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listener.go
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listener.go
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package mqtt
import (
"context"
"encoding/json"
"errors"
"fmt"
"github.com/eclipse/paho.golang/autopaho"
"github.com/eclipse/paho.golang/paho"
"github.com/thoughtworks/maeve-csms/manager/transport"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/codes"
"go.opentelemetry.io/otel/propagation"
semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
"go.opentelemetry.io/otel/trace"
"go.opentelemetry.io/otel/trace/noop"
"golang.org/x/exp/slog"
"math/rand"
"net/url"
"strings"
"time"
)
type Listener struct {
connectionDetails
mqttGroup string
tracer trace.Tracer
}
func NewListener(opts ...Opt[Listener]) *Listener {
l := new(Listener)
for _, opt := range opts {
opt(l)
}
ensureListenerDefaults(l)
return l
}
func ensureListenerDefaults(l *Listener) {
if l.mqttBrokerUrls == nil {
u, err := url.Parse("mqtt://127.0.0.1:1883/")
if err != nil {
panic(err)
}
l.mqttBrokerUrls = []*url.URL{u}
}
if l.mqttPrefix == "" {
l.mqttPrefix = "cs"
}
if l.mqttGroup == "" {
l.mqttGroup = "manager"
}
if l.mqttConnectTimeout == 0 {
l.mqttConnectTimeout = 10 * time.Second
}
if l.mqttConnectRetryDelay == 0 {
l.mqttConnectRetryDelay = 1 * time.Second
}
if l.mqttKeepAliveInterval == 0 {
l.mqttKeepAliveInterval = 10
}
if l.tracer == nil {
l.tracer = noop.NewTracerProvider().Tracer("")
}
}
func (l *Listener) Connect(ctx context.Context, ocppVersion transport.OcppVersion, chargeStationId *string, handler transport.MessageHandler) (transport.Connection, error) {
var err error
ctx, cancel := context.WithTimeout(ctx, l.mqttConnectTimeout)
defer cancel()
clientId := fmt.Sprintf("%s-%s", l.mqttGroup, randSeq(5))
readyCh := make(chan struct{})
var topic string
if chargeStationId != nil {
topic = fmt.Sprintf("%s/in/%s/%s", l.mqttPrefix, ocppVersion, *chargeStationId)
} else {
topic = fmt.Sprintf("$share/%s/%s/in/%s/#", l.mqttGroup, l.mqttPrefix, ocppVersion)
}
conn := new(connection)
mqttRouter := paho.NewStandardRouter()
conn.mqttConn, err = autopaho.NewConnection(context.Background(), autopaho.ClientConfig{
BrokerUrls: l.mqttBrokerUrls,
KeepAlive: l.mqttKeepAliveInterval,
ConnectRetryDelay: l.mqttConnectRetryDelay,
OnConnectionUp: func(manager *autopaho.ConnectionManager, connack *paho.Connack) {
_, err := manager.Subscribe(ctx, &paho.Subscribe{
Subscriptions: map[string]paho.SubscribeOptions{
topic: {},
},
})
if err != nil {
slog.Error("failed to subscribe to topic", "topic", topic)
return
}
mqttRouter.UnregisterHandler(topic)
mqttRouter.RegisterHandler(topic, func(mqttMsg *paho.Publish) {
ctx := context.Background()
// extract trace id
if mqttMsg.Properties != nil && mqttMsg.Properties.CorrelationData != nil {
correlationMap := make(map[string]string)
err := json.Unmarshal(mqttMsg.Properties.CorrelationData, &correlationMap)
if err != nil {
slog.Warn("failed to unmarshal correlation data", "error", err)
} else {
ctx = otel.GetTextMapPropagator().Extract(ctx, propagation.MapCarrier(correlationMap))
}
}
// create span
newCtx, span := l.tracer.Start(ctx,
fmt.Sprintf("%s receive", getTopicPattern(mqttMsg.Topic)),
trace.WithSpanKind(trace.SpanKindConsumer),
trace.WithAttributes(
semconv.MessagingSystem("mqtt"),
semconv.MessagingConsumerID(clientId),
semconv.MessagingMessagePayloadSizeBytes(len(mqttMsg.Payload)),
semconv.MessagingOperationKey.String("receive"),
))
defer span.End()
// determine charge station id
topicParts := strings.Split(mqttMsg.Topic, "/")
var chargeStationId = topicParts[len(topicParts)-1]
// unmarshal the message
var msg transport.Message
err := json.Unmarshal(mqttMsg.Payload, &msg)
if err != nil {
span.RecordError(err)
span.SetStatus(codes.Error, "unable to unmarshal message")
slog.Warn("unable to unmarshal message", "err", err)
return
}
// add additional span attributes
version, _ := strings.CutPrefix(string(ocppVersion), "ocpp")
span.SetAttributes(
attribute.String("csId", chargeStationId),
attribute.String("ocpp.version", version),
attribute.String(fmt.Sprintf("%s.action", msg.MessageType), msg.Action),
semconv.MessagingMessageConversationID(msg.MessageId),
)
if msg.MessageType == transport.MessageTypeCallError {
span.SetAttributes(
attribute.String(fmt.Sprintf("%s.code", msg.MessageType), string(msg.ErrorCode)),
attribute.String(fmt.Sprintf("%s.description", msg.MessageType), msg.ErrorDescription))
}
// execute the handler
handler.Handle(newCtx, chargeStationId, &msg)
})
readyCh <- struct{}{}
},
ClientConfig: paho.ClientConfig{
ClientID: clientId,
Router: mqttRouter,
},
})
if err != nil {
return nil, err
}
select {
case <-ctx.Done():
return nil, errors.New("timeout waiting for mqtt connectionDetails setup")
case <-readyCh:
return conn, nil
}
}
type connection struct {
mqttConn *autopaho.ConnectionManager
}
func (c *connection) Disconnect(ctx context.Context) error {
if c.mqttConn != nil {
err := c.mqttConn.Disconnect(ctx)
if err != nil {
return err
}
c.mqttConn = nil
}
return nil
}
var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
func randSeq(n int) string {
b := make([]rune, n)
for i := range b {
//#nosec G404 - client suffix does not require secure random number generator
b[i] = letters[rand.Intn(len(letters))]
}
return string(b)
}
func getTopicPattern(topic string) string {
parts := strings.Split(topic, "/")
parts[len(parts)-1] = "#"
return strings.Join(parts, "/")
}