Change the protocol to solve sessionTicket inconsistency

This commit is contained in:
Qian Wang 2019-07-26 17:05:46 +01:00
parent 592175f73d
commit 75fecacd20
7 changed files with 185 additions and 154 deletions

View File

@ -4,6 +4,7 @@ package main
import (
"encoding/base64"
"encoding/binary"
"flag"
"fmt"
"io"
@ -176,16 +177,18 @@ start:
log.Println("Attemtping to start a new session")
// sessionID is usergenerated. There shouldn't be a security concern because the scope of
// sessionID is limited to its UID.
rand.Seed(time.Now().UnixNano())
sessionID := rand.Uint32()
quad := make([]byte, 4)
rand.Read(quad)
sta.SessionID = binary.BigEndian.Uint32(quad)
sta.UpdateIntervalKeys()
if adminUID != nil {
sessionID = 0
sta.SessionID = 0
sta.UID = adminUID
sta.NumConn = 1
}
sta.SetSessionID(sessionID)
var crypto mux.Crypto
switch sta.EncryptionMethod {
case 0x00:
@ -204,11 +207,8 @@ start:
}
}
sessionKey := make([]byte, 32)
rand.Read(sessionKey)
sta.SessionKey = sessionKey
sesh := mux.MakeSession(sessionID, mux.UNLIMITED_VALVE, mux.MakeObfs(sta.SessionKey, crypto), mux.MakeDeobfs(sta.SessionKey, crypto), util.ReadTLS)
_, tthKey, _ := sta.GetIntervalKeys()
sesh := mux.MakeSession(sta.SessionID, mux.UNLIMITED_VALVE, mux.MakeObfs(tthKey, crypto), mux.MakeDeobfs(tthKey, crypto), util.ReadTLS)
var wg sync.WaitGroup
for i := 0; i < sta.NumConn; i++ {
@ -227,7 +227,7 @@ start:
}
wg.Wait()
log.Printf("Session %v established", sessionID)
log.Printf("Session %v established", sta.SessionID)
for {
if sesh.IsBroken() {

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@ -73,7 +73,7 @@ func dispatchConnection(conn net.Conn, sta *server.State) {
return
}
isCloak, UID, sessionID, proxyMethod, encryptionMethod, sessionKey := server.TouchStone(ch, sta)
isCloak, UID, sessionID, proxyMethod, encryptionMethod, tthKey := server.TouchStone(ch, sta)
if !isCloak {
log.Printf("+1 non Cloak TLS traffic from %v\n", conn.RemoteAddr())
goWeb(data)
@ -109,8 +109,8 @@ func dispatchConnection(conn net.Conn, sta *server.State) {
return
}
obfs := mux.MakeObfs(sessionKey, crypto)
deobfs := mux.MakeDeobfs(sessionKey, crypto)
obfs := mux.MakeObfs(tthKey, crypto)
deobfs := mux.MakeDeobfs(tthKey, crypto)
finishHandshake := func() error {
reply := server.ComposeReply(ch)

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@ -1,67 +1,52 @@
package client
import (
"crypto"
"crypto/rand"
"crypto/sha256"
"encoding/binary"
"io"
"github.com/cbeuw/Cloak/internal/ecdh"
"github.com/cbeuw/Cloak/internal/util"
)
type keyPair struct {
crypto.PrivateKey
crypto.PublicKey
}
func MakeRandomField(sta *State) []byte {
// [4 bytes sessionId] [12 bytes random] [16 bytes hash]
t := make([]byte, 8)
binary.BigEndian.PutUint64(t, uint64(sta.Now().Unix()/(12*60*60)))
rdm := make([]byte, 16)
io.ReadFull(rand.Reader, rdm)
front := make([]byte, 16)
binary.BigEndian.PutUint32(front[0:4], sta.SessionID)
rand.Read(front[4:])
preHash := make([]byte, 56)
copy(preHash[0:32], sta.UID)
copy(preHash[32:40], t)
copy(preHash[40:56], rdm)
copy(preHash[40:56], front)
h := sha256.New()
h.Write(preHash)
ret := make([]byte, 32)
copy(ret[0:16], rdm)
copy(ret[0:16], front)
