--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2017-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+package tun
+
+import (
+ "bytes"
+ "errors"
+ "fmt"
+ "git.zx2c4.com/wireguard-go/rwcancel"
+ "golang.org/x/net/ipv6"
+ "golang.org/x/sys/unix"
+ "net"
+ "os"
+ "syscall"
+ "unsafe"
+)
+
+// _TUNSIFHEAD, value derived from sys/net/{if_tun,ioccom}.h
+// const _TUNSIFHEAD = ((0x80000000) | (((4) & ((1 << 13) - 1) ) << 16) | (uint32(byte('t')) << 8) | (96))
+const _TUNSIFHEAD = 0x80047460
+const _TUNSIFMODE = 0x8004745e
+const _TUNSIFPID = 0x2000745f
+
+// Iface status string max len
+const _IFSTATMAX = 800
+
+const SIZEOF_UINTPTR = 4 << (^uintptr(0) >> 32 & 1)
+
+// structure for iface requests with a pointer
+type ifreq_ptr struct {
+ Name [unix.IFNAMSIZ]byte
+ Data uintptr
+ Pad0 [24 - SIZEOF_UINTPTR]byte
+}
+
+// Structure for iface mtu get/set ioctls
+type ifreq_mtu struct {
+ Name [unix.IFNAMSIZ]byte
+ MTU uint32
+ Pad0 [12]byte
+}
+
+// Structure for interface status request ioctl
+type ifstat struct {
+ IfsName [unix.IFNAMSIZ]byte
+ Ascii [_IFSTATMAX]byte
+}
+
+type nativeTun struct {
+ name string
+ origName string
+ fd *os.File
+ rwcancel *rwcancel.RWCancel
+ events chan TUNEvent
+ errors chan error
+ routeSocket int
+}
+
+func (tun *nativeTun) routineRouteListener(tunIfindex int) {
+ var (
+ statusUp bool
+ statusMTU int
+ )
+
+ defer close(tun.events)
+
+ data := make([]byte, os.Getpagesize())
+ for {
+ retry:
+ n, err := unix.Read(tun.routeSocket, data)
+ if err != nil {
+ if errno, ok := err.(syscall.Errno); ok && errno == syscall.EINTR {
+ goto retry
+ }
+ 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 tunName(fd uintptr) (string, error) {
+ //Terrible hack to make up for freebsd not having a TUNGIFNAME
+
+ //First, make sure the tun pid matches this proc's pid
+ _, _, errno := unix.Syscall(
+ unix.SYS_IOCTL,
+ uintptr(fd),
+ uintptr(_TUNSIFPID),
+ uintptr(0),
+ )
+
+ if errno != 0 {
+ return "", fmt.Errorf("failed to set tun device PID: %s", errno.Error())
+ }
+
+ // Open iface control socket
+
+ confd, err := unix.Socket(
+ unix.AF_INET,
+ unix.SOCK_DGRAM,
+ 0,
+ )
+
+ if err != nil {
+ return "", err
+ }
+
+ defer unix.Close(confd)
+
+ procPid := os.Getpid()
+
+ //Try to find interface with matching PID
+ for i := 1; ; i++ {
+ iface, _ := net.InterfaceByIndex(i)
+ if err != nil || iface == nil {
+ break
+ }
+
+ // Structs for getting data in and out of SIOCGIFSTATUS ioctl
+ var ifstatus ifstat
+ copy(ifstatus.IfsName[:], iface.Name)
+
+ // Make the syscall to get the status string
+ _, _, errno := unix.Syscall(
+ unix.SYS_IOCTL,
+ uintptr(confd),
+ uintptr(unix.SIOCGIFSTATUS),
+ uintptr(unsafe.Pointer(&ifstatus)),
+ )
+
+ if errno != 0 {
+ continue
+ }
+
+ nullStr := ifstatus.Ascii[:]
+ i := bytes.IndexByte(nullStr, 0)
+ if i < 1 {
+ continue
+ }
+ statStr := string(nullStr[:i])
+ var pidNum int = 0
+
+ // Finally get the owning PID
+ // Format string taken from sys/net/if_tun.c
+ _, err := fmt.Sscanf(statStr, "\tOpened by PID %d\n", &pidNum)
+ if err != nil {
+ continue
+ }
+
+ if pidNum == procPid {
+ return iface.Name, nil
+ }
+ }
+
+ return "", nil
+}
+
+// Rename an interface with SIOCSIFNAME
+func renameTun(oldName string, newName string) (error) {
+ // Open control socket
+ confd, err := unix.Socket(
+ unix.AF_INET,
+ unix.SOCK_DGRAM,
+ 0,
+ )
+
+ if err != nil {
+ return err
+ }
+
+ defer unix.Close(confd)
+
+ // set up struct for iface rename
+ var newnp [unix.IFNAMSIZ]byte
+ copy(newnp[:], newName)
+
+ var ifr ifreq_ptr
+ copy(ifr.Name[:], oldName)
+ ifr.Data = uintptr(unsafe.Pointer(&newnp[0]))
+
+ //do actual ioctl to rename iface
