TUN inbound: Add macOS support (#5559)

2026-07-02 17:58:46 +00:00 · 2026-01-18 11:39:39 +08:00
parent cfc78b3ac1
commit 6d6c045a5a
3 changed files with 371 additions and 1 deletions
@@ -0,0 +1,169 @@
+//go:build darwin
+
+package tun
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
+
+const (
+	utunControlName = "com.apple.net.utun_control"
+	utunOptIfName   = 2
+	sysprotoControl = 2
+)
+
+type DarwinTun struct {
+	tunFd   int
+	name    string
+	options TunOptions
+}
+
+var _ Tun = (*DarwinTun)(nil)
+var _ GVisorTun = (*DarwinTun)(nil)
+
+func NewTun(options TunOptions) (Tun, error) {
+	tunFd, name, err := openUTun(options.Name)
+	if err != nil {
+		return nil, err
+	}
+
+	return &DarwinTun{
+		tunFd:   tunFd,
+		name:    name,
+		options: options,
+	}, nil
+}
+
+func (t *DarwinTun) Start() error {
+	if t.options.MTU > 0 {
+		if err := setMTU(t.name, int(t.options.MTU)); err != nil {
+			return err
+		}
+	}
+	return setState(t.name, true)
+}
+
+func (t *DarwinTun) Close() error {
+	_ = setState(t.name, false)
+	return unix.Close(t.tunFd)
+}
+
+func (t *DarwinTun) newEndpoint() (stack.LinkEndpoint, error) {
+	return newDarwinEndpoint(t.tunFd, t.options.MTU), nil
+}
+
+func openUTun(name string) (int, string, error) {
+	fd, err := unix.Socket(unix.AF_SYSTEM, unix.SOCK_DGRAM, sysprotoControl)
+	if err != nil {
+		return -1, "", err
+	}
+
+	ctlInfo := &unix.CtlInfo{}
+	copy(ctlInfo.Name[:], utunControlName)
+	if err := unix.IoctlCtlInfo(fd, ctlInfo); err != nil {
+		_ = unix.Close(fd)
+		return -1, "", err
+	}
+
+	sockaddr := &unix.SockaddrCtl{
+		ID:   ctlInfo.Id,
+		Unit: parseUTunUnit(name),
+	}
+
+	if err := unix.Connect(fd, sockaddr); err != nil {
+		_ = unix.Close(fd)
+		return -1, "", err
+	}
+
+	if err := unix.SetNonblock(fd, true); err != nil {
+		_ = unix.Close(fd)
+		return -1, "", err
+	}
+
+	tunName, err := unix.GetsockoptString(fd, sysprotoControl, utunOptIfName)
+	if err != nil {
+		_ = unix.Close(fd)
+		return -1, "", err
+	}
+
+	tunName = strings.TrimRight(tunName, "\x00")
+	if tunName == "" {
+		_ = unix.Close(fd)
+		return -1, "", errors.New("empty utun name")
+	}
+
+	return fd, tunName, nil
+}
+
+func parseUTunUnit(name string) uint32 {
+	var unit uint32
+	if _, err := fmt.Sscanf(name, "utun%d", &unit); err != nil {
+		return 0
+	}
+	return unit + 1
+}
+
+type ifreqMTU struct {
+	Name [unix.IFNAMSIZ]byte
+	MTU  int32
+	_    [12]byte
+}
+
+type ifreqFlags struct {
+	Name  [unix.IFNAMSIZ]byte
+	Flags int16
+	_     [14]byte
+}
+
+func setMTU(name string, mtu int) error {
+	if mtu <= 0 {
+		return nil
+	}
+
+	fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = unix.Close(fd) }()
+
+	ifr := ifreqMTU{MTU: int32(mtu)}
+	copy(ifr.Name[:], name)
+	return ioctlPtr(fd, unix.SIOCSIFMTU, unsafe.Pointer(&ifr))
+}
+
+func setState(name string, up bool) error {
+	fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = unix.Close(fd) }()
+
+	ifr := ifreqFlags{}
+	copy(ifr.Name[:], name)
+
+	if err := ioctlPtr(fd, unix.SIOCGIFFLAGS, unsafe.Pointer(&ifr)); err != nil {
+		return err
+	}
+
+	if up {
+		ifr.Flags |= unix.IFF_UP
+	} else {
+		ifr.Flags &^= unix.IFF_UP
+	}
+
+	return ioctlPtr(fd, unix.SIOCSIFFLAGS, unsafe.Pointer(&ifr))
+}
+
+func ioctlPtr(fd int, req uint, arg unsafe.Pointer) error {
+	_, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uintptr(req), uintptr(arg))
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}