copy(ret[16:32], h.Sum(nil)[0:16])
return ret
}
func MakeSessionTicket(sta *State) []byte {
// sessionTicket: [marshalled ephemeral pub key 32 bytes][encrypted UID+sessionID 20 bytes, proxy method 16 bytes, encryption method 1 byte, sessionKey 32 bytes][16 bytes authentication tag][padding 75 bytes]
// sessionTicket: [marshalled ephemeral pub key 32 bytes][encrypted UID 16 bytes, proxy method 16 bytes, encryption method 1 byte][16 bytes authentication tag][padding 111 bytes]
// The first 12 bytes of the marshalled ephemeral public key is used as the nonce
// for encrypting the UID
tthInterval := sta.Now().Unix() / int64(sta.TicketTimeHint)
sta.keyPairsM.Lock()
ephKP := sta.keyPairs[tthInterval]
if ephKP == nil {
ephPv, ephPub, _ := ecdh.GenerateKey(rand.Reader)
ephKP = &keyPair{
ephPv,
ephPub,
}
sta.keyPairs[tthInterval] = ephKP
}
sta.keyPairsM.Unlock()
ticket := make([]byte, 192)
copy(ticket[0:32], ecdh.Marshal(ephKP.PublicKey))
key := ecdh.GenerateSharedSecret(ephKP.PrivateKey, sta.staticPub)
plain := make([]byte, 69)
//TODO: error when the interval has expired
ephPub, intervalKey, seed := sta.GetIntervalKeys()
copy(ticket[0:32], ecdh.Marshal(ephPub))
plain := make([]byte, 33)
copy(plain, sta.UID)
binary.BigEndian.PutUint32(plain[16:20], sta.sessionID)
copy(plain[20:36], []byte(sta.ProxyMethod))
plain[36] = sta.EncryptionMethod
copy(plain[37:69], sta.SessionKey)
copy(plain[16:32], []byte(sta.ProxyMethod))
plain[32] = sta.EncryptionMethod
cipher, _ := util.AESGCMEncrypt(ticket[0:12], key, plain)
copy(ticket[32:117], cipher)
cipher, _ := util.AESGCMEncrypt(ticket[0:12], intervalKey, plain)
copy(ticket[32:81], cipher)
// The purpose of adding sessionID is that, the generated padding of sessionTicket needs to be unpredictable.
// As shown in auth.go, the padding is generated by a psudo random generator. The seed
// needs to be the same for each TicketTimeHint interval. However the value of epoch/TicketTimeHint
@ -72,6 +57,6 @@ func MakeSessionTicket(sta *State) []byte {
// With the sessionID value generated at startup of ckclient and used as a part of the seed, the
// sessionTicket is still identical for each TicketTimeHint interval, but others won't be able to know
// how it was generated. It will also be different for each client.
copy(ticket[117:192], util.PsudoRandBytes(75, tthInterval+int64(sta.sessionID)))
copy(ticket[81:192], util.PsudoRandBytes(111, seed))
return ticket
}

View File

@ -2,6 +2,7 @@ package client
import (
"bytes"
"encoding/gob"
//"crypto/aes"
//"crypto/cipher"
//"crypto/rand"
@ -15,89 +16,75 @@ import (
//"github.com/cbeuw/Cloak/internal/ecdh"
)
/*
func TestMakeSessionTicket(t *testing.T) {
UID, _ := hex.DecodeString("26a8e88bcd7c64a69ca051740851d22a6818de2fddafc00882331f1c5a8b866c")
staticPv, staticPub, _ := ecdh.GenerateKey(rand.Reader)
mockSta := &State{
Now: time.Now,
sessionID: 42,
UID: UID,
staticPub: staticPub,
keyPairs: make(map[int64]*keyPair),
TicketTimeHint: 3600,
}
stateGob, _ := hex.DecodeString("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")
buf := bytes.NewBuffer(stateGob)
mockSta := &State{}
gob.NewDecoder(buf).Decode(mockSta)
mockSta.intervalData = &tthIntervalKeys{}
