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Commit f156fea

Browse filesBrowse files
mingyechmingyech
committed
feat: add support for ECH when using custom clienthello specs
1 parent e430876 commit f156fea
Copy full SHA for f156fea

6 files changed

+156
-24
lines changed

‎ech.go

Copy file name to clipboardExpand all lines: ech.go
+9-1Lines changed: 9 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -207,8 +207,16 @@ func pickECHCipherSuite(suites []echCipher) (echCipher, error) {
207207
return echCipher{}, errors.New("tls: no supported symmetric ciphersuites for ECH")
208208
}
209209

210+
// [uTLS SECTION BEGIN]
210211
func encodeInnerClientHello(inner *clientHelloMsg, maxNameLength int) ([]byte, error) {
211-
h, err := inner.marshalMsg(true)
212+
return encodeInnerClientHelloReorderOuterExts(inner, maxNameLength, nil)
213+
}
214+
215+
// [uTLS SECTION END]
216+
217+
// func encodeInnerClientHello(inner *clientHelloMsg, maxNameLength int) ([]byte, error) {
218+
func encodeInnerClientHelloReorderOuterExts(inner *clientHelloMsg, maxNameLength int, outerExts []uint16) ([]byte, error) { // uTLS
219+
h, err := inner.marshalMsgReorderOuterExts(true, outerExts)
212220
if err != nil {
213221
return nil, err
214222
}

‎handshake_client.go

Copy file name to clipboardExpand all lines: handshake_client.go
+3-3Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -214,9 +214,9 @@ func (c *Conn) makeClientHello() (*clientHelloMsg, *keySharePrivateKeys, *echCli
214214

215215
var ech *echClientContext
216216
if c.config.EncryptedClientHelloConfigList != nil {
217-
if c.config.MinVersion != 0 && c.config.MinVersion < VersionTLS13 {
218-
return nil, nil, nil, errors.New("tls: MinVersion must be >= VersionTLS13 if EncryptedClientHelloConfigList is populated")
219-
}
217+
// if c.config.MinVersion != 0 && c.config.MinVersion < VersionTLS13 {
218+
// return nil, nil, nil, errors.New("tls: MinVersion must be >= VersionTLS13 if EncryptedClientHelloConfigList is populated")
219+
// }
220220
if c.config.MaxVersion != 0 && c.config.MaxVersion <= VersionTLS12 {
221221
return nil, nil, nil, errors.New("tls: MaxVersion must be >= VersionTLS13 if EncryptedClientHelloConfigList is populated")
222222
}

‎handshake_client_tls13.go

Copy file name to clipboardExpand all lines: handshake_client_tls13.go
+13-1Lines changed: 13 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -75,9 +75,21 @@ func (hs *clientHandshakeStateTLS13) handshake() error {
7575

7676
if hs.echContext != nil {
7777
hs.echContext.innerTranscript = hs.suite.hash.New()
78-
if err := transcriptMsg(hs.echContext.innerHello, hs.echContext.innerTranscript); err != nil {
78+
// [uTLS SECTION BEGIN]
79+
encodedInner, err := encodeInnerClientHelloReorderOuterExts(hs.echContext.innerHello, int(hs.echContext.config.MaxNameLength), hs.uconn.extensionsList())
80+
if err != nil {
81+
return err
82+
}
83+
84+
decodedInner, err := decodeInnerClientHello(hs.hello, encodedInner)
85+
if err != nil {
86+
return err
87+
}
88+
89+
if err := transcriptMsg(decodedInner, hs.echContext.innerTranscript); err != nil {
7990
return err
8091
}
92+
// [uTLS SECTION END]
8193
}
8294

8395
if bytes.Equal(hs.serverHello.random, helloRetryRequestRandom) {

‎handshake_messages.go

Copy file name to clipboardExpand all lines: handshake_messages.go
+29-11Lines changed: 29 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -105,7 +105,15 @@ type clientHelloMsg struct {
105105
nextProtoNeg bool
106106
}
107107

