Replace hard-coded 4 with const for channel size

server/mdns_client.go

@@ -16,6 +16,7 @@ const (
 	// TODO: introduce caching so we don't have to wait this long on every call.
 	mDNSTimeout = 250 * time.Millisecond
 	MaxDuration = time.Duration(math.MaxInt64)
+	ChannelSize = 16
 )
 
 var (
@@ -88,7 +89,7 @@ func (c *MDNSClient) Start(ifi *net.Interface) error {
 	c.server = &dns.Server{Listener: nil, PacketConn: multicast, Handler: dns.HandlerFunc(handleMDNS)}
 	go c.server.ActivateAndServe()
 
-	queryChan := make(chan *MDNSInteraction, 4)
+	queryChan := make(chan *MDNSInteraction, ChannelSize)
 	c.queryChan = queryChan
 	go c.queryLoop(queryChan)
 

server/server.go

@@ -57,7 +57,7 @@ func queryHandler(zone Zone, mdnsClient *MDNSClient) dns.HandlerFunc {
 		} else {
 			log.Printf("Failed lookup for %s; sending mDNS query", q.Name)
 			// We don't know the answer; see if someone else does
-			channel := make(chan *ResponseA, 4)
+			channel := make(chan *ResponseA, ChannelSize)
 			replies := make([]net.IP, 0)
 			go func() {
 				// Loop terminates when channel is closed by MDNSClient on timeout