mockSta.intervalData.interval = 434487
ephPub, _ := hex.DecodeString("7b7e0db16bb8c83355771a424234e36c02fd752b6a9310968d27787d7c117b10")
ephPv, _ := hex.DecodeString("68584fed8ede64e2b17619b9cc0effb2678feb2face92456a8414dafa629334b")
mockSta.intervalData.intervalKey, _ = hex.DecodeString("47e1c2413f1a6b397fbd61d6cf21397b20a2338cef48fae68643602881d93d4b")
mockSta.intervalData.seed = 7518847459617826018
staticPub, _ := hex.DecodeString("218a14ce495efd3fe4ae213e51f766ec01d0b487869c159b8619536e60e95142")
var a, b, c [32]byte
copy(a[:], ephPub)
copy(b[:], ephPv)
copy(c[:], staticPub)
mockSta.intervalData.ephPub = &a
mockSta.intervalData.ephPv = &b
mockSta.staticPub = &c
target, _ := hex.DecodeString("7b7e0db16bb8c83355771a424234e36c02fd752b6a9310968d27787d7c117b103a2d246fd8b7d9e4243d6b83a7365858bd9cb583ba950287c4f4edc249cea935e235eda92c48569f455fca34ff6e4d37cf8f519b1d66e7cd51b31c1766ffb03134576e8d61ad5eae58a9ce4153ec33af73c7a8d04ab56d51155ac19fe731c792c17ee98a97fbfef8efc952964b7fd61dd2a35d7de4128abc730e20ba44e069e44ba8e29b66a8e4f114b9ab4cc2fba944a925086d7f09892a59147d990b58d393")
ticket := MakeSessionTicket(mockSta)
// verification
ephPub, _ := ecdh.Unmarshal(ticket[0:32])
key := ecdh.GenerateSharedSecret(staticPv, ephPub)
// aes decrypt
UIDsID := make([]byte, len(ticket[32:68]))
copy(UIDsID, ticket[32:68]) // Because XORKeyStream is inplace, but we don't want the input to be changed
block, _ := aes.NewCipher(key)
stream := cipher.NewCTR(block, ticket[0:16])
stream.XORKeyStream(UIDsID, UIDsID)
decryUID := UIDsID[0:32]
decrySessionID := binary.BigEndian.Uint32(UIDsID[32:36])
// check padding
tthInterval := mockSta.Now().Unix() / int64(mockSta.TicketTimeHint)
r := prand.New(prand.NewSource(tthInterval + int64(mockSta.sessionID)))
pad := make([]byte, 124)
r.Read(pad)
if !bytes.Equal(mockSta.UID, decryUID) {
if !bytes.Equal(target, ticket) {
t.Error(
"For", "UID",
"expecting", fmt.Sprintf("%x", mockSta.UID),
"got", fmt.Sprintf("%x", decryUID),
)
}
if mockSta.sessionID != decrySessionID {
t.Error(
"For", "sessionID",
"expecting", mockSta.sessionID,
"got", decrySessionID,
)
}
if !bytes.Equal(pad, ticket[68:]) {
t.Error(
"For", "Padding",
"expecting", fmt.Sprintf("%x", pad),
"got", fmt.Sprintf("%x", ticket[68:]),
"For", "sessionTicket generation",
"expecting", fmt.Sprintf("%x", target),
"got", fmt.Sprintf("%x", ticket),
)
}
}
*/
func TestMakeRandomField(t *testing.T) {
UID, _ := hex.DecodeString("26a8e88bcd7c64a69ca051740851d22a6818de2fddafc00882331f1c5a8b866c")
UID, _ := hex.DecodeString("4cd8cc15600d7eb68131fd8097673746")
mockSta := &State{
Now: time.Now,
UID: UID,
Now: time.Now,
UID: UID,
SessionID: 1,
}
random := MakeRandomField(mockSta)
// verification
tb := make([]byte, 8)
binary.BigEndian.PutUint64(tb, uint64(time.Now().Unix()/(12*60*60)))
rdm := random[0:16]
front := random[0:16]
preHash := make([]byte, 56)
copy(preHash[0:32], UID)
copy(preHash[32:40], tb)
copy(preHash[40:56], rdm)
copy(preHash[40:56], front)
h := sha256.New()
h.Write(preHash)
exp := h.Sum(nil)[0:16]
if !bytes.Equal(exp, random[16:32]) {
t.Error(
"For", "Random",
"For", "Random generation",
"expecting", fmt.Sprintf("%x", exp),
