fix: lock subscription before closing it

waku/v2/node/wakunode2.go

@@ -41,10 +41,11 @@ type MessagePair struct {
 }
 
 type Subscription struct {
-	C      chan *protocol.WakuMessage
-	closed bool
-	mutex  sync.Mutex
-	quit   chan struct{}
+	C               chan *protocol.WakuMessage
+	closed          bool
+	mutex           sync.Mutex
+	pubSubscription *pubsub.Subscription
+	quit            chan struct{}
 }
 
 type WakuNode struct {
@@ -175,6 +176,7 @@ func (node *WakuNode) Subscribe(topic *Topic) (*Subscription, error) {
 
 	subscription := new(Subscription)
 	subscription.closed = false
+	subscription.pubSubscription = sub
 	subscription.C = make(chan *protocol.WakuMessage)
 	subscription.quit = make(chan struct{})
 
@@ -182,6 +184,8 @@ func (node *WakuNode) Subscribe(topic *Topic) (*Subscription, error) {
 		for {
 			select {
 			case <-subscription.quit:
+				subscription.mutex.Lock()
+				defer subscription.mutex.Unlock()
 				close(subscription.C)
 				subscription.closed = true
 				return
@@ -215,6 +219,12 @@ func (subs *Subscription) Unsubscribe() {
 	}
 }
 
+func (subs *Subscription) IsClosed() bool {
+	subs.mutex.Lock()
+	defer subs.mutex.Unlock()
+	return subs.closed
+}
+
 func (node *WakuNode) upsertTopic(topic *Topic) (*pubsub.Topic, error) {
 	defer node.topicsLock.Unlock()
 	node.topicsLock.Lock()