client/web: use tsaddr helpers

Updates #cleanup

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

client/web/web.go

@@ -17,7 +17,6 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"slices"
 	"strings"
 	"sync"
 	"time"
@@ -35,6 +34,7 @@ import (
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/logger"
+	"tailscale.com/types/views"
 	"tailscale.com/util/httpm"
 	"tailscale.com/version"
 	"tailscale.com/version/distro"
@@ -113,11 +113,6 @@ const (
 	ManageServerMode ServerMode = "manage"
 )
 
-var (
-	exitNodeRouteV4 = netip.MustParsePrefix("0.0.0.0/0")
-	exitNodeRouteV6 = netip.MustParsePrefix("::/0")
-)
-
 // ServerOpts contains options for constructing a new Server.
 type ServerOpts struct {
 	// Mode specifies the mode of web client being constructed.
@@ -927,10 +922,10 @@ func (s *Server) serveGetNodeData(w http.ResponseWriter, r *http.Request) {
 			return p == route
 		})
 	}
-	data.AdvertisingExitNodeApproved = routeApproved(exitNodeRouteV4) || routeApproved(exitNodeRouteV6)
+	data.AdvertisingExitNodeApproved = routeApproved(tsaddr.AllIPv4()) || routeApproved(tsaddr.AllIPv6())
 
 	for _, r := range prefs.AdvertiseRoutes {
-		if r == exitNodeRouteV4 || r == exitNodeRouteV6 {
+		if tsaddr.IsExitRoute(r) {
 			data.AdvertisingExitNode = true
 		} else {
 			data.AdvertisedRoutes = append(data.AdvertisedRoutes, subnetRoute{
@@ -1071,7 +1066,7 @@ func (s *Server) servePostRoutes(ctx context.Context, data postRoutesRequest) er
 	var currNonExitRoutes []string
 	var currAdvertisingExitNode bool
 	for _, r := range prefs.AdvertiseRoutes {
-		if r == exitNodeRouteV4 || r == exitNodeRouteV6 {
+		if tsaddr.IsExitRoute(r) {
 			currAdvertisingExitNode = true
 			continue
 		}
@@ -1092,12 +1087,7 @@ func (s *Server) servePostRoutes(ctx context.Context, data postRoutesRequest) er
 		return err
 	}
 
-	hasExitNodeRoute := func(all []netip.Prefix) bool {
+	if !data.UseExitNode.IsZero() && tsaddr.ContainsExitRoutes(views.SliceOf(routes)) {
-		return slices.Contains(all, exitNodeRouteV4) ||
-			slices.Contains(all, exitNodeRouteV6)
-	}
-
-	if !data.UseExitNode.IsZero() && hasExitNodeRoute(routes) {
 		return errors.New("cannot use and advertise exit node at same time")
 	}