func setTunIP(iface *water.Interface, ip net.IP, subnet *net.IPNet) (err error) {
ip = ip.To4()
logger.Debug("%v", ip)
if ip[3]%2 == 0 {
return invalidAddr
}
peer := net.IP(make([]byte, 4))
copy([]byte(peer), []byte(ip))
peer[3]++
tun_peer = peer
sargs := fmt.Sprintf("addr add dev %s local %s peer %s", iface.Name(), ip, peer)
args := strings.Split(sargs, " ")
cmd := exec.Command("ip", args...)
logger.Info("ip %s", sargs)
err = cmd.Run()
if err != nil {
return err
}
sargs = fmt.Sprintf("route add %s via %s dev %s", subnet, peer, iface.Name())
args = strings.Split(sargs, " ")
cmd = exec.Command("ip", args...)
logger.Info("ip %s", sargs)
err = cmd.Run()
return err
}
func rcvrThread(proto string, port int, iface *water.Interface) {
conn, err := reuseport.NewReusableUDPPortConn(proto, fmt.Sprintf(":%v", port))
if nil != err {
log.Fatalln("Unable to get UDP socket:", err)
}
buf := make([]byte, BUFFERSIZE)
for {
n, _, err := conn.ReadFrom(buf)
if err != nil {
fmt.Println("Error: ", err)
continue
}
// ReadFromUDP can return 0 bytes on timeout
if 0 == n {
continue
}
if n%aes.BlockSize != 0 {
fmt.Println("packet size ", n, " is not a multiple of the block size")
continue
}
iv := buf[:aes.BlockSize]
ciphertext := buf[aes.BlockSize:n]
conf := config.Load().(VPNState)
mode := cipher.NewCBCDecrypter(conf.Main.block, iv)
var size int
if conf.Main.hasalt {
// if we have alternative key we need store orig packet for second try
pcopy := make([]byte, n)
copy(pcopy, buf[:n])
mode.CryptBlocks(ciphertext, ciphertext)
size = int(ciphertext[0]) + (256 * int(ciphertext[1]))
if (n-aes.BlockSize-2)-size > 16 || (n-aes.BlockSize-2)-size < 0 || 4 != ((ciphertext)[2]>>4) {
// don't looks like anything is ok, trying second key
copy(buf[:n], pcopy)
cipher.NewCBCDecrypter(conf.Main.altblock, iv).CryptBlocks(ciphertext, ciphertext)
size = int(ciphertext[0]) + (256 * int(ciphertext[1]))
if (n-aes.BlockSize-2)-size > 16 || (n-aes.BlockSize-2)-size < 0 || 4 != ((ciphertext)[2]>>4) {
fmt.Println("Invalid size field or IPv4 id in decrypted message", size, (n - aes.BlockSize - 2))
continue
}
}
} else {
mode.CryptBlocks(ciphertext, ciphertext)
size = int(ciphertext[0]) + (256 * int(ciphertext[1]))
if (n-aes.BlockSize-2)-size > 16 || (n-aes.BlockSize-2)-size < 0 {
fmt.Println("Invalid size field in decrypted message", size, (n - aes.BlockSize - 2))
continue
}
if 4 != ((ciphertext)[2] >> 4) {
fmt.Println("Non IPv4 packet after decryption, possible corupted packet")
continue
}
}
iface.Write(ciphertext[2 : 2+size])
}
}
func sndrThread(conn *net.UDPConn, iface *water.Interface) {
// first time fill with random numbers
ivbuf := make([]byte, aes.BlockSize)
if _, err := io.ReadFull(rand.Reader, ivbuf); err != nil {
log.Fatalln("Unable to get rand data:", err)
}
var packet IPPacket = make([]byte, BUFFERSIZE)
for {
plen, err := iface.Read(packet[2 : MTU+2])
if err != nil {
break
}
if 4 != packet.IPver() {
header, _ := ipv4.ParseHeader(packet[2:])
log.Printf("Non IPv4 packet [%+v]\n", header)
continue
}
// each time get pointer to (probably) new config
c := config.Load().(VPNState)
dst := packet.Dst()
wanted := false
addr, ok := c.remotes[dst]
if ok {
wanted = true
}
if dst == c.Main.bcastIP || packet.IsMulticast() {
wanted = true
}
// very ugly and useful only for a limited numbers of routes!
if !wanted {
ip := packet.DstV4()
for n, s := range c.routes {
if n.Contains(ip) {
addr = s
ok = true
wanted = true
break
}
}
}
if wanted {
// store orig packet len
packet[0] = byte(plen % 256)
packet[1] = byte(plen / 256)
// encrypt
clen := plen + 2
if clen%aes.BlockSize != 0 {
clen += aes.BlockSize - (clen % aes.BlockSize)
}
if clen > len(packet) {
log.Println("clen > len(package)", clen, len(packet))
continue
}
ciphertext := make([]byte, aes.BlockSize+clen)
iv := ciphertext[:aes.BlockSize]
copy(iv, ivbuf)
mode := cipher.NewCBCEncrypter(c.Main.block, iv)
mode.CryptBlocks(ciphertext[aes.BlockSize:], packet[:clen])
// save new iv
copy(ivbuf, ciphertext[clen-aes.BlockSize:])
if ok {
n, err := conn.WriteToUDP(ciphertext, addr)
if nil != err {
log.Println("Error sending package:", err)
}
if n != len(ciphertext) {
log.Println("Only ", n, " bytes of ", len(ciphertext), " sent")
}
} else {
// multicast or broadcast
for _, addr := range c.remotes {
n, err := conn.WriteToUDP(ciphertext, addr)
if nil != err {
log.Println("Error sending package:", err)
}
if n != len(ciphertext) {
log.Println("Only ", n, " bytes of ", len(ciphertext), " sent")
}
}
}
} else {
fmt.Println("Unknown dst", dst)
}
}
}
