-
Notifications
You must be signed in to change notification settings - Fork 4.6k
/
common.go
1230 lines (1061 loc) · 42 KB
/
common.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 qtls
import (
"container/list"
"crypto"
"crypto/rand"
"crypto/sha512"
"crypto/tls"
"crypto/x509"
"errors"
"fmt"
"io"
"math/big"
"net"
"strings"
"sync"
"time"
)
const (
VersionSSL30 = 0x0300
VersionTLS10 = 0x0301
VersionTLS11 = 0x0302
VersionTLS12 = 0x0303
VersionTLS13 = 0x0304
)
const (
maxPlaintext = 16384 // maximum plaintext payload length
maxCiphertext = 16384 + 2048 // maximum ciphertext payload length
recordHeaderLen = 5 // record header length
maxHandshake = 65536 // maximum handshake we support (protocol max is 16 MB)
maxWarnAlertCount = 5 // maximum number of consecutive warning alerts
minVersion = VersionTLS12
maxVersion = VersionTLS13
)
// TLS record types.
type recordType uint8
const (
recordTypeChangeCipherSpec recordType = 20
recordTypeAlert recordType = 21
recordTypeHandshake recordType = 22
recordTypeApplicationData recordType = 23
)
// TLS handshake message types.
const (
typeHelloRequest uint8 = 0
typeClientHello uint8 = 1
typeServerHello uint8 = 2
typeNewSessionTicket uint8 = 4
typeEndOfEarlyData uint8 = 5
typeEncryptedExtensions uint8 = 8
typeCertificate uint8 = 11
typeServerKeyExchange uint8 = 12
typeCertificateRequest uint8 = 13
typeServerHelloDone uint8 = 14
typeCertificateVerify uint8 = 15
typeClientKeyExchange uint8 = 16
typeFinished uint8 = 20
typeCertificateStatus uint8 = 22
typeNextProtocol uint8 = 67 // Not IANA assigned
)
// TLS compression types.
const (
compressionNone uint8 = 0
)
type Extension struct {
Type uint16
Data []byte
}
// TLS extension numbers
const (
extensionServerName uint16 = 0
extensionStatusRequest uint16 = 5
extensionSupportedCurves uint16 = 10 // Supported Groups in 1.3 nomenclature
extensionSupportedPoints uint16 = 11
extensionSignatureAlgorithms uint16 = 13
extensionALPN uint16 = 16
extensionSCT uint16 = 18 // https://tools.ietf.org/html/rfc6962#section-6
extensionEMS uint16 = 23
extensionSessionTicket uint16 = 35
extensionPreSharedKey uint16 = 41
extensionEarlyData uint16 = 42
extensionSupportedVersions uint16 = 43
extensionPSKKeyExchangeModes uint16 = 45
extensionCAs uint16 = 47
extensionSignatureAlgorithmsCert uint16 = 50
extensionKeyShare uint16 = 51
extensionNextProtoNeg uint16 = 13172 // not IANA assigned
extensionRenegotiationInfo uint16 = 0xff01
extensionDelegatedCredential uint16 = 0xff02 // TODO(any) Get IANA assignment
)
// TLS signaling cipher suite values
const (
scsvRenegotiation uint16 = 0x00ff
)
// PSK Key Exchange Modes
// https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.7
const (
pskDHEKeyExchange uint8 = 1
)
// CurveID is tls.CurveID
// TLS 1.3 refers to these as Groups, but this library implements only
// curve-based ones anyway. See https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.4.
type CurveID = tls.CurveID
const (
// Exported IDs
CurveP256 = tls.CurveP256
CurveP384 = tls.CurveP384
CurveP521 = tls.CurveP521
X25519 = tls.X25519
// Experimental KEX
HybridSIDHp503Curve25519 CurveID = 0xFE30
)
// TLS 1.3 Key Share
// See https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.5
type keyShare struct {
group CurveID
data []byte
}
// TLS 1.3 PSK Identity and Binder, as sent by the client
// https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.6
type psk struct {
identity []byte
obfTicketAge uint32
binder []byte
}
// TLS Elliptic Curve Point Formats
// http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-9
const (
pointFormatUncompressed uint8 = 0
)
// TLS CertificateStatusType (RFC 3546)
const (
statusTypeOCSP uint8 = 1
)
// Certificate types (for certificateRequestMsg)
const (
certTypeRSASign = 1 // A certificate containing an RSA key
certTypeDSSSign = 2 // A certificate containing a DSA key
certTypeRSAFixedDH = 3 // A certificate containing a static DH key
certTypeDSSFixedDH = 4 // A certificate containing a static DH key
// See RFC 4492 sections 3 and 5.5.
certTypeECDSASign = 64 // A certificate containing an ECDSA-capable public key, signed with ECDSA.
certTypeRSAFixedECDH = 65 // A certificate containing an ECDH-capable public key, signed with RSA.
certTypeECDSAFixedECDH = 66 // A certificate containing an ECDH-capable public key, signed with ECDSA.
