batcher: send endpoint and derp only updates. (#2856)

hscontrol/types/change/change.go

@@ -34,6 +34,8 @@ const (
 	NodeRemove      Change = 23
 	NodeKeyExpiry   Change = 24
 	NodeNewOrUpdate Change = 25
+	NodeEndpoint    Change = 26
+	NodeDERP        Change = 27
 
 	// User changes.
 	UserNewOrUpdate Change = 51
@@ -174,17 +176,19 @@ func NodeRemoved(id types.NodeID) ChangeSet {
 	}
 }
 
-func NodeOnline(id types.NodeID) ChangeSet {
+func NodeOnline(node types.NodeView) ChangeSet {
 	return ChangeSet{
-		Change: NodeCameOnline,
-		NodeID: id,
+		Change:         NodeCameOnline,
+		NodeID:         node.ID(),
+		IsSubnetRouter: node.IsSubnetRouter(),
 	}
 }
 
-func NodeOffline(id types.NodeID) ChangeSet {
+func NodeOffline(node types.NodeView) ChangeSet {
 	return ChangeSet{
-		Change: NodeWentOffline,
-		NodeID: id,
+		Change:         NodeWentOffline,
+		NodeID:         node.ID(),
+		IsSubnetRouter: node.IsSubnetRouter(),
 	}
 }
 
@@ -196,6 +200,20 @@ func KeyExpiry(id types.NodeID, expiry time.Time) ChangeSet {
 	}
 }
 
+func EndpointUpdate(id types.NodeID) ChangeSet {
+	return ChangeSet{
+		Change: NodeEndpoint,
+		NodeID: id,
+	}
+}
+
+func DERPUpdate(id types.NodeID) ChangeSet {
+	return ChangeSet{
+		Change: NodeDERP,
+		NodeID: id,
+	}
+}
+
 func UserAdded(id types.UserID) ChangeSet {
 	return ChangeSet{
 		Change: UserNewOrUpdate,

hscontrol/types/change/change_string.go

@@ -18,6 +18,8 @@ func _() {
 	_ = x[NodeRemove-23]
 	_ = x[NodeKeyExpiry-24]
 	_ = x[NodeNewOrUpdate-25]
+	_ = x[NodeEndpoint-26]
+	_ = x[NodeDERP-27]
 	_ = x[UserNewOrUpdate-51]
 	_ = x[UserRemove-52]
 }
@@ -26,13 +28,13 @@ const (
 	_Change_name_0 = "ChangeUnknown"
 	_Change_name_1 = "Full"
 	_Change_name_2 = "PolicyDERPExtraRecords"
-	_Change_name_3 = "NodeCameOnlineNodeWentOfflineNodeRemoveNodeKeyExpiryNodeNewOrUpdate"
+	_Change_name_3 = "NodeCameOnlineNodeWentOfflineNodeRemoveNodeKeyExpiryNodeNewOrUpdateNodeEndpointNodeDERP"
 	_Change_name_4 = "UserNewOrUpdateUserRemove"
 )
 
 var (
 	_Change_index_2 = [...]uint8{0, 6, 10, 22}
-	_Change_index_3 = [...]uint8{0, 14, 29, 39, 52, 67}
+	_Change_index_3 = [...]uint8{0, 14, 29, 39, 52, 67, 79, 87}
 	_Change_index_4 = [...]uint8{0, 15, 25}
 )
 
@@ -45,7 +47,7 @@ func (i Change) String() string {
 	case 11 <= i && i <= 13:
 		i -= 11
 		return _Change_name_2[_Change_index_2[i]:_Change_index_2[i+1]]
-	case 21 <= i && i <= 25:
+	case 21 <= i && i <= 27:
 		i -= 21
 		return _Change_name_3[_Change_index_3[i]:_Change_index_3[i+1]]
 	case 51 <= i && i <= 52:

hscontrol/types/node.go

@@ -535,8 +535,10 @@ func (node *Node) PeerChangeFromMapRequest(req tailcfg.MapRequest) tailcfg.PeerC
 		}
 	}
 
-	// TODO(kradalby): Find a good way to compare updates
-	ret.Endpoints = req.Endpoints
+	// Compare endpoints using order-independent comparison
+	if EndpointsChanged(node.Endpoints, req.Endpoints) {
+		ret.Endpoints = req.Endpoints
+	}
 
 	now := time.Now()
 	ret.LastSeen = &now
@@ -544,6 +546,32 @@ func (node *Node) PeerChangeFromMapRequest(req tailcfg.MapRequest) tailcfg.PeerC
 	return ret
 }
 
+// EndpointsChanged compares two endpoint slices and returns true if they differ.
+// The comparison is order-independent - endpoints are sorted before comparison.
+func EndpointsChanged(oldEndpoints, newEndpoints []netip.AddrPort) bool {
+	if len(oldEndpoints) != len(newEndpoints) {
+		return true
+	}
+
+	if len(oldEndpoints) == 0 {
+		return false
+	}
+
+	// Make copies to avoid modifying the original slices
+	oldCopy := slices.Clone(oldEndpoints)
+	newCopy := slices.Clone(newEndpoints)
+
+	// Sort both slices to enable order-independent comparison
+	slices.SortFunc(oldCopy, func(a, b netip.AddrPort) int {
+		return a.Compare(b)
+	})
+	slices.SortFunc(newCopy, func(a, b netip.AddrPort) int {
+		return a.Compare(b)
+	})
+
+	return !slices.Equal(oldCopy, newCopy)
+}
+
 func (node *Node) RegisterMethodToV1Enum() v1.RegisterMethod {
 	switch node.RegisterMethod {
 	case "authkey":