Fix most known data races (#396)

This change fixes all of the known data races that `make smoke-docker-race` finds, except for one.

Most of these races are around the handshake phase for a hostinfo, so we add a RWLock to the hostinfo and Lock during each of the handshake stages.

Some of the other races are around consistently using `atomic` around the `messageCounter` field. To make this harder to mess up, I have renamed the field to `atomicMessageCounter` (I also removed the unnecessary extra pointer deference as we can just point directly to the struct field).

The last remaining data race is around reading `ConnectionInfo.ready`, which is a boolean that is only written to once when the handshake has finished. Due to it being in the hot path for packets and the rare case that this could actually be an issue, holding off on fixing that one for now.

here is the results of `make smoke-docker-race`:

before:

    lighthouse1: Found 2 data race(s)
    host2:       Found 36 data race(s)
    host3:       Found 17 data race(s)
    host4:       Found 31 data race(s)

after:

    host2: Found 1 data race(s)
    host4: Found 1 data race(s)

Fixes: #147
Fixes: #226
Fixes: #283
Fixes: #316

hostmap.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/rcrowley/go-metrics"
@@ -35,6 +36,8 @@ type HostMap struct {
 }
 
 type HostInfo struct {
+	sync.RWMutex
+
 	remote            *udpAddr
 	Remotes           []*HostInfoDest
 	promoteCounter    uint32
@@ -231,6 +234,9 @@ func (hm *HostMap) DeleteIndex(index uint32) {
 	hm.Lock()
 	hostinfo, ok := hm.Indexes[index]
 	if ok {
+		hostinfo.Lock()
+		defer hostinfo.Unlock()
+
 		delete(hm.Indexes, index)
 		delete(hm.RemoteIndexes, hostinfo.remoteIndexId)
 
@@ -513,8 +519,7 @@ func (i *HostInfo) TryPromoteBest(preferredRanges []*net.IPNet, ifce *Interface)
 		return
 	}
 
-	i.promoteCounter++
-	if i.promoteCounter%PromoteEvery == 0 {
+	if atomic.AddUint32(&i.promoteCounter, 1)&PromoteEvery == 0 {
 		// return early if we are already on a preferred remote
 		rIP := udp2ip(i.remote)
 		for _, l := range preferredRanges {
@@ -615,10 +620,12 @@ func (i *HostInfo) cachePacket(t NebulaMessageType, st NebulaMessageSubType, pac
 		copy(tempPacket, packet)
 		//l.WithField("trace", string(debug.Stack())).Error("Caching packet", tempPacket)
 		i.packetStore = append(i.packetStore, &cachedPacket{t, st, f, tempPacket})
-		i.logger().
-			WithField("length", len(i.packetStore)).
-			WithField("stored", true).
-			Debugf("Packet store")
+		if l.Level >= logrus.DebugLevel {
+			i.logger().
+				WithField("length", len(i.packetStore)).
+				WithField("stored", true).
+				Debugf("Packet store")
+		}
 
 	} else if l.Level >= logrus.DebugLevel {
 		i.logger().
@@ -638,7 +645,7 @@ func (i *HostInfo) handshakeComplete() {
 	i.HandshakeComplete = true
 	//TODO: this should be managed by the handshake state machine to set it based on how many handshake were seen.
 	// Clamping it to 2 gets us out of the woods for now
-	*i.ConnectionState.messageCounter = 2
+	atomic.StoreUint64(&i.ConnectionState.atomicMessageCounter, 2)
 	i.logger().Debugf("Sending %d stored packets", len(i.packetStore))
 	nb := make([]byte, 12, 12)
 	out := make([]byte, mtu)