"got", fmt.Sprintf("%x", random[16:32]),
)
}
random2 := MakeRandomField(mockSta)
if bytes.Equal(random, random2) {
t.Error(
"For", "Duplicate random generation",
"expecting", "two different randoms",
"got", fmt.Sprintf("the same: %x", random),
)
}
}

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@ -2,7 +2,9 @@ package client
import (
"crypto"
"crypto/rand"
"encoding/base64"
"encoding/binary"
"encoding/json"
"errors"
"io/ioutil"
@ -24,6 +26,14 @@ type rawConfig struct {
NumConn int
}
type tthIntervalKeys struct {
interval int64
ephPv crypto.PrivateKey
ephPub crypto.PublicKey
intervalKey []byte
seed int64
}
// State stores global variables
type State struct {
LocalHost string
@ -31,13 +41,13 @@ type State struct {
RemoteHost string
RemotePort string
Now func() time.Time
sessionID uint32
SessionKey []byte
UID []byte
staticPub crypto.PublicKey
keyPairsM sync.RWMutex
keyPairs map[int64]*keyPair
Now func() time.Time
SessionID uint32
UID []byte
staticPub crypto.PublicKey
intervalDataM sync.Mutex
intervalData *tthIntervalKeys
ProxyMethod string
EncryptionMethod byte
@ -49,17 +59,36 @@ type State struct {
func InitState(localHost, localPort, remoteHost, remotePort string, nowFunc func() time.Time) *State {
ret := &State{
LocalHost: localHost,
LocalPort: localPort,
RemoteHost: remoteHost,
RemotePort: remotePort,
Now: nowFunc,
LocalHost: localHost,
LocalPort: localPort,
RemoteHost: remoteHost,
RemotePort: remotePort,
Now: nowFunc,
intervalData: &tthIntervalKeys{},
}
ret.keyPairs = make(map[int64]*keyPair)
return ret
}
func (sta *State) SetSessionID(id uint32) { sta.sessionID = id }
func (sta *State) UpdateIntervalKeys() {
sta.intervalDataM.Lock()
currentInterval := sta.Now().Unix() / int64(sta.TicketTimeHint)
if currentInterval == sta.intervalData.interval {
sta.intervalDataM.Unlock()
return
}
sta.intervalData.interval = currentInterval
ephPv, ephPub, _ := ecdh.GenerateKey(rand.Reader)
intervalKey := ecdh.GenerateSharedSecret(ephPv, sta.staticPub)
seed := int64(binary.BigEndian.Uint64(ephPv.(*[32]byte)[0:8]))
sta.intervalData.ephPv, sta.intervalData.ephPub, sta.intervalData.intervalKey, sta.intervalData.seed = ephPv, ephPub, intervalKey, seed
sta.intervalDataM.Unlock()
}
func (sta *State) GetIntervalKeys() (crypto.PublicKey, []byte, int64) {
sta.intervalDataM.Lock()
defer sta.intervalDataM.Unlock()
return sta.intervalData.ephPub, sta.intervalData.intervalKey, sta.intervalData.seed
}
// semi-colon separated value. This is for Android plugin options
func ssvToJson(ssv string) (ret []byte) {

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@ -5,37 +5,37 @@ import (
"crypto"
"crypto/sha256"
"encoding/binary"
"log"
"github.com/cbeuw/Cloak/internal/ecdh"
"github.com/cbeuw/Cloak/internal/util"
"log"
)
// input ticket, return UID
func decryptSessionTicket(staticPv crypto.PrivateKey, ticket []byte) ([]byte, uint32, string, byte, []byte) {
func decryptSessionTicket(staticPv crypto.PrivateKey, ticket []byte) (UID []byte, proxyMethod string, encryptionMethod byte, tthKey []byte) {
// sessionTicket: [marshalled ephemeral pub key 32 bytes][encrypted UID 16 bytes, proxy method 16 bytes, encryption method 1 byte][16 bytes authentication tag][padding 111 bytes]
