claude did not want netbsd

overlay/tun_netbsd.go

@@ -1,59 +1,111 @@
-//go:build netbsd && !e2e_testing
-// +build netbsd,!e2e_testing
+//go:build !e2e_testing
+// +build !e2e_testing
 
 package overlay
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"net/netip"
-	"os/exec"
-	"strconv"
-	"strings"
+	"os"
+	"regexp"
+	"sync/atomic"
+	"syscall"
+	"unsafe"
 
+	"github.com/gaissmai/bart"
 	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/config"
+	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
-	wgtun "golang.zx2c4.com/wireguard/tun"
+	netroute "golang.org/x/net/route"
+	"golang.org/x/sys/unix"
 )
 
-type tun struct{}
+const (
+	SIOCAIFADDR_IN6 = 0x8080696b
+	TUNSIFHEAD      = 0x80047442
+	TUNSIFMODE      = 0x80047458
+)
 
-func newTunFromFd(_ *config.C, _ *logrus.Logger, _ int, _ []netip.Prefix) (*wgTun, error) {
-	return nil, fmt.Errorf("newTunFromFd not supported on NetBSD")
+type ifreqAlias4 struct {
+	Name     [unix.IFNAMSIZ]byte
+	Addr     unix.RawSockaddrInet4
+	DstAddr  unix.RawSockaddrInet4
+	MaskAddr unix.RawSockaddrInet4
 }
 
-func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, _ bool) (*wgTun, error) {
-	deviceName := c.GetString("tun.dev", "tun")
-	mtu := c.GetInt("tun.mtu", DefaultMTU)
+type ifreqAlias6 struct {
+	Name       [unix.IFNAMSIZ]byte
+	Addr       unix.RawSockaddrInet6
+	DstAddr    unix.RawSockaddrInet6
+	PrefixMask unix.RawSockaddrInet6
+	Flags      uint32
+	Lifetime   addrLifetime
+}
 
-	// Create WireGuard TUN device
-	tunDevice, err := wgtun.CreateTUN(deviceName, mtu)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create TUN device: %w", err)
+type ifreq struct {
+	Name [unix.IFNAMSIZ]byte
+	data int
+}
+
+type addrLifetime struct {
+	Expire    uint64
+	Preferred uint64
+	Vltime    uint32
+	Pltime    uint32
+}
+
+type tun struct {
+	Device      string
+	vpnNetworks []netip.Prefix
+	MTU         int
+	Routes      atomic.Pointer[[]Route]
+	routeTree   atomic.Pointer[bart.Table[routing.Gateways]]
+	l           *logrus.Logger
+	f           *os.File
+	fd          int
+}
+
+var deviceNameRE = regexp.MustCompile(`^tun[0-9]+$`)
+
+func newTunFromFd(_ *config.C, _ *logrus.Logger, _ int, _ []netip.Prefix) (*tun, error) {
+	return nil, fmt.Errorf("newTunFromFd not supported in NetBSD")
+}
+
+func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, _ bool) (*tun, error) {
+	// Try to open tun device
+	var err error
+	deviceName := c.GetString("tun.dev", "")
+	if deviceName == "" {
+		return nil, fmt.Errorf("a device name in the format of /dev/tunN must be specified")
+	}
+	if !deviceNameRE.MatchString(deviceName) {
+		return nil, fmt.Errorf("a device name in the format of /dev/tunN must be specified")
 	}
 
-	// Get the actual device name
-	actualName, err := tunDevice.Name()
+	fd, err := unix.Open("/dev/"+deviceName, os.O_RDWR, 0)
 	if err != nil {
-		tunDevice.Close()
-		return nil, fmt.Errorf("failed to get TUN device name: %w", err)
+		return nil, err
 	}
 
-	t := &wgTun{
-		tunDevice:   tunDevice,
+	err = unix.SetNonblock(fd, true)
+	if err != nil {
+		l.WithError(err).Warn("Failed to set the tun device as nonblocking")
+	}
+
+	t := &tun{
+		f:           os.NewFile(uintptr(fd), ""),
+		fd:          fd,
+		Device:      deviceName,
 		vpnNetworks: vpnNetworks,
-		MaxMTU:      mtu,
-		DefaultMTU:  mtu,
+		MTU:         c.GetInt("tun.mtu", DefaultMTU),
 		l:           l,
 	}
 
