lbry.go/dht/token_manager.go

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package dht
import (
"bytes"
"crypto/rand"
"crypto/sha256"
"net"
"strconv"
"sync"
"time"
"github.com/lbryio/lbry.go/stopOnce"
)
type tokenManager struct {
secret []byte
prevSecret []byte
lock *sync.RWMutex
wg *sync.WaitGroup
done *stopOnce.Stopper
}
func (tm *tokenManager) Start(interval time.Duration) {
tm.secret = make([]byte, 64)
tm.prevSecret = make([]byte, 64)
tm.lock = &sync.RWMutex{}
tm.wg = &sync.WaitGroup{}
tm.done = stopOnce.New()
tm.rotateSecret()
tm.wg.Add(1)
go func() {
defer tm.wg.Done()
tick := time.NewTicker(interval)
for {
select {
case <-tick.C:
tm.rotateSecret()
case <-tm.done.Chan():
return
}
}
}()
}
func (tm *tokenManager) Stop() {
tm.done.Stop()
tm.wg.Wait()
}
func (tm *tokenManager) Get(nodeID Bitmap, addr *net.UDPAddr) string {
return genToken(tm.secret, nodeID, addr)
}
func (tm *tokenManager) Verify(token string, nodeID Bitmap, addr *net.UDPAddr) bool {
return token == genToken(tm.secret, nodeID, addr) || token == genToken(tm.prevSecret, nodeID, addr)
}
func genToken(secret []byte, nodeID Bitmap, addr *net.UDPAddr) string {
buf := bytes.Buffer{}
buf.Write(nodeID[:])
buf.Write(addr.IP)
buf.WriteString(strconv.Itoa(addr.Port))
buf.Write(secret)
t := sha256.Sum256(buf.Bytes())
return string(t[:])
}
func (tm *tokenManager) rotateSecret() {
tm.lock.Lock()
defer tm.lock.Unlock()
copy(tm.prevSecret, tm.secret)
_, err := rand.Read(tm.secret)
if err != nil {
panic(err)
}
}