IP_SRC_OFF
__u32 old_ip = _htonl(load_word(skb, IP_SRC_OFF));
bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0);
ret = bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0);