-	// Create NetBSD-specific route manager
-	t.routeManager = &tun{}
-
 	err = t.reload(c, true)
 	if err != nil {
-		tunDevice.Close()
 		return nil, err
 	}
 
@@ -64,86 +116,294 @@ func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, _ bool) (
 		}
 	})
 
-	l.WithField("name", actualName).Info("Created WireGuard TUN device")
-
 	return t, nil
 }
 
-func (rm *tun) Activate(t *wgTun) error {
-	name, err := t.tunDevice.Name()
+func (t *tun) Close() error {
+	if t.f != nil {
+		if err := t.f.Close(); err != nil {
+			return fmt.Errorf("error closing tun file: %w", err)
+		}
+
+		// t.f.Close should have handled it for us but let's be extra sure
+		_ = unix.Close(t.fd)
+
+		s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_IP)
 		if err != nil {
-		return fmt.Errorf("failed to get device name: %w", err)
+			return err
+		}
+		defer syscall.Close(s)
+
+		ifr := ifreq{Name: t.deviceBytes()}
+		err = ioctl(uintptr(s), syscall.SIOCIFDESTROY, uintptr(unsafe.Pointer(&ifr)))
+		return err
+	}
+	return nil
+}
+
+func (t *tun) Read(to []byte) (int, error) {
+	rc, err := t.f.SyscallConn()
+	if err != nil {
+		return 0, fmt.Errorf("failed to get syscall conn for tun: %w", err)
 	}
 
-	// Set the MTU
-	rm.SetMTU(t, t.MaxMTU)
+	var errno syscall.Errno
+	var n uintptr
+	err = rc.Read(func(fd uintptr) bool {
+		// first 4 bytes is protocol family, in network byte order
+		head := [4]byte{}
+		iovecs := []syscall.Iovec{
+			{&head[0], 4},
+			{&to[0], uint64(len(to))},
+		}
 
-	// Add IP addresses
-	for _, network := range t.vpnNetworks {
-		if err := rm.addIP(t, name, network); err != nil {
+		n, _, errno = syscall.Syscall(syscall.SYS_READV, fd, uintptr(unsafe.Pointer(&iovecs[0])), uintptr(2))
+		if errno.Temporary() {
+			// We got an EAGAIN, EINTR, or EWOULDBLOCK, go again
+			return false
+		}
+		return true
+	})
+	if err != nil {
+		if err == syscall.EBADF || err.Error() == "use of closed file" {
+			// Go doesn't export poll.ErrFileClosing but happily reports it to us so here we are
+			// https://github.com/golang/go/blob/master/src/internal/poll/fd_poll_runtime.go#L121
+			return 0, os.ErrClosed
+		}
+		return 0, fmt.Errorf("failed to make read call for tun: %w", err)
+	}
+
+	if errno != 0 {
+		return 0, fmt.Errorf("failed to make inner read call for tun: %w", errno)
+	}
+
+	// fix bytes read number to exclude header
+	bytesRead := int(n)
+	if bytesRead < 0 {
+		return bytesRead, nil
+	} else if bytesRead < 4 {
+		return 0, nil
+	} else {
+		return bytesRead - 4, nil
+	}
+}
+
+// Write is only valid for single threaded use
+func (t *tun) Write(from []byte) (int, error) {
+	if len(from) <= 1 {
+		return 0, syscall.EIO
+	}
+
+	ipVer := from[0] >> 4
+	var head [4]byte
+	// first 4 bytes is protocol family, in network byte order
+	if ipVer == 4 {
+		head[3] = syscall.AF_INET
+	} else if ipVer == 6 {
+		head[3] = syscall.AF_INET6
+	} else {
+		return 0, fmt.Errorf("unable to determine IP version from packet")
+	}
+
+	rc, err := t.f.SyscallConn()
+	if err != nil {
+		return 0, err
+	}
+
+	var errno syscall.Errno
+	var n uintptr
+	err = rc.Write(func(fd uintptr) bool {
+		iovecs := []syscall.Iovec{
+			{&head[0], 4},
+			{&from[0], uint64(len(from))},
+		}
+
+		n, _, errno = syscall.Syscall(syscall.SYS_WRITEV, fd, uintptr(unsafe.Pointer(&iovecs[0])), uintptr(2))
+		// According to NetBSD documentation for TUN, writes will only return errors in which
+		// this packet will never be delivered so just go on living life.
+		return true
+	})
+	if err != nil {
+		return 0, err
+	}
+
+	if errno != 0 {
+		return 0, errno
+	}
+
+	return int(n) - 4, err
+}
+
+func (t *tun) addIp(cidr netip.Prefix) error {
+	if cidr.Addr().Is4() {
+		var req ifreqAlias4
+		req.Name = t.deviceBytes()
+		req.Addr = unix.RawSockaddrInet4{
+			Len:    unix.SizeofSockaddrInet4,
+			Family: unix.AF_INET,
+			Addr:   cidr.Addr().As4(),
+		}
+		req.DstAddr = unix.RawSockaddrInet4{
+			Len:    unix.SizeofSockaddrInet4,
+			Family: unix.AF_INET,
+			Addr:   cidr.Addr().As4(),
+		}
+		req.MaskAddr = unix.RawSockaddrInet4{
+			Len:    unix.SizeofSockaddrInet4,
+			Family: unix.AF_INET,
+			Addr:   prefixToMask(cidr).As4(),
+		}
+
+		s, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_IP)
+		if err != nil {
+			return err
+		}
+		defer syscall.Close(s)
+
+		if err := ioctl(uintptr(s), unix.SIOCAIFADDR, uintptr(unsafe.Pointer(&req))); err != nil {
+			return fmt.Errorf("failed to set tun address %s: %s", cidr.Addr(), err)
+		}
+
+		return nil
+	}
+
+	if cidr.Addr().Is6() {
+		var req ifreqAlias6
+		req.Name = t.deviceBytes()
+		req.Addr = unix.RawSockaddrInet6{
+			Len:    unix.SizeofSockaddrInet6,
+			Family: unix.AF_INET6,
+			Addr:   cidr.Addr().As16(),
+		}
+		req.PrefixMask = unix.RawSockaddrInet6{
+			Len:    unix.SizeofSockaddrInet6,
+			Family: unix.AF_INET6,
+			Addr:   prefixToMask(cidr).As16(),
+		}
+		req.Lifetime = addrLifetime{
+			Vltime: 0xffffffff,
+			Pltime: 0xffffffff,
+		}
+
+		s, err := unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM, unix.IPPROTO_IP)
+		if err != nil {
+			return err
+		}
+		defer syscall.Close(s)
+
+		if err := ioctl(uintptr(s), SIOCAIFADDR_IN6, uintptr(unsafe.Pointer(&req))); err != nil {
+			return fmt.Errorf("failed to set tun address %s: %s", cidr.Addr().String(), err)
+		}
+		return nil
+	}
+
+	return fmt.Errorf("unknown address type %v", cidr)
+}
+
+func (t *tun) Activate() error {
+	mode := int32(unix.IFF_BROADCAST)
+	err := ioctl(uintptr(t.fd), TUNSIFMODE, uintptr(unsafe.Pointer(&mode)))
+	if err != nil {
+		return fmt.Errorf("failed to set tun device mode: %w", err)
+	}
+
+	v := 1
+	err = ioctl(uintptr(t.fd), TUNSIFHEAD, uintptr(unsafe.Pointer(&v)))
+	if err != nil {
+		return fmt.Errorf("failed to set tun device head: %w", err)
+	}
+
+	err = t.doIoctlByName(unix.SIOCSIFMTU, uint32(t.MTU))
+	if err != nil {
+		return fmt.Errorf("failed to set tun mtu: %w", err)
+	}
+
+	for i := range t.vpnNetworks {
+		err = t.addIp(t.vpnNetworks[i])
+		if err != nil {
 			return err
 		}
 	}
 
