Deprecate legacy VMess header with a planned decommission (#717)

proxy/vmess/encoding/server.go

@@ -191,11 +191,16 @@ func (s *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Request
 		decryptor = bytes.NewReader(aeadData)
 		s.isAEADRequest = true
 
-	case !s.isAEADForced && errorAEAD == vmessaead.ErrNotFound:
+	case errorAEAD == vmessaead.ErrNotFound:
 		userLegacy, timestamp, valid, userValidationError := s.userValidator.Get(buffer.Bytes())
 		if !valid || userValidationError != nil {
 			return nil, drainConnection(newError("invalid user").Base(userValidationError))
 		}
+		if s.isAEADForced {
+			return nil, drainConnection(newError("invalid user: VMessAEAD is enforced and a non VMessAEAD connection is received. You can still disable this security feature with environment variable v2ray.vmess.aead.forced = false . You will not be able to enable legacy header workaround in the future."))
+		} else {
+			newError("Critical Warning: potentially invalid user: a non VMessAEAD connection is received. From 2022 Jan 1st, this kind of connection will be rejected by default. You should update or replace your client software now. ").AtWarning().WriteToLog()
+		}
 		user = userLegacy
 		iv := hashTimestamp(md5.New(), timestamp)
 		vmessAccount = userLegacy.Account.(*vmess.MemoryAccount)

proxy/vmess/inbound/inbound.go

@@ -353,16 +353,26 @@ func (h *Handler) generateCommand(ctx context.Context, request *protocol.Request
 }
 
 var aeadForced = false
+var aeadForced2022 = false
 
 func init() {
 	common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
 		return New(ctx, config.(*Config))
 	}))
 
-	const defaultFlagValue = "NOT_DEFINED_AT_ALL"
+	var defaultFlagValue = "NOT_DEFINED_AT_ALL"
+
+	if time.Now().Year() >= 2022 {
+		defaultFlagValue = "true_by_default_2022"
+	}
 
 	isAeadForced := platform.NewEnvFlag("v2ray.vmess.aead.forced").GetValue(func() string { return defaultFlagValue })
 	if isAeadForced == "true" {
 		aeadForced = true
 	}
+
+	if isAeadForced == "true_by_default_2022" {
+		aeadForced = true
+		aeadForced2022 = true
+	}
 }