feat: Support REALITY protocol

component/tls/reality.go

@@ -0,0 +1,163 @@
+package tls
+
+import (
+	"bytes"
+	"context"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/ed25519"
+	"crypto/hmac"
+	"crypto/sha256"
+	"crypto/sha512"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/binary"
+	"errors"
+	"net"
+	"net/http"
+	"reflect"
+	"strings"
+	"time"
+	"unsafe"
+
+	"github.com/Dreamacro/clash/log"
+
+	utls "github.com/sagernet/utls"
+	"github.com/zhangyunhao116/fastrand"
+	"golang.org/x/crypto/curve25519"
+	"golang.org/x/crypto/hkdf"
+	"golang.org/x/net/http2"
+)
+
+type RealityConfig struct {
+	ServerName string
+	PublicKey  [curve25519.ScalarSize]byte
+	ShortID    []byte
+}
+
+func GetRealityConn(ctx context.Context, conn net.Conn, ClientFingerprint string, tlsConfig *tls.Config, realityConfig *RealityConfig) (net.Conn, error) {
+	if fingerprint, exists := GetFingerprint(ClientFingerprint); exists {
+		verifier := &realityVerifier{
+			serverName: realityConfig.ServerName,
+		}
+		uConfig := copyConfig(tlsConfig)
+		uConfig.ServerName = realityConfig.ServerName
+		uConfig.InsecureSkipVerify = true
+		uConfig.SessionTicketsDisabled = true
+		uConfig.VerifyPeerCertificate = verifier.VerifyPeerCertificate
+		clientID := utls.ClientHelloID{
+			Client:  fingerprint.Client,
+			Version: fingerprint.Version,
+			Seed:    fingerprint.Seed,
+		}
+		uConn := utls.UClient(conn, uConfig, clientID)
+		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:], realityConfig.ShortID)
+
+		//log.Debugln("REALITY hello.sessionId[:16]: %v", hello.SessionId[:16])
+
+		authKey := uConn.HandshakeState.State13.EcdheParams.SharedKey(realityConfig.PublicKey[:])
+		if authKey == nil {
+			return nil, errors.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)
+		//log.Debugln("REALITY hello.sessionId: %v", hello.SessionId)
+		//log.Debugln("REALITY uConn.AuthKey: %v", authKey)
+
+		err = uConn.HandshakeContext(ctx)
+		if err != nil {
+			return nil, err
+		}
+
+		log.Debugln("REALITY Authentication: %v", verifier.verified)
+
+		if !verifier.verified {
+			go realityClientFallback(uConn, uConfig.ServerName, clientID)
+			return nil, errors.New("REALITY authentication failed")
+		}
+
+		return uConn, nil
+	}
+	return nil, errors.New("unknown uTLS fingerprint")
+}
+
+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", fastrand.Intn(32)+30)})
+	response, err := client.Do(request)
+	if err != nil {
+		return
+	}
+	//_, _ = io.Copy(io.Discard, response.Body)
+	time.Sleep(time.Duration(5 + fastrand.Int63n(10)))
+	response.Body.Close()
+	client.CloseIdleConnections()
+}
+
+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
+}