all: use immutable node view in read path

This commit changes most of our (*)types.Node to
types.NodeView, which is a readonly version of the
underlying node ensuring that there is no mutations
happening in the read path.

Based on the migration, there didnt seem to be any, but the
idea here is to prevent it in the future and simplify other
new implementations.

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/mapper/tail.go

@@ -8,24 +8,25 @@ import (
 	"github.com/samber/lo"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/views"
 )
 
 // NodeCanHaveTagChecker is an interface for checking if a node can have a tag
 type NodeCanHaveTagChecker interface {
-	NodeCanHaveTag(node *types.Node, tag string) bool
+	NodeCanHaveTag(node types.NodeView, tag string) bool
 }
 
 func tailNodes(
-	nodes types.Nodes,
+	nodes views.Slice[types.NodeView],
 	capVer tailcfg.CapabilityVersion,
 	checker NodeCanHaveTagChecker,
 	primaryRouteFunc routeFilterFunc,
 	cfg *types.Config,
 ) ([]*tailcfg.Node, error) {
-	tNodes := make([]*tailcfg.Node, len(nodes))
+	tNodes := make([]*tailcfg.Node, 0, nodes.Len())
 
-	for index, node := range nodes {
-		node, err := tailNode(
+	for _, node := range nodes.All() {
+		tNode, err := tailNode(
 			node,
 			capVer,
 			checker,
@@ -36,7 +37,7 @@ func tailNodes(
 			return nil, err
 		}
 
-		tNodes[index] = node
+		tNodes = append(tNodes, tNode)
 	}
 
 	return tNodes, nil
@@ -44,7 +45,7 @@ func tailNodes(
 
 // tailNode converts a Node into a Tailscale Node.
 func tailNode(
-	node *types.Node,
+	node types.NodeView,
 	capVer tailcfg.CapabilityVersion,
 	checker NodeCanHaveTagChecker,
 	primaryRouteFunc routeFilterFunc,
@@ -57,61 +58,64 @@ func tailNode(
 	// TODO(kradalby): legacyDERP was removed in tailscale/tailscale@2fc4455e6dd9ab7f879d4e2f7cffc2be81f14077
 	// and should be removed after 111 is the minimum capver.
 	var legacyDERP string
-	if node.Hostinfo != nil && node.Hostinfo.NetInfo != nil {
-		legacyDERP = fmt.Sprintf("127.3.3.40:%d", node.Hostinfo.NetInfo.PreferredDERP)
-		derp = node.Hostinfo.NetInfo.PreferredDERP
+	if node.Hostinfo().Valid() && node.Hostinfo().NetInfo().Valid() {
+		legacyDERP = fmt.Sprintf("127.3.3.40:%d", node.Hostinfo().NetInfo().PreferredDERP())
+		derp = node.Hostinfo().NetInfo().PreferredDERP()
 	} else {
 		legacyDERP = "127.3.3.40:0" // Zero means disconnected or unknown.
 	}
 
 	var keyExpiry time.Time
-	if node.Expiry != nil {
-		keyExpiry = *node.Expiry
+	if node.Expiry().Valid() {
+		keyExpiry = node.Expiry().Get()
 	} else {
 		keyExpiry = time.Time{}
 	}
 
 	hostname, err := node.GetFQDN(cfg.BaseDomain)
 	if err != nil {
-		return nil, fmt.Errorf("tailNode, failed to create FQDN: %s", err)
+		return nil, err
 	}
 
 	var tags []string
-	for _, tag := range node.RequestTags() {
+	for _, tag := range node.RequestTagsSlice().All() {
 		if checker.NodeCanHaveTag(node, tag) {
 			tags = append(tags, tag)
 		}
 	}
-	tags = lo.Uniq(append(tags, node.ForcedTags...))
+	for _, tag := range node.ForcedTags().All() {
+		tags = append(tags, tag)
+	}
+	tags = lo.Uniq(tags)
 
-	routes := primaryRouteFunc(node.ID)
-	allowed := append(node.Prefixes(), routes...)
+	routes := primaryRouteFunc(node.ID())
+	allowed := append(addrs, routes...)
 	allowed = append(allowed, node.ExitRoutes()...)
 	tsaddr.SortPrefixes(allowed)
 
 	tNode := tailcfg.Node{
-		ID:       tailcfg.NodeID(node.ID), // this is the actual ID
-		StableID: node.ID.StableID(),
+		ID:       tailcfg.NodeID(node.ID()), // this is the actual ID
+		StableID: node.ID().StableID(),
 		Name:     hostname,
 		Cap:      capVer,
 
-		User: tailcfg.UserID(node.UserID),
+		User: tailcfg.UserID(node.UserID()),
 
-		Key:       node.NodeKey,
+		Key:       node.NodeKey(),
 		KeyExpiry: keyExpiry.UTC(),
 
-		Machine:          node.MachineKey,
-		DiscoKey:         node.DiscoKey,
+		Machine:          node.MachineKey(),
+		DiscoKey:         node.DiscoKey(),
 		Addresses:        addrs,
 		PrimaryRoutes:    routes,
 		AllowedIPs:       allowed,
-		Endpoints:        node.Endpoints,
+		Endpoints:        node.Endpoints().AsSlice(),
 		HomeDERP:         derp,
 		LegacyDERPString: legacyDERP,
-		Hostinfo:         node.Hostinfo.View(),
-		Created:          node.CreatedAt.UTC(),
+		Hostinfo:         node.Hostinfo(),
+		Created:          node.CreatedAt().UTC(),
 
-		Online: node.IsOnline,
+		Online: node.IsOnline().Clone(),
 
 		Tags: tags,
 
@@ -129,10 +133,13 @@ func tailNode(
 		tNode.CapMap[tailcfg.NodeAttrRandomizeClientPort] = []tailcfg.RawMessage{}
 	}
 
-	if node.IsOnline == nil || !*node.IsOnline {
+	if !node.IsOnline().Valid() || !node.IsOnline().Get() {
 		// LastSeen is only set when node is
 		// not connected to the control server.
-		tNode.LastSeen = node.LastSeen
+		if node.LastSeen().Valid() {
+			lastSeen := node.LastSeen().Get()
+			tNode.LastSeen = &lastSeen
+		}
 	}
 
 	return &tNode, nil