L3PacketSocket does not set correct ethertype for IPv6 when using TUN devices.

Change send method in L3PacketSocket to detect the type of the packet to send
and set ethertype magic accordingly.

scapy/arch/linux.py

@@ -376,8 +376,8 @@ class L3PacketSocket(SuperSocket):
         self.outs.bind(sdto)
         sn = self.outs.getsockname()
         ll = lambda x:x
-        if sn[3] in (ARPHDR_PPP,ARPHDR_TUN):
-            sdto = (iff, ETH_P_IP)
+        if type(x) in conf.l3types:
+            sdto = (iff, conf.l3types[type(x)])
         if sn[3] in conf.l2types:
             ll = lambda x:conf.l2types[sn[3]]()/x
         try: