claude first stab and first cleanup - ugh

overlay/tun_openbsd.go

@@ -1,104 +1,59 @@
-//go:build !e2e_testing
-// +build !e2e_testing
+//go:build openbsd && !e2e_testing
+// +build openbsd,!e2e_testing
 
 package overlay
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"net/netip"
-	"os"
-	"regexp"
-	"sync/atomic"
-	"syscall"
-	"unsafe"
+	"os/exec"
+	"strconv"
+	"strings"
 
-	"github.com/gaissmai/bart"
 	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
-	netroute "golang.org/x/net/route"
-	"golang.org/x/sys/unix"
+	wgtun "golang.zx2c4.com/wireguard/tun"
 )
 
-const (
-	SIOCAIFADDR_IN6 = 0x8080691a
-)
+type tun struct{}
 
-type ifreqAlias4 struct {
-	Name     [unix.IFNAMSIZ]byte
-	Addr     unix.RawSockaddrInet4
-	DstAddr  unix.RawSockaddrInet4
-	MaskAddr unix.RawSockaddrInet4
+func newTunFromFd(_ *config.C, _ *logrus.Logger, _ int, _ []netip.Prefix) (*wgTun, error) {
+	return nil, fmt.Errorf("newTunFromFd not supported on OpenBSD")
 }
 
-type ifreqAlias6 struct {
-	Name       [unix.IFNAMSIZ]byte
-	Addr       unix.RawSockaddrInet6
-	DstAddr    unix.RawSockaddrInet6
-	PrefixMask unix.RawSockaddrInet6
-	Flags      uint32
-	Lifetime   [2]uint32
-}
+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 ifreq struct {
-	Name [unix.IFNAMSIZ]byte
-	data int
-}
-
-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
-	// cache out buffer since we need to prepend 4 bytes for tun metadata
-	out []byte
-}
-
-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 openbsd")
-}
-
-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")
-	}
-
-	fd, err := unix.Open("/dev/"+deviceName, os.O_RDWR, 0)
+	// Create WireGuard TUN device
+	tunDevice, err := wgtun.CreateTUN(deviceName, mtu)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to create TUN device: %w", err)
 	}
 
-	err = unix.SetNonblock(fd, true)
+	// Get the actual device name
+	actualName, err := tunDevice.Name()
 	if err != nil {
-		l.WithError(err).Warn("Failed to set the tun device as nonblocking")
+		tunDevice.Close()
+		return nil, fmt.Errorf("failed to get TUN device name: %w", err)
 	}
 
-	t := &tun{
-		f:           os.NewFile(uintptr(fd), ""),
-		fd:          fd,
-		Device:      deviceName,
+	t := &wgTun{
+		tunDevice:   tunDevice,
 		vpnNetworks: vpnNetworks,
-		MTU:         c.GetInt("tun.mtu", DefaultMTU),
+		MaxMTU:      mtu,
+		DefaultMTU:  mtu,
 		l:           l,
 	}
 
+	// Create OpenBSD-specific route manager
+	t.routeManager = &tun{}
+
 	err = t.reload(c, true)
 	if err != nil {
+		tunDevice.Close()
 		return nil, err
 	}
 
@@ -109,221 +64,86 @@ 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 (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)
-	}
-	return nil
-}
-
-func (t *tun) Read(to []byte) (int, error) {
-	buf := make([]byte, len(to)+4)
-
-	n, err := t.f.Read(buf)
-
-	copy(to, buf[4:])
-	return n - 4, err
-}
-
-// Write is only valid for single threaded use
-func (t *tun) Write(from []byte) (int, error) {
-	buf := t.out
-	if cap(buf) < len(from)+4 {
-		buf = make([]byte, len(from)+4)
-		t.out = buf
-	}
-	buf = buf[:len(from)+4]
-
-	if len(from) == 0 {
-		return 0, syscall.EIO
-	}
-
-	// Determine the IP Family for the NULL L2 Header
-	ipVer := from[0] >> 4
-	if ipVer == 4 {
-		buf[3] = syscall.AF_INET
-	} else if ipVer == 6 {
-		buf[3] = syscall.AF_INET6
-	} else {
-		return 0, fmt.Errorf("unable to determine IP version from packet")
-	}
-
-	copy(buf[4:], from)
-
-	n, err := t.f.Write(buf)
-	return 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)
-		}
-
-		err = addRoute(cidr, t.vpnNetworks)
-		if err != nil {
-			return fmt.Errorf("failed to set route for vpn network %v: %w", cidr, 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[0] = 0xffffffff
-		req.Lifetime[1] = 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 {
-	err := t.doIoctlByName(unix.SIOCSIFMTU, uint32(t.MTU))
+func (rm *tun) Activate(t *wgTun) error {
+	name, err := t.tunDevice.Name()
 	if err != nil {
-		return fmt.Errorf("failed to set tun mtu: %w", err)
+		return fmt.Errorf("failed to get device name: %w", err)
 	}
 
