if config.Bugs.ExpectGREASE && !containsGREASE(hs.clientHello.cipherSuites) {
return errors.New("tls: no GREASE cipher suite value found")
}
var greaseFound bool
for _, curve := range hs.clientHello.supportedCurves {
if isGREASEValue(uint16(curve)) {
greaseFound = true
break
}
}
if !greaseFound && config.Bugs.ExpectGREASE {
return errors.New("tls: no GREASE curve value found")
}
if len(hs.clientHello.keyShares) > 0 {
greaseFound = false
for _, keyShare := range hs.clientHello.keyShares {
if isGREASEValue(uint16(keyShare.group)) {
greaseFound = true
break
}
}
if !greaseFound && config.Bugs.ExpectGREASE {
return errors.New("tls: no GREASE curve value found")
}
}
if err := checkRSAPSSSupport(config.Bugs.ExpectRSAPSSSupport, hs.clientHello.signatureAlgorithms, hs.clientHello.signatureAlgorithmsCert); err != nil {
return err
}
applyBugsToClientHello(hs.clientHello, config)
return nil
}
func applyBugsToClientHello(clientHello *clientHelloMsg, config *Config) {
if config.Bugs.IgnorePeerSignatureAlgorithmPreferences {
clientHello.signatureAlgorithms = config.signSignatureAlgorithms()
}
if config.Bugs.IgnorePeerCurvePreferences {
clientHello.supportedCurves = config.curvePreferences()
}
if config.Bugs.IgnorePeerCipherPreferences {
clientHello.cipherSuites = config.cipherSuites()
}
}
func (hs *serverHandshakeState) doTLS13Handshake() error {
c := hs.c
config := c.config
// We've read the ClientHello, so the next record must be preceded with ChangeCipherSpec.
c.expectTLS13ChangeCipherSpec = true
hs.hello = &serverHelloMsg{
isDTLS: c.isDTLS,
vers: c.wireVersion,
sessionId: hs.clientHello.sessionId,
compressionMethod: config.Bugs.SendCompressionMethod,
versOverride: config.Bugs.SendServerHelloVersion,
supportedVersOverride: config.Bugs.SendServerSupportedVersionExtension,
omitSupportedVers: config.Bugs.OmitServerSupportedVersionExtension,
customExtension: config.Bugs.CustomUnencryptedExtension,
unencryptedALPN: config.Bugs.SendUnencryptedALPN,
}
hs.hello.random = make([]byte, 32)
if _, err := io.ReadFull(config.rand(), hs.hello.random); err != nil {
c.sendAlert(alertInternalError)
return err
}
// TLS 1.3 forbids clients from advertising any non-null compression.
if len(hs.clientHello.compressionMethods) != 1 || hs.clientHello.compressionMethods[0] != compressionNone {
return errors.New("tls: client sent compression method other than null for TLS 1.3")
}
// Prepare an EncryptedExtensions message, but do not send it yet.
encryptedExtensions := new(encryptedExtensionsMsg)
encryptedExtensions.empty = config.Bugs.EmptyEncryptedExtensions
if err := hs.processClientExtensions(&encryptedExtensions.extensions); err != nil {
return err
}
// Select the cipher suite.
