wip

internal/wireguard/constructor.go

@@ -4,10 +4,11 @@ type Wireguard struct {
 	logger   Logger
 	settings Settings
 	netlink  NetLinker
+	routing  Routing
 }
 
 func New(settings Settings, netlink NetLinker,
-	logger Logger,
+	routing Routing, logger Logger,
 ) (w *Wireguard, err error) {
 	settings.SetDefaults()
 	if err := settings.Check(); err != nil {
@@ -18,5 +19,6 @@ func New(settings Settings, netlink NetLinker,
 		logger:   logger,
 		settings: settings,
 		netlink:  netlink,
+		routing:  routing,
 	}, nil
 }

internal/wireguard/interfaces.go

@@ -0,0 +1,7 @@
+package wireguard
+
+import "net/netip"
+
+type Routing interface {
+	VPNLocalGatewayIP(vpnInterface string) (gateway netip.Addr, err error)
+}

internal/wireguard/netlinker.go

@@ -1,6 +1,8 @@
 package wireguard
 
-import "github.com/qdm12/gluetun/internal/netlink"
+import (
+	"github.com/qdm12/gluetun/internal/netlink"
+)
 
 //go:generate mockgen -destination=netlinker_mock_test.go -package wireguard . NetLinker
 
@@ -15,6 +17,7 @@ type NetLinker interface {
 type Router interface {
 	RouteList(family int) (routes []netlink.Route, err error)
 	RouteAdd(route netlink.Route) error
+	RouteReplace(route netlink.Route) error
 }
 
 type Ruler interface {

internal/wireguard/route.go

@@ -1,6 +1,7 @@
 package wireguard
 
 import (
+	"errors"
 	"fmt"
 	"net/netip"
 	"strings"
@@ -29,6 +30,10 @@ func (w *Wireguard) addRoutes(link netlink.Link, destinations []netip.Prefix,
 	return nil
 }
 
+var (
+	ErrDefaultRouteNotFound = errors.New("default route not found")
+)
+
 func (w *Wireguard) addRoute(link netlink.Link, dst netip.Prefix,
 	firewallMark uint32,
 ) (err error) {
@@ -45,5 +50,39 @@ func (w *Wireguard) addRoute(link netlink.Link, dst netip.Prefix,
 			link.Name, dst, firewallMark, err)
 	}
 
+	vpnGatewayIP, err := w.routing.VPNLocalGatewayIP(link.Name)
+	if err != nil {
+		return fmt.Errorf("getting VPN gateway IP: %w", err)
+	}
+
+	routes, err := w.netlink.RouteList(netlink.FamilyV4)
+	if err != nil {
+		return fmt.Errorf("listing routes: %w", err)
+	}
+
+	var defaultRoute netlink.Route
+	var defaultRouteFound bool
+	for _, route = range routes {
+		if !route.Dst.IsValid() || route.Dst.Addr().IsUnspecified() {
+			defaultRoute = route
+			defaultRouteFound = true
+			break
+		}
+	}
+
+	if !defaultRouteFound {
+		return fmt.Errorf("%w: in %d routes", ErrDefaultRouteNotFound, len(routes))
+	}
+
+	// Equivalent replacement to:
+	// ip route replace default via <vpn-gateway> dev tun0
+	defaultRoute.Gw = vpnGatewayIP
+	defaultRoute.LinkIndex = link.Index
+
+	err = w.netlink.RouteReplace(defaultRoute)
+	if err != nil {
+		return fmt.Errorf("replacing default route: %w", err)
+	}
+
 	return err
 }