Added ssl/tls support

internal/mqtt/mqtt.go

@@ -1,29 +1,37 @@
 package mqtt
 
 import (
+	"fmt"
 	"MQTTLogger/config"
 	"MQTTLogger/internal/csv"
+	"crypto/tls"
+	"math/rand/v2"
 	"time"
 
 	mqtt "github.com/eclipse/paho.mqtt.golang"
 	"go.uber.org/zap"
 )
 
-func NewClient(logger *zap.Logger, config *config.Config, csvHelper *csv.Helper) mqtt.Client {
+func NewClient(logger *zap.Logger, config *config.Config, csvHelper *csv.Helper, tlsConfig *tls.Config) mqtt.Client {
+	
 	var f mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
 		csvHelper.AddEntry(time.Now().UTC().Format("2006-01-02 15:04:05"), msg.Topic(), string(msg.Payload()))
 	}
 
-	opts := mqtt.NewClientOptions().AddBroker(config.URI).SetClientID("mqtt-logger")
+	randomClientID := "mqtt-logger-" + fmt.Sprint(rand.Int())
+	logger.Info("Creating MQTT client", zap.String("clientID", randomClientID))
+	opts := mqtt.NewClientOptions().AddBroker(config.URI).SetClientID(randomClientID)
+	if tlsConfig != nil {
+		opts.SetTLSConfig(tlsConfig)
+	}
 	opts.SetKeepAlive(2 * time.Second)
 	opts.SetDefaultPublishHandler(f)
-	opts.SetPingTimeout(1 * time.Second)
-	// TODO: Check this option and see if it solves the re-subscribe on reconnect issue
-	// opts.SetCleanSession(false)
+	opts.SetPingTimeout(1 * time.Second)	
 	opts.SetConnectionNotificationHandler(func(client mqtt.Client, notification mqtt.ConnectionNotification) {
 		switch n := notification.(type) {
 		case mqtt.ConnectionNotificationConnected:
 			logger.Info("Connected to MQTT broker")
+			// Re-susbcribe to topics on reconnect
 			StartListening(logger, config, client)
 		case mqtt.ConnectionNotificationConnecting:
 			logger.Info("connecting", zap.Bool("isReconnect", n.IsReconnect), zap.Int("attempt", n.Attempt))

internal/mqtt/tls.go

@@ -0,0 +1,34 @@
+package mqtt
+
+import (
+	"MQTTLogger/config"
+	"crypto/tls"
+	"crypto/x509"
+	"os"
+
+	"go.uber.org/zap"
+)
+
+func NewTLSConfig(logger *zap.Logger, config *config.Config) *tls.Config {
+
+	if config.CACert == "" {
+		return nil
+	}
+
+	certpool := x509.NewCertPool()
+	pemCerts, err := os.ReadFile(config.CACert)
+	if err == nil {
+		certpool.AppendCertsFromPEM(pemCerts)
+	} else {
+		logger.Fatal("error loading CA cert", zap.Error(err))
+	}
+
+	return &tls.Config{
+		RootCAs: certpool,
+		// We use the provided cert not the one server sends.
+		ClientAuth:         tls.NoClientCert,
+		ClientCAs:          nil,
+		InsecureSkipVerify: true, // I know
+		Certificates: nil,
+	}
+}