remove DNS lookups from IPv6 check, close the connection

log ipv6 availability logic

more debugging for ipv6 availability checks

more debugging for ipv6 availability checks

internal/clientinfo/mdns.go

@@ -102,11 +102,14 @@ func (m *mdns) init(quitCh chan struct{}) error {
 			v4ConnList = append(v4ConnList, conn)
 			go m.readLoop(conn)
 		}
+		ctrld.ProxyLogger.Load().Debug().Msgf("checking for IPv6 availability in mdns init")
 		if ctrldnet.IPv6Available(context.Background()) {
 			if conn, err := net.ListenMulticastUDP("udp6", &iface, mdnsV6Addr); err == nil {
 				v6ConnList = append(v6ConnList, conn)
 				go m.readLoop(conn)
 			}
+		} else {
+			ctrld.ProxyLogger.Load().Debug().Msgf("IPv6 is not available in mdns init")
 		}
 	}
 

internal/net/net.go

@@ -49,8 +49,12 @@ func init() {
 }
 
 func supportIPv6(ctx context.Context) bool {
-	_, err := probeStackDialer.DialContext(ctx, "tcp6", net.JoinHostPort(controldIPv6Test, "443"))
-	return err == nil
+	c, err := probeStackDialer.DialContext(ctx, "tcp6", v6BootstrapDNS)
+	if err != nil {
+		return false
+	}
+	c.Close()
+	return true
 }
 
 func supportListenIPv6Local() bool {