netbird/client/internal/routemanager/systemops/systemops_linux_test.go

//go:build !android && privileged

package systemops

import (
	"errors"
	"net"
	"syscall"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/vishvananda/netlink"

	"github.com/netbirdio/netbird/client/internal/routemanager/vars"
)

func init() {
	testCases = append(testCases, []testCase{
		{
			name:              "To more specific route without custom dialer via physical interface",
			expectedInterface: expectedInternalInt,
			dialer:            &net.Dialer{},
			expectedPacket:    createPacketExpectation("192.168.1.1", 12345, "10.10.0.2", 53),
		},
	}...)
}

func createAndSetupDummyInterface(t *testing.T, interfaceName, ipAddressCIDR string) string {
	t.Helper()

	dummy := &netlink.Dummy{LinkAttrs: netlink.LinkAttrs{Name: interfaceName}}
	err := netlink.LinkDel(dummy)
	if err != nil && !errors.Is(err, syscall.EINVAL) {
		t.Logf("Failed to delete dummy interface: %v", err)
	}

	err = netlink.LinkAdd(dummy)
	require.NoError(t, err)

	err = netlink.LinkSetUp(dummy)
	require.NoError(t, err)

	if ipAddressCIDR != "" {
		addr, err := netlink.ParseAddr(ipAddressCIDR)
		require.NoError(t, err)
		err = netlink.AddrAdd(dummy, addr)
		require.NoError(t, err)
	}

	t.Cleanup(func() {
		err := netlink.LinkDel(dummy)
		assert.NoError(t, err)
	})

	return dummy.Name
}

func addDummyRoute(t *testing.T, dstCIDR string, gw net.IP, intf string) {
	t.Helper()

	_, dstIPNet, err := net.ParseCIDR(dstCIDR)
	require.NoError(t, err)

	link, err := netlink.LinkByName(intf)
	require.NoError(t, err)
	linkIndex := link.Attrs().Index

	route := &netlink.Route{
		Dst:       dstIPNet,
		Gw:        gw,
		LinkIndex: linkIndex,
	}

	// Handle existing routes with metric 0
	var originalNexthop net.IP
	var originalLinkIndex int
	if dstIPNet.String() == "0.0.0.0/0" {
		var err error
		originalNexthop, originalLinkIndex, err = fetchOriginalGateway(netlink.FAMILY_V4)
		if err != nil && !errors.Is(err, vars.ErrRouteNotFound) {
			t.Logf("Failed to fetch original gateway: %v", err)
		}

		if originalNexthop != nil {
			// remove original route
			err = netlink.RouteDel(&netlink.Route{Dst: dstIPNet, Priority: 0})
			assert.NoError(t, err)

			// add new route
			assert.NoError(t, netlink.RouteAdd(route))

			t.Cleanup(func() {
				// restore original route
				assert.NoError(t, netlink.RouteDel(route))
				err := netlink.RouteAdd(&netlink.Route{Dst: dstIPNet, Gw: originalNexthop, LinkIndex: originalLinkIndex, Priority: 0})
				assert.NoError(t, err)
			})

			return
		}
	}

	err = netlink.RouteDel(route)
	if err != nil && !errors.Is(err, syscall.ESRCH) {
		t.Logf("Failed to delete route: %v", err)
	}

	err = netlink.RouteAdd(route)
	if err != nil && !errors.Is(err, syscall.EEXIST) {
		t.Fatalf("Failed to add route: %v", err)
	}
}

func fetchOriginalGateway(family int) (net.IP, int, error) {
	routes, err := netlink.RouteList(nil, family)
	if err != nil {
		return nil, 0, err
	}

	for _, route := range routes {
		ones := -1
		if route.Dst != nil {
			ones, _ = route.Dst.Mask.Size()
		}
		if route.Dst == nil || ones == 0 && route.Priority == 0 {
			return route.Gw, route.LinkIndex, nil
		}
	}

	return nil, 0, vars.ErrRouteNotFound
}

func setupDummyInterfacesAndRoutes(t *testing.T) {
	t.Helper()

	defaultDummy := createAndSetupDummyInterface(t, "dummyext0", "192.168.0.1/24")
	addDummyRoute(t, "0.0.0.0/0", net.IPv4(192, 168, 0, 1), defaultDummy)

	otherDummy := createAndSetupDummyInterface(t, "dummyint0", "192.168.1.1/24")
	addDummyRoute(t, "10.0.0.0/8", net.IPv4(192, 168, 1, 1), otherDummy)
}