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package standardstek
import (
"log"
"sync"
"time"
"github.com/caddyserver/caddy"
"github.com/caddyserver/caddy/modules/caddytls"
)
func init() {
caddy.RegisterModule(caddy.Module{
Name: "tls.stek.standard",
New: func() interface{} { return new(standardSTEKProvider) },
})
}
type standardSTEKProvider struct {
stekConfig *caddytls.SessionTicketService
timer *time.Timer
}
// Initialize sets the configuration for s and returns the starting keys.
func (s *standardSTEKProvider) Initialize(config *caddytls.SessionTicketService) ([][32]byte, error) {
// keep a reference to the config; we'll need it when rotating keys
s.stekConfig = config
itvl := time.Duration(s.stekConfig.RotationInterval)
mutex.Lock()
defer mutex.Unlock()
// if this is our first rotation or we are overdue
// for one, perform a rotation immediately; otherwise,
// we assume that the keys are non-empty and fresh
since := time.Since(lastRotation)
if lastRotation.IsZero() || since > itvl {
var err error
keys, err = s.stekConfig.RotateSTEKs(keys)
if err != nil {
return nil, err
}
since = 0 // since this is overdue or is the first rotation, use full interval
lastRotation = time.Now()
}
// create timer for the remaining time on the interval;
// this timer is cleaned up only when Next() returns
s.timer = time.NewTimer(itvl - since)
return keys, nil
}
// Next returns a channel which transmits the latest session ticket keys.
func (s *standardSTEKProvider) Next(doneChan <-chan struct{}) <-chan [][32]byte {
keysChan := make(chan [][32]byte)
go s.rotate(doneChan, keysChan)
return keysChan
}
// rotate rotates keys on a regular basis, sending each updated set of
// keys down keysChan, until doneChan is closed.
func (s *standardSTEKProvider) rotate(doneChan <-chan struct{}, keysChan chan<- [][32]byte) {
for {
select {
case now := <-s.timer.C:
// copy the slice header to avoid races
mutex.RLock()
keysCopy := keys
mutex.RUnlock()
// generate a new key, rotating old ones
var err error
keysCopy, err = s.stekConfig.RotateSTEKs(keysCopy)
if err != nil {
// TODO: improve this handling
log.Printf("[ERROR] Generating STEK: %v", err)
continue
}
// replace keys slice with updated value and
// record the timestamp of rotation
mutex.Lock()
keys = keysCopy
lastRotation = now
mutex.Unlock()
// send the updated keys to the service
keysChan <- keysCopy
// timer channel is already drained, so reset directly (see godoc)
s.timer.Reset(time.Duration(s.stekConfig.RotationInterval))
case <-doneChan:
// again, see godocs for why timer is stopped this way
if !s.timer.Stop() {
<-s.timer.C
}
return
}
}
}
var (
lastRotation time.Time
keys [][32]byte
mutex sync.RWMutex // protects keys and lastRotation
)
// Interface guard
var _ caddytls.STEKProvider = (*standardSTEKProvider)(nil)
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