var preferenceList, supportedList []uint16
if config.PreferServerCipherSuites {
preferenceList = config.cipherSuites()
supportedList = hs.clientHello.cipherSuites
} else {
preferenceList = hs.clientHello.cipherSuites
supportedList = config.cipherSuites()
}
for _, id := range preferenceList {
if hs.suite = c.tryCipherSuite(id, supportedList, c.vers, true, true); hs.suite != nil {
break
}
}
if hs.suite == nil {
c.sendAlert(alertHandshakeFailure)
return errors.New("tls: no cipher suite supported by both client and server")
}
hs.hello.cipherSuite = hs.suite.id
if c.config.Bugs.SendCipherSuite != 0 {
hs.hello.cipherSuite = c.config.Bugs.SendCipherSuite
}
hs.finishedHash = newFinishedHash(c.wireVersion, c.isDTLS, hs.suite)
hs.finishedHash.discardHandshakeBuffer()
hs.writeClientHash(hs.clientHello.marshal())
supportedCurve := false
var selectedCurve CurveID
preferredCurves := config.curvePreferences()
Curves:
for _, curve := range hs.clientHello.supportedCurves {
for _, supported := range preferredCurves {
if supported == curve {
supportedCurve = true
selectedCurve = curve
break Curves
}
}
}
if !supportedCurve {
c.sendAlert(alertHandshakeFailure)
return errors.New("tls: no curve supported by both client and server")
}
pskIdentities := hs.clientHello.pskIdentities
pskKEModes := hs.clientHello.pskKEModes
if len(pskIdentities) == 0 && len(hs.clientHello.sessionTicket) > 0 && c.config.Bugs.AcceptAnySession {
psk := pskIdentity{
ticket: hs.clientHello.sessionTicket,
}
pskIdentities = []pskIdentity{psk}
pskKEModes = []byte{pskDHEKEMode}
}
var pskIndex int
foundKEMode := bytes.IndexByte(pskKEModes, pskDHEKEMode) >= 0
if foundKEMode && !config.SessionTicketsDisabled {
for i, pskIdentity := range pskIdentities {
// TODO(svaldez): Check the obfuscatedTicketAge before accepting 0-RTT.
sessionState, ok := c.decryptTicket(pskIdentity.ticket)
if !ok {
continue
}
if !config.Bugs.AcceptAnySession {
if sessionState.vers != c.vers {
continue
}
if sessionState.ticketExpiration.Before(c.config.time()) {
continue
}
sessionCipher := cipherSuiteFromID(sessionState.cipherSuite)
if sessionCipher == nil || sessionCipher.hash() != hs.suite.hash() {
continue
}
}
clientTicketAge := time.Duration(uint32(pskIdentity.obfuscatedTicketAge-sessionState.ticketAgeAdd)) * time.Millisecond
if config.Bugs.ExpectTicketAge != 0 && clientTicketAge != config.Bugs.ExpectTicketAge {
c.sendAlert(alertHandshakeFailure)
return errors.New("tls: invalid ticket age")
}
hs.sessionState = sessionState
hs.hello.hasPSKIdentity = true
hs.hello.pskIdentity = uint16(i)
pskIndex = i
if config.Bugs.SelectPSKIdentityOnResume != 0 {
hs.hello.pskIdentity = config.Bugs.SelectPSKIdentityOnResume
}
c.didResume = true
break
}
}
if config.Bugs.AlwaysSelectPSKIdentity {
hs.hello.hasPSKIdentity = true
hs.hello.pskIdentity = 0
}
// Verify the PSK binder. Note there may not be a PSK binder if
// AcceptAnyBinder is set. See https://crbug.com/boringssl/115.
if hs.sessionState != nil && !config.Bugs.AcceptAnySession {
binderToVerify := hs.clientHello.pskBinders[pskIndex]
if err := verifyPSKBinder(c.wireVersion, hs.clientHello, hs.sessionState, binderToVerify, []byte{}, []byte{}); err != nil {
return err
}
}
// Resolve PSK and compute the early secret.
