add meta packet statistics (#230)

This change add more metrics around "meta" (non "message" type packets).
For lighthouse packets, we also record statistics around the specific
lighthouse meta type.

We don't keep statistics for the "message" type so that we don't slow
down the fast path (and you can just look at metrics on the tun
interface to find that information).

main.go

@@ -172,6 +172,7 @@ func Main(configPath string, configTest bool, buildVersion string) {
 	hostMap := NewHostMap("main", tunCidr, preferredRanges)
 	hostMap.SetDefaultRoute(ip2int(net.ParseIP(config.GetString("default_route", "0.0.0.0"))))
 	hostMap.addUnsafeRoutes(&unsafeRoutes)
+	hostMap.metricsEnabled = config.GetBool("stats.message_metrics", false)
 
 	l.WithField("network", hostMap.vpnCIDR).WithField("preferredRanges", hostMap.preferredRanges).Info("Main HostMap created")
 
@@ -226,6 +227,7 @@ func Main(configPath string, configTest bool, buildVersion string) {
 		udpServer,
 		punchy.Respond,
 		punchy.Delay,
+		config.GetBool("stats.lighthouse_metrics", false),
 	)
 
 	remoteAllowList, err := config.GetAllowList("lighthouse.remote_allow_list", false)
@@ -280,10 +282,19 @@ func Main(configPath string, configTest bool, buildVersion string) {
 		l.WithError(err).Error("Lighthouse unreachable")
 	}
 
+	var messageMetrics *MessageMetrics
+	if config.GetBool("stats.message_metrics", false) {
+		messageMetrics = newMessageMetrics()
+	} else {
+		messageMetrics = newMessageMetricsOnlyRecvError()
+	}
+
 	handshakeConfig := HandshakeConfig{
 		tryInterval:  config.GetDuration("handshakes.try_interval", DefaultHandshakeTryInterval),
 		retries:      config.GetInt("handshakes.retries", DefaultHandshakeRetries),
 		waitRotation: config.GetInt("handshakes.wait_rotation", DefaultHandshakeWaitRotation),
+
+		messageMetrics: messageMetrics,
 	}
 
 	handshakeManager := NewHandshakeManager(tunCidr, preferredRanges, hostMap, lightHouse, udpServer, handshakeConfig)
@@ -310,6 +321,7 @@ func Main(configPath string, configTest bool, buildVersion string) {
 		DropLocalBroadcast:      config.GetBool("tun.drop_local_broadcast", false),
 		DropMulticast:           config.GetBool("tun.drop_multicast", false),
 		UDPBatchSize:            config.GetInt("listen.batch", 64),
+		MessageMetrics:          messageMetrics,
 	}
 
 	switch ifConfig.Cipher {