VLESS Encryption: Randomize seconds in ticket and simplify expiration mechanism

https://github.com/XTLS/Xray-core/pull/5067#issuecomment-3246925902

infra/conf/vless.go

@@ -96,16 +96,18 @@ func (c *VLessInboundConfig) Build() (proto.Message, error) {
 		default:
 			return false
 		}
-		if s[2] != "1rtt" {
-			t := strings.TrimSuffix(s[2], "s")
-			if t == s[2] {
-				return false
-			}
-			i, err := strconv.Atoi(t)
+		t := strings.SplitN(strings.TrimSuffix(s[2], "s"), "-", 2)
+		i, err := strconv.Atoi(t[0])
+		if err != nil {
+			return false
+		}
+		config.SecondsFrom = uint32(i)
+		if len(t) > 1 {
+			i, err := strconv.Atoi(t[1])
 			if err != nil {
 				return false
 			}
-			config.Seconds = uint32(i)
+			config.SecondsTo = uint32(i)
 		}
 		padding := 0
 		for _, r := range s[3:] {

proxy/vless/encryption/server.go

@@ -18,7 +18,6 @@ import (
 )
 
 type ServerSession struct {
-	Expire  time.Time
 	PfsKey  []byte
 	NfsKeys sync.Map
 }
@@ -29,16 +28,16 @@ type ServerInstance struct {
 	Hash32s       [][32]byte
 	RelaysLength  int
 	XorMode       uint32
-	Seconds       uint32
+	SecondsFrom   uint32
+	SecondsTo     uint32
 	PaddingLens   [][3]int
 	PaddingGaps   [][3]int
 
 	RWLock   sync.RWMutex
 	Sessions map[[16]byte]*ServerSession
-	Closed   bool
 }
 
-func (i *ServerInstance) Init(nfsSKeysBytes [][]byte, xorMode, seconds uint32, padding string) (err error) {
+func (i *ServerInstance) Init(nfsSKeysBytes [][]byte, xorMode, secondsFrom, secondsTo uint32, padding string) (err error) {
 	if i.NfsSKeys != nil {
 		return errors.New("already initialized")
 	}
@@ -67,37 +66,12 @@ func (i *ServerInstance) Init(nfsSKeysBytes [][]byte, xorMode, seconds uint32, p
 	}
 	i.RelaysLength -= 32
 	i.XorMode = xorMode
-	if seconds > 0 {
-		i.Seconds = seconds
-		i.Sessions = make(map[[16]byte]*ServerSession)
-		go func() {
-			for {
-				time.Sleep(time.Minute)
-				i.RWLock.Lock()
-				if i.Closed {
-					i.RWLock.Unlock()
-					return
-				}
-				now := time.Now()
-				for ticket, session := range i.Sessions {
-					if now.After(session.Expire) {
-						delete(i.Sessions, ticket)
-					}
-				}
-				i.RWLock.Unlock()
-			}
-		}()
-	}
+	i.SecondsFrom = secondsFrom
+	i.SecondsTo = secondsTo
+	i.Sessions = make(map[[16]byte]*ServerSession)
 	return ParsePadding(padding, &i.PaddingLens, &i.PaddingGaps)
 }
 
-func (i *ServerInstance) Close() (err error) {
-	i.RWLock.Lock()
-	i.Closed = true
-	i.RWLock.Unlock()
-	return
-}
-
 func (i *ServerInstance) Handshake(conn net.Conn, fallback *[]byte) (*CommonConn, error) {
 	if i.NfsSKeys == nil {
 		return nil, errors.New("uninitialized")
@@ -132,7 +106,7 @@ func (i *ServerInstance) Handshake(conn net.Conn, fallback *[]byte) (*CommonConn
 				return nil, err
 			}
 			if publicKey.Bytes()[31] > 127 { // we just don't want the observer can change even one bit without breaking the connection, though it has nothing to do with security
-				return nil, errors.New("the highest bit of the last byte of the peer-sent X25519 public key must be 0")
+				return nil, errors.New("the highest bit of the last byte of the peer-sent X25519 public key is not 0")
 			}
 			nfsKey, err = k.ECDH(publicKey)
 			if err != nil {
@@ -180,7 +154,7 @@ func (i *ServerInstance) Handshake(conn net.Conn, fallback *[]byte) (*CommonConn
 	length := DecodeLength(decryptedLength)
 
 	if length == 32 {
-		if i.Seconds == 0 {
+		if i.SecondsFrom == 0 && i.SecondsTo == 0 {
 			return nil, errors.New("0-RTT is not allowed")
 		}
 		encryptedTicket := make([]byte, 32)
@@ -252,14 +226,23 @@ func (i *ServerInstance) Handshake(conn net.Conn, fallback *[]byte) (*CommonConn
 
