1 files changed, 382 insertions, 0 deletions
diff --git a/tun/tun_darwin.go b/tun/tun_darwin.go
new file mode 100644
index 0000000..fcbb4f9
--- /dev/null
+++ b/tun/tun_darwin.go
@@ -0,0 +1,382 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2017-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * Copyright (C) 2017-2018 Mathias N. Hall-Andersen <mathias@hall-andersen.dk>.
+ */
+
+package tun
+
+import (
+	"../rwcancel"
+	"errors"
+	"fmt"
+	"golang.org/x/net/ipv6"
+	"golang.org/x/sys/unix"
+	"io/ioutil"
+	"net"
+	"os"
+	"unsafe"
+)
+
+const utunControlName = "com.apple.net.utun_control"
+
+// _CTLIOCGINFO value derived from /usr/include/sys/{kern_control,ioccom}.h
+const _CTLIOCGINFO = (0x40000000 | 0x80000000) | ((100 & 0x1fff) << 16) | uint32(byte('N'))<<8 | 3
+
+// sockaddr_ctl specifeid in /usr/include/sys/kern_control.h
+type sockaddrCtl struct {
+	scLen      uint8
+	scFamily   uint8
+	ssSysaddr  uint16
+	scID       uint32
+	scUnit     uint32
+	scReserved [5]uint32
+}
+
+type nativeTun struct {
+	name        string
+	fd          *os.File
+	rwcancel    *rwcancel.RWCancel
+	events      chan TUNEvent
+	errors      chan error
+	routeSocket int
+}
+
+var sockaddrCtlSize uintptr = 32
+
+func (tun *nativeTun) routineRouteListener(tunIfindex int) {
+	var (
+		statusUp  bool
+		statusMTU int
+	)
+
+	defer close(tun.events)
+
+	data := make([]byte, os.Getpagesize())
+	for {
+		n, err := unix.Read(tun.routeSocket, data)
+		if err != nil {
+			tun.errors <- err
+			return
+		}
+
+		if n < 14 {
+			continue
+		}
+
+		if data[3 /* type */] != unix.RTM_IFINFO {
+			continue
+		}
+		ifindex := int(*(*uint16)(unsafe.Pointer(&data[12 /* ifindex */])))
+		if ifindex != tunIfindex {
+			continue
+		}
+
+		iface, err := net.InterfaceByIndex(ifindex)
+		if err != nil {
+			tun.errors <- err
+			return
+		}
+
+		// Up / Down event
+		up := (iface.Flags & net.FlagUp) != 0
+		if up != statusUp && up {
+			tun.events <- TUNEventUp
+		}
+		if up != statusUp && !up {
+			tun.events <- TUNEventDown
+		}
+		statusUp = up
+
+		// MTU changes
+		if iface.MTU != statusMTU {
+			tun.events <- TUNEventMTUUpdate
+		}
+		statusMTU = iface.MTU
+	}
+}
+
+func CreateTUN(name string, mtu int) (TUNDevice, error) {
+	ifIndex := -1
+	if name != "utun" {
+		_, err := fmt.Sscanf(name, "utun%d", &ifIndex)
+		if err != nil || ifIndex < 0 {
+			return nil, fmt.Errorf("Interface name must be utun[0-9]*")
+		}
+	}
+
+	fd, err := unix.Socket(unix.AF_SYSTEM, unix.SOCK_DGRAM, 2)
+
+	if err != nil {
+		return nil, err
+	}
+
+	var ctlInfo = &struct {
+		ctlID   uint32
+		ctlName [96]byte
+	}{}
+
+	copy(ctlInfo.ctlName[:], []byte(utunControlName))
+
+	_, _, errno := unix.Syscall(
+		unix.SYS_IOCTL,
+		uintptr(fd),
+		uintptr(_CTLIOCGINFO),
+		uintptr(unsafe.Pointer(ctlInfo)),
+	)
+
+	if errno != 0 {
+		return nil, fmt.Errorf("_CTLIOCGINFO: %v", errno)
+	}
+
+	sc := sockaddrCtl{
+		scLen:     uint8(sockaddrCtlSize),
+		scFamily:  unix.AF_SYSTEM,
+		ssSysaddr: 2,
+		scID:      ctlInfo.ctlID,
+		scUnit:    uint32(ifIndex) + 1,
+	}
+
+	scPointer := unsafe.Pointer(&sc)
+
+	_, _, errno = unix.RawSyscall(
+		unix.SYS_CONNECT,
+		uintptr(fd),
+		uintptr(scPointer),
+		uintptr(sockaddrCtlSize),
+	)
+
+	if errno != 0 {
+		return nil, fmt.Errorf("SYS_CONNECT: %v", errno)
+	}
+
+	tun, err := CreateTUNFromFile(os.NewFile(uintptr(fd), ""), mtu)
+
+	if err == nil && name == "utun" {
+		fname := os.Getenv("WG_TUN_NAME_FILE")
+		if fname != "" {
+			ioutil.WriteFile(fname, []byte(tun.(*nativeTun).name+"\n"), 0400)
+		}
+	}
+
+	return tun, err
+}
+
+func CreateTUNFromFile(file *os.File, mtu int) (TUNDevice, error) {
+
+	tun := &nativeTun{
+		fd:     file,
+		events: make(chan TUNEvent, 10),
+		errors: make(chan error, 1),
+	}
+
+	name, err := tun.Name()
+	if err != nil {
