1868d15914
And outbound routing I am not entirely convinced the use of net.IP is a good idea, since the internal representation of net.IP is a byte slice and all constructor functions in "net" return 16 byte slices (padded for IPv4), while the use in this project uses 4 byte slices. Which may be confusing.
81 lines
1.4 KiB
Go
81 lines
1.4 KiB
Go
package main
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import (
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"encoding/binary"
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"errors"
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"os"
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"strings"
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"syscall"
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"unsafe"
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)
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/* Platform dependent functions for interacting with
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* TUN devices on linux systems
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*
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*/
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const CloneDevicePath = "/dev/net/tun"
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const (
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IFF_NO_PI = 0x1000
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IFF_TUN = 0x1
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IFNAMSIZ = 0x10
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TUNSETIFF = 0x400454CA
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)
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type NativeTun struct {
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fd *os.File
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name string
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mtu uint
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}
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func (tun *NativeTun) Name() string {
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return tun.name
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}
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func (tun *NativeTun) MTU() uint {
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return tun.mtu
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}
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func (tun *NativeTun) Write(d []byte) (int, error) {
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return tun.fd.Write(d)
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}
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func (tun *NativeTun) Read(d []byte) (int, error) {
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return tun.fd.Read(d)
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}
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func CreateTUN(name string) (TUN, error) {
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// Open clone device
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fd, err := os.OpenFile(CloneDevicePath, os.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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// Prepare ifreq struct
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var ifr [18]byte
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var flags uint16 = IFF_TUN | IFF_NO_PI
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nameBytes := []byte(name)
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if len(nameBytes) >= IFNAMSIZ {
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return nil, errors.New("Name size too long")
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}
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copy(ifr[:], nameBytes)
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binary.LittleEndian.PutUint16(ifr[16:], flags)
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// Create new device
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL,
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uintptr(fd.Fd()), uintptr(TUNSETIFF),
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uintptr(unsafe.Pointer(&ifr[0])))
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if errno != 0 {
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return nil, errors.New("Failed to create tun, ioctl call failed")
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}
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// Read name of interface
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newName := string(ifr[:])
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newName = newName[:strings.Index(newName, "\000")]
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return &NativeTun{
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fd: fd,
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name: newName,
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}, nil
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}
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