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Change how timestamp's validity is checked

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This commit is contained in:
Qian Wang 2019-08-08 15:05:36 +01:00
parent fc9f227ccf
commit 82fe177c24
2 changed files with 10 additions and 9 deletions
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5
internal/server/auth.go
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@ -7,6 +7,7 @@ import (
"fmt"
"github.com/cbeuw/Cloak/internal/ecdh"
"github.com/cbeuw/Cloak/internal/util"
"time"
)
var ErrReplay = errors.New("duplicate random")
@ -50,7 +51,9 @@ func TouchStone(ch *ClientHello, sta *State) (UID []byte, sessionID uint32, prox
proxyMethod = string(bytes.Trim(plaintext[16:28], "\x00"))
encryptionMethod = plaintext[28]
timestamp := int64(binary.BigEndian.Uint64(plaintext[29:37]))
if timestamp/int64(TIMESTAMP_WINDOW.Seconds()) != sta.Now().Unix()/int64(TIMESTAMP_WINDOW.Seconds()) {
clientTime := time.Unix(timestamp, 0)
serverTime := sta.Now()
if !(clientTime.After(serverTime.Truncate(TIMESTAMP_TOLERANCE)) && clientTime.Before(serverTime.Add(TIMESTAMP_TOLERANCE))) {
err = fmt.Errorf("%v: received timestamp %v", ErrTimestampOutOfWindow, timestamp)
return
}

14
internal/server/state.go
View File

@ -121,20 +121,18 @@ func (sta *State) IsBypass(UID []byte) bool {
return exist
}
// This is the accepting window of the encrypted timestamp from client
// we reject the client if the timestamp is outside of this window.
// This is for replay prevention so that we don't have to save unlimited amount of
// random
const TIMESTAMP_WINDOW = 12 * time.Hour
const TIMESTAMP_TOLERANCE = 180 * time.Second
const CACHE_CLEAN_INTERVAL = 12 * time.Hour
// UsedRandomCleaner clears the cache of used random fields every 12 hours
func (sta *State) UsedRandomCleaner() {
for {
time.Sleep(TIMESTAMP_WINDOW)
now := sta.Now().Unix()
time.Sleep(CACHE_CLEAN_INTERVAL)
now := sta.Now()
sta.usedRandomM.Lock()
for key, t := range sta.usedRandom {
if now-t > int64(TIMESTAMP_WINDOW.Seconds()) {
if time.Unix(t, 0).Before(now.Add(TIMESTAMP_TOLERANCE)) {
delete(sta.usedRandom, key)
}
}