108+
// [uTLS SECTION BEGIN]
108109
func (m *clientHelloMsg) marshalMsg(echInner bool) ([]byte, error) {
110+
return m.marshalMsgReorderOuterExts(echInner, nil)
111+
}
112+
113+
// [uTLS SECTION END]
114+
115+
// func (m *clientHelloMsg) marshalMsg(echInner bool) ([]byte, error) {
116+
func (m *clientHelloMsg) marshalMsgReorderOuterExts(echInner bool, outerExts []uint16) ([]byte, error) { // uTLS
109117
var exts cryptobyte.Builder
110118
if len(m.serverName) > 0 {
111119
// RFC 6066, Section 3
@@ -254,18 +262,14 @@ func (m *clientHelloMsg) marshalMsg(echInner bool) ([]byte, error) {
254262
}
255263
if len(m.supportedVersions) > 0 {
256264
// RFC 8446, Section 4.2.1
257-
if echInner {
258-
echOuterExts = append(echOuterExts, extensionSupportedVersions)
259-
} else {
260-
exts.AddUint16(extensionSupportedVersions)
261-
exts.AddUint16LengthPrefixed(func(exts *cryptobyte.Builder) {
262-
exts.AddUint8LengthPrefixed(func(exts *cryptobyte.Builder) {
263-
for _, vers := range m.supportedVersions {
264-
exts.AddUint16(vers)
265-
}
266-
})
265+
exts.AddUint16(extensionSupportedVersions)
266+
exts.AddUint16LengthPrefixed(func(exts *cryptobyte.Builder) {
267+
exts.AddUint8LengthPrefixed(func(exts *cryptobyte.Builder) {
268+
for _, vers := range m.supportedVersions {
269+
exts.AddUint16(vers)
270+
}
267271
})
268-
}
272+
})
269273
}
270274
if len(m.cookie) > 0 {
271275
// RFC 8446, Section 4.2.2
@@ -311,6 +315,20 @@ func (m *clientHelloMsg) marshalMsg(echInner bool) ([]byte, error) {
311315
})
312316
}
313317
}
318+
// [uTLS SECTION BEGIN]
319+
if echInner && outerExts != nil {
320+
echOuterExtsReordered := slices.Collect(func(yield func(uint16) bool) {
321+
for _, ext := range outerExts {
322+
if slices.Contains(echOuterExts, ext) {
323+
if !yield(ext) {
324+
return
325+
}
326+
}
327+
}
328+
})
329+
echOuterExts = echOuterExtsReordered
330+
}
331+
// [uTLS SECTION END]
314332
if len(echOuterExts) > 0 && echInner {
315333
exts.AddUint16(extensionECHOuterExtensions)
316334
exts.AddUint16LengthPrefixed(func(exts *cryptobyte.Builder) {

‎u_conn.go

Copy file name to clipboardExpand all lines: u_conn.go
+98-4Lines changed: 98 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,10 @@ import (
1414
"fmt"
1515
"hash"
1616
"net"
17+
"slices"
1718
"strconv"
19+
20+
"golang.org/x/crypto/cryptobyte"
1821
)
1922

2023
type ClientHelloBuildStatus int
@@ -487,15 +490,106 @@ func (uconn *UConn) ApplyConfig() error {
487490
return nil
488491
}
489492