// Rest of these are reserved by the TLS spec
)
// Signature algorithms (for internal signaling use). Starting at 16 to avoid overlap with
// TLS 1.2 codepoints (RFC 5246, section A.4.1), with which these have nothing to do.
const (
signaturePKCS1v15 uint8 = iota + 16
signatureECDSA
signatureRSAPSS
)
// supportedSignatureAlgorithms contains the signature and hash algorithms that
// the code advertises as supported in a TLS 1.2 ClientHello and in a TLS 1.2
// CertificateRequest. The two fields are merged to match with TLS 1.3.
// Note that in TLS 1.2, the ECDSA algorithms are not constrained to P-256, etc.
var supportedSignatureAlgorithms = []SignatureScheme{
PKCS1WithSHA256,
ECDSAWithP256AndSHA256,
PKCS1WithSHA384,
ECDSAWithP384AndSHA384,
PKCS1WithSHA512,
ECDSAWithP521AndSHA512,
PKCS1WithSHA1,
ECDSAWithSHA1,
}
// supportedSignatureAlgorithms13 lists the advertised signature algorithms
// allowed for digital signatures. It includes TLS 1.2 + PSS.
var supportedSignatureAlgorithms13 = []SignatureScheme{
PSSWithSHA256,
PKCS1WithSHA256,
ECDSAWithP256AndSHA256,
PSSWithSHA384,
PKCS1WithSHA384,
ECDSAWithP384AndSHA384,
PSSWithSHA512,
PKCS1WithSHA512,
ECDSAWithP521AndSHA512,
PKCS1WithSHA1,
ECDSAWithSHA1,
}
// ConnectionState records basic TLS details about the connection.
type ConnectionState struct {
ConnectionID []byte // Random unique connection id
Version uint16 // TLS version used by the connection (e.g. VersionTLS12)
HandshakeComplete bool // TLS handshake is complete
DidResume bool // connection resumes a previous TLS connection
CipherSuite uint16 // cipher suite in use (TLS_RSA_WITH_RC4_128_SHA, ...)
NegotiatedProtocol string // negotiated next protocol (not guaranteed to be from Config.NextProtos)
NegotiatedProtocolIsMutual bool // negotiated protocol was advertised by server (client side only)
ServerName string // server name requested by client, if any (server side only)
PeerCertificates []*x509.Certificate // certificate chain presented by remote peer
VerifiedChains [][]*x509.Certificate // verified chains built from PeerCertificates
SignedCertificateTimestamps [][]byte // SCTs from the server, if any
OCSPResponse []byte // stapled OCSP response from server, if any
DelegatedCredential []byte // Delegated credential sent by the server, if any
// TLSUnique contains the "tls-unique" channel binding value (see RFC
// 5929, section 3). For resumed sessions this value will be nil
// because resumption does not include enough context (see
// https://mitls.org/pages/attacks/3SHAKE#channelbindings). This will
// change in future versions of Go once the TLS master-secret fix has
// been standardized and implemented.
TLSUnique []byte
// HandshakeConfirmed is true once all data returned by Read
// (past and future) is guaranteed not to be replayed.
HandshakeConfirmed bool
// Unique0RTTToken is a value that never repeats, and can be used
// to detect replay attacks against 0-RTT connections.
// Unique0RTTToken is only present if HandshakeConfirmed is false.
