first code/readme/license commit

src/yggdrasil/tun.go

@@ -0,0 +1,56 @@
+package yggdrasil
+
+// This manages the tun driver to send/recv packets to/from applications
+
+import water "github.com/songgao/water"
+
+const IPv6_HEADER_LENGTH = 40
+
+type tunDevice struct {
+  core *Core
+  send chan<- []byte
+  recv <-chan []byte
+  mtu int
+  iface *water.Interface
+}
+
+func (tun *tunDevice) init(core *Core) {
+  tun.core = core
+}
+
+func (tun *tunDevice) setup(addr string, mtu int) error {
+	iface, err := water.New(water.Config{ DeviceType: water.TUN })
+	if err != nil { panic(err) }
+  tun.iface = iface
+  tun.mtu = mtu //1280 // Lets default to the smallest thing allowed for now
+  return tun.setupAddress(addr)
+}
+
+func (tun *tunDevice) write() error {
+  for {
+    data := <-tun.recv
+    if _, err := tun.iface.Write(data); err != nil { return err }
+    util_putBytes(data)
+  }
+}
+
+func (tun *tunDevice) read() error {
+  buf := make([]byte, tun.mtu)
+  for {
+    n, err := tun.iface.Read(buf)
+    if err != nil { return err }
+    if buf[0] & 0xf0 != 0x60 ||
+       n != 256*int(buf[4]) + int(buf[5]) + IPv6_HEADER_LENGTH {
+      // Either not an IPv6 packet or not the complete packet for some reason
+      panic("Should not happen in testing")
+      continue
+    }
+    packet := append(util_getBytes(), buf[:n]...)
+    tun.send<-packet
+  }
+}
+
+func (tun *tunDevice) close() error {
+  return tun.iface.Close()
+}
+