-	// Bring up the interface
-	if err := runCommandBSD("ifconfig", name, "up"); err != nil {
-		return fmt.Errorf("failed to bring up interface: %w", err)
+	return t.addRoutes(false)
+}
+
+func (t *tun) doIoctlByName(ctl uintptr, value uint32) error {
+	s, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_IP)
+	if err != nil {
+		return err
+	}
+	defer syscall.Close(s)
+
+	ir := ifreq{Name: t.deviceBytes(), data: int(value)}
+	err = ioctl(uintptr(s), ctl, uintptr(unsafe.Pointer(&ir)))
+	return err
+}
+
+func (t *tun) reload(c *config.C, initial bool) error {
+	change, routes, err := getAllRoutesFromConfig(c, t.vpnNetworks, initial)
+	if err != nil {
+		return err
 	}
 
-	// Set the routes
-	if err := rm.AddRoutes(t, false); err != nil {
+	if !initial && !change {
+		return nil
+	}
+
+	routeTree, err := makeRouteTree(t.l, routes, false)
+	if err != nil {
 		return err
 	}
 
+	// Teach nebula how to handle the routes before establishing them in the system table
+	oldRoutes := t.Routes.Swap(&routes)
+	t.routeTree.Store(routeTree)
+
+	if !initial {
+		// Remove first, if the system removes a wanted route hopefully it will be re-added next
+		err := t.removeRoutes(findRemovedRoutes(routes, *oldRoutes))
+		if err != nil {
+			util.LogWithContextIfNeeded("Failed to remove routes", err, t.l)
+		}
+
+		// Ensure any routes we actually want are installed
+		err = t.addRoutes(true)
+		if err != nil {
+			// Catch any stray logs
+			util.LogWithContextIfNeeded("Failed to add routes", err, t.l)
+		}
+	}
+
 	return nil
 }
 
-func (rm *tun) SetMTU(t *wgTun, mtu int) {
-	name, err := t.tunDevice.Name()
-	if err != nil {
-		t.l.WithError(err).Error("Failed to get device name for MTU set")
-		return
-	}
-
-	if err := runCommandBSD("ifconfig", name, "mtu", strconv.Itoa(mtu)); err != nil {
-		t.l.WithError(err).Error("Failed to set tun mtu")
-	}
+func (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
+	r, _ := t.routeTree.Load().Lookup(ip)
+	return r
 }
 
-func (rm *tun) SetDefaultRoute(t *wgTun, cidr netip.Prefix) error {
-	// On NetBSD, routes are set via ifconfig and route commands
-	return nil
+func (t *tun) Networks() []netip.Prefix {
+	return t.vpnNetworks
 }
 
-func (rm *tun) AddRoutes(t *wgTun, logErrors bool) error {
-	name, err := t.tunDevice.Name()
-	if err != nil {
-		return fmt.Errorf("failed to get device name: %w", err)
-	}
+func (t *tun) Name() string {
+	return t.Device
+}
 
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for netbsd")
+}
+
+func (t *tun) addRoutes(logErrors bool) error {
 	routes := *t.Routes.Load()
+
 	for _, r := range routes {
-		if !r.Install {
+		if len(r.Via) == 0 || !r.Install {
+			// We don't allow route MTUs so only install routes with a via
 			continue
 		}
 
-		// Add route using route command
-		args := []string{"add"}
-
-		if r.Cidr.Addr().Is6() {
-			args = append(args, "-inet6")
-		} else {
-			args = append(args, "-inet")
-		}
-
-		args = append(args, r.Cidr.String(), "-interface", name)
-
-		if r.Metric > 0 {
-			// NetBSD doesn't support route metrics directly like Linux
-			t.l.WithField("route", r).Warn("Route metrics are not fully supported on NetBSD")
-		}
-
-		err := runCommandBSD("route", args...)
+		err := addRoute(r.Cidr, t.vpnNetworks)
 		if err != nil {
 			retErr := util.NewContextualError("Failed to add route", map[string]any{"route": r}, err)
 			if logErrors {
@@ -159,72 +419,169 @@ func (rm *tun) AddRoutes(t *wgTun, logErrors bool) error {
 	return nil
 }
 