Unique0RTTToken []byte
ClientHello []byte // ClientHello packet
}
// The ClientAuthType is the tls.ClientAuthType
type ClientAuthType = tls.ClientAuthType
const (
NoClientCert = tls.NoClientCert
RequestClientCert = tls.RequestClientCert
RequireAnyClientCert = tls.RequireAnyClientCert
VerifyClientCertIfGiven = tls.VerifyClientCertIfGiven
RequireAndVerifyClientCert = tls.RequireAndVerifyClientCert
)
// ClientSessionState contains the state needed by clients to resume TLS
// sessions.
type ClientSessionState struct {
sessionTicket []uint8 // Encrypted ticket used for session resumption with server
vers uint16 // SSL/TLS version negotiated for the session
cipherSuite uint16 // Ciphersuite negotiated for the session
masterSecret []byte // MasterSecret generated by client on a full handshake
serverCertificates []*x509.Certificate // Certificate chain presented by the server
verifiedChains [][]*x509.Certificate // Certificate chains we built for verification
useEMS bool // State of extended master secret
}
// ClientSessionCache is a cache of ClientSessionState objects that can be used
// by a client to resume a TLS session with a given server. ClientSessionCache
// implementations should expect to be called concurrently from different
// goroutines. Only ticket-based resumption is supported, not SessionID-based
// resumption.
type ClientSessionCache interface {
// Get searches for a ClientSessionState associated with the given key.
// On return, ok is true if one was found.
Get(sessionKey string) (session *ClientSessionState, ok bool)
// Put adds the ClientSessionState to the cache with the given key.
Put(sessionKey string, cs *ClientSessionState)
}
// SignatureScheme is a tls.SignatureScheme
type SignatureScheme = tls.SignatureScheme
const (
PKCS1WithSHA1 = tls.PKCS1WithSHA1
PKCS1WithSHA256 = tls.PKCS1WithSHA256
PKCS1WithSHA384 = tls.PKCS1WithSHA384
PKCS1WithSHA512 = tls.PKCS1WithSHA512
PSSWithSHA256 = tls.PSSWithSHA256
PSSWithSHA384 = tls.PSSWithSHA384
PSSWithSHA512 = tls.PSSWithSHA512
ECDSAWithP256AndSHA256 = tls.ECDSAWithP256AndSHA256
ECDSAWithP384AndSHA384 = tls.ECDSAWithP384AndSHA384
ECDSAWithP521AndSHA512 = tls.ECDSAWithP521AndSHA512
// Legacy signature and hash algorithms for TLS 1.2.
ECDSAWithSHA1 = tls.ECDSAWithSHA1
)
// ClientHelloInfo contains information from a ClientHello message in order to
// guide certificate selection in the GetCertificate callback.
type ClientHelloInfo struct {
// CipherSuites lists the CipherSuites supported by the client (e.g.
// TLS_RSA_WITH_RC4_128_SHA).
CipherSuites []uint16
// ServerName indicates the name of the server requested by the client
// in order to support virtual hosting. ServerName is only set if the
// client is using SNI (see
// http://tools.ietf.org/html/rfc4366#section-3.1).
ServerName string
// SupportedCurves lists the elliptic curves supported by the client.
// SupportedCurves is set only if the Supported Elliptic Curves
// Extension is being used (see
// http://tools.ietf.org/html/rfc4492#section-5.1.1).
SupportedCurves []CurveID
// SupportedPoints lists the point formats supported by the client.
// SupportedPoints is set only if the Supported Point Formats Extension
// is being used (see
// http://tools.ietf.org/html/rfc4492#section-5.1.2).
SupportedPoints []uint8
// SignatureSchemes lists the signature and hash schemes that the client
// is willing to verify. SignatureSchemes is set only if the Signature
// Algorithms Extension is being used (see
// https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1).
SignatureSchemes []SignatureScheme
// SupportedProtos lists the application protocols supported by the client.
// SupportedProtos is set only if the Application-Layer Protocol
// Negotiation Extension is being used (see
// https://tools.ietf.org/html/rfc7301#section-3.1).
//
// Servers can select a protocol by setting Config.NextProtos in a
// GetConfigForClient return value.
SupportedProtos []string
// SupportedVersions lists the TLS versions supported by the client.
// For TLS versions less than 1.3, this is extrapolated from the max
// version advertised by the client, so values other than the greatest
// might be rejected if used.
SupportedVersions []uint16
// Conn is the underlying net.Conn for the connection. Do not read
// from, or write to, this connection; that will cause the TLS
// connection to fail.
Conn net.Conn
// Offered0RTTData is true if the client announced that it will send
// 0-RTT data. If the server Config.Accept0RTTData is true, and the
// client offered a session ticket valid for that purpose, it will
// be notified that the 0-RTT data is accepted and it will be made
// immediately available for Read.
Offered0RTTData bool
// AcceptsDelegatedCredential is true if the client indicated willingness
// to negotiate the delegated credential extension.
AcceptsDelegatedCredential bool
// The Fingerprint is an sequence of bytes unique to this Client Hello.