if hs.sessionState != nil {
hs.finishedHash.addEntropy(hs.sessionState.masterSecret)
} else {
hs.finishedHash.addEntropy(hs.finishedHash.zeroSecret())
}
hs.hello.hasKeyShare = true
if hs.sessionState != nil && config.Bugs.NegotiatePSKResumption {
hs.hello.hasKeyShare = false
}
if config.Bugs.MissingKeyShare {
hs.hello.hasKeyShare = false
}
firstHelloRetryRequest := true
ResendHelloRetryRequest:
var sendHelloRetryRequest bool
cipherSuite := hs.suite.id
if config.Bugs.SendHelloRetryRequestCipherSuite != 0 {
cipherSuite = config.Bugs.SendHelloRetryRequestCipherSuite
}
helloRetryRequest := &helloRetryRequestMsg{
vers: c.wireVersion,
sessionId: hs.clientHello.sessionId,
cipherSuite: cipherSuite,
compressionMethod: config.Bugs.SendCompressionMethod,
duplicateExtensions: config.Bugs.DuplicateHelloRetryRequestExtensions,
}
if config.Bugs.AlwaysSendHelloRetryRequest {
sendHelloRetryRequest = true
}
if config.Bugs.SendHelloRetryRequestCookie != nil {
sendHelloRetryRequest = true
helloRetryRequest.cookie = config.Bugs.SendHelloRetryRequestCookie
}
if len(config.Bugs.CustomHelloRetryRequestExtension) > 0 {
sendHelloRetryRequest = true
helloRetryRequest.customExtension = config.Bugs.CustomHelloRetryRequestExtension
}
var selectedKeyShare *keyShareEntry
if hs.hello.hasKeyShare {
// Look for the key share corresponding to our selected curve.
for i := range hs.clientHello.keyShares {
if hs.clientHello.keyShares[i].group == selectedCurve {
selectedKeyShare = &hs.clientHello.keyShares[i]
break
}
}
if config.Bugs.ExpectMissingKeyShare && selectedKeyShare != nil {
return errors.New("tls: expected missing key share")
}
if selectedKeyShare == nil {
helloRetryRequest.hasSelectedGroup = true
helloRetryRequest.selectedGroup = selectedCurve
sendHelloRetryRequest = true
}
}
if config.Bugs.SendHelloRetryRequestCurve != 0 {
helloRetryRequest.hasSelectedGroup = true
helloRetryRequest.selectedGroup = config.Bugs.SendHelloRetryRequestCurve
sendHelloRetryRequest = true
}
if config.Bugs.SkipHelloRetryRequest {
sendHelloRetryRequest = false
}
if sendHelloRetryRequest {
if err := hs.finishedHash.UpdateForHelloRetryRequest(); err != nil {
return err
}
oldClientHelloBytes := hs.clientHello.marshal()
hs.writeServerHash(helloRetryRequest.marshal())
c.writeRecord(recordTypeHandshake, helloRetryRequest.marshal())
c.flushHandshake()
if !c.config.Bugs.SkipChangeCipherSpec {
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
}
if hs.clientHello.hasEarlyData {
c.skipEarlyData = true
}
// Read new ClientHello.
newMsg, err := c.readHandshake()
if err != nil {
return err
}
newClientHello, ok := newMsg.(*clientHelloMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(newClientHello, newMsg)
}
hs.writeClientHash(newClientHello.marshal())
if config.Bugs.ExpectNoTLS13PSKAfterHRR && len(newClientHello.pskIdentities) > 0 {
return fmt.Errorf("tls: client offered unexpected PSK identities after HelloRetryRequest")
}
if newClientHello.hasEarlyData {
return errors.New("tls: EarlyData sent in new ClientHello")
}
applyBugsToClientHello(newClientHello, config)
// Check that the new ClientHello matches the old ClientHello,
// except for relevant modifications.
//
// TODO(davidben): Make this check more precise.
oldClientHelloCopy := *hs.clientHello
oldClientHelloCopy.raw = nil
oldClientHelloCopy.hasEarlyData = false
newClientHelloCopy := *newClientHello
newClientHelloCopy.raw = nil
if helloRetryRequest.hasSelectedGroup {
newKeyShares := newClientHelloCopy.keyShares
if len(newKeyShares) != 1 || newKeyShares[0].group != helloRetryRequest.selectedGroup {
return errors.New("tls: KeyShare from HelloRetryRequest not in new ClientHello")
}
selectedKeyShare = &newKeyShares[0]
newClientHelloCopy.keyShares = oldClientHelloCopy.keyShares
}
if len(helloRetryRequest.cookie) > 0 {
if !bytes.Equal(newClientHelloCopy.tls13Cookie, helloRetryRequest.cookie) {
return errors.New("tls: cookie from HelloRetryRequest not present in new ClientHello")
}
newClientHelloCopy.tls13Cookie = nil
}
// PSK binders and obfuscated ticket age are both updated in the
// second ClientHello.