+ _, _, errno := unix.Syscall(
+ unix.SYS_IOCTL,
+ uintptr(confd),
+ uintptr(unix.SIOCSIFNAME),
+ uintptr(unsafe.Pointer(&ifr)),
+ )
+ if errno != 0 {
+ return fmt.Errorf("failed to rename %s to %s: %s", oldName, newName, errno.Error())
+ }
+
+ return nil
+}
+
+func CreateTUN(name string, mtu int) (TUNDevice, error) {
+ if len(name) > unix.IFNAMSIZ-1 {
+ return nil, errors.New("interface name too long")
+ }
+
+ // See if interface already exists
+ iface, err := net.InterfaceByName(name)
+ if iface != nil {
+ return nil, fmt.Errorf("interface %s already exists", name)
+ }
+
+ var tunfile *os.File
+
+ // Try and open a usable tun device
+ for i := 0; i < 99; i++ {
+ // Try opening the tun dev file
+ tunfile, err = os.OpenFile(fmt.Sprintf("/dev/tun%d",i), unix.O_RDWR, 0)
+
+ // If we don't get an EBUSY or ENOEXIST, this should be a valid, usable tunnel interface
+ if err == nil{
+ break
+ }
+ }
+ // If we've not found a free /dev/tunN interface, open a new one
+ if tunfile == nil {
+ tunfile, err = os.OpenFile("/dev/tun", unix.O_RDWR, 0)
+
+ if err != nil {
+ return nil, err
+ }
+ }
+
+ tunfd := tunfile.Fd()
+
+ assignedName, err := tunName(tunfd)
+ if err != nil {
+ tunfile.Close()
+ return nil, err
+ }
+
+ // Enable ifhead mode, otherwise tun will complain if it gets a non-AF_INET packet
+ ifheadmode := 1
+ _, _, errno := unix.Syscall(
+ unix.SYS_IOCTL,
+ uintptr(tunfd),
+ uintptr(_TUNSIFHEAD),
+ uintptr(unsafe.Pointer(&ifheadmode)),
+ )
+
+ if errno != 0 {
+ return nil, fmt.Errorf("error %s", errno.Error())
+ }
+
+ // Set TUN iface to broadcast mode. TUN inferfaces on dragonflybsd come up in point to point by default
+ ifmodemode := unix.IFF_BROADCAST
+ _, _, errno = unix.Syscall(
+ unix.SYS_IOCTL,
+ uintptr(tunfd),
+ uintptr(_TUNSIFMODE),
+ uintptr(unsafe.Pointer(&ifmodemode)),
+ )
+
+ if errno != 0 {
+ return nil, fmt.Errorf("error %s", errno.Error())
+ }
+
+ // Rename tun interface
+ err = renameTun(assignedName,name)
+
+ if err != nil {
+ tunfile.Close()
+ return nil, err
+ }
+
+ var natTun *nativeTun;
+ natTun, err = CreateTUNFromFile(tunfile, mtu)
+
+ if err != nil {
+ tunfile.Close()
+ return nil, err
+ }
+
+ natTun.origName = assignedName
+
+ return natTun, err
+}
+
+func CreateTUNFromFile(file *os.File, mtu int) (*nativeTun, 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
+ }
+ tun.origName = name
+
+ 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) {
+ name, err := tunName(tun.fd.Fd())
+ if err != nil {
+ return "", err
+ }
+ tun.name = name
+ return 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.RetryAfterError(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 err4 error
+ // Rename tun back to original name if it's been changed
+ if tun.name != tun.origName {
+ err4 = renameTun(tun.name,tun.origName)
+ }
+
+ err1 := tun.rwcancel.Cancel()
+ err2 := tun.fd.Close()
+ if tun.routeSocket != -1 {
+ unix.Shutdown(tun.routeSocket, unix.SHUT_RDWR)
+ err4 = 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 err4
+}
+
+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 ifreq_mtu
+ copy(ifr.Name[:], tun.name)
+ ifr.MTU = uint32(n)
+
+ _, _, errno := unix.Syscall(
+ unix.SYS_IOCTL,
+ uintptr(fd),
+ uintptr(unix.SIOCSIFMTU),
+ uintptr(unsafe.Pointer(&ifr)),
+ )
+
+ 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 ifreq_mtu
+ copy(ifr.Name[:], tun.name)
+
+ _, _, errno := unix.Syscall(
+ unix.SYS_IOCTL,
+ uintptr(fd),
+ uintptr(unix.SIOCGIFMTU),
+ uintptr(unsafe.Pointer(&ifr)),
+ )
+ if errno != 0 {
+ return 0, fmt.Errorf("failed to get MTU on %s", tun.name)
+ }
+
+ return int(*(*int32)(unsafe.Pointer(&ifr.MTU))), nil
+}
projects / thirdparty / wireguard-go.git / commitdiff