// It can be used to prevent or mitigate 0-RTT data replays as it's
// guaranteed that a replayed connection will have the same Fingerprint.
Fingerprint []byte
}
// The CertificateRequestInfo is a tls.CertificateRequestInfo
type CertificateRequestInfo = tls.CertificateRequestInfo
// RenegotiationSupport is a tls.RenegotiationSupport
type RenegotiationSupport = tls.RenegotiationSupport
const (
// RenegotiateNever disables renegotiation.
RenegotiateNever = tls.RenegotiateNever
// RenegotiateOnceAsClient allows a remote server to request
// renegotiation once per connection.
RenegotiateOnceAsClient = tls.RenegotiateOnceAsClient
// RenegotiateFreelyAsClient allows a remote server to repeatedly
// request renegotiation.
RenegotiateFreelyAsClient = tls.RenegotiateFreelyAsClient
)
// A Config structure is used to configure a TLS client or server.
// After one has been passed to a TLS function it must not be
// modified. A Config may be reused; the tls package will also not
// modify it.
type Config struct {
// Rand provides the source of entropy for nonces and RSA blinding.
// If Rand is nil, TLS uses the cryptographic random reader in package
// crypto/rand.
// The Reader must be safe for use by multiple goroutines.
Rand io.Reader
// Time returns the current time as the number of seconds since the epoch.
// If Time is nil, TLS uses time.Now.
Time func() time.Time
// Certificates contains one or more certificate chains to present to
// the other side of the connection. Server configurations must include
// at least one certificate or else set GetCertificate. Clients doing
// client-authentication may set either Certificates or
// GetClientCertificate.
Certificates []Certificate
// NameToCertificate maps from a certificate name to an element of
// Certificates. Note that a certificate name can be of the form
// '*.example.com' and so doesn't have to be a domain name as such.
// See Config.BuildNameToCertificate
// The nil value causes the first element of Certificates to be used
// for all connections.
NameToCertificate map[string]*Certificate
// GetCertificate returns a Certificate based on the given
// ClientHelloInfo. It will only be called if the client supplies SNI
// information or if Certificates is empty.
//
// If GetCertificate is nil or returns nil, then the certificate is
// retrieved from NameToCertificate. If NameToCertificate is nil, the
// first element of Certificates will be used.
GetCertificate func(*ClientHelloInfo) (*Certificate, error)
// GetClientCertificate, if not nil, is called when a server requests a
// certificate from a client. If set, the contents of Certificates will
// be ignored.
//
// If GetClientCertificate returns an error, the handshake will be
// aborted and that error will be returned. Otherwise
// GetClientCertificate must return a non-nil Certificate. If
// Certificate.Certificate is empty then no certificate will be sent to
// the server. If this is unacceptable to the server then it may abort
// the handshake.
//
// GetClientCertificate may be called multiple times for the same
// connection if renegotiation occurs or if TLS 1.3 is in use.
GetClientCertificate func(*CertificateRequestInfo) (*Certificate, error)
// GetConfigForClient, if not nil, is called after a ClientHello is
// received from a client. It may return a non-nil Config in order to
// change the Config that will be used to handle this connection. If
// the returned Config is nil, the original Config will be used. The
// Config returned by this callback may not be subsequently modified.
//
// If GetConfigForClient is nil, the Config passed to Server() will be
// used for all connections.
//
// Uniquely for the fields in the returned Config, session ticket keys
// will be duplicated from the original Config if not set.
// Specifically, if SetSessionTicketKeys was called on the original
// config but not on the returned config then the ticket keys from the
// original config will be copied into the new config before use.
// Otherwise, if SessionTicketKey was set in the original config but
// not in the returned config then it will be copied into the returned
// config before use. If neither of those cases applies then the key
// material from the returned config will be used for session tickets.
GetConfigForClient func(*ClientHelloInfo) (*Config, error)
// VerifyPeerCertificate, if not nil, is called after normal
// certificate verification by either a TLS client or server. It
// receives the raw ASN.1 certificates provided by the peer and also
// any verified chains that normal processing found. If it returns a
// non-nil error, the handshake is aborted and that error results.
//
// If normal verification fails then the handshake will abort before
// considering this callback. If normal verification is disabled by
// setting InsecureSkipVerify, or (for a server) when ClientAuth is
// RequestClientCert or RequireAnyClientCert, then this callback will
// be considered but the verifiedChains argument will always be nil.
VerifyPeerCertificate func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error
// RootCAs defines the set of root certificate authorities
// that clients use when verifying server certificates.
