+ /* skb->cb is overloaded: prior to this point it is IP{6}CB
+ * which has interface index (iif) as the first member of the
+ * underlying inet{6}_skb_parm struct. This code then overlays
+ * PKTINFO_SKB_CB and in_pktinfo also has iif as the first
+ * element so the iif is picked up from the prior IPCB
+ */