chore: sync vless encryption code

transport/vless/encryption/client.go

@@ -115,9 +115,9 @@ func (i *ClientInstance) Handshake(conn net.Conn) (net.Conn, error) {
 	if _, err := c.Conn.Write(clientHello); err != nil {
 		return nil, err
 	}
-	// client can send more padding / NFS AEAD messages if needed
+	// client can send more paddings / NFS AEAD messages if needed
 
-	_, t, l, err := ReadAndDiscardPaddings(c.Conn)
+	_, t, l, err := ReadAndDiscardPaddings(c.Conn) // allow paddings before server hello
 	if err != nil {
 		return nil, err
 	}
@@ -201,9 +201,9 @@ func (c *ClientConn) Read(b []byte) (int, error) {
 		return 0, nil
 	}
 	if c.peerAead == nil {
-		_, t, l, err := ReadAndDiscardPaddings(c.Conn)
+		_, t, l, err := ReadAndDiscardPaddings(c.Conn) // allow paddings before random hello
 		if err != nil {
-			if c.instance != nil && strings.HasPrefix(err.Error(), "invalid header: ") { // from 0-RTT
+			if c.instance != nil && strings.HasPrefix(err.Error(), "invalid header: ") { // 0-RTT's 0-RTT
 				c.instance.Lock()
 				if bytes.Equal(c.ticket, c.instance.ticket) {
 					c.instance.expire = time.Now() // expired

transport/vless/encryption/common.go

@@ -48,7 +48,7 @@ func DecodeHeader(h []byte) (t byte, l int, err error) {
 		l = 0
 	}
 	if l < 17 || l > 17000 { // TODO: TLSv1.3 max length
-		err = fmt.Errorf("invalid header: %v", h[:5]) // relied by client's Read()
+		err = fmt.Errorf("invalid header: %v", h[:5]) // DO NOT CHANGE: relied by client's Read()
 	}
 	return
 }

transport/vless/encryption/doc.go

@@ -10,4 +10,5 @@
 // https://github.com/XTLS/Xray-core/commit/0fd7691d6b28e05922d7a5a9313d97745a51ea63
 // https://github.com/XTLS/Xray-core/commit/09cc92c61d9067e0d65c1cae9124664ecfc78f43
 // https://github.com/XTLS/Xray-core/commit/2807ee432a1fbeb301815647189eacd650b12a8b
+// https://github.com/XTLS/Xray-core/commit/bfe4820f2f086daf639b1957eb23dc13c843cad1
 package encryption

transport/vless/encryption/server.go

@@ -97,7 +97,7 @@ func (i *ServerInstance) Handshake(conn net.Conn) (net.Conn, error) {
 	}
 	c := &ServerConn{Conn: conn}
 
-	_, t, l, err := ReadAndDiscardPaddings(c.Conn)
+	_, t, l, err := ReadAndDiscardPaddings(c.Conn) // allow paddings before client/ticket hello
 	if err != nil {
 		return nil, err
 	}
@@ -117,9 +117,13 @@ func (i *ServerInstance) Handshake(conn net.Conn) (net.Conn, error) {
 		s := i.sessions[[21]byte(peerTicketHello)]
 		i.RUnlock()
 		if s == nil {
-			noise := make([]byte, randBetween(100, 1000))
-			rand.Read(noise)
-			c.Conn.Write(noise) // make client do new handshake
+			noises := make([]byte, randBetween(100, 1000))
+			var err error
+			for err == nil {
+				rand.Read(noises)
+				_, _, err = DecodeHeader(noises)
+			}
+			c.Conn.Write(noises) // make client do new handshake
 			return nil, errors.New("expired ticket")
 		}
 		if _, replay := s.randoms.LoadOrStore([32]byte(peerTicketHello[21:]), true); replay {
@@ -169,7 +173,7 @@ func (i *ServerInstance) Handshake(conn net.Conn) (net.Conn, error) {
 	if _, err := c.Conn.Write(serverHello); err != nil {
 		return nil, err
 	}
-	// server can send more padding / PFS AEAD messages if needed
+	// server can send more paddings / PFS AEAD messages if needed
 
 	if i.minutes > 0 {
 		i.Lock()
@@ -189,8 +193,8 @@ func (c *ServerConn) Read(b []byte) (int, error) {
 		return 0, nil
 	}
 	if c.peerAead == nil {
-		if c.peerRandom == nil { // from 1-RTT
-			_, t, l, err := ReadAndDiscardPaddings(c.Conn)
+		if c.peerRandom == nil { // 1-RTT's 0-RTT
+			_, t, l, err := ReadAndDiscardPaddings(c.Conn) // allow paddings before ticket hello
 			if err != nil {
 				return 0, err
 			}

transport/vless/encryption/xor.go

@@ -22,7 +22,7 @@ func NewXorConn(conn net.Conn, key []byte) *XorConn {
 	//chacha20.NewUnauthenticatedCipher()
 }
 
-func (c *XorConn) Write(b []byte) (int, error) { // two records at most
+func (c *XorConn) Write(b []byte) (int, error) { // whole one/two records
 	if len(b) == 0 {
 		return 0, nil
 	}
@@ -34,10 +34,10 @@ func (c *XorConn) Write(b []byte) (int, error) { // two records at most
 		c.ctr = cipher.NewCTR(block, iv)
 	}
 	t, l, _ := DecodeHeader(b)
-	if t != 23 {
-		l += 10 // 5+l+5
-	} else {
+	if t == 23 { // single 23
 		l = 5
+	} else { // 1/0 + 23, or noises only
+		l += 10
 	}
 	c.ctr.XORKeyStream(b[:l], b[:l]) // caller MUST discard b
 	if iv != nil {
@@ -73,8 +73,8 @@ func (c *XorConn) Read(b []byte) (int, error) { // 5-bytes, data, 5-bytes...
 		return len(b), nil
 	}
 	c.peerCtr.XORKeyStream(b, b)
-	if c.isHeader {
-		if t, _, _ := DecodeHeader(b); t == 23 { // always 5-bytes
+	if c.isHeader { // always 5-bytes
+		if t, _, _ := DecodeHeader(b); t == 23 {
 			c.skipNext = true
 		} else {
 			c.isHeader = false