refactor: reduce coupling of nameserver to router

The nameserver no longer knows anything about router.Peers and
router.Peer. That only leaves PeerName, Gossip and GossipData.

nameserver/dns_test.go

@@ -18,7 +18,7 @@ import (
 func startServer(t *testing.T, upstream *dns.ClientConfig) (*DNSServer, *Nameserver, int, int) {
 	peername, err := router.PeerNameFromString("00:00:00:02:00:00")
 	require.Nil(t, err)
-	nameserver := New(peername, nil, "")
+	nameserver := New(peername, "", func(router.PeerName) bool { return true })
 	dnsserver, err := NewDNSServer(nameserver, "weave.local.", "0.0.0.0:0", "", 30, 5*time.Second)
 	require.Nil(t, err)
 	udpPort := dnsserver.servers[0].PacketConn.LocalAddr().(*net.UDPAddr).Port

nameserver/nameserver.go

@@ -37,25 +37,21 @@ const (
 // - Update is O(n) for now
 type Nameserver struct {
 	sync.RWMutex
-	ourName router.PeerName
-	domain  string
-	gossip  router.Gossip
-	entries Entries
-	peers   *router.Peers
-	quit    chan struct{}
+	ourName     router.PeerName
+	domain      string
+	gossip      router.Gossip
+	entries     Entries
+	isKnownPeer func(router.PeerName) bool
+	quit        chan struct{}
 }
 
-func New(ourName router.PeerName, peers *router.Peers, domain string) *Nameserver {
-	ns := &Nameserver{
-		ourName: ourName,
-		domain:  dns.Fqdn(domain),
-		peers:   peers,
-		quit:    make(chan struct{}),
+func New(ourName router.PeerName, domain string, isKnownPeer func(router.PeerName) bool) *Nameserver {
+	return &Nameserver{
+		ourName:     ourName,
+		domain:      dns.Fqdn(domain),
+		isKnownPeer: isKnownPeer,
+		quit:        make(chan struct{}),
 	}
-	if peers != nil {
-		peers.OnGC(ns.PeerGone)
-	}
-	return ns
 }
 
 func (n *Nameserver) SetGossip(gossip router.Gossip) {
@@ -147,12 +143,12 @@ func (n *Nameserver) ContainerDied(ident string) {
 	}
 }
 
-func (n *Nameserver) PeerGone(peer *router.Peer) {
+func (n *Nameserver) PeerGone(peer router.PeerName) {
 	n.infof("peer %s gone", peer.String())
 	n.Lock()
 	defer n.Unlock()
 	n.entries.filter(func(e *Entry) bool {
-		return e.Origin != peer.Name
+		return e.Origin != peer
 	})
 }
 
@@ -219,11 +215,9 @@ func (n *Nameserver) receiveGossip(msg []byte) (router.GossipData, router.Gossip
 	n.Lock()
 	defer n.Unlock()
 
-	if n.peers != nil {
-		gossip.Entries.filter(func(e *Entry) bool {
-			return n.peers.Fetch(e.Origin) != nil
-		})
-	}
+	gossip.Entries.filter(func(e *Entry) bool {
+		return n.isKnownPeer(e.Origin)
+	})
 
 	newEntries := n.entries.merge(gossip.Entries)
 	if len(newEntries) > 0 {

nameserver/nameserver_test.go

@@ -17,13 +17,17 @@ import (
 	"github.com/weaveworks/weave/testing/gossip"
 )
 
+func makeNameserver(name router.PeerName) *Nameserver {
+	return New(name, "", func(router.PeerName) bool { return true })
+}
+
 func makeNetwork(size int) ([]*Nameserver, *gossip.TestRouter) {
 	gossipRouter := gossip.NewTestRouter(0.0)
 	nameservers := make([]*Nameserver, size)
 
 	for i := 0; i < size; i++ {
 		name, _ := router.PeerNameFromString(fmt.Sprintf("%02d:00:00:02:00:00", i))
-		nameserver := New(name, nil, "")
+		nameserver := makeNameserver(name)
 		nameserver.SetGossip(gossipRouter.Connect(nameserver.ourName, nameserver))
 		nameserver.Start()
 		nameservers[i] = nameserver
@@ -205,7 +209,7 @@ func testNameservers(t *testing.T) {
 func TestContainerAndPeerDeath(t *testing.T) {
 	peername, err := router.PeerNameFromString("00:00:00:02:00:00")
 	require.Nil(t, err)
-	nameserver := New(peername, nil, "")
+	nameserver := makeNameserver(peername)
 
 	err = nameserver.AddEntry("hostname", "containerid", peername, address.Address(0))
 	require.Nil(t, err)
@@ -218,7 +222,7 @@ func TestContainerAndPeerDeath(t *testing.T) {
 	require.Nil(t, err)
 	require.Equal(t, []address.Address{0}, nameserver.Lookup("hostname"))
 
-	nameserver.PeerGone(&router.Peer{Name: peername})
+	nameserver.PeerGone(peername)
 	require.Equal(t, []address.Address{}, nameserver.Lookup("hostname"))
 }
 
@@ -229,7 +233,7 @@ func TestTombstoneDeletion(t *testing.T) {
 
 	peername, err := router.PeerNameFromString("00:00:00:02:00:00")
 	require.Nil(t, err)
-	nameserver := New(peername, nil, "")
+	nameserver := makeNameserver(peername)
 
 	err = nameserver.AddEntry("hostname", "containerid", peername, address.Address(0))
 	require.Nil(t, err)

prog/weaver/main.go

@@ -264,7 +264,11 @@ func main() {
 		dnsserver *nameserver.DNSServer
 	)
 	if !noDNS {
-		ns = nameserver.New(router.Ourself.Peer.Name, router.Peers, dnsDomain)
+		isKnownPeer := func(name weave.PeerName) bool {
+			return router.Peers.Fetch(name) != nil
+		}
+		ns = nameserver.New(router.Ourself.Peer.Name, dnsDomain, isKnownPeer)
+		router.Peers.OnGC(func(peer *weave.Peer) { ns.PeerGone(peer.Name) })
 		ns.SetGossip(router.NewGossip("nameserver", ns))
 		observeContainers(ns)
 		ns.Start()