IPN: Update ServeConfig to accept configuration for Services.

This commit updates ServeConfig to allow configuration to Services (VIPServices for now) via Serve.
The scope of this commit is only adding the Services field to ServeConfig. The field doesn't actually
allow packet flowing yet. The purpose of this commit is to unblock other work on k8s end.

Updates #22953

Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com>

ipn/ipn_view.go

@@ -18,7 +18,7 @@ import (
 	"tailscale.com/types/views"
 )
 
-//go:generate go run tailscale.com/cmd/cloner  -clonefunc=false -type=Prefs,ServeConfig,TCPPortHandler,HTTPHandler,WebServerConfig
+//go:generate go run tailscale.com/cmd/cloner  -clonefunc=false -type=Prefs,ServeConfig,ServiceConfig,TCPPortHandler,HTTPHandler,WebServerConfig
 
 // View returns a readonly view of Prefs.
 func (p *Prefs) View() PrefsView {
@@ -195,6 +195,12 @@ func (v ServeConfigView) Web() views.MapFn[HostPort, *WebServerConfig, WebServer
 	})
 }
 
+func (v ServeConfigView) Services() views.MapFn[string, *ServiceConfig, ServiceConfigView] {
+	return views.MapFnOf(v.ж.Services, func(t *ServiceConfig) ServiceConfigView {
+		return t.View()
+	})
+}
+
 func (v ServeConfigView) AllowFunnel() views.Map[HostPort, bool] {
 	return views.MapOf(v.ж.AllowFunnel)
 }
@@ -210,11 +216,77 @@ func (v ServeConfigView) ETag() string { return v.ж.ETag }
 var _ServeConfigViewNeedsRegeneration = ServeConfig(struct {
 	TCP         map[uint16]*TCPPortHandler
 	Web         map[HostPort]*WebServerConfig
+	Services    map[string]*ServiceConfig
 	AllowFunnel map[HostPort]bool
 	Foreground  map[string]*ServeConfig
 	ETag        string
 }{})
 
+// View returns a readonly view of ServiceConfig.
+func (p *ServiceConfig) View() ServiceConfigView {
+	return ServiceConfigView{ж: p}
+}
+
+// ServiceConfigView provides a read-only view over ServiceConfig.
+//
+// Its methods should only be called if `Valid()` returns true.
+type ServiceConfigView struct {
+	// ж is the underlying mutable value, named with a hard-to-type
+	// character that looks pointy like a pointer.
+	// It is named distinctively to make you think of how dangerous it is to escape
+	// to callers. You must not let callers be able to mutate it.
+	ж *ServiceConfig
+}
+
+// Valid reports whether underlying value is non-nil.
+func (v ServiceConfigView) Valid() bool { return v.ж != nil }
+
+// AsStruct returns a clone of the underlying value which aliases no memory with
+// the original.
+func (v ServiceConfigView) AsStruct() *ServiceConfig {
+	if v.ж == nil {
+		return nil
+	}
+	return v.ж.Clone()
+}
+
+func (v ServiceConfigView) MarshalJSON() ([]byte, error) { return json.Marshal(v.ж) }
+
+func (v *ServiceConfigView) UnmarshalJSON(b []byte) error {
+	if v.ж != nil {
+		return errors.New("already initialized")
+	}
+	if len(b) == 0 {
+		return nil
+	}
+	var x ServiceConfig
+	if err := json.Unmarshal(b, &x); err != nil {
+		return err
+	}
+	v.ж = &x
+	return nil
+}
+
+func (v ServiceConfigView) TCP() views.MapFn[uint16, *TCPPortHandler, TCPPortHandlerView] {
+	return views.MapFnOf(v.ж.TCP, func(t *TCPPortHandler) TCPPortHandlerView {
+		return t.View()
+	})
+}
+
+func (v ServiceConfigView) Web() views.MapFn[HostPort, *WebServerConfig, WebServerConfigView] {
+	return views.MapFnOf(v.ж.Web, func(t *WebServerConfig) WebServerConfigView {
+		return t.View()
+	})
+}
+func (v ServiceConfigView) Tun() bool { return v.ж.Tun }
+
+// A compilation failure here means this code must be regenerated, with the command at the top of this file.
+var _ServiceConfigViewNeedsRegeneration = ServiceConfig(struct {
+	TCP map[uint16]*TCPPortHandler
+	Web map[HostPort]*WebServerConfig
+	Tun bool
+}{})
+
 // View returns a readonly view of TCPPortHandler.
 func (p *TCPPortHandler) View() TCPPortHandlerView {
 	return TCPPortHandlerView{ж: p}