From 0a63188afab1dd49380f916963307f9b2efdcac1 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Wed, 23 May 2018 02:10:54 +0200 Subject: Move tun to subpackage --- tun/tun_darwin.go | 382 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 382 insertions(+) create mode 100644 tun/tun_darwin.go (limited to 'tun/tun_darwin.go') 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 . All Rights Reserved. + * Copyright (C) 2017-2018 Mathias N. Hall-Andersen . + */ + +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 +} -- cgit v1.2.3