ephPub, _ := ecdh.Unmarshal(ticket[0:32])
key := ecdh.GenerateSharedSecret(staticPv, ephPub)
plain, err := util.AESGCMDecrypt(ticket[0:12], key, ticket[32:117])
tthKey = ecdh.GenerateSharedSecret(staticPv, ephPub)
plain, err := util.AESGCMDecrypt(ticket[0:12], tthKey, ticket[32:81])
if err != nil {
return nil, 0, "", 0x00, nil
return
}
sessionID := binary.BigEndian.Uint32(plain[16:20])
return plain[0:16], sessionID, string(bytes.Trim(plain[20:36], "\x00")), plain[36], plain[37:69]
return plain[0:16], string(bytes.Trim(plain[16:32], "\x00")), plain[32], tthKey
}
func validateRandom(random []byte, UID []byte, time int64) bool {
func validateRandom(random []byte, UID []byte, time int64) (bool, uint32) {
t := make([]byte, 8)
binary.BigEndian.PutUint64(t, uint64(time/(12*60*60)))
rdm := random[0:16]
front := random[0:16]
preHash := make([]byte, 56)
copy(preHash[0:32], UID)
copy(preHash[32:40], t)
copy(preHash[40:56], rdm)
copy(preHash[40:56], front)
h := sha256.New()
h.Write(preHash)
return bytes.Equal(h.Sum(nil)[0:16], random[16:32])
sessionID := binary.BigEndian.Uint32(front[0:4])
return bytes.Equal(h.Sum(nil)[0:16], random[16:32]), sessionID
}
func TouchStone(ch *ClientHello, sta *State) (isCK bool, UID []byte, sessionID uint32, proxyMethod string, encryptionMethod byte, sessionKey []byte) {
func TouchStone(ch *ClientHello, sta *State) (isCK bool, UID []byte, sessionID uint32, proxyMethod string, encryptionMethod byte, tthKey []byte) {
var random [32]byte
copy(random[:], ch.random)
@ -50,14 +50,17 @@ func TouchStone(ch *ClientHello, sta *State) (isCK bool, UID []byte, sessionID u
}
ticket := ch.extensions[[2]byte{0x00, 0x23}]
if len(ticket) < 68 {
if len(ticket) < 81 {
return
}
UID, sessionID, proxyMethod, encryptionMethod, sessionKey = decryptSessionTicket(sta.staticPv, ticket)
UID, proxyMethod, encryptionMethod, tthKey = decryptSessionTicket(sta.staticPv, ticket)
if len(UID) < 16 {
return
}
isCK = validateRandom(ch.random, UID, sta.Now().Unix())
isCK, sessionID = validateRandom(ch.random, UID, sta.Now().Unix())
if !isCK {
return
}

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@ -1,22 +1,27 @@
package server
import (
"bytes"
//"bytes"
"encoding/hex"
"fmt"
"github.com/cbeuw/Cloak/internal/ecdh"
"testing"
//"github.com/cbeuw/Cloak/internal/ecdh"
)
/*
func TestDecryptSessionTicket(t *testing.T) {
UID, _ := hex.DecodeString("26a8e88bcd7c64a69ca051740851d22a6818de2fddafc00882331f1c5a8b866c")
sessionID := uint32(42)
pvb, _ := hex.DecodeString("083794692e77b28fa2152dfee53142185fd58ea8172d3545fdeeaea97b3c597c")
UID, _ := hex.DecodeString("4cd8cc15600d7eb68131fd8097673746")
pvb, _ := hex.DecodeString("10de5a3c4a4d04efafc3e06d1506363a72bd6d053baef123e6a9a79a0c04b547")
staticPv, _ := ecdh.Unmarshal(pvb)
sessionTicket, _ := hex.DecodeString("f586223b50cada583d61dc9bf3d01cc3a45aab4b062ed6a31ead0badb87f7761aab4f9f737a1d8ff2a2aa4d50ceb808844588ee3c8fdf36c33a35ef5003e287337659c8164a7949e9e63623090763fc24d0386c8904e47bdd740e09dd9b395c72de669629c2a865ed581452d23306adf26de0c8a46ee05e3dac876f2bcd9a2de946d319498f579383d06b3e66b3aca05f533fdc5f017eeba45b42080aabd4f71151fa0dfc1b0e23be4ed3abdb47adc0d5740ca7b7689ad34426309fb6984a086")