-	for i := range t.vpnNetworks {
-		err = t.addIp(t.vpnNetworks[i])
-		if err != nil {
+	// Set the MTU
+	rm.SetMTU(t, t.MaxMTU)
+
+	// Add IP addresses
+	for _, network := range t.vpnNetworks {
+		if err := rm.addIP(t, name, network); err != nil {
 			return err
 		}
 	}
 
-	return t.addRoutes(false)
-}
+	// Bring up the interface
+	if err := runCommandBSD("ifconfig", name, "up"); err != nil {
+		return fmt.Errorf("failed to bring up interface: %w", err)
+	}
 
-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 {
+	// Set the routes
+	if err := rm.AddRoutes(t, false); 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
-	}
-
-	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 (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
-	r, _ := t.routeTree.Load().Lookup(ip)
-	return r
+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) Networks() []netip.Prefix {
-	return t.vpnNetworks
+func (rm *tun) SetDefaultRoute(t *wgTun, cidr netip.Prefix) error {
+	// On OpenBSD, routes are set via ifconfig and route commands
+	return nil
 }
 
-func (t *tun) Name() string {
-	return t.Device
-}
+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) NewMultiQueueReader() (io.ReadWriteCloser, error) {
-	return nil, fmt.Errorf("TODO: multiqueue not implemented for openbsd")
-}
-
-func (t *tun) addRoutes(logErrors bool) error {
 	routes := *t.Routes.Load()
-
 	for _, r := range routes {
-		if len(r.Via) == 0 || !r.Install {
-			// We don't allow route MTUs so only install routes with a via
+		if !r.Install {
 			continue
 		}
 
-		err := addRoute(r.Cidr, t.vpnNetworks)
+		// 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 {
+			// OpenBSD doesn't support route metrics directly like Linux
+			t.l.WithField("route", r).Warn("Route metrics are not fully supported on OpenBSD")
+		}
+
+		err := runCommandBSD("route", args...)
 		if err != nil {
 			retErr := util.NewContextualError("Failed to add route", map[string]any{"route": r}, err)
 			if logErrors {
@@ -339,131 +159,72 @@ func (t *tun) addRoutes(logErrors bool) error {
 	return nil
 }
 
-func (t *tun) removeRoutes(routes []Route) error {
+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
+	}
+
 	for _, r := range routes {
 		if !r.Install {
 			continue
 		}
 
-		err := delRoute(r.Cidr, t.vpnNetworks)
+		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...)
 		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 (t *tun) deviceBytes() (o [16]byte) {
-	for i, c := range t.Device {
-		o[i] = byte(c)
-	}
-	return
+func (rm *tun) NewMultiQueueReader(t *wgTun) (io.ReadWriteCloser, error) {
+	// OpenBSD 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 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)
+func (rm *tun) addIP(t *wgTun, name string, network netip.Prefix) error {
+	addr := network.Addr()
 
-	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()},
+	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)
 		}
 	} else {
-		gw, err := selectGateway(prefix, gateways)
-		if err != nil {
-			return err
+		// 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)
 		}
-		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)
+func runCommandBSD(name string, args ...string) error {
+	cmd := exec.Command(name, args...)
+	output, err := cmd.CombinedOutput()
 	if err != nil {
-		return fmt.Errorf("unable to create AF_ROUTE socket: %v", err)
+		return fmt.Errorf("%s %s failed: %w\nOutput: %s", name, strings.Join(args, " "), err, string(output))
 	}
-	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
 }