ipvs: support ipv4 in ipv6 and ipv6 in ipv4 tunnel forwarding

Pull the common logic for preparing an skb to prepend the header into a
single function and then set fields such that they can be used in either
case (generalize tos and tclass to dscp, hop_limit and ttl to ttl, etc)

Signed-off-by: Alex Gartrell <agartrell@fb.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index fdb4880..13e9cee 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -488,7 +488,12 @@
 		break;
 
 	case IP_VS_CONN_F_TUNNEL:
-		cp->packet_xmit = ip_vs_tunnel_xmit;
+#ifdef CONFIG_IP_VS_IPV6
+		if (cp->daf == AF_INET6)
+			cp->packet_xmit = ip_vs_tunnel_xmit_v6;
+		else
+#endif
+			cp->packet_xmit = ip_vs_tunnel_xmit;
 		break;
 
 	case IP_VS_CONN_F_DROUTE:
@@ -514,7 +519,10 @@
 		break;
 
 	case IP_VS_CONN_F_TUNNEL:
-		cp->packet_xmit = ip_vs_tunnel_xmit_v6;
+		if (cp->daf == AF_INET6)
+			cp->packet_xmit = ip_vs_tunnel_xmit_v6;
+		else
+			cp->packet_xmit = ip_vs_tunnel_xmit;
 		break;
 
 	case IP_VS_CONN_F_DROUTE: