Add serial to address mappings cache to Keba listener for making simple messages routable via serial (#546)

#429 introduced a bug when KEBA was configured using serial number.

The TCH :OK messages received from KEBA could not be routed to the subscriber since they don't contain serial numbers. This PR adds a serial<->address cache to the listener for maintaining this mapping and hence make the OK responses routable.

charger/keba.go

@@ -58,8 +58,8 @@ func NewKebaFromConfig(other map[string]interface{}) (api.Charger, error) {
 func NewKeba(uri, serial string, rfid RFID, timeout time.Duration) (api.Charger, error) {
 	log := util.NewLogger("keba")
 
-	var err error
 	if keba.Instance == nil {
+		var err error
 		keba.Instance, err = keba.New(log)
 		if err != nil {
 			return nil, err
@@ -68,7 +68,7 @@ func NewKeba(uri, serial string, rfid RFID, timeout time.Duration) (api.Charger,
 
 	// add default port
 	conn := util.DefaultPort(uri, keba.Port)
-	sender, err := keba.NewSender(uri)
+	sender, err := keba.NewSender(log, conn)
 
 	c := &Keba{
 		log:     log,

charger/keba/listener.go

@@ -40,6 +40,7 @@ type Listener struct {
 	log     *util.Logger
 	conn    *net.UDPConn
 	clients map[string]chan<- UDPMsg
+	cache   map[string]string
 }
 
 // New creates a UDP listener that clients can subscribe to
@@ -58,6 +59,7 @@ func New(log *util.Logger) (*Listener, error) {
 		log:     log,
 		conn:    conn,
 		clients: make(map[string]chan<- UDPMsg),
+		cache:   make(map[string]string),
 	}
 
 	go l.listen()
@@ -65,7 +67,7 @@ func New(log *util.Logger) (*Listener, error) {
 	return l, nil
 }
 
-// Subscribe adds a client address and message channel
+// Subscribe adds a client address or serial and message channel to the list of subscribers
 func (l *Listener) Subscribe(addr string, c chan<- UDPMsg) {
 	l.mux.Lock()
 	defer l.mux.Unlock()
@@ -94,7 +96,7 @@ func (l *Listener) listen() {
 		if body != OK {
 			var report Report
 			if err := json.Unmarshal([]byte(body), &report); err != nil {
-				l.log.WARN.Printf("listener: %v", err)
+				l.log.WARN.Printf("recv: invalid message: %v", err)
 				continue
 			}
 
@@ -105,15 +107,25 @@ func (l *Listener) listen() {
 	}
 }
 
-// addrMatches checks if either message sender or serial matched given addr
+// addrMatches checks if either message sender or serial matches given addr
 func (l *Listener) addrMatches(addr string, msg UDPMsg) bool {
 	switch {
 	case addr == Any:
 		return true
+
 	case addr == msg.Addr:
 		return true
-	case msg.Report != nil && addr == msg.Report.Serial:
+
+	// simple response like TCH :OK where cached serial for sender address matches
+	case l.cache[addr] == msg.Addr:
 		return true
+
+	// report response with matching serial
+	case msg.Report != nil && addr == msg.Report.Serial:
+		// cache address for serial to make simple TCH :OK messages routable using serial
+		l.cache[msg.Report.Serial] = msg.Addr
+		return true
+
 	default:
 		return false
 	}

charger/keba/sender.go

@@ -10,11 +10,13 @@ import (
 
 // Sender is a KEBA UDP sender
 type Sender struct {
+	log  *util.Logger
+	addr string
 	conn *net.UDPConn
 }
 
 // NewSender creates KEBA UDP sender
-func NewSender(addr string) (*Sender, error) {
+func NewSender(log *util.Logger, addr string) (*Sender, error) {
 	addr = util.DefaultPort(addr, Port)
 	raddr, err := net.ResolveUDPAddr("udp", addr)
 
@@ -24,6 +26,8 @@ func NewSender(addr string) (*Sender, error) {
 	}
 
 	c := &Sender{
+		log:  log,
+		addr: addr,
 		conn: conn,
 	}
 
@@ -32,6 +36,7 @@ func NewSender(addr string) (*Sender, error) {
 
 // Send msg to receiver
 func (c *Sender) Send(msg string) error {
+	c.log.TRACE.Printf("send to %s %v", c.addr, msg)
 	_, err := io.Copy(c.conn, strings.NewReader(msg))
 	return err
 }

detect/keba.go

@@ -50,7 +50,7 @@ func (h *KEBAHandler) Test(log *util.Logger, ip string) []interface{} {
 	resC := make(chan keba.UDPMsg)
 	h.listener.Subscribe(ip, resC)
 
-	sender, err := keba.NewSender(ip)
+	sender, err := keba.NewSender(log, ip)
 	if err != nil {
 		log.ERROR.Println("keba:", err)
 		return nil