get the fd instead of depending on water to do it

src/yggdrasil/tun.go

@@ -2,29 +2,19 @@ package yggdrasil
 
 // This manages the tun driver to send/recv packets to/from applications
 
-import "os"
-import ethernet "github.com/songgao/packets/ethernet"
+import "github.com/songgao/packets/ethernet"
+import "github.com/yggdrasil-network/water"
 
 const IPv6_HEADER_LENGTH = 40
 const ETHER_HEADER_LENGTH = 14
 
-type tunInterface interface {
-	IsTUN() bool
-	IsTAP() bool
-	Name() string
-	Read(to []byte) (int, error)
-	Write(from []byte) (int, error)
-	Close() error
-	FD() *os.File
-}
-
 type tunDevice struct {
 	core   *Core
 	icmpv6 icmpv6
 	send   chan<- []byte
 	recv   <-chan []byte
 	mtu    int
-	iface  tunInterface
+	iface  *water.Interface
 }
 
 type tunDefaultParameters struct {

src/yggdrasil/tun_bsd.go

@@ -2,12 +2,13 @@
 
 package yggdrasil
 
+import "os"
 import "os/exec"
 import "unsafe"
 
 import "golang.org/x/sys/unix"
 
-import water "github.com/yggdrasil-network/water"
+import "github.com/yggdrasil-network/water"
 
 type in6_addrlifetime struct {
 	ia6t_expire    float64
@@ -61,7 +62,7 @@ func (tun *tunDevice) setup(ifname string, iftapmode bool, addr string, mtu int)
 }
 
 func (tun *tunDevice) setupAddress(addr string) error {
-	fd := tun.iface.FD().Fd()
+	fd := tun.iface.ReadWriteCloser.(*os.File).Fd()
 	var err error
 	var ti tuninfo