// If RootCAs is nil, TLS uses the host's root CA set.
RootCAs *x509.CertPool
// NextProtos is a list of supported, application level protocols.
NextProtos []string
// ServerName is used to verify the hostname on the returned
// certificates unless InsecureSkipVerify is given. It is also included
// in the client's handshake to support virtual hosting unless it is
// an IP address.
ServerName string
// ClientAuth determines the server's policy for
// TLS Client Authentication. The default is NoClientCert.
ClientAuth ClientAuthType
// ClientCAs defines the set of root certificate authorities
// that servers use if required to verify a client certificate
// by the policy in ClientAuth.
ClientCAs *x509.CertPool
// InsecureSkipVerify controls whether a client verifies the
// server's certificate chain and host name.
// If InsecureSkipVerify is true, TLS accepts any certificate
// presented by the server and any host name in that certificate.
// In this mode, TLS is susceptible to man-in-the-middle attacks.
// This should be used only for testing.
InsecureSkipVerify bool
// CipherSuites is a list of supported cipher suites to be used in
// TLS 1.0-1.2. If CipherSuites is nil, TLS uses a list of suites
// supported by the implementation.
CipherSuites []uint16
// PreferServerCipherSuites controls whether the server selects the
// client's most preferred ciphersuite, or the server's most preferred
// ciphersuite. If true then the server's preference, as expressed in
// the order of elements in CipherSuites, is used.
PreferServerCipherSuites bool
// SessionTicketsDisabled may be set to true to disable session ticket
// (resumption) support. Note that on clients, session ticket support is
// also disabled if ClientSessionCache is nil.
SessionTicketsDisabled bool
// SessionTicketKey is used by TLS servers to provide session
// resumption. See RFC 5077. If zero, it will be filled with
// random data before the first server handshake.
//
// If multiple servers are terminating connections for the same host
// they should all have the same SessionTicketKey. If the
// SessionTicketKey leaks, previously recorded and future TLS
// connections using that key are compromised.
SessionTicketKey [32]byte
// ClientSessionCache is a cache of ClientSessionState entries for TLS
// session resumption. It is only used by clients.
ClientSessionCache ClientSessionCache
// MinVersion contains the minimum SSL/TLS version that is acceptable.
// If zero, then TLS 1.0 is taken as the minimum.
MinVersion uint16
// MaxVersion contains the maximum SSL/TLS version that is acceptable.
// If zero, then the maximum version supported by this package is used,
// which is currently TLS 1.2.
MaxVersion uint16
// CurvePreferences contains the elliptic curves that will be used in
// an ECDHE handshake, in preference order. If empty, the default will
// be used.
CurvePreferences []CurveID
// DynamicRecordSizingDisabled disables adaptive sizing of TLS records.
// When true, the largest possible TLS record size is always used. When
// false, the size of TLS records may be adjusted in an attempt to
// improve latency.
DynamicRecordSizingDisabled bool
// Renegotiation controls what types of renegotiation are supported.
// The default, none, is correct for the vast majority of applications.
Renegotiation RenegotiationSupport
// KeyLogWriter optionally specifies a destination for TLS master secrets
// in NSS key log format that can be used to allow external programs
// such as Wireshark to decrypt TLS connections.
// See https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format.
// Use of KeyLogWriter compromises security and should only be
// used for debugging.
KeyLogWriter io.Writer
// If Max0RTTDataSize is not zero, the client will be allowed to use
// session tickets to send at most this number of bytes of 0-RTT data.
// 0-RTT data is subject to replay and has memory DoS implications.
// The server will later be able to refuse the 0-RTT data with
// Accept0RTTData, or wait for the client to prove that it's not
// replayed with Conn.ConfirmHandshake.
//
// It has no meaning on the client.
//
// See https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-2.3.
Max0RTTDataSize uint32
// Accept0RTTData makes the 0-RTT data received from the client
// immediately available to Read. 0-RTT data is subject to replay.
// Use Conn.ConfirmHandshake to wait until the data is known not
// to be replayed after reading it.
//
// It has no meaning on the client.
//
// See https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-2.3.
Accept0RTTData bool
// SessionTicketSealer, if not nil, is used to wrap and unwrap
// session tickets, instead of SessionTicketKey.
SessionTicketSealer SessionTicketSealer
// AcceptDelegatedCredential is true if the client is willing to negotiate
// the delegated credential extension.
//
// This value has no meaning for the server.
//
// See https://tools.ietf.org/html/draft-ietf-tls-subcerts-02.
