macOS: repair network recovery and improve diagnostics

cmd/cli/network_monitor_test.go

@@ -0,0 +1,54 @@
+package cli
+
+import (
+	"context"
+	"net"
+	"testing"
+
+	"tailscale.com/net/netmon"
+
+	"github.com/Control-D-Inc/ctrld"
+)
+
+type sourceTestMonitor struct {
+	callback netmon.ChangeFunc
+	started  bool
+}
+
+func (m *sourceTestMonitor) RegisterChangeCallback(fn netmon.ChangeFunc) func() {
+	m.callback = fn
+	return func() {}
+}
+func (*sourceTestMonitor) IsMajorChangeFrom(*netmon.State, *netmon.State) bool { return true }
+func (m *sourceTestMonitor) Start()                                            { m.started = true }
+
+func TestNetworkMonitorRegistersSourceCleanup(t *testing.T) {
+	sourceTestGlobals(t)
+	old := newNetworkChangeMonitorFn
+	t.Cleanup(func() { newNetworkChangeMonitorFn = old })
+	mon := &sourceTestMonitor{}
+	newNetworkChangeMonitorFn = func(func(string, ...any)) (networkChangeMonitor, error) { return mon, nil }
+	ctrld.SetDefaultLocalIPv4(context.Background(), net.ParseIP("192.0.2.10"))
+	ctrld.SetDefaultLocalIPv6(context.Background(), net.ParseIP("2001:db8::10"))
+	calls := 0
+	networkChangeReconcileFn = func(*prog, context.Context, uint64) {
+		calls++
+		if ctrld.GetDefaultLocalIPv4() != nil {
+			t.Fatal("departed IPv4 survived to reconciliation")
+		}
+	}
+	p := sourceTestProg(&prog{cfg: &ctrld.Config{}, dnsInterceptState: &interceptStateStub{}})
+	if err := p.monitorNetworkChanges(context.Background()); err != nil {
+		t.Fatal(err)
+	}
+	if !mon.started || mon.callback == nil {
+		t.Fatal("monitor did not register/start")
+	}
+	mon.callback(&netmon.ChangeDelta{
+		Old: sourceTestState("en0", true, "192.0.2.10/24", "2001:db8::10/64"),
+		New: sourceTestState("en0", true, "2001:db8::10/64"),
+	})
+	if calls != 1 {
+		t.Fatalf("registered callback never reached source reconciliation: %d", calls)
+	}
+}