网络子系统85_inet协议族-l3向上

//ip数据报向本地传递//调用路径：ip_rcv->dst_input->...->ip_local_deliver1.1 int ip_local_deliver(struct sk_buff *skb){//如果ip数据报被分片，则重组if (ip_is_fragment(ip_hdr(skb))) {if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))return 0;}//通过hook点，向上传递return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, skb, skb->dev, NULL,       ip_local_deliver_finish);}//ip数据报向本地传递//步骤：//1.向raw套接字传递一份skb//2.根据ip报头的协议号在inet_protos中找到l4协议//3.调用l4协议处理函数1.2 static int ip_local_deliver_finish(struct sk_buff *skb){struct net *net = dev_net(skb->dev);//使skb有足够的ip报头__skb_pull(skb, ip_hdrlen(skb));//使指针指向ip报文内容skb_reset_transport_header(skb);rcu_read_lock();{int protocol = ip_hdr(skb)->protocol;const struct net_protocol *ipprot;int raw;resubmit://向raw套接字传递raw = raw_local_deliver(skb, protocol);//通过l4协议号查找上层协议//在inet_init中，通过inet_add_protocol注册l4协议到inet_protos数组ipprot = rcu_dereference(inet_protos[protocol]);if (ipprot != NULL) {int ret;//l4协议处理函数ret = ipprot->handler(skb);if (ret < 0) {protocol = -ret;goto resubmit;}//snmp统计IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);}...} out:rcu_read_unlock();return 0;}