- u8 nexthdr = skb->nh.ipv6h->nexthdr;
- u8 prev_nhoff = (u8 *)&skb->nh.ipv6h->nexthdr - skb->data;
- int start = (u8 *)(skb->nh.ipv6h+1) - skb->data;
+ u8 nexthdr = ipv6_hdr(skb)->nexthdr;
+ const int netoff = skb_network_offset(skb);
+ u8 prev_nhoff = netoff + offsetof(struct ipv6hdr, nexthdr);
+ int start = netoff + sizeof(struct ipv6hdr);