if len(oldClientHelloCopy.pskIdentities) != len(newClientHelloCopy.pskIdentities) {
newClientHelloCopy.pskIdentities = oldClientHelloCopy.pskIdentities
} else {
if len(oldClientHelloCopy.pskIdentities) != len(newClientHelloCopy.pskIdentities) {
return errors.New("tls: PSK identity count from old and new ClientHello do not match")
}
for i, identity := range oldClientHelloCopy.pskIdentities {
newClientHelloCopy.pskIdentities[i].obfuscatedTicketAge = identity.obfuscatedTicketAge
}
}
newClientHelloCopy.pskBinders = oldClientHelloCopy.pskBinders
newClientHelloCopy.hasEarlyData = oldClientHelloCopy.hasEarlyData
if !oldClientHelloCopy.equal(&newClientHelloCopy) {
return errors.New("tls: new ClientHello does not match")
}
if firstHelloRetryRequest && config.Bugs.SecondHelloRetryRequest {
firstHelloRetryRequest = false
goto ResendHelloRetryRequest
}
// Verify the PSK binder. Note there may not be a PSK binder if
// AcceptAnyBinder is set. See https://crbug.com/115.
if hs.sessionState != nil && !config.Bugs.AcceptAnySession {
binderToVerify := newClientHello.pskBinders[pskIndex]
if err := verifyPSKBinder(c.wireVersion, newClientHello, hs.sessionState, binderToVerify, oldClientHelloBytes, helloRetryRequest.marshal()); err != nil {
return err
}
}
}
// Decide whether or not to accept early data.
if !sendHelloRetryRequest && hs.clientHello.hasEarlyData {
if !config.Bugs.AlwaysRejectEarlyData && hs.sessionState != nil {
if c.clientProtocol == string(hs.sessionState.earlyALPN) || config.Bugs.AlwaysAcceptEarlyData {
encryptedExtensions.extensions.hasEarlyData = true
}
}
if encryptedExtensions.extensions.hasEarlyData {
earlyTrafficSecret := hs.finishedHash.deriveSecret(earlyTrafficLabel)
c.earlyExporterSecret = hs.finishedHash.deriveSecret(earlyExporterLabel)
if err := c.useInTrafficSecret(c.wireVersion, hs.suite, earlyTrafficSecret); err != nil {
return err
}
c.earlyCipherSuite = hs.suite
for _, expectedMsg := range config.Bugs.ExpectEarlyData {
if err := c.readRecord(recordTypeApplicationData); err != nil {
return err
}
msg := c.input.data[c.input.off:]
if !bytes.Equal(msg, expectedMsg) {
return fmt.Errorf("tls: got early data record %x, wanted %x", msg, expectedMsg)
}
c.in.freeBlock(c.input)
c.input = nil
}
} else {
c.skipEarlyData = true
}
}
if config.Bugs.SendEarlyDataExtension {
encryptedExtensions.extensions.hasEarlyData = true
}
// Resolve ECDHE and compute the handshake secret.
if hs.hello.hasKeyShare {
// Once a curve has been selected and a key share identified,
// the server needs to generate a public value and send it in
// the ServerHello.
curve, ok := curveForCurveID(selectedCurve, config)
if !ok {
panic("tls: server failed to look up curve ID")
}
c.curveID = selectedCurve
var peerKey []byte
if config.Bugs.SkipHelloRetryRequest {
// If skipping HelloRetryRequest, use a random key to
// avoid crashing.