+		tun.fd.Close()
+		return nil, err
+	}
+
+	tunIfindex, err := func() (int, error) {
+		iface, err := net.InterfaceByName(name)
+		if err != nil {
+			return -1, err
+		}
+		return iface.Index, nil
+	}()
+	if err != nil {
+		tun.fd.Close()
+		return nil, err
+	}
+
+	tun.rwcancel, err = rwcancel.NewRWCancel(int(file.Fd()))
+	if err != nil {
+		tun.fd.Close()
+		return nil, err
+	}
+
+	tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
+	if err != nil {
+		tun.fd.Close()
+		return nil, err
+	}
+
+	go tun.routineRouteListener(tunIfindex)
+
+	err = tun.setMTU(mtu)
+	if err != nil {
+		tun.Close()
+		return nil, err
+	}
+
+	return tun, nil
+}
+
+func (tun *nativeTun) Name() (string, error) {
+
+	var ifName struct {
+		name [16]byte
+	}
+	ifNameSize := uintptr(16)
+
+	_, _, errno := unix.Syscall6(
+		unix.SYS_GETSOCKOPT,
+		uintptr(tun.fd.Fd()),
+		2, /* #define SYSPROTO_CONTROL 2 */
+		2, /* #define UTUN_OPT_IFNAME 2 */
+		uintptr(unsafe.Pointer(&ifName)),
+		uintptr(unsafe.Pointer(&ifNameSize)), 0)
+
+	if errno != 0 {
+		return "", fmt.Errorf("SYS_GETSOCKOPT: %v", errno)
+	}
+
+	tun.name = string(ifName.name[:ifNameSize-1])
+	return tun.name, nil
+}
+
+func (tun *nativeTun) File() *os.File {
+	return tun.fd
+}
+
+func (tun *nativeTun) Events() chan TUNEvent {
+	return tun.events
+}
+
+func (tun *nativeTun) doRead(buff []byte, offset int) (int, error) {
+	select {
+	case err := <-tun.errors:
+		return 0, err
+	default:
+		buff := buff[offset-4:]
+		n, err := tun.fd.Read(buff[:])
+		if n < 4 {
+			return 0, err
+		}
+		return n - 4, err
+	}
+}
+
+func (tun *nativeTun) Read(buff []byte, offset int) (int, error) {
+	for {
+		n, err := tun.doRead(buff, offset)
+		if err == nil || !rwcancel.ErrorIsEAGAIN(err) {
+			return n, err
+		}
+		if !tun.rwcancel.ReadyRead() {
+			return 0, errors.New("tun device closed")
+		}
+	}
+}
+
+func (tun *nativeTun) Write(buff []byte, offset int) (int, error) {
+
+	// reserve space for header
+
+	buff = buff[offset-4:]
+
+	// add packet information header
+
+	buff[0] = 0x00
+	buff[1] = 0x00
+	buff[2] = 0x00
+
+	if buff[4]>>4 == ipv6.Version {
+		buff[3] = unix.AF_INET6
+	} else {
+		buff[3] = unix.AF_INET
+	}
+
+	// write
+
+	return tun.fd.Write(buff)
+}
+
+func (tun *nativeTun) Close() error {
+	var err3 error
+	err1 := tun.rwcancel.Cancel()
+	err2 := tun.fd.Close()
+	if tun.routeSocket != -1 {
+		unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)
+		err3 = unix.Close(tun.routeSocket)
+		tun.routeSocket = -1
+	} else if tun.events != nil {
+		close(tun.events)
+	}
+	if err1 != nil {
+		return err1
+	}
+	if err2 != nil {
+		return err2
+	}
+	return err3
+}
+
+func (tun *nativeTun) setMTU(n int) error {
+
+	// open datagram socket
+
+	var fd int
+
+	fd, err := unix.Socket(
+		unix.AF_INET,
+		unix.SOCK_DGRAM,
+		0,
+	)
+
+	if err != nil {
+		return err
+	}
+
+	defer unix.Close(fd)
+
+	// do ioctl call
+
+	var ifr [32]byte
+	copy(ifr[:], tun.name)
+	*(*uint32)(unsafe.Pointer(&ifr[unix.IFNAMSIZ])) = uint32(n)
+	_, _, errno := unix.Syscall(
+		unix.SYS_IOCTL,
+		uintptr(fd),
+		uintptr(unix.SIOCSIFMTU),
+		uintptr(unsafe.Pointer(&ifr[0])),
+	)
+
+	if errno != 0 {
+		return fmt.Errorf("failed to set MTU on %s", tun.name)
+	}
+
+	return nil
+}
+
+func (tun *nativeTun) MTU() (int, error) {
+
+	// open datagram socket
+
+	fd, err := unix.Socket(
+		unix.AF_INET,
+		unix.SOCK_DGRAM,
+		0,
+	)
+
+	if err != nil {
+		return 0, err
+	}
+
+	defer unix.Close(fd)
+
+	// do ioctl call
+
+	var ifr [64]byte
+	copy(ifr[:], tun.name)
+	_, _, errno := unix.Syscall(
+		unix.SYS_IOCTL,
+		uintptr(fd),
+		uintptr(unix.SIOCGIFMTU),
+		uintptr(unsafe.Pointer(&ifr[0])),
+	)
+	if errno != 0 {
+		return 0, fmt.Errorf("failed to get MTU on %s", tun.name)
+	}
+
+	return int(*(*int32)(unsafe.Pointer(&ifr[16]))), nil
+}