Commit fixes for MQTT

broker/mqtt/mqtt.go

@@ -5,11 +5,12 @@ package mqtt
 	This can be integrated with any broker that supports MQTT,
 	including Mosquito and AWS IoT.
 
-	TODO: Add encoding
-	Usually we'll translate Message headers over to
-	the equivalent in a broker. In MQTT we don't have that
-	and we don't want to assume data format because the whole
-	point is that it could be anything. So we'll defer for now.
+	TODO: Strip encoding?
+	Where brokers don't support headers we're actually
+	encoding the broker.Message in json to simplify usage
+	and cross broker compatibility. To actually use the
+	MQTT broker more widely on the internet we may need to
+	support stripping the encoding.
 
 	Note: Because of the way the MQTT library works, when you
 	unsubscribe from a topic it will unsubscribe all subscribers.
@@ -19,6 +20,7 @@ package mqtt
 */
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"log"
@@ -116,8 +118,8 @@ func setAddrs(addrs []string) []string {
 func newClient(addrs []string, opts broker.Options) mqtt.Client {
 	// create opts
 	cOpts := mqtt.NewClientOptions()
-	cOpts.SetAutoReconnect(true)
-	cOpts.SetClientID(fmt.Sprintf("%d-%d", rand.Intn(10), time.Now().UnixNano()))
+	cOpts.SetClientID(fmt.Sprintf("%d%d", time.Now().UnixNano(), rand.Intn(10)))
+	cOpts.SetCleanSession(false)
 
 	// setup tls
 	if opts.TLSConfig != nil {
@@ -157,13 +159,21 @@ func (m *mqttBroker) Address() string {
 }
 
 func (m *mqttBroker) Connect() error {
+	if m.client.IsConnected() {
+		return nil
+	}
+
 	if t := m.client.Connect(); t.Wait() && t.Error() != nil {
 		return t.Error()
 	}
+
 	return nil
 }
 
 func (m *mqttBroker) Disconnect() error {
+	if !m.client.IsConnected() {
+		return nil
+	}
 	m.client.Disconnect(0)
 	return nil
 }
@@ -183,19 +193,37 @@ func (m *mqttBroker) Init(opts ...broker.Option) error {
 }
 
 func (m *mqttBroker) Publish(topic string, msg *broker.Message, opts ...broker.PublishOption) error {
-	// TODO: Support encoding to preserve headers
-	t := m.client.Publish(topic, 0, false, msg.Body)
+	if !m.client.IsConnected() {
+		return errors.New("not connected")
+	}
+
+	b, err := json.Marshal(msg)
+	if err != nil {
+		return err
+	}
+
+	t := m.client.Publish(topic, 1, false, b)
 	return t.Error()
 }
 
 func (m *mqttBroker) Subscribe(topic string, h broker.Handler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	if !m.client.IsConnected() {
+		return nil, errors.New("not connected")
+	}
+
 	var options broker.SubscribeOptions
 	for _, o := range opts {
 		o(&options)
 	}
 
-	t := m.client.Subscribe(topic, 0, func(c mqtt.Client, m mqtt.Message) {
-		if err := h(&mqttPub{msg: m}); err != nil {
+	t := m.client.Subscribe(topic, 1, func(c mqtt.Client, m mqtt.Message) {
+		var msg *broker.Message
+		if err := json.Unmarshal(m.Payload(), &msg); err != nil {
+			log.Println(err)
+			return
+		}
+
+		if err := h(&mqttPub{topic: topic, msg: msg}); err != nil {
 			log.Println(err)
 		}
 	})