curve2, _ := curveForCurveID(selectedCurve, config)
var err error
peerKey, err = curve2.offer(config.rand())
if err != nil {
return err
}
} else {
peerKey = selectedKeyShare.keyExchange
}
publicKey, ecdheSecret, err := curve.accept(config.rand(), peerKey)
if err != nil {
c.sendAlert(alertHandshakeFailure)
return err
}
hs.finishedHash.nextSecret()
hs.finishedHash.addEntropy(ecdheSecret)
hs.hello.hasKeyShare = true
curveID := selectedCurve
if c.config.Bugs.SendCurve != 0 {
curveID = config.Bugs.SendCurve
}
if c.config.Bugs.InvalidECDHPoint {
publicKey[0] ^= 0xff
}
hs.hello.keyShare = keyShareEntry{
group: curveID,
keyExchange: publicKey,
}
if config.Bugs.EncryptedExtensionsWithKeyShare {
encryptedExtensions.extensions.hasKeyShare = true
encryptedExtensions.extensions.keyShare = keyShareEntry{
group: curveID,
keyExchange: publicKey,
}
}
} else {
hs.finishedHash.nextSecret()
hs.finishedHash.addEntropy(hs.finishedHash.zeroSecret())
}
// Send unencrypted ServerHello.
hs.writeServerHash(hs.hello.marshal())
if config.Bugs.PartialEncryptedExtensionsWithServerHello {
helloBytes := hs.hello.marshal()
toWrite := make([]byte, 0, len(helloBytes)+1)
toWrite = append(toWrite, helloBytes...)
toWrite = append(toWrite, typeEncryptedExtensions)
c.writeRecord(recordTypeHandshake, toWrite)
} else {
c.writeRecord(recordTypeHandshake, hs.hello.marshal())
}
c.flushHandshake()
if !c.config.Bugs.SkipChangeCipherSpec && !sendHelloRetryRequest {
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
}
for i := 0; i < c.config.Bugs.SendExtraChangeCipherSpec; i++ {
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
}
// Switch to handshake traffic keys.
serverHandshakeTrafficSecret := hs.finishedHash.deriveSecret(serverHandshakeTrafficLabel)
c.useOutTrafficSecret(c.wireVersion, hs.suite, serverHandshakeTrafficSecret)
// Derive handshake traffic read key, but don't switch yet.
clientHandshakeTrafficSecret := hs.finishedHash.deriveSecret(clientHandshakeTrafficLabel)
// Send EncryptedExtensions.
hs.writeServerHash(encryptedExtensions.marshal())
if config.Bugs.PartialEncryptedExtensionsWithServerHello {
// The first byte has already been sent.
c.writeRecord(recordTypeHandshake, encryptedExtensions.marshal()[1:])
} else {
c.writeRecord(recordTypeHandshake, encryptedExtensions.marshal())
}
if hs.sessionState == nil {
if config.ClientAuth >= RequestClientCert {
// Request a client certificate
certReq := &certificateRequestMsg{
vers: c.wireVersion,
hasSignatureAlgorithm: !config.Bugs.OmitCertificateRequestAlgorithms,
hasRequestContext: true,
requestContext: config.Bugs.SendRequestContext,
customExtension: config.Bugs.SendCustomCertificateRequest,
}
if !config.Bugs.NoSignatureAlgorithms {
certReq.signatureAlgorithms = config.verifySignatureAlgorithms()
}
// An empty list of certificateAuthorities signals to
// the client that it may send any certificate in response
// to our request. When we know the CAs we trust, then
// we can send them down, so that the client can choose
// an appropriate certificate to give to us.