-func (rm *tun) RemoveRoutes(t *wgTun, routes []Route) {
-	name, err := t.tunDevice.Name()
-	if err != nil {
-		t.l.WithError(err).Error("Failed to get device name for route removal")
-		return
-	}
-
+func (t *tun) removeRoutes(routes []Route) error {
 	for _, r := range routes {
 		if !r.Install {
 			continue
 		}
 
-		args := []string{"delete"}
-
-		if r.Cidr.Addr().Is6() {
-			args = append(args, "-inet6")
-		} else {
-			args = append(args, "-inet")
-		}
-
-		args = append(args, r.Cidr.String(), "-interface", name)
-
-		err := runCommandBSD("route", args...)
+		err := delRoute(r.Cidr, t.vpnNetworks)
 		if err != nil {
 			t.l.WithError(err).WithField("route", r).Error("Failed to remove route")
 		} else {
 			t.l.WithField("route", r).Info("Removed route")
 		}
 	}
+	return nil
 }
 
-func (rm *tun) NewMultiQueueReader(t *wgTun) (io.ReadWriteCloser, error) {
-	// NetBSD doesn't support multi-queue TUN devices in the same way as Linux
-	// Return a reader that wraps the same device
-	return &wgTunReader{
-		parent:    t,
-		tunDevice: t.tunDevice,
-		batchSize: 64,
-		offset:    0,
-		l:         t.l,
-	}, nil
+func (t *tun) deviceBytes() (o [16]byte) {
+	for i, c := range t.Device {
+		o[i] = byte(c)
+	}
+	return
 }
 
-func (rm *tun) addIP(t *wgTun, name string, network netip.Prefix) error {
-	addr := network.Addr()
+func addRoute(prefix netip.Prefix, gateways []netip.Prefix) error {
+	sock, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
+	if err != nil {
+		return fmt.Errorf("unable to create AF_ROUTE socket: %v", err)
+	}
+	defer unix.Close(sock)
 