proxyMethod := "shadowsocks"
encryptionMethod := byte(0)
tthKey, _ := hex.DecodeString("92389a9b2769e2b76514c4cb163217bed0c5500bceb4a5ade1ceae597616db23")
sessionTicket, _ := hex.DecodeString("9ee339202508b6fbe9c19988575330c547efbc27b0d072ed93c0cc265b67d826825a49211b8f86b4364b436ed5db15925774c3bec4a1776f70a17db68ba541dc4c23871d2cc1a5074b081bbe0f8b86f1c7f7749964517dcfd8830532eddc8ac707544ec04b754a133b9595ebc2af988156dbe1e4f3b89c9dc289d441cb5a15d72cc59423981d43a498292d509e5fa5c8e8bf8ee85a2e4991ae126fcd6e4d2aa1119e918c80afa2dc38bec1ef621c9c3994af43b1983c241c68e04e8043c95d74")
decryUID, decryProxyMethod, decryEncryptionMethod, decryTthKey := decryptSessionTicket(staticPv, sessionTicket)
decryUID, decrySessionID, _, _ := decryptSessionTicket(staticPv, sessionTicket)
if !bytes.Equal(decryUID, UID) {
t.Error(
"For", "UID",
@ -24,43 +29,65 @@ func TestDecryptSessionTicket(t *testing.T) {
"got", fmt.Sprintf("%x", decryUID),
)
}
if decrySessionID != sessionID {
if proxyMethod != decryProxyMethod {
t.Error(
"For", "sessionID",
"expecting", fmt.Sprintf("%x", sessionID),
"got", fmt.Sprintf("%x", decrySessionID),
"For", "proxyMethod",
"expecting", fmt.Sprintf("%x", proxyMethod),
"got", fmt.Sprintf("%x", decryProxyMethod),
)
}
if encryptionMethod != decryEncryptionMethod {
t.Error(
"For", "encryptionMethod",
"expecting", fmt.Sprintf("%x", encryptionMethod),
"got", fmt.Sprintf("%x", decryEncryptionMethod),
)
}
if !bytes.Equal(tthKey, decryTthKey) {
t.Error(
"For", "tthKey",
"expecting", fmt.Sprintf("%x", tthKey),
"got", fmt.Sprintf("%x", decryTthKey),
)
}
}
*/
func TestValidateRandom(t *testing.T) {
UID, _ := hex.DecodeString("26a8e88bcd7c64a69ca051740851d22a6818de2fddafc00882331f1c5a8b866c")
random, _ := hex.DecodeString("6274de9992a6f96a86fc35cf6644a5e7844951889a802e9531add440eabb939b")
right := validateRandom(random, UID, 1547912444)
sessionID := uint32(2422026642)
random, _ := hex.DecodeString("905d319272711946f6400db4f5028d6893f7b22659c78371c1f72386191a8ab4")
UID, _ := hex.DecodeString("4cd8cc15600d7eb68131fd8097673746")
right, decrySessionID := validateRandom(random, UID, 1564150721)
if !right {
t.Error(
"For", fmt.Sprintf("good random: %x at time %v", random, 1547912444),
"For", fmt.Sprintf("good random: %x at time %v", random, 1564150721),
"expecting", true,
"got", false,
)
}
if sessionID != decrySessionID {
t.Error(
"For", fmt.Sprintf("good random: %x at time %v", random, 1564150721),
"expecting", sessionID,
"got", decrySessionID,
)
}
replay := validateRandom(random, UID, 1547955645)
replay, _ := validateRandom(random, UID, 1764150721)
if replay {
t.Error(
"For", fmt.Sprintf("expired random: %x at time %v", random, 1547955645),
"For", fmt.Sprintf("expired random: %x at time %v", random, 1764150721),
"expecting", false,
"got", true,
)
}
random[13] = 0x42
bogus := validateRandom(random, UID, 1547912444)
bogus, _ := validateRandom(random, UID, 1564150721)
if bogus {
t.Error(
"For", fmt.Sprintf("bogus random: %x at time %v", random, 1547912444),
"For", fmt.Sprintf("bogus random: %x at time %v", random, 1564150721),
"expecting", false,
"got", true,
)