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).

handshake_manager.go

@@ -31,6 +31,8 @@ type HandshakeConfig struct {
 	tryInterval  time.Duration
 	retries      int
 	waitRotation int
+
+	messageMetrics *MessageMetrics
 }
 
 type HandshakeManager struct {
@@ -42,6 +44,8 @@ type HandshakeManager struct {
 
 	OutboundHandshakeTimer *SystemTimerWheel
 	InboundHandshakeTimer  *SystemTimerWheel
+
+	messageMetrics *MessageMetrics
 }
 
 func NewHandshakeManager(tunCidr *net.IPNet, preferredRanges []*net.IPNet, mainHostMap *HostMap, lightHouse *LightHouse, outside *udpConn, config HandshakeConfig) *HandshakeManager {
@@ -55,6 +59,8 @@ func NewHandshakeManager(tunCidr *net.IPNet, preferredRanges []*net.IPNet, mainH
 
 		OutboundHandshakeTimer: NewSystemTimerWheel(config.tryInterval, config.tryInterval*time.Duration(config.retries)),
 		InboundHandshakeTimer:  NewSystemTimerWheel(config.tryInterval, config.tryInterval*time.Duration(config.retries)),
+
+		messageMetrics: config.messageMetrics,
 	}
 }
 
@@ -111,6 +117,7 @@ func (c *HandshakeManager) NextOutboundHandshakeTimerTick(now time.Time, f EncWr
 
 			// Ensure the handshake is ready to avoid a race in timer tick and stage 0 handshake generation
 			if hostinfo.HandshakeReady && hostinfo.remote != nil {
+				c.messageMetrics.Tx(handshake, NebulaMessageSubType(hostinfo.HandshakePacket[0][1]), 1)
 				err := c.outside.WriteTo(hostinfo.HandshakePacket[0], hostinfo.remote)
 				if err != nil {
 					hostinfo.logger().WithField("udpAddr", hostinfo.remote).