if config.ClientCAs != nil {
certReq.certificateAuthorities = config.ClientCAs.Subjects()
}
hs.writeServerHash(certReq.marshal())
c.writeRecord(recordTypeHandshake, certReq.marshal())
}
certMsg := &certificateMsg{
hasRequestContext: true,
}
if !config.Bugs.EmptyCertificateList {
for i, certData := range hs.cert.Certificate {
cert := certificateEntry{
data: certData,
}
if i == 0 {
if hs.clientHello.ocspStapling && !c.config.Bugs.NoOCSPStapling {
cert.ocspResponse = hs.cert.OCSPStaple
}
if hs.clientHello.sctListSupported && !c.config.Bugs.NoSignedCertificateTimestamps {
cert.sctList = hs.cert.SignedCertificateTimestampList
}
cert.duplicateExtensions = config.Bugs.SendDuplicateCertExtensions
cert.extraExtension = config.Bugs.SendExtensionOnCertificate
} else {
if config.Bugs.SendOCSPOnIntermediates != nil {
cert.ocspResponse = config.Bugs.SendOCSPOnIntermediates
}
if config.Bugs.SendSCTOnIntermediates != nil {
cert.sctList = config.Bugs.SendSCTOnIntermediates
}
}
certMsg.certificates = append(certMsg.certificates, cert)
}
}
certMsgBytes := certMsg.marshal()
sentCompressedCertMsg := false
FindCertCompressionAlg:
for candidate, alg := range c.config.CertCompressionAlgs {
for _, id := range hs.clientHello.compressedCertAlgs {
if id == candidate {
if expected := config.Bugs.ExpectedCompressedCert; expected != 0 && expected != id {
return fmt.Errorf("expected to send compressed cert with alg %d, but picked %d", expected, id)
}
if override := config.Bugs.SendCertCompressionAlgId; override != 0 {
id = override
}
uncompressed := certMsgBytes[4:]
uncompressedLen := uint32(len(uncompressed))
if override := config.Bugs.SendCertUncompressedLength; override != 0 {
uncompressedLen = override
}
compressedCertMsgBytes := (&compressedCertificateMsg{
algID: id,
uncompressedLength: uncompressedLen,
compressed: alg.Compress(uncompressed),
}).marshal()
hs.writeServerHash(compressedCertMsgBytes)
c.writeRecord(recordTypeHandshake, compressedCertMsgBytes)
sentCompressedCertMsg = true
break FindCertCompressionAlg
}
}
}
if !sentCompressedCertMsg {
if config.Bugs.ExpectedCompressedCert != 0 {
return errors.New("unexpectedly sent uncompressed certificate")
}
hs.writeServerHash(certMsgBytes)
c.writeRecord(recordTypeHandshake, certMsgBytes)
}
certVerify := &certificateVerifyMsg{
hasSignatureAlgorithm: true,
}
// Determine the hash to sign.
privKey := hs.cert.PrivateKey
var err error
certVerify.signatureAlgorithm, err = selectSignatureAlgorithm(c.vers, privKey, config, hs.clientHello.signatureAlgorithms)
if err != nil {
c.sendAlert(alertInternalError)
return err
}
input := hs.finishedHash.certificateVerifyInput(serverCertificateVerifyContextTLS13)
certVerify.signature, err = signMessage(c.vers, privKey, c.config, certVerify.signatureAlgorithm, input)
if err != nil {
c.sendAlert(alertInternalError)
return err
}
if config.Bugs.SendSignatureAlgorithm != 0 {
certVerify.signatureAlgorithm = config.Bugs.SendSignatureAlgorithm
}
if !config.Bugs.SkipCertificateVerify {
hs.writeServerHash(certVerify.marshal())
c.writeRecord(recordTypeHandshake, certVerify.marshal())
}
} else if hs.sessionState != nil {
// Pick up certificates from the session instead.
if len(hs.sessionState.certificates) > 0 {
if _, err := hs.processCertsFromClient(hs.sessionState.certificates); err != nil {
return err
}
}
}
finished := new(finishedMsg)
finished.verifyData = hs.finishedHash.serverSum(serverHandshakeTrafficSecret)
if config.Bugs.BadFinished {
finished.verifyData[0]++
}
hs.writeServerHash(finished.marshal())
c.writeRecord(recordTypeHandshake, finished.marshal())
if c.config.Bugs.SendExtraFinished {
c.writeRecord(recordTypeHandshake, finished.marshal())
}
c.flushHandshake()
if encryptedExtensions.extensions.hasEarlyData && !c.skipEarlyData {
for _, expectedMsg := range config.Bugs.ExpectLateEarlyData {
if err := c.readRecord(recordTypeApplicationData); err != nil {
return err
}
if !bytes.Equal(c.input.data[c.input.off:], expectedMsg) {
return errors.New("ExpectLateEarlyData: did not get expected message")
}
c.in.freeBlock(c.input)
c.input = nil
}