mirror of
https://git.zx2c4.com/wireguard-go
synced 2024-11-15 01:05:15 +01:00
508 lines
9.2 KiB
Go
508 lines
9.2 KiB
Go
/* SPDX-License-Identifier: GPL-2.0
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*
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* Copyright (C) 2017-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*/
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package main
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import (
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"./rwcancel"
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"bytes"
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"errors"
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"fmt"
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"golang.org/x/net/ipv6"
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"golang.org/x/sys/unix"
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"io/ioutil"
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"net"
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"os"
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"path/filepath"
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"time"
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"unsafe"
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)
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// _TUNSIFHEAD, value derived from sys/net/{if_tun,ioccom}.h
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// const _TUNSIFHEAD = ((0x80000000) | (((4) & ((1 << 13) - 1) ) << 16) | (uint32(byte('t')) << 8) | (96))
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const _TUNSIFHEAD = 0x80047460
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const _TUNSIFMODE = 0x8004745e
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const _TUNSIFPID = 0x2000745f
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// Iface status string max len
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const _IFSTATMAX = 800
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// Structure for iface mtu get/set ioctls
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type ifreq_mtu struct {
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Name [_IFNAMESIZ]byte
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MTU uint32
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Pad0 [12]byte
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}
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// Structure for interface status request ioctl
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type ifstat struct {
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IfsName [_IFNAMESIZ]byte
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Ascii [_IFSTATMAX]byte
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}
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// NativeTun is a hack to work around the first 4 bytes "packet
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// information" because there doesn't seem to be an IFF_NO_PI for darwin.
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type NativeTun struct {
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name string
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fd *os.File
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rwcancel *rwcancel.RWCancel
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mtu int
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events chan TUNEvent
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errors chan error
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statusListenersShutdown chan struct{}
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}
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// Figure out the interface name for an open tun device file descriptor
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func TunIfaceName(f *os.File) (string, error) {
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//Terrible hack to make up for freebsd not having a TUNGIFNAME
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fd := f.Fd()
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//First, make sure the tun pid matches this proc's pid
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(fd),
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uintptr(_TUNSIFPID),
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uintptr(0),
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)
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if errno != 0 {
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return "", fmt.Errorf("Failed to set tun device PID: %s", errno.Error())
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}
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// Open iface control socket
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confd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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defer unix.Close(confd)
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if err != nil {
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return "", err
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}
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procPid := os.Getpid()
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//Try to find interface with matching PID
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for i := 1; ; i++ {
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iface, _ := net.InterfaceByIndex(i)
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if err != nil || iface == nil {
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break
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}
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// Structs for getting data in and out of SIOCGIFSTATUS ioctl
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var ifstatus ifstat
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ifname := iface.Name
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copy(ifstatus.IfsName[:], ifname)
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// Make the syscall to get the status string
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(confd),
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uintptr(unix.SIOCGIFSTATUS),
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uintptr(unsafe.Pointer(&ifstatus)),
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)
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if errno != 0 {
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continue
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}
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nullStr := ifstatus.Ascii[:]
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i := bytes.IndexByte(nullStr, 0)
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if i < 1 {
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continue
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}
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if i != -1 {
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nullStr = nullStr[:i]
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}
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statStr := string(nullStr)
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var pidNum int = 0
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// Finally get the owning PID
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// Format string taken from sys/net/if_tun.c
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_, err := fmt.Sscanf(statStr, "\tOpened by PID %d\n", &pidNum)
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if err != nil {
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return "", err
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}
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if pidNum == procPid {
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return ifname, nil
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}
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}
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return "", nil
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}
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// Destroy a named system interface
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func DestroyIface(name string) error {
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// open control socket
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var fd int
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fd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return err
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}
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defer unix.Close(fd)
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// do ioctl call
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var ifr [32]byte
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copy(ifr[:], name)
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(fd),
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uintptr(unix.SIOCIFDESTROY),
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uintptr(unsafe.Pointer(&ifr[0])),
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)
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if errno != 0 {
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return fmt.Errorf("Failed to destroy interface %s: %s", name, errno.Error())
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}
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return nil
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}
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func CreateTUN(name string) (TUNDevice, error) {
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if len(name) > _IFNAMESIZ-1 {
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return nil, errors.New("Interface name too long")
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}
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// See if interface already exists
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iface, _ := net.InterfaceByName(name)
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if iface != nil {
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return nil, fmt.Errorf("Interface %s already exists", name)
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}
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tunfile, err := os.OpenFile("/dev/tun", unix.O_RDWR, 0)
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if err != nil {
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return nil, err
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}
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nameif, err := TunIfaceName(tunfile)
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if err != nil {
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tunfile.Close()
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return nil, err
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}
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tunfd := tunfile.Fd()
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// Enable ifhead mode, otherwise tun will complain if it gets a non-AF_INET packet
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ifheadmode := 1
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(tunfd),
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uintptr(_TUNSIFHEAD),
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uintptr(unsafe.Pointer(&ifheadmode)),
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)
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if errno != 0 {
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return nil, fmt.Errorf("Error %s", errno.Error())
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}
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/* Set TUN iface to broadcast mode. TUN inferfaces on freebsd come up
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* point to point by default */
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ifmodemode := unix.IFF_BROADCAST
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_, _, errno = unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(tunfd),
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uintptr(_TUNSIFMODE),
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uintptr(unsafe.Pointer(&ifmodemode)),
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)
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if errno != 0 {
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return nil, fmt.Errorf("Error %s", errno.Error())
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}
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// Rename tun interface
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// Open control socket
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ctfd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return nil, err
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}
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defer unix.Close(ctfd)
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// set up struct for iface rename
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var newnp [_IFNAMESIZ]byte
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copy(newnp[:], name)
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var ifr ifreq_ptr
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copy(ifr.Name[:], nameif)
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ifr.Data = uintptr(unsafe.Pointer(&newnp[0]))
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//do actual ioctl to rename iface
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_, _, errno = unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(ctfd),
