Fix panic when max-age is set to zero.

Fixes #81

authority/provisioner/keystore.go

@@ -18,7 +18,7 @@ const (
 	defaultCacheJitter = 1 * time.Hour
 )
 
-var maxAgeRegex = regexp.MustCompile("max-age=([0-9]*)")
+var maxAgeRegex = regexp.MustCompile("max-age=([0-9]+)")
 
 type keyStore struct {
 	sync.RWMutex
@@ -81,13 +81,13 @@ func (ks *keyStore) reload() {
 	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 {
 	n := rand.Int63n(int64(ks.jitter))
 	age -= time.Duration(n)
-	if age < 0 {
-		age = 0
-	}
-	return age
+	return abs(age)
 }
 
 func getKeysFromJWKsURI(uri string) (jose.JSONWebKeySet, time.Duration, error) {
@@ -125,6 +125,10 @@ 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
 	default:
 		return age / 3
 	}
@@ -133,3 +137,13 @@ func getCacheJitter(age time.Duration) time.Duration {
 func getExpirationTime(age time.Duration) time.Time {
 	return time.Now().Truncate(time.Second).Add(age)
 }
+
+// abs returns the absolute value of n using the two's complement form.
+//
+// It will overflow with math.MinInt64 in the same way a branching version
+// would, this is not a problem because maxAgeRegex will block negative numbers
+// and the logic will never produce that number.
+func abs(n time.Duration) time.Duration {
+	y := n >> 63
+	return (n ^ y) - y
+}

authority/provisioner/keystore_test.go

@@ -91,6 +91,49 @@ func Test_keyStore(t *testing.T) {
 	assert.True(t, hits.Hits > 1, fmt.Sprintf("invalid number of hits: %d is not greater than 1", hits.Hits))
 }
 
+func Test_keyStore_noCache(t *testing.T) {
+	srv := generateJWKServer(2)
+	defer srv.Close()
+
+	ks, err := newKeyStore(srv.URL + "/no-cache")
+	assert.FatalError(t, err)
+	defer ks.Close()
+	ks.RLock()
+	keySet1 := ks.keySet
+	ks.RUnlock()
+	// The keys will rotate on Get.
+	// So we won't be able to find the cached ones
+	assert.Len(t, 2, keySet1.Keys)
+	assert.Len(t, 0, ks.Get(keySet1.Keys[0].KeyID))
+	assert.Len(t, 0, ks.Get(keySet1.Keys[1].KeyID))
+	assert.Len(t, 0, ks.Get("foobar"))
+
+	ks.RLock()
+	keySet2 := ks.keySet
+	ks.RUnlock()
+	if reflect.DeepEqual(keySet1, keySet2) {
+		t.Error("keyStore did not rotated")
+	}
+
+	// The keys will rotate on Get.
+	// So we won't be able to find the cached ones
+	assert.Len(t, 2, keySet2.Keys)
+	assert.Len(t, 0, ks.Get(keySet2.Keys[0].KeyID))
+	assert.Len(t, 0, ks.Get(keySet2.Keys[1].KeyID))
+	assert.Len(t, 0, ks.Get("foobar"))
+
+	// Check hits
+	resp, err := srv.Client().Get(srv.URL + "/hits")
+	assert.FatalError(t, err)
+	hits := struct {
+		Hits int `json:"hits"`
+	}{}
+	defer resp.Body.Close()
+	err = json.NewDecoder(resp.Body).Decode(&hits)
+	assert.FatalError(t, err)
+	assert.True(t, hits.Hits > 1, fmt.Sprintf("invalid number of hits: %d is not greater than 1", hits.Hits))
+}
+
 func Test_keyStore_Get(t *testing.T) {
 	srv := generateJWKServer(2)
 	defer srv.Close()
@@ -119,3 +162,31 @@ func Test_keyStore_Get(t *testing.T) {
 		})
 	}
 }
+
+func Test_abs(t *testing.T) {
+	maxInt64 := time.Duration(1<<63 - 1)
+	minInt64 := time.Duration(-1 << 63)
+	type args struct {
+		n time.Duration
+	}
+	tests := []struct {
+		name string
+		args args
+		want time.Duration
+	}{
+		{"ok", args{0}, 0},
+		{"ok", args{-time.Hour}, time.Hour},
+		{"ok", args{time.Hour}, time.Hour},
+		{"ok maxInt64", args{maxInt64}, maxInt64},
+		{"ok minInt64 + 1", args{minInt64 + 1}, maxInt64},
+		{"overflow on minInt64", args{minInt64}, minInt64},
+		{"overflow on minInt64", args{minInt64}, -minInt64},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := abs(tt.args.n); got != tt.want {
+				t.Errorf("abs() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

authority/provisioner/utils_test.go

@@ -658,7 +658,7 @@ func generateJWKServer(n int) *httptest.Server {
 		return ret
 	}
 
-	defaultKeySet := must(generateJSONWebKeySet(2))[0].(jose.JSONWebKeySet)
+	defaultKeySet := must(generateJSONWebKeySet(n))[0].(jose.JSONWebKeySet)
 	srv := httptest.NewUnstartedServer(nil)
 	srv.Config.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		hits.Hits++
@@ -670,9 +670,13 @@ func generateJWKServer(n int) *httptest.Server {
 		case "/openid-configuration", "/.well-known/openid-configuration":
 			writeJSON(w, openIDConfiguration{Issuer: "the-issuer", JWKSetURI: srv.URL + "/jwks_uri"})
 		case "/random":
-			keySet := must(generateJSONWebKeySet(2))[0].(jose.JSONWebKeySet)
+			keySet := must(generateJSONWebKeySet(n))[0].(jose.JSONWebKeySet)
 			w.Header().Add("Cache-Control", "max-age=5")
 			writeJSON(w, getPublic(keySet))
+		case "/no-cache":
+			keySet := must(generateJSONWebKeySet(n))[0].(jose.JSONWebKeySet)
+			w.Header().Add("Cache-Control", "no-cache, no-store, max-age=0, must-revalidate")
+			writeJSON(w, getPublic(keySet))
 		case "/private":
 			writeJSON(w, defaultKeySet)
 		default: