Fix race between punchback and lighthouse handler reset (#566)

CHANGELOG.md

@@ -45,6 +45,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   will immediately switch to a preferred remote address after the reception of
   a handshake packet (instead of waiting until 1,000 packets have been sent).
   (#532)
+  
+- A race condition when `punchy.respond` is enabled and ensures the correct
+  vpn ip is sent a punch back response in highly queried node. (#566)
 
 ## [1.4.0] - 2021-05-11
 

lighthouse.go

@@ -632,15 +632,16 @@ func (lhh *LightHouseHandler) handleHostPunchNotification(n *NebulaMeta, vpnIp i
 	// of a double nat or other difficult scenario, this may help establish
 	// a tunnel.
 	if lhh.lh.punchBack {
+		queryVpnIp := iputil.VpnIp(n.Details.VpnIp)
 		go func() {
 			time.Sleep(time.Second * 5)
 			if lhh.l.Level >= logrus.DebugLevel {
-				lhh.l.Debugf("Sending a nebula test packet to vpn ip %s", iputil.VpnIp(n.Details.VpnIp))
+				lhh.l.Debugf("Sending a nebula test packet to vpn ip %s", queryVpnIp)
 			}
 			//NOTE: we have to allocate a new output buffer here since we are spawning a new goroutine
 			// for each punchBack packet. We should move this into a timerwheel or a single goroutine
 			// managed by a channel.
-			w.SendMessageToVpnIp(header.Test, header.TestRequest, iputil.VpnIp(n.Details.VpnIp), []byte(""), make([]byte, 12, 12), make([]byte, mtu))
+			w.SendMessageToVpnIp(header.Test, header.TestRequest, queryVpnIp, []byte(""), make([]byte, 12, 12), make([]byte, mtu))
 		}()
 	}
 }