state/nodestore: in memory representation of nodes

Initial work on a nodestore which stores all of the nodes
and their relations in memory with relationship for peers
precalculated.

It is a copy-on-write structure, replacing the "snapshot"
when a change to the structure occurs. It is optimised for reads,
and while batches are not fast, they are grouped together
to do less of the expensive peer calculation if there are many
changes rapidly.

Writes will block until commited, while reads are never
blocked.

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

hscontrol/types/change/change.go

@@ -45,6 +45,7 @@ func (c Change) AlsoSelf() bool {
 	case NodeRemove, NodeKeyExpiry, NodeNewOrUpdate:
 		return true
 	}
+
 	return false
 }
 

hscontrol/types/node.go

@@ -13,6 +13,7 @@ import (
 	v1 "github.com/juanfont/headscale/gen/go/headscale/v1"
 	"github.com/juanfont/headscale/hscontrol/policy/matcher"
 	"github.com/juanfont/headscale/hscontrol/util"
+	"github.com/rs/zerolog/log"
 	"go4.org/netipx"
 	"google.golang.org/protobuf/types/known/timestamppb"
 	"tailscale.com/net/tsaddr"
@@ -355,6 +356,7 @@ func (node *Node) Proto() *v1.Node {
 		GivenName:   node.GivenName,
 		User:        node.User.Proto(),
 		ForcedTags:  node.ForcedTags,
+		Online:      node.IsOnline != nil && *node.IsOnline,
 
 		// Only ApprovedRoutes and AvailableRoutes is set here. SubnetRoutes has
 		// to be populated manually with PrimaryRoute, to ensure it includes the
@@ -419,6 +421,11 @@ func (node *Node) AnnouncedRoutes() []netip.Prefix {
 }
 
 // SubnetRoutes returns the list of routes that the node announces and are approved.
+//
+// IMPORTANT: This method is used for internal data structures and should NOT be used
+// for the gRPC Proto conversion. For Proto, SubnetRoutes must be populated manually
+// with PrimaryRoutes to ensure it includes only routes actively served by the node.
+// See the comment in Proto() method and the implementation in grpcv1.go/nodesToProto.
 func (node *Node) SubnetRoutes() []netip.Prefix {
 	var routes []netip.Prefix
 
@@ -511,11 +518,25 @@ func (node *Node) ApplyHostnameFromHostInfo(hostInfo *tailcfg.Hostinfo) {
 	}
 
 	if node.Hostname != hostInfo.Hostname {
+		log.Trace().
+			Str("node.id", node.ID.String()).
+			Str("old_hostname", node.Hostname).
+			Str("new_hostname", hostInfo.Hostname).
+			Str("old_given_name", node.GivenName).
+			Bool("given_name_changed", node.GivenNameHasBeenChanged()).
+			Msg("Updating hostname from hostinfo")
+
 		if node.GivenNameHasBeenChanged() {
 			node.GivenName = util.ConvertWithFQDNRules(hostInfo.Hostname)
 		}
 
 		node.Hostname = hostInfo.Hostname
+
+		log.Trace().
+			Str("node.id", node.ID.String()).
+			Str("new_hostname", node.Hostname).
+			Str("new_given_name", node.GivenName).
+			Msg("Hostname updated")
 	}
 }
 
@@ -759,6 +780,22 @@ func (v NodeView) ExitRoutes() []netip.Prefix {
 	return v.ж.ExitRoutes()
 }
 
+// RequestTags returns the ACL tags that the node is requesting.
+func (v NodeView) RequestTags() []string {
+	if !v.Valid() || !v.Hostinfo().Valid() {
+		return []string{}
+	}
+	return v.Hostinfo().RequestTags().AsSlice()
+}
+
+// Proto converts the NodeView to a protobuf representation.
+func (v NodeView) Proto() *v1.Node {
+	if !v.Valid() {
+		return nil
+	}
+	return v.ж.Proto()
+}
+
 // HasIP reports if a node has a given IP address.
 func (v NodeView) HasIP(i netip.Addr) bool {
 	if !v.Valid() {