[#66501] linux-client: goroutine-safe getDeviceToken method

This commit adds a mutexed method for fetching a valid device token that
can be used instead of directly accessing the `deviceToken` field of the
`Device` structure. This allows for multiple independent goroutines to
get a valid device token safely.

devices/linux-client/daemon/device.go

@@ -36,8 +36,7 @@ const MSG_RECV_TIMEOUT_INTERVALS = 10
 const MSG_RECV_INTERVAL_S = 1
 const RSA_DEVICE_KEY_SIZE = 4096
 const MGMT_LOOP_RECOVERY_INTERVAL = 30
-
-var tokenMutex sync.Mutex
+const TOKEN_EXPIRY_MIN_ALLOWED = 5
 
 type Device struct {
 	name          string
@@ -48,6 +47,7 @@ type Device struct {
 	macAddr       string
 	rdfmCtx       *app.RDFM
 	deviceToken   string
+	tokenMutex    sync.Mutex
 	httpTransport *http.Transport
 }
 
@@ -192,12 +192,12 @@ func (d *Device) connect() error {
 	}
 
 	// Get device token
-	err = d.authenticateDeviceWithServer()
+	deviceToken, err := d.getDeviceToken()
 	if err != nil {
 		return err
 	}
 	authHeader := http.Header{
-		"Authorization": []string{"Bearer token=" + d.deviceToken},
+		"Authorization": []string{"Bearer token=" + deviceToken},
 	}
 
 	// Open a WebSocket connection
@@ -269,10 +269,33 @@ func (d *Device) managementWsLoop(done chan bool) {
 	panic(err)
 }
 
-func (d Device) getDeviceToken() string {
-	tokenMutex.Lock()
-	defer tokenMutex.Unlock()
-	return d.deviceToken
+func (d *Device) getDeviceToken() (string, error) {
+	d.tokenMutex.Lock()
+	defer d.tokenMutex.Unlock()
+
+	payload, err := netUtils.ExtractJwtPayload(d.deviceToken)
+	if err == nil {
+		// check if reauth needed in the next TOKEN_EXPIRY_MIN_ALLOWED or less seconds
+		if payload.CreatedAt+payload.Expires-TOKEN_EXPIRY_MIN_ALLOWED <= time.Now().Unix() {
+			log.Println("Device token expired, reauthenticating...")
+			err = d.authenticateDeviceWithServer()
+			if err != nil {
+				return "", err
+			}
+		} else {
+			log.Println("Device token up to date")
+		}
+	} else {
+		// extraction failed
+		log.Println("Device token missing or malformed, authenticating...")
+		err := d.authenticateDeviceWithServer()
+		if err != nil {
+			return "", err
+		}
+	}
+
+	// d.authenticateDeviceWithServer should have taken care of fetching the token if necessary
+	return d.deviceToken, nil
 }
 
 func getPublicKey(privateKey *rsa.PrivateKey) []byte {
@@ -406,8 +429,6 @@ func (d *Device) authenticateDeviceWithServer() error {
 				log.Println("Failed to deserialize package metadata", err)
 				return err
 			}
-			tokenMutex.Lock()
-			defer tokenMutex.Unlock()
 			d.deviceToken = response["token"].(string)
 			log.Println("Authorization token expires in", response["expires"], "seconds")
 			if len(d.deviceToken) == 0 {

devices/linux-client/daemon/updates.go

@@ -17,8 +17,6 @@ import (
 const MIN_RETRY_INTERVAL = 1
 const MAX_RETRY_INTERVAL = 60
 
-var NotAuthorizedError = errors.New("Device did not provide authorization data, or the authorization has expired")
-
 func (d *Device) checkUpdate() error {
 	devType, err := d.rdfmCtx.GetCurrentDeviceType()
 	if err != nil {
@@ -45,7 +43,11 @@ func (d *Device) checkUpdate() error {
 		bytes.NewBuffer(serializedMetadata),
 	)
 	req.Header.Set("Content-Type", "application/json")
-	req.Header.Add("Authorization", "Bearer token="+d.deviceToken)
+	deviceToken, err := d.getDeviceToken()
+	if err != nil {
+		return errors.New("Failed to fetch the device token: " + err.Error())
+	}
+	req.Header.Add("Authorization", "Bearer token="+deviceToken)
 
 	log.Println("Checking updates...")
 
@@ -82,7 +84,7 @@ func (d *Device) checkUpdate() error {
 	case 400:
 		return errors.New("Device metadata is missing device type and/or software version")
 	case 401:
-		return NotAuthorizedError
+		return errors.New("Device did not provide authorization data, or the authorization has expired")
 	default:
 		return errors.New("Unexpected status code from the server: " + res.Status)
 	}
@@ -92,7 +94,6 @@ func (d *Device) checkUpdate() error {
 func (d *Device) updateCheckerLoop(done chan bool) {
 	var err error
 	var info string
-	var count int
 
 	// Recover the goroutine if it panics
 	defer func() {
@@ -112,27 +113,12 @@ func (d *Device) updateCheckerLoop(done chan bool) {
 
 	for {
 		err = d.checkUpdate()
-		if err == NotAuthorizedError {
-			log.Println(err)
-			err = d.authenticateDeviceWithServer()
-			if err == nil {
-				retryInterval := count * MIN_RETRY_INTERVAL
-				if retryInterval > MAX_RETRY_INTERVAL {
-					retryInterval = MAX_RETRY_INTERVAL
-				}
-				time.Sleep(time.Duration(retryInterval) * time.Second)
-				count = (count + 1) * 2
-				continue
-			}
-			err = errors.New("Failed to autheniticate with the server: " + err.Error())
-		}
 		if err != nil {
 			log.Println("Update check failed:", err)
 		}
 		updateDuration := time.Duration(d.rdfmCtx.RdfmConfig.UpdatePollIntervalSeconds) * time.Second
 		log.Printf("Next update check in %s\n", updateDuration)
 		time.Sleep(time.Duration(updateDuration))
-		count = 0
 	}
 	panic(err)
 }