certificates/authority/provisioner/keystore.go

148 lines
3.2 KiB
Go
Raw Normal View History

package provisioner
import (
"encoding/json"
"math/rand"
"net/http"
"regexp"
"strconv"
"sync"
"time"
"github.com/pkg/errors"
"github.com/smallstep/cli/jose"
)
const (
defaultCacheAge = 12 * time.Hour
defaultCacheJitter = 1 * time.Hour
)
var maxAgeRegex = regexp.MustCompile("max-age=([0-9]+)")
type keyStore struct {
sync.RWMutex
uri string
2019-03-08 20:19:44 +00:00
keySet jose.JSONWebKeySet
timer *time.Timer
expiry time.Time
2019-03-08 23:08:18 +00:00
jitter time.Duration
}
func newKeyStore(uri string) (*keyStore, error) {
keys, age, err := getKeysFromJWKsURI(uri)
if err != nil {
return nil, err
}
ks := &keyStore{
uri: uri,
2019-03-08 20:19:44 +00:00
keySet: keys,
expiry: getExpirationTime(age),
2019-03-08 23:08:18 +00:00
jitter: getCacheJitter(age),
}
2019-03-08 23:08:18 +00:00
next := ks.nextReloadDuration(age)
ks.timer = time.AfterFunc(next, ks.reload)
return ks, nil
}
func (ks *keyStore) Close() {
ks.timer.Stop()
}
func (ks *keyStore) Get(kid string) (keys []jose.JSONWebKey) {
ks.RLock()
// Force reload if expiration has passed
if time.Now().After(ks.expiry) {
ks.RUnlock()
ks.reload()
ks.RLock()
}
2019-03-08 20:19:44 +00:00
keys = ks.keySet.Key(kid)
ks.RUnlock()
return
}
func (ks *keyStore) reload() {
var next time.Duration
keys, age, err := getKeysFromJWKsURI(ks.uri)
if err != nil {
2019-03-08 23:08:18 +00:00
next = ks.nextReloadDuration(ks.jitter / 2)
} else {
ks.Lock()
2019-03-08 20:19:44 +00:00
ks.keySet = keys
2019-03-08 23:08:18 +00:00
ks.expiry = getExpirationTime(age)
ks.jitter = getCacheJitter(age)
next = ks.nextReloadDuration(age)
2019-03-08 23:08:18 +00:00
ks.Unlock()
}
ks.Lock()
ks.timer.Reset(next)
ks.Unlock()
}
// nextReloadDuration would return the duration for the next rotation. If age is
// 0 it will randomly rotate between 0-12 hours, but every time we call to Get
// it will automatically rotate.
func (ks *keyStore) nextReloadDuration(age time.Duration) time.Duration {
2019-03-08 23:08:18 +00:00
n := rand.Int63n(int64(ks.jitter))
age -= time.Duration(n)
return abs(age)
}
func getKeysFromJWKsURI(uri string) (jose.JSONWebKeySet, time.Duration, error) {
var keys jose.JSONWebKeySet
resp, err := http.Get(uri)
if err != nil {
return keys, 0, errors.Wrapf(err, "failed to connect to %s", uri)
}
defer resp.Body.Close()
if err := json.NewDecoder(resp.Body).Decode(&keys); err != nil {
return keys, 0, errors.Wrapf(err, "error reading %s", uri)
}
return keys, getCacheAge(resp.Header.Get("cache-control")), nil
}
func getCacheAge(cacheControl string) time.Duration {
age := defaultCacheAge
if len(cacheControl) > 0 {
match := maxAgeRegex.FindAllStringSubmatch(cacheControl, -1)
if len(match) > 0 {
if len(match[0]) == 2 {
maxAge := match[0][1]
maxAgeInt, err := strconv.ParseInt(maxAge, 10, 64)
if err != nil {
return defaultCacheAge
}
age = time.Duration(maxAgeInt) * time.Second
}
}
}
return age
}
2019-03-08 23:08:18 +00:00
func getCacheJitter(age time.Duration) time.Duration {
switch {
case age > time.Hour:
return defaultCacheJitter
case age == 0:
// Avoids a 0 jitter. The duration is not important as it will rotate
// automatically on each Get request.
return defaultCacheJitter
2019-03-08 23:08:18 +00:00
default:
return age / 3
}
}
func getExpirationTime(age time.Duration) time.Time {
return time.Now().Truncate(time.Second).Add(age)
}
2019-06-25 18:04:48 +00:00
// abs returns the absolute value of n.
func abs(n time.Duration) time.Duration {
2019-06-25 18:04:48 +00:00
if n < 0 {
return -n
}
return n
}