AcceptDelegatedCredential bool
// GetDelegatedCredential returns a DC and its private key for use in the
// delegated credential extension. The inputs to the callback are some
// information parsed from the ClientHello, as well as the protocol version
// selected by the server. This is necessary because the DC is bound to the
// protocol version in which it's used. The return value is the raw DC
// encoded in the wire format specified in
// https://tools.ietf.org/html/draft-ietf-tls-subcerts-02. If the return
// value is nil, then the server will not offer negotiate the extension.
//
// This value has no meaning for the client.
GetDelegatedCredential func(*ClientHelloInfo, uint16) ([]byte, crypto.PrivateKey, error)
// GetExtensions, if not nil, is called before a message that allows
// sending of extensions is sent.
// Currently only implemented for the ClientHello message (for the client)
// and for the EncryptedExtensions message (for the server).
// Only valid for TLS 1.3.
GetExtensions func(handshakeMessageType uint8) []Extension
// ReceivedExtensions, if not nil, is called when a message that allows the
// inclusion of extensions is received.
// It is called with an empty slice of extensions, if the message didn't
// contain any extensions.
// Currently only implemented for the ClientHello message (sent by the
// client) and for the EncryptedExtensions message (sent by the server).
// Only valid for TLS 1.3.
ReceivedExtensions func(handshakeMessageType uint8, exts []Extension) error
serverInitOnce sync.Once // guards calling (*Config).serverInit
// mutex protects sessionTicketKeys.
mutex sync.RWMutex
// sessionTicketKeys contains zero or more ticket keys. If the length
// is zero, SessionTicketsDisabled must be true. The first key is used
// for new tickets and any subsequent keys can be used to decrypt old
// tickets.
sessionTicketKeys []ticketKey
// UseExtendedMasterSecret indicates whether or not the connection
// should use the extended master secret computation if available
UseExtendedMasterSecret bool
// AlternativeRecordLayer is used by QUIC
AlternativeRecordLayer RecordLayer
}
type RecordLayer interface {
SetReadKey(suite *CipherSuite, trafficSecret []byte)
SetWriteKey(suite *CipherSuite, trafficSecret []byte)
ReadHandshakeMessage() ([]byte, error)
WriteRecord([]byte) (int, error)
}
// ticketKeyNameLen is the number of bytes of identifier that is prepended to
// an encrypted session ticket in order to identify the key used to encrypt it.
const ticketKeyNameLen = 16
// ticketKey is the internal representation of a session ticket key.
type ticketKey struct {
// keyName is an opaque byte string that serves to identify the session
// ticket key. It's exposed as plaintext in every session ticket.
keyName [ticketKeyNameLen]byte
aesKey [16]byte
hmacKey [16]byte
}
// ticketKeyFromBytes converts from the external representation of a session
// ticket key to a ticketKey. Externally, session ticket keys are 32 random
// bytes and this function expands that into sufficient name and key material.
func ticketKeyFromBytes(b [32]byte) (key ticketKey) {
hashed := sha512.Sum512(b[:])
copy(key.keyName[:], hashed[:ticketKeyNameLen])
copy(key.aesKey[:], hashed[ticketKeyNameLen:ticketKeyNameLen+16])
copy(key.hmacKey[:], hashed[ticketKeyNameLen+16:ticketKeyNameLen+32])
return key
}
// Clone returns a shallow clone of c. It is safe to clone a Config that is
// being used concurrently by a TLS client or server.
func (c *Config) Clone() *Config {
// Running serverInit ensures that it's safe to read
// SessionTicketsDisabled.
