sing-box/common/tls/reality_client.go

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//go:build with_utls
package tls
import (
"bytes"
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"context"
"crypto/aes"
"crypto/cipher"
"crypto/ed25519"
"crypto/hmac"
"crypto/sha256"
"crypto/sha512"
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"crypto/tls"
"crypto/x509"
"encoding/base64"
"encoding/binary"
"encoding/hex"
"fmt"
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"io"
mRand "math/rand"
"net"
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"net/http"
"reflect"
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"strings"
"time"
"unsafe"
"github.com/sagernet/sing-box/adapter"
"github.com/sagernet/sing-box/option"
"github.com/sagernet/sing/common/debug"
E "github.com/sagernet/sing/common/exceptions"
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aTLS "github.com/sagernet/sing/common/tls"
utls "github.com/sagernet/utls"
"golang.org/x/crypto/hkdf"
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"golang.org/x/net/http2"
)
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var _ ConfigCompat = (*RealityClientConfig)(nil)
type RealityClientConfig struct {
uClient *UTLSClientConfig
publicKey []byte
shortID [8]byte
}
func NewRealityClient(router adapter.Router, serverAddress string, options option.OutboundTLSOptions) (*RealityClientConfig, error) {
if options.UTLS == nil || !options.UTLS.Enabled {
return nil, E.New("uTLS is required by reality client")
}
uClient, err := NewUTLSClient(router, serverAddress, options)
if err != nil {
return nil, err
}
publicKey, err := base64.RawURLEncoding.DecodeString(options.Reality.PublicKey)
if err != nil {
return nil, E.Cause(err, "decode public_key")
}
if len(publicKey) != 32 {
return nil, E.New("invalid public_key")
}
var shortID [8]byte
decodedLen, err := hex.Decode(shortID[:], []byte(options.Reality.ShortID))
if err != nil {
return nil, E.Cause(err, "decode short_id")
}
if decodedLen > 8 {
return nil, E.New("invalid short_id")
}
return &RealityClientConfig{uClient, publicKey, shortID}, nil
}
func (e *RealityClientConfig) ServerName() string {
return e.uClient.ServerName()
}
func (e *RealityClientConfig) SetServerName(serverName string) {
e.uClient.SetServerName(serverName)
}
func (e *RealityClientConfig) NextProtos() []string {
return e.uClient.NextProtos()
}
func (e *RealityClientConfig) SetNextProtos(nextProto []string) {
e.uClient.SetNextProtos(nextProto)
}
func (e *RealityClientConfig) Config() (*STDConfig, error) {
return nil, E.New("unsupported usage for reality")
}
func (e *RealityClientConfig) Client(conn net.Conn) (Conn, error) {
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return ClientHandshake(context.Background(), conn, e)
}
func (e *RealityClientConfig) ClientHandshake(ctx context.Context, conn net.Conn) (aTLS.Conn, error) {
verifier := &realityVerifier{
serverName: e.uClient.ServerName(),
}
uConfig := e.uClient.config.Clone()
uConfig.InsecureSkipVerify = true
uConfig.SessionTicketsDisabled = true
uConfig.VerifyPeerCertificate = verifier.VerifyPeerCertificate
uConn := utls.UClient(conn, uConfig, e.uClient.id)
verifier.UConn = uConn
err := uConn.BuildHandshakeState()
if err != nil {
return nil, err
}
hello := uConn.HandshakeState.Hello
hello.SessionId = make([]byte, 32)
copy(hello.Raw[39:], hello.SessionId)
var nowTime time.Time
if uConfig.Time != nil {
nowTime = uConfig.Time()
} else {
nowTime = time.Now()
}
binary.BigEndian.PutUint64(hello.SessionId, uint64(nowTime.Unix()))
hello.SessionId[0] = 1
hello.SessionId[1] = 7
hello.SessionId[2] = 5
copy(hello.SessionId[8:], e.shortID[:])
if debug.Enabled {
fmt.Printf("REALITY hello.sessionId[:16]: %v\n", hello.SessionId[:16])
}
authKey := uConn.HandshakeState.State13.EcdheParams.SharedKey(e.publicKey)
if authKey == nil {
return nil, E.New("nil auth_key")
}
verifier.authKey = authKey
_, err = hkdf.New(sha256.New, authKey, hello.Random[:20], []byte("REALITY")).Read(authKey)
if err != nil {
return nil, err
}
aesBlock, _ := aes.NewCipher(authKey)
aesGcmCipher, _ := cipher.NewGCM(aesBlock)
aesGcmCipher.Seal(hello.SessionId[:0], hello.Random[20:], hello.SessionId[:16], hello.Raw)
copy(hello.Raw[39:], hello.SessionId)
if debug.Enabled {
fmt.Printf("REALITY hello.sessionId: %v\n", hello.SessionId)
fmt.Printf("REALITY uConn.AuthKey: %v\n", authKey)
}
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err = uConn.HandshakeContext(ctx)
if err != nil {
return nil, err
}
if debug.Enabled {
fmt.Printf("REALITY Conn.Verified: %v\n", verifier.verified)
}
if !verifier.verified {
go realityClientFallback(uConn, e.uClient.ServerName(), e.uClient.id)
return nil, E.New("reality verification failed")
}
return &utlsConnWrapper{uConn}, nil
}
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func realityClientFallback(uConn net.Conn, serverName string, fingerprint utls.ClientHelloID) {
defer uConn.Close()
client := &http.Client{
Transport: &http2.Transport{
DialTLSContext: func(ctx context.Context, network, addr string, config *tls.Config) (net.Conn, error) {
return uConn, nil
},
},
}
request, _ := http.NewRequest("GET", "https://"+serverName, nil)
request.Header.Set("User-Agent", fingerprint.Client)
request.AddCookie(&http.Cookie{Name: "padding", Value: strings.Repeat("0", mRand.Intn(32)+30)})
response, err := client.Do(request)
if err != nil {
return
}
_, _ = io.Copy(io.Discard, response.Body)
response.Body.Close()
}
func (e *RealityClientConfig) SetSessionIDGenerator(generator func(clientHello []byte, sessionID []byte) error) {
e.uClient.config.SessionIDGenerator = generator
}
func (e *RealityClientConfig) Clone() Config {
return &RealityClientConfig{
e.uClient.Clone().(*UTLSClientConfig),
e.publicKey,
e.shortID,
}
}
type realityVerifier struct {
*utls.UConn
serverName string
authKey []byte
verified bool
}
func (c *realityVerifier) VerifyPeerCertificate(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error {
p, _ := reflect.TypeOf(c.Conn).Elem().FieldByName("peerCertificates")
certs := *(*([]*x509.Certificate))(unsafe.Pointer(uintptr(unsafe.Pointer(c.Conn)) + p.Offset))
if pub, ok := certs[0].PublicKey.(ed25519.PublicKey); ok {
h := hmac.New(sha512.New, c.authKey)
h.Write(pub)
if bytes.Equal(h.Sum(nil), certs[0].Signature) {
c.verified = true
return nil
}
}
opts := x509.VerifyOptions{
DNSName: c.serverName,
Intermediates: x509.NewCertPool(),
}
for _, cert := range certs[1:] {
opts.Intermediates.AddCert(cert)
}
if _, err := certs[0].Verify(opts); err != nil {
return err
}
return nil
}