Drain Connection Based on Uuid based Behavior seed

common/dice/dice.go

@@ -28,6 +28,25 @@ func RollUint16() uint16 {
 	return uint16(rand.Intn(65536))
 }
 
+func RollUint64() uint64 {
+	return rand.Uint64()
+}
+
+func NewDeterministicDice(seed int64) *deterministicDice {
+	return &deterministicDice{rand.New(rand.NewSource(seed))}
+}
+
+type deterministicDice struct {
+	*rand.Rand
+}
+
+func (dd *deterministicDice) Roll(n int) int {
+	if n == 1 {
+		return 0
+	}
+	return dd.Intn(n)
+}
+
 func init() {
 	rand.Seed(time.Now().Unix())
 }

proxy/vmess/encoding/server.go

@@ -125,7 +125,26 @@ func parseSecurityType(b byte) protocol.SecurityType {
 // DecodeRequestHeader decodes and returns (if successful) a RequestHeader from an input stream.
 func (s *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.RequestHeader, error) {
 	buffer := buf.New()
-	defer buffer.Release()
+	behaviorRand := dice.NewDeterministicDice(int64(s.userValidator.GetBehaviorSeed()))
+	DrainSize := behaviorRand.Roll(387) + 16 + 38
+	readSizeRemain := DrainSize
+
+	drainConnection := func(e error) error {
+		//We read a deterministic generated length of data before closing the connection to offset padding read pattern
+		readSizeRemain -= int(buffer.Len())
+		if readSizeRemain > 0 {
+			err := s.DrainConnN(reader, readSizeRemain)
+			if err != nil {
+				return newError("failed to drain connection").Base(err).Base(e)
+			}
+			return newError("connection drained DrainSize = ", DrainSize).Base(e)
+		}
+		return e
+	}
+
+	defer func() {
+		buffer.Release()
+	}()
 
 	if _, err := buffer.ReadFullFrom(reader, protocol.IDBytesLen); err != nil {
 		return nil, newError("failed to read request header").Base(err)
@@ -133,7 +152,8 @@ func (s *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Request
 
 	user, timestamp, valid := s.userValidator.Get(buffer.Bytes())
 	if !valid {
-		return nil, newError("invalid user")
+		//It is possible that we are under attack described in https://github.com/v2ray/v2ray-core/issues/2523
+		return nil, drainConnection(newError("invalid user"))
 	}
 
 	iv := hashTimestamp(md5.New(), timestamp)
@@ -142,6 +162,7 @@ func (s *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Request
 	aesStream := crypto.NewAesDecryptionStream(vmessAccount.ID.CmdKey(), iv[:])
 	decryptor := crypto.NewCryptionReader(aesStream, reader)
 
+	readSizeRemain -= int(buffer.Len())
 	buffer.Clear()
 	if _, err := buffer.ReadFullFrom(decryptor, 38); err != nil {
 		return nil, newError("failed to read request header").Base(err)
@@ -197,12 +218,7 @@ func (s *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Request
 
 	if actualHash != expectedHash {
 		//It is possible that we are under attack described in https://github.com/v2ray/v2ray-core/issues/2523
-		//We read a deterministic generated length of data before closing the connection to offset padding read pattern
-		drainSum := dice.RollDeterministic(48, int64(actualHash))
-		if err := s.DrainConnN(reader, drainSum); err != nil {
-			return nil, newError("invalid auth, failed to drain connection").Base(err)
-		}
-		return nil, newError("invalid auth, connection drained")
+		return nil, drainConnection(newError("invalid auth"))
 	}
 
 	if request.Address == nil {

proxy/vmess/validator.go

@@ -3,9 +3,11 @@
 package vmess
 
 import (
+	"hash/crc64"
 	"strings"
 	"sync"
 	"time"
+	"v2ray.com/core/common/dice"
 
 	"v2ray.com/core/common"
 	"v2ray.com/core/common/protocol"
@@ -26,11 +28,13 @@ type user struct {
 // TimedUserValidator is a user Validator based on time.
 type TimedUserValidator struct {
 	sync.RWMutex
-	users    []*user
-	userHash map[[16]byte]indexTimePair
-	hasher   protocol.IDHash
-	baseTime protocol.Timestamp
-	task     *task.Periodic
+	users         []*user
+	userHash      map[[16]byte]indexTimePair
+	hasher        protocol.IDHash
+	baseTime      protocol.Timestamp
+	task          *task.Periodic
+	behaviorSeed  uint64
+	behaviorFused bool
 }
 
 type indexTimePair struct {
@@ -124,6 +128,11 @@ func (v *TimedUserValidator) Add(u *protocol.MemoryUser) error {
 	v.users = append(v.users, uu)
 	v.generateNewHashes(protocol.Timestamp(nowSec), uu)
 
+	if v.behaviorFused == false {
+		account := uu.user.Account.(*MemoryAccount)
+		crc64.Update(v.behaviorSeed, crc64.MakeTable(crc64.ECMA), account.ID.Bytes())
+	}
+
 	return nil
 }
 
@@ -131,6 +140,8 @@ func (v *TimedUserValidator) Get(userHash []byte) (*protocol.MemoryUser, protoco
 	defer v.RUnlock()
 	v.RLock()
 
+	v.behaviorFused = true
+
 	var fixedSizeHash [16]byte
 	copy(fixedSizeHash[:], userHash)
 	pair, found := v.userHash[fixedSizeHash]
@@ -170,3 +181,13 @@ func (v *TimedUserValidator) Remove(email string) bool {
 func (v *TimedUserValidator) Close() error {
 	return v.task.Close()
 }
+
+func (v *TimedUserValidator) GetBehaviorSeed() uint64 {
+	v.Lock()
+	defer v.Unlock()
+	v.behaviorFused = true
+	if v.behaviorSeed == 0 {
+		v.behaviorSeed = dice.RollUint64()
+	}
+	return v.behaviorSeed
+}