[client] Reconcile external nft accept rules on external changes (#5912)

client/firewall/nftables/external_chain_monitor_linux_test.go

@@ -0,0 +1,137 @@
+package nftables
+
+import (
+	"testing"
+
+	"github.com/google/nftables"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsMonitoredFamily(t *testing.T) {
+	tests := []struct {
+		family nftables.TableFamily
+		want   bool
+	}{
+		{nftables.TableFamilyIPv4, true},
+		{nftables.TableFamilyIPv6, true},
+		{nftables.TableFamilyINet, true},
+		{nftables.TableFamilyARP, false},
+		{nftables.TableFamilyBridge, false},
+		{nftables.TableFamilyNetdev, false},
+		{nftables.TableFamilyUnspecified, false},
+	}
+	for _, tc := range tests {
+		assert.Equal(t, tc.want, isMonitoredFamily(tc.family), "family=%d", tc.family)
+	}
+}
+
+func TestIsRelevantMonitorEvent(t *testing.T) {
+	inetTable := &nftables.Table{Name: "firewalld", Family: nftables.TableFamilyINet}
+	ipTable := &nftables.Table{Name: "filter", Family: nftables.TableFamilyIPv4}
+	arpTable := &nftables.Table{Name: "arp", Family: nftables.TableFamilyARP}
+
+	tests := []struct {
+		name string
+		ev   *nftables.MonitorEvent
+		want bool
+	}{
+		{
+			name: "new chain in inet firewalld",
+			ev: &nftables.MonitorEvent{
+				Type: nftables.MonitorEventTypeNewChain,
+				Data: &nftables.Chain{Name: "filter_INPUT", Table: inetTable},
+			},
+			want: true,
+		},
+		{
+			name: "new chain in ip filter",
+			ev: &nftables.MonitorEvent{
+				Type: nftables.MonitorEventTypeNewChain,
+				Data: &nftables.Chain{Name: "INPUT", Table: ipTable},
+			},
+			want: true,
+		},
+		{
+			name: "new chain in unwatched arp family",
+			ev: &nftables.MonitorEvent{
+				Type: nftables.MonitorEventTypeNewChain,
+				Data: &nftables.Chain{Name: "x", Table: arpTable},
+			},
+			want: false,
+		},
+		{
+			name: "new table inet",
+			ev: &nftables.MonitorEvent{
+				Type: nftables.MonitorEventTypeNewTable,
+				Data: inetTable,
+			},
+			want: true,
+		},
+		{
+			name: "del chain (we only act on new)",
+			ev: &nftables.MonitorEvent{
+				Type: nftables.MonitorEventTypeDelChain,
+				Data: &nftables.Chain{Name: "filter_INPUT", Table: inetTable},
+			},
+			want: false,
+		},
+		{
+			name: "chain with nil table",
+			ev: &nftables.MonitorEvent{
+				Type: nftables.MonitorEventTypeNewChain,
+				Data: &nftables.Chain{Name: "x"},
+			},
+			want: false,
+		},
+		{
+			name: "nil data",
+			ev: &nftables.MonitorEvent{
+				Type: nftables.MonitorEventTypeNewChain,
+				Data: (*nftables.Chain)(nil),
+			},
+			want: false,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.want, isRelevantMonitorEvent(tc.ev))
+		})
+	}
+}
+
+// fakeReconciler records reconcile invocations for debounce tests.
+type fakeReconciler struct {
+	calls chan struct{}
+}
+
+func (f *fakeReconciler) reconcileExternalChains() error {
+	f.calls <- struct{}{}
+	return nil
+}
+
+func TestExternalChainMonitorStopWithoutStart(t *testing.T) {
+	m := newExternalChainMonitor(&fakeReconciler{calls: make(chan struct{}, 1)})
+	// Must not panic or block.
+	m.stop()
+}
+
+func TestExternalChainMonitorDoubleStart(t *testing.T) {
+	// start() twice should be a no-op; stop() cleans up once.
+	// We avoid exercising the netlink watch loop here because it needs root.
+	m := newExternalChainMonitor(&fakeReconciler{calls: make(chan struct{}, 1)})
+
+	// Replace run with a stub that just waits for cancel, so start() stays
+	// deterministic without opening a netlink socket.
+	origDone := make(chan struct{})
+	m.done = origDone
+	m.cancel = func() { close(origDone) }
+
+	// Second start should be a no-op (cancel already set).
+	m.start()
+	assert.NotNil(t, m.cancel)
+
+	m.stop()
+	assert.Nil(t, m.cancel)
+	assert.Nil(t, m.done)
+}