fix(c-bindings): simplify discv5 API

library/api_discovery.go

@@ -17,17 +17,3 @@ func waku_dns_discovery(url *C.char, nameserver *C.char, ms C.int) *C.char {
 	response := mobile.DnsDiscovery(C.GoString(url), C.GoString(nameserver), int(ms))
 	return C.CString(response)
 }
-
-// Starts DiscoveryV5 service to discover and connect to new peers
-//export waku_discv5_start
-func waku_discv5_start() *C.char {
-	response := mobile.StartDiscoveryV5()
-	return C.CString(response)
-}
-
-// Stops DiscoveryV5 service
-//export waku_discv5_stop
-func waku_discv5_stop() *C.char {
-	response := mobile.StopDiscoveryV5()
-	return C.CString(response)
-}

mobile/api.go

@@ -207,6 +207,13 @@ func Start() string {
 		return MakeJSONResponse(err)
 	}
 
+	if wakuNode.DiscV5() != nil {
+		if err := wakuNode.DiscV5().Start(context.Background()); err != nil {
+			wakuNode.Stop()
+			return MakeJSONResponse(err)
+		}
+	}
+
 	wakuStarted = true
 
 	return MakeJSONResponse(nil)

waku/v2/discv5/discover.go

@@ -209,11 +209,13 @@ func (d *DiscoveryV5) Stop() {
 
 	d.cancel()
 
-	d.listener.Close()
-	d.listener = nil
 	d.started = false
 
-	d.log.Info("stopped Discovery V5")
+	if d.listener != nil {
+		d.listener.Close()
+		d.listener = nil
+		d.log.Info("stopped Discovery V5")
+	}
 
 	d.wg.Wait()
 }