c.serverInitOnce.Do(func() { c.serverInit(nil) })
var sessionTicketKeys []ticketKey
c.mutex.RLock()
sessionTicketKeys = c.sessionTicketKeys
c.mutex.RUnlock()
return &Config{
Rand: c.Rand,
Time: c.Time,
Certificates: c.Certificates,
NameToCertificate: c.NameToCertificate,
GetCertificate: c.GetCertificate,
GetClientCertificate: c.GetClientCertificate,
GetConfigForClient: c.GetConfigForClient,
VerifyPeerCertificate: c.VerifyPeerCertificate,
RootCAs: c.RootCAs,
NextProtos: c.NextProtos,
ServerName: c.ServerName,
ClientAuth: c.ClientAuth,
ClientCAs: c.ClientCAs,
InsecureSkipVerify: c.InsecureSkipVerify,
CipherSuites: c.CipherSuites,
PreferServerCipherSuites: c.PreferServerCipherSuites,
SessionTicketsDisabled: c.SessionTicketsDisabled,
SessionTicketKey: c.SessionTicketKey,
ClientSessionCache: c.ClientSessionCache,
MinVersion: c.MinVersion,
MaxVersion: c.MaxVersion,
CurvePreferences: c.CurvePreferences,
DynamicRecordSizingDisabled: c.DynamicRecordSizingDisabled,
Renegotiation: c.Renegotiation,
KeyLogWriter: c.KeyLogWriter,
Accept0RTTData: c.Accept0RTTData,
Max0RTTDataSize: c.Max0RTTDataSize,
SessionTicketSealer: c.SessionTicketSealer,
AcceptDelegatedCredential: c.AcceptDelegatedCredential,
GetDelegatedCredential: c.GetDelegatedCredential,
GetExtensions: c.GetExtensions,
ReceivedExtensions: c.ReceivedExtensions,
sessionTicketKeys: sessionTicketKeys,
UseExtendedMasterSecret: c.UseExtendedMasterSecret,
}
}
// serverInit is run under c.serverInitOnce to do initialization of c. If c was
// returned by a GetConfigForClient callback then the argument should be the
// Config that was passed to Server, otherwise it should be nil.
func (c *Config) serverInit(originalConfig *Config) {
if c.SessionTicketsDisabled || len(c.ticketKeys()) != 0 || c.SessionTicketSealer != nil {
return
}
alreadySet := false
for _, b := range c.SessionTicketKey {
if b != 0 {
alreadySet = true
break
}
}
if !alreadySet {
if originalConfig != nil {
copy(c.SessionTicketKey[:], originalConfig.SessionTicketKey[:])
} else if _, err := io.ReadFull(c.rand(), c.SessionTicketKey[:]); err != nil {
c.SessionTicketsDisabled = true
return
}
}
if originalConfig != nil {
originalConfig.mutex.RLock()
c.sessionTicketKeys = originalConfig.sessionTicketKeys
originalConfig.mutex.RUnlock()
} else {
c.sessionTicketKeys = []ticketKey{ticketKeyFromBytes(c.SessionTicketKey)}
}
}
func (c *Config) ticketKeys() []ticketKey {
c.mutex.RLock()
// c.sessionTicketKeys is constant once created. SetSessionTicketKeys
// will only update it by replacing it with a new value.
ret := c.sessionTicketKeys
c.mutex.RUnlock()
return ret
}
// SetSessionTicketKeys updates the session ticket keys for a server. The first
// key will be used when creating new tickets, while all keys can be used for
// decrypting tickets. It is safe to call this function while the server is
// running in order to rotate the session ticket keys. The function will panic
// if keys is empty.
func (c *Config) SetSessionTicketKeys(keys [][32]byte) {
if len(keys) == 0 {
panic("tls: keys must have at least one key")
}
newKeys := make([]ticketKey, len(keys))
for i, bytes := range keys {
newKeys[i] = ticketKeyFromBytes(bytes)
}
c.mutex.Lock()
c.sessionTicketKeys = newKeys
c.mutex.Unlock()
}
func (c *Config) rand() io.Reader {
r := c.Rand
if r == nil {
return rand.Reader
}
return r
}
func (c *Config) time() time.Time {
t := c.Time
if t == nil {
t = time.Now
}
return t()
}
func hasOverlappingCipherSuites(cs1, cs2 []uint16) bool {
for _, c1 := range cs1 {
for _, c2 := range cs2 {
if c1 == c2 {
return true
}
}
}
return false
}
func (c *Config) cipherSuites() []uint16 {
s := c.CipherSuites
if s == nil {
s = defaultCipherSuites()
} else if c.maxVersion() >= VersionTLS13 {
// Ensure that TLS 1.3 suites are always present, but respect
// the application cipher suite preferences.
s13 := defaultTLS13CipherSuites()
if !hasOverlappingCipherSuites(s, s13) {
allSuites := make([]uint16, len(s13)+len(s))
allSuites = append(allSuites, s13...)
s = append(allSuites, s...)