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uintptr(unix.SIOCSIFNAME),
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uintptr(unsafe.Pointer(&ifr)),
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)
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if errno != 0 {
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tunfile.Close()
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DestroyIface(name)
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return nil, fmt.Errorf("Failed to rename %s to %s: %s", nameif, name, errno.Error())
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}
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tun, err := CreateTUNFromFile(tunfile)
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if err != nil {
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return nil, err
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}
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if err == nil && name == "tun" {
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fname := os.Getenv("WG_FREEBSD_TUN_NAME_FILE")
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if fname != "" {
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os.MkdirAll(filepath.Dir(fname), 0700)
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ioutil.WriteFile(fname, []byte(tun.(*NativeTun).name+"\n"), 0400)
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}
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}
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return tun, err
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}
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func CreateTUNFromFile(file *os.File) (TUNDevice, error) {
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tun := &NativeTun{
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fd: file,
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mtu: 1500,
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events: make(chan TUNEvent, 10),
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errors: make(chan error, 1),
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statusListenersShutdown: make(chan struct{}),
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}
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_, err := tun.Name()
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if err != nil {
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tun.fd.Close()
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return nil, err
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}
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tun.rwcancel, err = rwcancel.NewRWCancel(int(file.Fd()))
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if err != nil {
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tun.fd.Close()
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return nil, err
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}
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// TODO: Fix this very naive implementation
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go func(tun *NativeTun) {
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var (
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statusUp bool
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statusMTU int
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)
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for {
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intr, err := net.InterfaceByName(tun.name)
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if err != nil {
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tun.errors <- err
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return
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}
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// Up / Down event
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up := (intr.Flags & net.FlagUp) != 0
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if up != statusUp && up {
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tun.events <- TUNEventUp
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}
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if up != statusUp && !up {
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tun.events <- TUNEventDown
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}
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statusUp = up
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// MTU changes
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if intr.MTU != statusMTU {
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tun.events <- TUNEventMTUUpdate
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}
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statusMTU = intr.MTU
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select {
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case <-time.After(time.Second / 10):
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case <-tun.statusListenersShutdown:
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return
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}
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}
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}(tun)
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// set default MTU
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err = tun.setMTU(DefaultMTU)
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if err != nil {
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tun.Close()
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return nil, err
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}
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return tun, nil
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}
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func (tun *NativeTun) Name() (string, error) {
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name, err := TunIfaceName(tun.fd)
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if err != nil {
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return "", err
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}
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tun.name = name
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return name, nil
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}
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func (tun *NativeTun) File() *os.File {
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return tun.fd
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}
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func (tun *NativeTun) Events() chan TUNEvent {
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return tun.events
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}
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func (tun *NativeTun) doRead(buff []byte, offset int) (int, error) {
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select {
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case err := <-tun.errors:
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return 0, err
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default:
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buff := buff[offset-4:]
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n, err := tun.fd.Read(buff[:])
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if n < 4 {
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return 0, err
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}
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return n - 4, err
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}
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}
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func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
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for {
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n, err := tun.doRead(buff, offset)
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if err == nil || !rwcancel.ErrorIsEAGAIN(err) {
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return n, err
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}
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if !tun.rwcancel.ReadyRead() {
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return 0, errors.New("tun device closed")
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}
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}
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}
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func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
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// reserve space for header
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buff = buff[offset-4:]
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// add packet information header
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buff[0] = 0x00
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buff[1] = 0x00
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buff[2] = 0x00
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if buff[4]>>4 == ipv6.Version {
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buff[3] = unix.AF_INET6
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} else {
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buff[3] = unix.AF_INET
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}
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// write
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return tun.fd.Write(buff)
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}
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func (tun *NativeTun) Close() error {
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close(tun.statusListenersShutdown)
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err1 := tun.rwcancel.Cancel()
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err2 := tun.fd.Close()
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err3 := DestroyIface(tun.name)
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close(tun.events)
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if err1 != nil {
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return err1
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}
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if err2 != nil {
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return err2
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}
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return err3
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}
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func (tun *NativeTun) setMTU(n int) error {
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// open datagram socket
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var fd int
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fd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return err
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}
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defer unix.Close(fd)
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// do ioctl call
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var ifr ifreq_mtu
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copy(ifr.Name[:], tun.name)
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ifr.MTU = uint32(n)
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(fd),
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uintptr(unix.SIOCSIFMTU),
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uintptr(unsafe.Pointer(&ifr)),
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)
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if errno != 0 {
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return fmt.Errorf("Failed to set MTU on %s", tun.name)
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}
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return nil
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}
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func (tun *NativeTun) MTU() (int, error) {
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// open datagram socket
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fd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return 0, err
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}
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defer unix.Close(fd)
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// do ioctl call
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var ifr ifreq_mtu
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copy(ifr.Name[:], tun.name)
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(fd),
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uintptr(unix.SIOCGIFMTU),
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uintptr(unsafe.Pointer(&ifr)),
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)
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if errno != 0 {
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return 0, fmt.Errorf("Failed to get MTU on %s", tun.name)
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}
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// convert result to signed 32-bit int
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mtu := ifr.MTU
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if mtu >= (1 << 31) {
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return int(mtu-(1<<31)) - (1 << 31), nil
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}
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return int(mtu), nil
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}
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