Refactor post-handshake records detection & imitation

https://github.com/XTLS/Xray-core/issues/4778#issuecomment-2948185205

record_detect.go

@@ -6,76 +6,78 @@ import (
 	"encoding/binary"
 	"io"
 	"net"
+	"sync"
 	"time"
+
+	"github.com/pires/go-proxyproto"
 )
 
-func DetectRecordFingerprint(target string) ([]int, error) {
-	NetConn, err := net.Dial("tcp", target)
-	if err != nil {
-		return nil, err
+var lock sync.Mutex
+
+var PostHandshakeRecordsLen map[*Config]map[string][]int
+
+func DetectPostHandshakeRecords(config *Config) {
+	lock.Lock()
+	if PostHandshakeRecordsLen == nil {
+		PostHandshakeRecordsLen = make(map[*Config]map[string][]int)
 	}
-	conn := &detectConn{
-		Conn:       NetConn,
-		resultChan: make(chan []int, 1),
-	}
-	host, _, err := net.SplitHostPort(target)
-	if err != nil {
-		return nil, err
-	}
-	tlsConfig := &tls.Config{
-		ServerName: host,
-	}
-	tlsConn := tls.Client(conn, tlsConfig)
-	err = tlsConn.Handshake()
-	if err != nil {
-		return nil, err
-	}
-	go func() {
-		io.Copy(io.Discard, tlsConn)
-	}()
-	select {
-	case result := <-conn.resultChan:
-		return result, nil
-	case <-time.After(2 * time.Second):
-		return nil, nil
+	if PostHandshakeRecordsLen[config] == nil {
+		PostHandshakeRecordsLen[config] = make(map[string][]int)
+		for sni := range config.ServerNames {
+			target, err := net.Dial("tcp", config.Dest)
+			if err != nil {
+				return
+			}
+			if config.Xver == 1 || config.Xver == 2 {
+				if _, err = proxyproto.HeaderProxyFromAddrs(config.Xver, target.LocalAddr(), target.RemoteAddr()).WriteTo(target); err != nil {
+					return
+				}
+			}
+			detectConn := &DetectConn{
+				Conn:   target,
+				config: config,
+				sni:    sni,
+			}
+			tlsConn := tls.Client(detectConn, &tls.Config{
+				ServerName: sni,
+			})
+			if err = tlsConn.Handshake(); err != nil {
+				return
+			}
+			io.Copy(io.Discard, tlsConn)
+		}
 	}
+	lock.Unlock()
 }
 
-type detectConn struct {
+type DetectConn struct {
 	net.Conn
-	ccsSent    bool
-	done       bool
-	resultChan chan ([]int)
+	config  *Config
+	sni     string
+	ccsSent bool
 }
 
-func (c *detectConn) Write(b []byte) (n int, err error) {
+func (c *DetectConn) Write(b []byte) (n int, err error) {
 	if len(b) >= 3 && bytes.Equal(b[:3], []byte{20, 3, 3}) {
 		c.ccsSent = true
 	}
 	return c.Conn.Write(b)
 }
 
-func (c *detectConn) Read(b []byte) (n int, err error) {
-	n, err = c.Conn.Read(b)
-	if c.ccsSent && !c.done {
-		data := make([]byte, len(b))
-		copy(data, b)
-		var result []int
-		for {
-			if len(data) > 3 && bytes.Equal(data[:3], []byte{23, 3, 3}) {
-				length := int(binary.BigEndian.Uint16(data[3:5]))
-				if len(data) > length+5 {
-					result = append(result, int(length))
-					data = data[length+5:]
-				}
-			} else {
-				break
-			}
-		}
-		if len(result) != 1 {
-			c.done = true
-			c.resultChan <- result
+func (c *DetectConn) Read(b []byte) (n int, err error) {
+	if !c.ccsSent {
+		return c.Conn.Read(b)
+	}
+	c.Conn.SetReadDeadline(time.Now().Add(5 * time.Second))
+	data, _ := io.ReadAll(c.Conn)
+	for {
+		if len(data) >= 5 && bytes.Equal(data[:3], []byte{23, 3, 3}) {
+			length := int(binary.BigEndian.Uint16(data[3:5])) + 5
+			PostHandshakeRecordsLen[c.config][c.sni] = append(PostHandshakeRecordsLen[c.config][c.sni], length)
+			data = data[length:]
+		} else {
+			break
 		}
 	}
-	return n, err
+	return 0, io.EOF
 }

tls.go

@@ -126,6 +126,8 @@ func Value(vals ...byte) (value int) {
 // The configuration config must be non-nil and must include
 // at least one certificate or else set GetCertificate.
 func Server(ctx context.Context, conn net.Conn, config *Config) (*Conn, error) {
+	DetectPostHandshakeRecords(config)
+
 	remoteAddr := conn.RemoteAddr().String()
 	if config.Show {
 		fmt.Printf("REALITY remoteAddr: %v\n", remoteAddr)
@@ -336,6 +338,19 @@ func Server(ctx context.Context, conn net.Conn, config *Config) (*Conn, error) {
 			if err != nil {
 				break
 			}
+			for _, length := range PostHandshakeRecordsLen[config][hs.clientHello.serverName] {
+				plainText := make([]byte, length-16)
+				plainText[0] = 23
+				plainText[1] = 3
+				plainText[2] = 3
+				plainText[3] = byte((length - 5) >> 8)
+				plainText[4] = byte((length - 5))
+				plainText[5] = 23
+				postHandshakeRecord := hs.c.out.cipher.(aead).Seal(plainText[:5], hs.c.out.seq[:], plainText[5:], plainText[:5])
+				hs.c.out.incSeq()
+				hs.c.write(postHandshakeRecord)
+				fmt.Printf("REALITY remoteAddr: %v\tlen(postHandshakeRecord): %v\n", remoteAddr, len(postHandshakeRecord))
+			}
 			hs.c.isHandshakeComplete.Store(true)
 			break
 		}