IPSKB_FORWARDED
bool forwarding = IPCB(skb)->flags & IPSKB_FORWARDED;
IPCB(skb)->flags |= IPSKB_FORWARDED;
!(IPCB(skb)->flags & IPSKB_FORWARDED))
IPCB(skb)->flags |= IPSKB_FORWARDED;
if (IPCB(skb)->flags & IPSKB_FORWARDED)
if (IPCB(skb)->flags & IPSKB_FORWARDED)
IPCB(skb)->flags = IPSKB_FORWARDED;