test: fix flaky test NodeAddressSort

There were two issues which showed up specifically under `race` tests:

1. As the address resources are added while the controller is running,
   and `default` address is immutable (by design), insert the future
   default address first, otherwise the controller might pick up another
   one it sees first randomly.

2. There was a bug in accumulative address handling when the sort only
   took into account addresses ignoring prefix lengths.

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>

internal/app/machined/pkg/controllers/network/node_address.go

@@ -224,7 +224,7 @@ func (ctrl *NodeAddressController) Run(ctx context.Context, r controller.Runtime
 
 		touchedIDs[network.NodeAddressRoutedID] = struct{}{}
 
-		if err = ctrl.updateAccumulativeAddresses(ctx, r, network.NodeAddressAccumulativeID, accumulative, algo); err != nil {
+		if err = ctrl.updateAccumulativeAddresses(ctx, r, network.NodeAddressAccumulativeID, accumulative, algo, compareFunc); err != nil {
 			return err
 		}
 
@@ -247,7 +247,7 @@ func (ctrl *NodeAddressController) Run(ctx context.Context, r controller.Runtime
 				return err
 			}
 
-			if err = ctrl.updateAccumulativeAddresses(ctx, r, network.FilteredNodeAddressID(network.NodeAddressAccumulativeID, filterID), filteredAccumulative, algo); err != nil {
+			if err = ctrl.updateAccumulativeAddresses(ctx, r, network.FilteredNodeAddressID(network.NodeAddressAccumulativeID, filterID), filteredAccumulative, algo, compareFunc); err != nil {
 				return err
 			}
 
@@ -293,17 +293,17 @@ func (ctrl *NodeAddressController) updateCurrentAddresses(ctx context.Context, r
 	return nil
 }
 
-func (ctrl *NodeAddressController) updateAccumulativeAddresses(ctx context.Context, r controller.Runtime, id resource.ID, accumulative []netip.Prefix, algo nethelpers.AddressSortAlgorithm) error {
+func (ctrl *NodeAddressController) updateAccumulativeAddresses(
+	ctx context.Context, r controller.Runtime, id resource.ID, accumulative []netip.Prefix, algo nethelpers.AddressSortAlgorithm, compare func(a, b netip.Prefix) int,
+) error {
 	if err := safe.WriterModify(ctx, r, network.NewNodeAddress(network.NamespaceName, id), func(r *network.NodeAddress) error {
 		spec := r.TypedSpec()
 
 		for _, ip := range accumulative {
 			// find insert position using binary search
-			pos, _ := slices.BinarySearchFunc(spec.Addresses, ip.Addr(), func(prefix netip.Prefix, addr netip.Addr) int {
-				return prefix.Addr().Compare(ip.Addr())
-			})
+			pos, _ := slices.BinarySearchFunc(spec.Addresses, ip, compare)
 
-			if pos < len(spec.Addresses) && spec.Addresses[pos].Addr().Compare(ip.Addr()) == 0 {
+			if pos < len(spec.Addresses) && compare(spec.Addresses[pos], ip) == 0 {
 				continue
 			}
 

internal/app/machined/pkg/controllers/network/node_address_test.go

@@ -227,10 +227,10 @@ func (suite *NodeAddressSuite) TestSortAlgorithmV2() {
 	suite.Require().NoError(suite.State().Create(suite.Ctx(), sortAlgorithm))
 
 	for _, addr := range []string{
+		"1.2.3.4/26", // insert default address first, otherwise the test would be flaky, as default address is immutable
 		"10.3.4.1/24",
 		"10.3.4.5/24",
 		"10.3.4.5/32",
-		"1.2.3.4/26",
 		"192.168.35.11/24",
 		"192.168.36.10/24",
 		"127.0.0.1/8",
@@ -269,7 +269,7 @@ func (suite *NodeAddressSuite) TestSortAlgorithmV2() {
 				)
 			case network.NodeAddressAccumulativeID:
 				asrt.Equal(
-					"1.2.3.4/26 10.0.0.2/8 10.3.4.1/24 10.3.4.5/32 192.168.3.7/24 192.168.35.11/24 192.168.36.10/24 fd01:cafe::5054:ff:fe1f:c7bd/64 fd01:cafe::f14c:9fa1:8496:557f/128",
+					"1.2.3.4/26 10.3.4.5/32 10.3.4.1/24 10.3.4.5/24 10.0.0.2/8 192.168.3.7/24 192.168.35.11/24 192.168.36.10/24 fd01:cafe::f14c:9fa1:8496:557f/128 fd01:cafe::5054:ff:fe1f:c7bd/64",
 					stringifyIPs(addrs),
 				)
 			}