}
}
return s
}
func (c *Config) minVersion() uint16 {
if c == nil || c.MinVersion == 0 {
return minVersion
}
return c.MinVersion
}
func (c *Config) maxVersion() uint16 {
if c == nil || c.MaxVersion == 0 {
return maxVersion
}
return c.MaxVersion
}
var defaultCurvePreferences = []CurveID{X25519, CurveP256, CurveP384, CurveP521}
func (c *Config) curvePreferences() []CurveID {
if c == nil || len(c.CurvePreferences) == 0 {
return defaultCurvePreferences
}
return c.CurvePreferences
}
// mutualVersion returns the protocol version to use given the advertised
// version of the peer using the legacy non-extension methods.
func (c *Config) mutualVersion(vers uint16) (uint16, bool) {
minVersion := c.minVersion()
maxVersion := c.maxVersion()
// Version 1.3 and higher are not negotiated via this mechanism.
if maxVersion > VersionTLS12 {
maxVersion = VersionTLS12
}
if vers < minVersion {
return 0, false
}
if vers > maxVersion {
vers = maxVersion
}
return vers, true
}
// pickVersion returns the protocol version to use given the advertised
// versions of the peer using the Supported Versions extension.
func (c *Config) pickVersion(peerSupportedVersions []uint16) (uint16, bool) {
supportedVersions := c.getSupportedVersions()
for _, supportedVersion := range supportedVersions {
for _, version := range peerSupportedVersions {
if version == supportedVersion {
return version, true
}
}
}
return 0, false
}
// configSuppVersArray is the backing array of Config.getSupportedVersions
var configSuppVersArray = [...]uint16{VersionTLS13, VersionTLS12, VersionTLS11, VersionTLS10, VersionSSL30}
// getSupportedVersions returns the protocol versions that are supported by the
// current configuration.
func (c *Config) getSupportedVersions() []uint16 {
minVersion := c.minVersion()
maxVersion := c.maxVersion()
// Sanity check to avoid advertising unsupported versions.
if minVersion < VersionSSL30 {
minVersion = VersionSSL30
}
if maxVersion > VersionTLS13 {
maxVersion = VersionTLS13
}
if maxVersion < minVersion {
return nil
}
return configSuppVersArray[VersionTLS13-maxVersion : VersionTLS13-minVersion+1]
}
// getCertificate returns the best certificate for the given ClientHelloInfo,
// defaulting to the first element of c.Certificates.
func (c *Config) getCertificate(clientHello *ClientHelloInfo) (*Certificate, error) {
if c.GetCertificate != nil &&
(len(c.Certificates) == 0 || len(clientHello.ServerName) > 0) {
cert, err := c.GetCertificate(clientHello)
if cert != nil || err != nil {
return cert, err
}
}
if len(c.Certificates) == 0 {
return nil, errors.New("tls: no certificates configured")
}
if len(c.Certificates) == 1 || c.NameToCertificate == nil {
// There's only one choice, so no point doing any work.
return &c.Certificates[0], nil
}
name := strings.ToLower(clientHello.ServerName)
for len(name) > 0 && name[len(name)-1] == '.' {
name = name[:len(name)-1]
}
if cert, ok := c.NameToCertificate[name]; ok {
return cert, nil
}
// try replacing labels in the name with wildcards until we get a
// match.
labels := strings.Split(name, ".")
for i := range labels {
labels[i] = "*"
candidate := strings.Join(labels, ".")
if cert, ok := c.NameToCertificate[candidate]; ok {
return cert, nil
}
}
// If nothing matches, return the first certificate.
return &c.Certificates[0], nil
}
// BuildNameToCertificate parses c.Certificates and builds c.NameToCertificate
// from the CommonName and SubjectAlternateName fields of each of the leaf
// certificates.
func (c *Config) BuildNameToCertificate() {
c.NameToCertificate = make(map[string]*Certificate)
for i := range c.Certificates {
cert := &c.Certificates[i]
x509Cert, err := x509.ParseCertificate(cert.Certificate[0])
if err != nil {
continue
}
if len(x509Cert.Subject.CommonName) > 0 {
c.NameToCertificate[x509Cert.Subject.CommonName] = cert
}
for _, san := range x509Cert.DNSNames {
c.NameToCertificate[san] = cert
}
}
}
// writeKeyLog logs client random and master secret if logging was enabled by
// setting c.KeyLogWriter.
func (c *Config) writeKeyLog(what string, clientRandom, masterSecret []byte) error {
if c.KeyLogWriter == nil {
return nil
}
logLine := []byte(fmt.Sprintf("%s %x %x\n", what, clientRandom, masterSecret))
writerMutex.Lock()
_, err := c.KeyLogWriter.Write(logLine)
writerMutex.Unlock()
return err
}
// writerMutex protects all KeyLogWriters globally. It is rarely enabled,