Unsubscribe surprisingly breaks previous subscribe

[rollulus]

Subscribing to /a/# works correctly.
However, if one subscribes to /a/b/# and unsubscribes from it afterwards, the earlier message handler doesn't receive anything anymore, although the broker publishes according to tcpdump.

To reproduce:

package main

import (
	"log"
	"time"

	mqtt "github.com/eclipse/paho.mqtt.golang"
)

func msgHandler(_ mqtt.Client, m mqtt.Message) {
	log.Printf("received message for topic %s: %s", m.Topic(), string(m.Payload()))
}

func main() {
	o := mqtt.NewClientOptions().AddBroker("tcp://" + "iot.eclipse.org:1883")
	c := mqtt.NewClient(o)
	if t := c.Connect(); t.Wait() && t.Error() != nil {
		panic(t.Error())
	}

	if t := c.Subscribe("/a/#", 1, msgHandler); t.Wait() && t.Error() != nil {
		panic(t.Error())
	}

	if t := c.Subscribe("/a/b/#", 1, msgHandler); t.Wait() && t.Error() != nil {
		panic(t.Error())
	}

	if t := c.Unsubscribe("/a/b/#"); t.Wait() && t.Error() != nil {
		panic(t.Error())
	}

	time.Sleep(time.Hour)
}

And publish messages from the console with:

mosquitto_pub -h iot.eclipse.org -t '/a/b/hello'   -d -m 'xxxx' -q 1
mosquitto_pub -h iot.eclipse.org -t '/a/hello'   -d -m 'xxxx' -q 1

My expectation is to receive those messages. In practice, nothing happens.

To verify that the example isn't broken itself, remove the last Subscribe and Unsubscribe.

[boki]

I think this is the same issue I ran into: router.addRoute uses route.match to update existing routes, resulting in wildcards being applied. The fix seems to be to change line 102 in route.go from

--- a/router.go
+++ b/router.go
@@ -105,7 +105,7 @@ func (r *router) addRoute(topic string, callback MessageHandler) {
        r.Lock()
        defer r.Unlock()
        for e := r.routes.Front(); e != nil; e = e.Next() {
-               if e.Value.(*route).match(topic) {
+               if e.Value.(*route).topic == topic {
                        r := e.Value.(*route)
                        r.callback = callback
                        return

[v-zhuravlev]

Had exactly the same issue with router.addRoute.
In my case, I have the client with subscriptions to #, topic1, topic2 with different callbacks set for each. Due to if e.Value.(*route).match(topic) {, new subscription overrides previous routes instead of creating new one and only last callback is working for all routes.

And in my app I expect:
If I publish something to topic1, I expect both callbacks for # and topic1 subscriptions to fire. Not just the last one.

[MattBrittan]

Closing this because a fix was committed a year ago; please feel free to reopen if its still an issue.