Mosquitto auth improvements (#61)

* Mention CAN-Interface name on connection error

* Rework MQTT Authentication

* use net/url package to parse URL
* Set username and password directly instead of function
* remove one useless variable layer
* client ID is now lowercase "can2mqtt"

---------

Co-authored-by: Malte Muench <[email protected]>

src/canbus.go

@@ -19,7 +19,7 @@ func canStart(canInterface string) {
 	slog.Debug("canbus: initializing CAN-Bus", "interface", canInterface)
 	bus, err = can.NewBusForInterfaceWithName(canInterface)
 	if err != nil {
-		slog.Error("canbus: error while initializing CAN-Bus", "error", err)
+		slog.Error("canbus: error while initializing CAN-Bus", "interface", canInterface, "error", err)
 		os.Exit(1)
 	}
 	slog.Info("canbus: connected to CAN")
@@ -70,4 +70,4 @@ func canPublish(frame can.Frame) {
 	if err != nil {
 		slog.Error("canbus: error while publishing CAN-Frame", "error", err)
 	}
-}
+}

src/mqtt.go

@@ -3,48 +3,44 @@ package main
 import (
 	MQTT "github.com/eclipse/paho.mqtt.golang"
 	"log/slog"
+	"net/url"
 	"os"
-	"strings"
 )
 
 var client MQTT.Client
 var user, pw string
 
 // uses the connectString to establish a connection to the MQTT
 // broker
-func mqttStart(suppliedString string) {
-	connectString := suppliedString
-	if strings.Contains(suppliedString, "@") {
-		// looks like authentication is required for this server
-		userPasswordHost := strings.TrimPrefix(suppliedString, "tcp://")
-		userPassword, host, found := strings.Cut(userPasswordHost, "@")
-		user, pw, found = strings.Cut(userPassword, ":")
-		if !found {
-			slog.Error("mqtt: missing colon(:) between username and password", "connect string", suppliedString)
-			os.Exit(1)
-		}
-		connectString = "tcp://" + host
+func mqttStart(URL string) {
+	// parse the supplied URL
+	u, err := url.Parse(URL)
+	if err != nil {
+		slog.Error("while parsing URL", "url", URL, "error", err)
+		os.Exit(1)
 	}
-	clientSettings := MQTT.NewClientOptions().AddBroker(connectString)
-	clientSettings.SetClientID("CAN2MQTT")
+
+	// create MQTT Client
+	clientSettings := MQTT.NewClientOptions().AddBroker(u.Scheme + "://" + u.Host)
+	clientSettings.SetClientID("can2mqtt")
 	clientSettings.SetDefaultPublishHandler(handleMQTT)
-	if strings.Contains(suppliedString, "@") {
-		clientSettings.SetCredentialsProvider(userPwCredProv)
+	if u.User != nil {
+		clientSettings.SetUsername(u.User.Username())
+		password, passwdSet := u.User.Password()
+		if passwdSet {
+			clientSettings.SetPassword(password)
+		}
 	}
+
 	client = MQTT.NewClient(clientSettings)
-	slog.Debug("mqtt: starting connection", "connectString", connectString)
+	slog.Debug("mqtt: starting connection", "connectString", URL)
 	if token := client.Connect(); token.Wait() && token.Error() != nil {
 		slog.Error("mqtt: could not connect to mqtt", "error", token.Error())
 		os.Exit(1)
 	}
 	slog.Info("mqtt: connected to mqtt")
 }
 
-// credentialsProvider
-func userPwCredProv() (username, password string) {
-	return user, pw
-}
-
 // subscribe to a new topic
 func mqttSubscribe(topic string) {
 	if token := client.Subscribe(topic, 0, nil); token.Wait() && token.Error() != nil {
@@ -69,4 +65,4 @@ func mqttPublish(topic string, payload []byte) {
 	token.Wait()
 	slog.Debug("mqtt: published message", "payload", payload, "topic", topic)
 	mqttSubscribe(topic)
-}
+}