Implement node function as type functions

This means nodeMeta can be private again, and also makes it
easier to pass a Node object to the cluster for local meta,
instead of a generic byte[] function.

For later updating, that node is passed using Update() instead
of New().

cluster/cluster.go

@@ -28,14 +28,14 @@ type State struct {
 type Cluster struct {
 	LocalName string // used to avoid LocalNode(); should not change
 	ml        *memberlist.Memberlist
-	getMeta   func(int) []byte
+	localNode common.Node
 	state     *State
 	events    chan memberlist.NodeEvent
 }
 
 const statePath = "/var/lib/wesher/state.json"
 
-func New(init bool, clusterKey []byte, bindAddr string, bindPort int, useIPAsName bool, getMeta func(int) []byte) (*Cluster, error) {
+func New(init bool, clusterKey []byte, bindAddr string, bindPort int, useIPAsName bool) (*Cluster, error) {
 	state := &State{}
 	if !init {
 		loadState(state)
@@ -64,7 +64,6 @@ func New(init bool, clusterKey []byte, bindAddr string, bindPort int, useIPAsNam
 	cluster := Cluster{
 		LocalName: ml.LocalNode().Name,
 		ml:        ml,
-		getMeta:   getMeta,
 		// The big channel buffer is a work-around for https://github.com/hashicorp/memberlist/issues/23
 		// More than this many simultaneous events will deadlock cluster.members()
 		events: make(chan memberlist.NodeEvent, 100),
@@ -82,7 +81,12 @@ func (c *Cluster) NotifyConflict(node, other *memberlist.Node) {
 }
 
 func (c *Cluster) NodeMeta(limit int) []byte {
-	return c.getMeta(limit)
+	encoded, err := c.localNode.Encode(limit)
+	if err != nil {
+		logrus.Errorf("failed to encode local node: %s", err)
+		return nil
+	}
+	return encoded
 }
 
 // none of these are used
@@ -112,7 +116,8 @@ func (c *Cluster) Leave() {
 	c.ml.Shutdown() //nolint: errcheck
 }
 
-func (c *Cluster) Update() {
+func (c *Cluster) Update(localNode common.Node) {
+	c.localNode = localNode
 	c.ml.UpdateNode(1 * time.Second) // we currently do not update after creation
 }
 

common/node.go

@@ -6,11 +6,10 @@ import (
 	"net"
 
 	"github.com/pkg/errors"
-	"github.com/sirupsen/logrus"
 )
 
-// NodeMeta holds metadata sent over the cluster
-type NodeMeta struct {
+// nodeMeta holds metadata sent over the cluster
+type nodeMeta struct {
 	OverlayAddr net.IPNet
 	PubKey      string
 }
@@ -20,32 +19,40 @@ type Node struct {
 	Name string
 	Addr net.IP
 	Meta []byte
-	NodeMeta
+	nodeMeta
 }
 
 func (n *Node) String() string {
 	return n.Addr.String()
 }
 
-func EncodeNodeMeta(nm NodeMeta, limit int) []byte {
-	buf := &bytes.Buffer{}
-	if err := gob.NewEncoder(buf).Encode(nm); err != nil {
-		logrus.Errorf("could not encode local state: %s", err)
-		return nil
+func MakeLocalNode(overlayAddr net.IPNet, pubKey string) Node {
+	return Node{
+		nodeMeta: nodeMeta{
+			OverlayAddr: overlayAddr,
+			PubKey:      pubKey,
+		},
 	}
-	if buf.Len() > limit {
-		logrus.Errorf("could not fit node metadata into %d bytes", limit)
-		return nil
-	}
-	return buf.Bytes()
 }
 
-func DecodeNodeMeta(b []byte) (NodeMeta, error) {
+func (n *Node) Encode(limit int) ([]byte, error) {
+	buf := &bytes.Buffer{}
+	if err := gob.NewEncoder(buf).Encode(n.nodeMeta); err != nil {
+		return nil, errors.Wrap(err, "could not encode local state")
+	}
+	if buf.Len() > limit {
+		return nil, errors.Errorf("could not fit node metadata into %d bytes", limit)
+	}
+	return buf.Bytes(), nil
+}
+
+func (n *Node) Decode() error {
 	// TODO: we blindly trust the info we get from the peers; We should be more defensive to limit the damage a leaked
 	// PSK can cause.
-	nm := NodeMeta{}
-	if err := gob.NewDecoder(bytes.NewReader(b)).Decode(&nm); err != nil {
-		return nm, errors.Wrap(err, "could not decode node meta")
+	nm := nodeMeta{}
+	if err := gob.NewDecoder(bytes.NewReader(n.Meta)).Decode(&nm); err != nil {
+		return errors.Wrap(err, "could not decode node meta")
 	}
-	return nm, nil
+	n.nodeMeta = nm
+	return nil
 }

main.go

@@ -38,19 +38,14 @@ func main() {
 		logrus.WithError(err).Fatal("could not instantiate wireguard controller")
 	}
 
-	getMeta := func(limit int) []byte {
-		return common.EncodeNodeMeta(common.NodeMeta{
-			OverlayAddr: wg.OverlayAddr,
-			PubKey:      wg.PubKey.String(),
-		}, limit)
-	}
-
-	cluster, err := cluster.New(config.Init, config.ClusterKey, config.BindAddr, config.ClusterPort, config.UseIPAsName, getMeta)
+	cluster, err := cluster.New(config.Init, config.ClusterKey, config.BindAddr, config.ClusterPort, config.UseIPAsName)
 	if err != nil {
 		logrus.WithError(err).Fatal("could not create cluster")
 	}
+
 	wg.AssignOverlayAddr((*net.IPNet)(config.OverlayNet), cluster.LocalName)
-	cluster.Update()
+	localNode := common.MakeLocalNode(wg.OverlayAddr, wg.PubKey.String())
+	cluster.Update(localNode)
 
 	nodec := cluster.Members() // avoid deadlocks by starting before join
 	if err := backoff.RetryNotify(
@@ -72,12 +67,10 @@ func main() {
 			logrus.Info("cluster members:\n")
 			nodes := make([]common.Node, 0, len(rawNodes))
 			for _, node := range rawNodes {
-				meta, err := common.DecodeNodeMeta(node.Meta)
-				if err != nil {
+				if err := node.Decode(); err != nil {
 					logrus.Warnf("\t addr: %s, could not decode metadata", node.Addr)
 					continue
 				}
-				node.NodeMeta = meta
 				nodes = append(nodes, node)
 				logrus.Infof("\taddr: %s, overlay: %s, pubkey: %s", node.Addr, node.OverlayAddr, node.PubKey)
 			}