-	if addr.Is4() {
-		// For IPv4: ifconfig tun0 10.0.0.1/24
-		if err := runCommandBSD("ifconfig", name, network.String()); err != nil {
-			return fmt.Errorf("failed to add IPv4 address: %w", err)
+	route := &netroute.RouteMessage{
+		Version: unix.RTM_VERSION,
+		Type:    unix.RTM_ADD,
+		Flags:   unix.RTF_UP | unix.RTF_GATEWAY,
+		Seq:     1,
+	}
+
+	if prefix.Addr().Is4() {
+		gw, err := selectGateway(prefix, gateways)
+		if err != nil {
+			return err
+		}
+		route.Addrs = []netroute.Addr{
+			unix.RTAX_DST:     &netroute.Inet4Addr{IP: prefix.Masked().Addr().As4()},
+			unix.RTAX_NETMASK: &netroute.Inet4Addr{IP: prefixToMask(prefix).As4()},
+			unix.RTAX_GATEWAY: &netroute.Inet4Addr{IP: gw.Addr().As4()},
 		}
 	} else {
-		// For IPv6: ifconfig tun0 inet6 add 2001:db8::1/64
-		if err := runCommandBSD("ifconfig", name, "inet6", "add", network.String()); err != nil {
-			return fmt.Errorf("failed to add IPv6 address: %w", err)
-		}
-	}
-
-	return nil
-}
-
-func runCommandBSD(name string, args ...string) error {
-	cmd := exec.Command(name, args...)
-	output, err := cmd.CombinedOutput()
+		gw, err := selectGateway(prefix, gateways)
 		if err != nil {
-		return fmt.Errorf("%s %s failed: %w\nOutput: %s", name, strings.Join(args, " "), err, string(output))
+			return err
+		}
+		route.Addrs = []netroute.Addr{
+			unix.RTAX_DST:     &netroute.Inet6Addr{IP: prefix.Masked().Addr().As16()},
+			unix.RTAX_NETMASK: &netroute.Inet6Addr{IP: prefixToMask(prefix).As16()},
+			unix.RTAX_GATEWAY: &netroute.Inet6Addr{IP: gw.Addr().As16()},
+		}
+	}
+
+	data, err := route.Marshal()
+	if err != nil {
+		return fmt.Errorf("failed to create route.RouteMessage: %w", err)
+	}
+
+	_, err = unix.Write(sock, data[:])
+	if err != nil {
+		if errors.Is(err, unix.EEXIST) {
+			// Try to do a change
+			route.Type = unix.RTM_CHANGE
+			data, err = route.Marshal()
+			if err != nil {
+				return fmt.Errorf("failed to create route.RouteMessage for change: %w", err)
+			}
+			_, err = unix.Write(sock, data[:])
+			return err
+		}
+		return fmt.Errorf("failed to write route.RouteMessage to socket: %w", err)
+	}
+
+	return nil
+}
+
+func delRoute(prefix netip.Prefix, gateways []netip.Prefix) error {
+	sock, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
+	if err != nil {
+		return fmt.Errorf("unable to create AF_ROUTE socket: %v", err)
+	}
+	defer unix.Close(sock)
+
+	route := netroute.RouteMessage{
+		Version: unix.RTM_VERSION,
+		Type:    unix.RTM_DELETE,
+		Seq:     1,
+	}
+
+	if prefix.Addr().Is4() {
+		gw, err := selectGateway(prefix, gateways)
+		if err != nil {
+			return err
+		}
+		route.Addrs = []netroute.Addr{
+			unix.RTAX_DST:     &netroute.Inet4Addr{IP: prefix.Masked().Addr().As4()},
+			unix.RTAX_NETMASK: &netroute.Inet4Addr{IP: prefixToMask(prefix).As4()},
+			unix.RTAX_GATEWAY: &netroute.Inet4Addr{IP: gw.Addr().As4()},
+		}
+	} else {
+		gw, err := selectGateway(prefix, gateways)
+		if err != nil {
+			return err
+		}
+		route.Addrs = []netroute.Addr{
+			unix.RTAX_DST:     &netroute.Inet6Addr{IP: prefix.Masked().Addr().As16()},
+			unix.RTAX_NETMASK: &netroute.Inet6Addr{IP: prefixToMask(prefix).As16()},
+			unix.RTAX_GATEWAY: &netroute.Inet6Addr{IP: gw.Addr().As16()},
+		}
+	}
+
+	data, err := route.Marshal()
+	if err != nil {
+		return fmt.Errorf("failed to create route.RouteMessage: %w", err)
+	}
+	_, err = unix.Write(sock, data[:])
+	if err != nil {
+		return fmt.Errorf("failed to write route.RouteMessage to socket: %w", err)
+	}
+
+	return nil
+}
+
+func ioctl(a1, a2, a3 uintptr) error {
+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, a1, a2, a3)
+	if errno != 0 {
+		return errno
 	}
 	return nil
 }
+
+func prefixToMask(prefix netip.Prefix) netip.Addr {
+	bits := prefix.Bits()
+	if prefix.Addr().Is4() {
+		mask := ^uint32(0) << (32 - bits)
+		return netip.AddrFrom4([4]byte{
+			byte(mask >> 24),
+			byte(mask >> 16),
+			byte(mask >> 8),
+			byte(mask),
+		})
+	}
+	var mask [16]byte
+	for i := 0; i < bits/8; i++ {
+		mask[i] = 0xff
+	}
+	if bits%8 != 0 {
+		mask[bits/8] = ^byte(0) << (8 - bits%8)
+	}
+	return netip.AddrFrom16(mask)
+}
+
+func selectGateway(prefix netip.Prefix, gateways []netip.Prefix) (netip.Prefix, error) {
+	for _, gw := range gateways {
+		if prefix.Addr().Is4() == gw.Addr().Is4() {
+			return gw, nil
+		}
+	}
+	return netip.Prefix{}, fmt.Errorf("no suitable gateway found for prefix %v", prefix)
+}

overlay/tun_wg.go

@@ -1,5 +1,5 @@
-//go:build !android && !e2e_testing
-// +build !android,!e2e_testing
+//go:build !android && !netbsd && !e2e_testing
+// +build !android,!netbsd,!e2e_testing
 
 package overlay