493+
func (uconn *UConn) extensionsList() []uint16 {
494+
495+
outerExts := []uint16{}
496+
for _, ext := range uconn.Extensions {
497+
buffer := cryptobyte.String(make([]byte, 2000))
498+
ext.Read(buffer)
499+
var extension uint16
500+
buffer.ReadUint16(&extension)
501+
outerExts = append(outerExts, extension)
502+
}
503+
return outerExts
504+
}
505+
490506
func (uconn *UConn) MarshalClientHello() error {
491-
if len(uconn.config.ECHConfigs) > 0 && uconn.ech != nil {
492-
if err := uconn.ech.Configure(uconn.config.ECHConfigs); err != nil {
507+
if len(uconn.config.EncryptedClientHelloConfigList) > 0 {
508+
inner, _, ech, err := uconn.makeClientHello()
509+
if err != nil {
493510
return err
494511
}
495-
return uconn.ech.MarshalClientHello(uconn)
512+
513+
inner.keyShares = KeyShares(uconn.HandshakeState.Hello.KeyShares).ToPrivate()
514+
inner.supportedSignatureAlgorithms = uconn.HandshakeState.Hello.SupportedSignatureAlgorithms
515+
inner.sessionId = uconn.HandshakeState.Hello.SessionId
516+
inner.supportedCurves = uconn.HandshakeState.Hello.SupportedCurves
517+
inner.supportedVersions = []uint16{VersionTLS13}
518+
519+
ech.innerHello = inner
520+
521+
encapKey := ech.encapsulatedKey
522+
523+
encodedInner, err := encodeInnerClientHelloReorderOuterExts(inner, int(ech.config.MaxNameLength), uconn.extensionsList())
524+
if err != nil {
525+
return err
526+
}
527+
528+
// NOTE: the tag lengths for all of the supported AEADs are the same (16
529+
// bytes), so we have hardcoded it here. If we add support for another AEAD
530+
// with a different tag length, we will need to change this.
531+
encryptedLen := len(encodedInner) + 16 // AEAD tag length
532+
outerECHExt, err := generateOuterECHExt(ech.config.ConfigID, ech.kdfID, ech.aeadID, encapKey, make([]byte, encryptedLen))
533+
if err != nil {
534+
return err
535+
}
536+
537+
sniExtIdex := slices.IndexFunc(uconn.Extensions, func(ext TLSExtension) bool {
538+
_, ok := ext.(*SNIExtension)
539+
return ok
540+
})
541+
uconn.Extensions[sniExtIdex] = &SNIExtension{
542+
ServerName: string(ech.config.PublicName),
543+
}
544+
545+
echExtIdx := slices.IndexFunc(uconn.Extensions, func(ext TLSExtension) bool {
546+
_, ok := ext.(EncryptedClientHelloExtension)
547+
return ok
548+
})
549+
uconn.Extensions[echExtIdx] = &GenericExtension{
550+
Id: extensionEncryptedClientHello,
551+
Data: outerECHExt,
552+
}
553+
554+
// uconn.HandshakeState.Hello.Random = make([]byte, 32)
555+
// _, err = io.ReadFull(uconn.config.rand(), uconn.HandshakeState.Hello.Random)
556+
// if err != nil {
557+
// return errors.New("tls: short read from Rand: " + err.Error())
558+
// }
559+
560+
if err := uconn.MarshalClientHelloNoECH(); err != nil {
561+
return err
562+
}
563+
564+
serializedOuter := uconn.HandshakeState.Hello.Raw
565+
serializedOuter = serializedOuter[4:] // strip the four byte prefix
566+
encryptedInner, err := ech.hpkeContext.Seal(serializedOuter, encodedInner)
567+
if err != nil {
568+
return err
569+
}
570+
outerECHExt, err = generateOuterECHExt(ech.config.ConfigID, ech.kdfID, ech.aeadID, encapKey, encryptedInner)
571+
if err != nil {
572+
return err
573+
}
574+
uconn.Extensions[echExtIdx] = &GenericExtension{
575+
Id: extensionEncryptedClientHello,
576+
Data: outerECHExt,
577+
}
578+
579+
if err := uconn.MarshalClientHelloNoECH(); err != nil {
580+
return err
581+
}
582+
583+
uconn.echCtx = ech
584+
return nil
496585
}
497586

498-
return uconn.MarshalClientHelloNoECH() // if no ECH pointer, just marshal normally
587+
if err := uconn.MarshalClientHelloNoECH(); err != nil {
588+
return err
589+
}
590+
591+
return nil
592+
499593
}
500594

501595
// MarshalClientHelloNoECH marshals ClientHello as if there was no

‎u_handshake_client.go

Copy file name to clipboardExpand all lines: u_handshake_client.go
+4-4Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -353,9 +353,9 @@ func (c *Conn) makeClientHelloForApplyPreset() (*clientHelloMsg, *keySharePrivat
353353

354354
var ech *echClientContext
355355
if c.config.EncryptedClientHelloConfigList != nil {
356-
if c.config.MinVersion != 0 && c.config.MinVersion < VersionTLS13 {
357-
return nil, nil, nil, errors.New("tls: MinVersion must be >= VersionTLS13 if EncryptedClientHelloConfigList is populated")
358-
}
356+
// if c.config.MinVersion != 0 && c.config.MinVersion < VersionTLS13 {
357+
// return nil, nil, nil, errors.New("tls: MinVersion must be >= VersionTLS13 if EncryptedClientHelloConfigList is populated")
358+
// }
359359
if c.config.MaxVersion != 0 && c.config.MaxVersion <= VersionTLS12 {
360360
return nil, nil, nil, errors.New("tls: MaxVersion must be >= VersionTLS13 if EncryptedClientHelloConfigList is populated")
361361
}
@@ -483,7 +483,7 @@ func (c *UConn) clientHandshake(ctx context.Context) (err error) {
483483
}()
484484
}
485485

486-
if ech != nil {
486+
if ech != nil && c.clientHelloBuildStatus == BuildByGoTLS {
487487
// Split hello into inner and outer
488488
ech.innerHello = hello.clone()
489489

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