tailcfg, control/controlclient: make Debug settings sticky in a map session [capver 37]

Fixes #4843

Change-Id: I3accfd91be474ac745cb47f5d6e866c37d5c5d2d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

control/controlclient/map_test.go

@@ -16,6 +16,8 @@ import (
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/key"
 	"tailscale.com/types/netmap"
+	"tailscale.com/types/opt"
+	"tailscale.com/util/must"
 )
 
 func TestUndeltaPeers(t *testing.T) {
@@ -449,3 +451,152 @@ func TestNetmapForResponse(t *testing.T) {
 		}
 	})
 }
+
+// TestDeltaDebug tests that tailcfg.Debug values can be omitted in MapResposnes
+// entirely or have their opt.Bool values unspecified between MapResponses in a
+// session and that should mean no change. (as of capver 37). But two Debug
+// fields existed prior to capver 37 that weren't opt.Bool; we test that we both
+// still accept the non-opt.Bool form from control for RandomizeClientPort and
+// ForceBackgroundSTUN and also accept the new form, keeping the old form in
+// sync.
+func TestDeltaDebug(t *testing.T) {
+	type step struct {
+		got  *tailcfg.Debug
+		want *tailcfg.Debug
+	}
+	tests := []struct {
+		name  string
+		steps []step
+	}{
+		{
+			name: "nothing-to-nothing",
+			steps: []step{
+				{nil, nil},
+				{nil, nil},
+			},
+		},
+		{
+			name: "sticky-with-old-style-randomize-client-port",
+			steps: []step{
+				{
+					&tailcfg.Debug{RandomizeClientPort: true},
+					&tailcfg.Debug{
+						RandomizeClientPort:    true,
+						SetRandomizeClientPort: "true",
+					},
+				},
+				{
+					nil, // not sent by server
+					&tailcfg.Debug{
+						RandomizeClientPort:    true,
+						SetRandomizeClientPort: "true",
+					},
+				},
+			},
+		},
+		{
+			name: "sticky-with-new-style-randomize-client-port",
+			steps: []step{
+				{
+					&tailcfg.Debug{SetRandomizeClientPort: "true"},
+					&tailcfg.Debug{
+						RandomizeClientPort:    true,
+						SetRandomizeClientPort: "true",
+					},
+				},
+				{
+					nil, // not sent by server
+					&tailcfg.Debug{
+						RandomizeClientPort:    true,
+						SetRandomizeClientPort: "true",
+					},
+				},
+			},
+		},
+		{
+			name: "opt-bool-sticky-changing-over-time",
+			steps: []step{
+				{nil, nil},
+				{nil, nil},
+				{
+					&tailcfg.Debug{OneCGNATRoute: "true"},
+					&tailcfg.Debug{OneCGNATRoute: "true"},
+				},
+				{
+					nil,
+					&tailcfg.Debug{OneCGNATRoute: "true"},
+				},
+				{
+					&tailcfg.Debug{OneCGNATRoute: "false"},
+					&tailcfg.Debug{OneCGNATRoute: "false"},
+				},
+				{
+					nil,
+					&tailcfg.Debug{OneCGNATRoute: "false"},
+				},
+			},
+		},
+		{
+			name: "legacy-ForceBackgroundSTUN",
+			steps: []step{
+				{
+					&tailcfg.Debug{ForceBackgroundSTUN: true},
+					&tailcfg.Debug{ForceBackgroundSTUN: true, SetForceBackgroundSTUN: "true"},
+				},
+			},
+		},
+		{
+			name: "opt-bool-SetForceBackgroundSTUN",
+			steps: []step{
+				{
+					&tailcfg.Debug{SetForceBackgroundSTUN: "true"},
+					&tailcfg.Debug{ForceBackgroundSTUN: true, SetForceBackgroundSTUN: "true"},
+				},
+			},
+		},
+		{
+			name: "server-reset-to-default",
+			steps: []step{
+				{
+					&tailcfg.Debug{SetForceBackgroundSTUN: "true"},
+					&tailcfg.Debug{ForceBackgroundSTUN: true, SetForceBackgroundSTUN: "true"},
+				},
+				{
+					&tailcfg.Debug{SetForceBackgroundSTUN: "unset"},
+					&tailcfg.Debug{ForceBackgroundSTUN: false, SetForceBackgroundSTUN: "unset"},
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ms := newTestMapSession(t)
+			for stepi, s := range tt.steps {
+				nm := ms.netmapForResponse(&tailcfg.MapResponse{Debug: s.got})
+				if !reflect.DeepEqual(nm.Debug, s.want) {
+					t.Errorf("unexpected result at step index %v; got: %s", stepi, must.Get(json.Marshal(nm.Debug)))
+				}
+			}
+		})
+	}
+}
+
+// Verifies that copyDebugOptBools doesn't missing any opt.Bools.
+func TestCopyDebugOptBools(t *testing.T) {
+	rt := reflect.TypeOf(tailcfg.Debug{})
+	for i := 0; i < rt.NumField(); i++ {
+		sf := rt.Field(i)
+		if sf.Type != reflect.TypeOf(opt.Bool("")) {
+			continue
+		}
+		var src, dst tailcfg.Debug
+		reflect.ValueOf(&src).Elem().Field(i).Set(reflect.ValueOf(opt.Bool("true")))
+		if src == (tailcfg.Debug{}) {
+			t.Fatalf("failed to set field %v", sf.Name)
+		}
+		copyDebugOptBools(&dst, &src)
+		if src != dst {
+			t.Fatalf("copyDebugOptBools didn't copy field %v", sf.Name)
+		}
+	}
+}