 	ticket := make([]byte, 16)
 	rand.Read(ticket)
-	copy(ticket, EncodeLength(int(i.Seconds*4/5)))
-	if i.Seconds > 0 {
+	seconds := 0
+	if i.SecondsTo == 0 {
+		seconds = int(i.SecondsFrom) * int(crypto.RandBetween(50, 100)) / 100
+	} else {
+		seconds = int(crypto.RandBetween(int64(i.SecondsFrom), int64(i.SecondsTo)))
+	}
+	copy(ticket, EncodeLength(int(seconds)))
+	if seconds > 0 {
 		i.RWLock.Lock()
-		i.Sessions[[16]byte(ticket)] = &ServerSession{
-			Expire: time.Now().Add(time.Duration(i.Seconds) * time.Second),
-			PfsKey: pfsKey,
-		}
+		i.Sessions[[16]byte(ticket)] = &ServerSession{PfsKey: pfsKey}
 		i.RWLock.Unlock()
+		go func() {
+			time.Sleep(time.Duration(seconds)*time.Second + time.Minute)
+			i.RWLock.Lock()
+			delete(i.Sessions, [16]byte(ticket))
+			i.RWLock.Unlock()
+		}()
 	}
 
 	pfsKeyExchangeLength := 1088 + 32 + 16

proxy/vless/inbound/config.pb.go

@@ -111,12 +111,13 @@ type Config struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	Clients    []*protocol.User `protobuf:"bytes,1,rep,name=clients,proto3" json:"clients,omitempty"`
-	Fallbacks  []*Fallback      `protobuf:"bytes,2,rep,name=fallbacks,proto3" json:"fallbacks,omitempty"`
-	Decryption string           `protobuf:"bytes,3,opt,name=decryption,proto3" json:"decryption,omitempty"`
-	XorMode    uint32           `protobuf:"varint,4,opt,name=xorMode,proto3" json:"xorMode,omitempty"`
-	Seconds    uint32           `protobuf:"varint,5,opt,name=seconds,proto3" json:"seconds,omitempty"`
-	Padding    string           `protobuf:"bytes,6,opt,name=padding,proto3" json:"padding,omitempty"`
+	Clients     []*protocol.User `protobuf:"bytes,1,rep,name=clients,proto3" json:"clients,omitempty"`
+	Fallbacks   []*Fallback      `protobuf:"bytes,2,rep,name=fallbacks,proto3" json:"fallbacks,omitempty"`
+	Decryption  string           `protobuf:"bytes,3,opt,name=decryption,proto3" json:"decryption,omitempty"`
+	XorMode     uint32           `protobuf:"varint,4,opt,name=xorMode,proto3" json:"xorMode,omitempty"`
+	SecondsFrom uint32           `protobuf:"varint,5,opt,name=seconds_from,json=secondsFrom,proto3" json:"seconds_from,omitempty"`
+	SecondsTo   uint32           `protobuf:"varint,6,opt,name=seconds_to,json=secondsTo,proto3" json:"seconds_to,omitempty"`
+	Padding     string           `protobuf:"bytes,7,opt,name=padding,proto3" json:"padding,omitempty"`
 }
 
 func (x *Config) Reset() {
@@ -177,9 +178,16 @@ func (x *Config) GetXorMode() uint32 {
 	return 0
 }
 
-func (x *Config) GetSeconds() uint32 {
+func (x *Config) GetSecondsFrom() uint32 {
 	if x != nil {
-		return x.Seconds
+		return x.SecondsFrom
+	}
+	return 0
+}
+
+func (x *Config) GetSecondsTo() uint32 {
+	if x != nil {
+		return x.SecondsTo
 	}
 	return 0
 }
@@ -207,7 +215,7 @@ var file_proxy_vless_inbound_config_proto_rawDesc = []byte{
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@@ -219,18 +227,20 @@ var file_proxy_vless_inbound_config_proto_rawDesc = []byte{
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 }
 
 var (

proxy/vless/inbound/config.proto

@@ -23,6 +23,7 @@ message Config {
 
   string decryption = 3;
   uint32 xorMode = 4;
-  uint32 seconds = 5;
-  string padding = 6;
+  uint32 seconds_from = 5;
+  uint32 seconds_to = 6;
+  string padding = 7;
 }

proxy/vless/inbound/inbound.go

@@ -93,7 +93,7 @@ func New(ctx context.Context, config *Config, dc dns.Client, validator vless.Val
 			nfsSKeysBytes = append(nfsSKeysBytes, b)
 		}
 		handler.decryption = &encryption.ServerInstance{}
-		if err := handler.decryption.Init(nfsSKeysBytes, config.XorMode, config.Seconds, config.Padding); err != nil {
+		if err := handler.decryption.Init(nfsSKeysBytes, config.XorMode, config.SecondsFrom, config.SecondsTo, config.Padding); err != nil {
 			return nil, errors.New("failed to use decryption").Base(err).AtError()
 		}
 	}
@@ -176,9 +176,6 @@ func isMuxAndNotXUDP(request *protocol.RequestHeader, first *buf.Buffer) bool {
 
 // Close implements common.Closable.Close().
 func (h *Handler) Close() error {
-	if h.decryption != nil {
-		h.decryption.Close()
-	}
 	return errors.Combine(common.Close(h.validator))
 }