tor: remove Onion Service upon shutdown

This commit adds a new method to call DEL_ONION when lnd is shutting
down. Tor controller will now be aware of the active serviceID and
removes the service upon shutdown.

tor/cmd_onion.go

@@ -244,6 +244,9 @@ func (c *Controller) AddOnion(cfg AddOnionConfig) (*OnionAddr, error) {
 		}
 	}
 
+	c.activeServiceID = serviceID
+	log.Debugf("serviceID:%s added to tor controller", serviceID)
+
 	// Finally, we'll return the onion address composed of the service ID,
 	// along with the onion suffix, and the port this onion service can be
 	// reached at externally.
@@ -252,3 +255,47 @@ func (c *Controller) AddOnion(cfg AddOnionConfig) (*OnionAddr, error) {
 		Port:         cfg.VirtualPort,
 	}, nil
 }
+
+// DelOnion tells the Tor daemon to remove an onion service, which satisfies
+// either,
+//   - the onion service was created on the same control connection as the
+//     "DEL_ONION" command.
+//   - the onion service was created using the "Detach" flag.
+func (c *Controller) DelOnion(serviceID string) error {
+	log.Debugf("removing serviceID:%s from tor controller", serviceID)
+
+	cmd := fmt.Sprintf("DEL_ONION %s", serviceID)
+
+	// Send the command to create the onion service to the Tor server and
+	// await its response.
+	code, _, err := c.sendCommand(cmd)
+
+	// Tor replies with "250 OK" on success, or a 512 if there are an
+	// invalid number of arguments, or a 552 if it doesn't recognize the
+	// ServiceID.
+	switch code {
+	// Replied 250 OK.
+	case success:
+		return nil
+
+	// Replied 512 for invalid arguments. This is most likely that the
+	// serviceID is not set(empty string).
+	case invalidNumOfArguments:
+		return fmt.Errorf("invalid arguments: %w", err)
+
+	// Replied 552, which means either,
+	//   - the serviceID is invalid.
+	//   - the onion service is not owned by the current control connection
+	//     and,
+	//   - the onion service is not a detached service.
+	// In either case, we will ignore the error and log a warning as there
+	// not much we can do from the controller side.
+	case serviceIDNotRecognized:
+		log.Warnf("removing serviceID:%v not found", serviceID)
+		return nil
+
+	default:
+		return fmt.Errorf("undefined response code: %v, err: %w",
+			code, err)
+	}
+}

tor/controller.go

@@ -20,6 +20,14 @@ const (
 	// request.
 	success = 250
 
+	// invalidNumOfArguments is the Tor Control response code representing
+	// there being an invalid number of arguments.
+	invalidNumOfArguments = 512
+
+	// serviceIDNotRecognized is the Tor Control response code representing
+	// the specified ServiceID is not recognized.
+	serviceIDNotRecognized = 552
+
 	// nonceLen is the length of a nonce generated by either the controller
 	// or the Tor server
 	nonceLen = 32
@@ -100,6 +108,9 @@ type Controller struct {
 	// to connect to the LND node.  This is required when the Tor server
 	// runs on another host, otherwise the service will not be reachable.
 	targetIPAddress string
+
+	// activeServiceID is the Onion ServiceID created by ADD_ONION.
+	activeServiceID string
 }
 
 // NewController returns a new Tor controller that will be able to interact with
@@ -142,6 +153,15 @@ func (c *Controller) Stop() error {
 
 	log.Info("Stopping tor controller")
 
+	// Remove the onion service.
+	if err := c.DelOnion(c.activeServiceID); err != nil {
+		log.Errorf("DEL_ONION got error: %v", err)
+		return err
+	}
+
+	// Reset service ID.
+	c.activeServiceID = ""
+
 	return c.conn.Close()
 }