ipv6 处理扩展头

160 static int ip6_input_finish(struct sk_buff *skb)
161 {
162         struct inet6_protocol *ipprot;   //注册协议结构体
163         unsigned int nhoff;
164         int nexthdr, raw;
165         u8 hash;
166         struct inet6_dev *idev;
167         struct net *net = dev_net(skb_dst(skb)->dev);
168 
169         /*
170          *      Parse extension headers
171          */
172 
173         rcu_read_lock();
174 resubmit:
175         idev = ip6_dst_idev(skb_dst(skb));
176         if (!pskb_pull(skb, skb_transport_offset(skb)))
177                 goto discard;
178         nhoff = IP6CB(skb)->nhoff;
179         nexthdr = skb_network_header(skb)[nhoff];
180 
181         raw = raw6_local_deliver(skb, nexthdr);
182 
183         hash = nexthdr & (MAX_INET_PROTOS - 1);
184         if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
185                 int ret;
186 
187                 if (ipprot->flags & INET6_PROTO_FINAL) {
188                         struct ipv6hdr *hdr;
189 
190                         /* Free reference early: we don't need it any more,
191                            and it may hold ip_conntrack module loaded
192                            indefinitely. */
193                         nf_reset(skb);
194 
195                         skb_postpull_rcsum(skb, skb_network_header(skb),
196                                            skb_network_header_len(skb));
197                         hdr = ipv6_hdr(skb);
198                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
199                             !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
200                             &hdr->saddr) &&
201                             !ipv6_is_mld(skb, nexthdr))
202                                 goto discard;
203                 }
204                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
205                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
206                         goto discard;
207 
208                 ret = ipprot->handler(skb);       //此处调用当前扩展头部解析函数
209                 if (ret > 0)
210                         goto resubmit;                  //直到扩展头被解析完，否则提交到上面，继续解析
211                 else if (ret == 0)
212                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
213         } else {
214                 if (!raw) {
215                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
216                                 IP6_INC_STATS_BH(net, idev,
217                                                  IPSTATS_MIB_INUNKNOWNPROTOS);
218                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
219                                             ICMPV6_UNK_NEXTHDR, nhoff,
220                                             skb->dev);
221                         }
222                 } else
223                         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS);
224                 kfree_skb(skb);
225         }
226         rcu_read_unlock();
227         return 0;
228 
229 discard:
230         IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS);
231         rcu_read_unlock();
232         kfree_skb(skb);
233         return 0;
234 }

协议注册结构体： 

50 struct inet6_protocol 
 51 {
 52         int     (*handler)(struct sk_buff *skb);
 53 
 54         void    (*err_handler)(struct sk_buff *skb,
 55                                struct inet6_skb_parm *opt,
 56                                u8 type, u8 code, int offset,
 57                                __be32 info);
 58 
 59         int     (*gso_send_check)(struct sk_buff *skb);
 60         struct sk_buff *(*gso_segment)(struct sk_buff *skb,
 61                                        int features);
 62         struct sk_buff **(*gro_receive)(struct sk_buff **head,
 63                                         struct sk_buff *skb);
 64         int     (*gro_complete)(struct sk_buff *skb);
 65 
 66         unsigned int    flags;  /* INET6_PROTO_xxx */
 67 };

 

 

 

  

常用解析函数：

 

 

      //ah协议头处理
 530 static struct inet6_protocol ah6_protocol = {
 531         .handler        =       xfrm6_rcv,
 532         .err_handler    =       ah6_err,
 533         .flags          =       INET6_PROTO_NOPOLICY,
 534 };
       //路由协议头处理
503 static struct inet6_protocol rthdr_protocol = {
504         .handler        =       ipv6_rthdr_rcv,
505         .flags          =       INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
506 };
       //目的协议头处理
508 static struct inet6_protocol destopt_protocol = {
509         .handler        =       ipv6_destopt_rcv,
510         .flags          =       INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
511 };

        
513 static struct inet6_protocol nodata_protocol = {
514         .handler        =       dst_discard,
515         .flags          =       INET6_PROTO_NOPOLICY,
516 };
        //tcp协议头处理
2095 static struct inet6_protocol tcpv6_protocol = {
2096         .handler        =       tcp_v6_rcv,
2097         .err_handler    =       tcp_v6_err,
2098         .gso_send_check =       tcp_v6_gso_send_check,
2099         .gso_segment    =       tcp_tso_segment,
2100         .gro_receive    =       tcp6_gro_receive,
2101         .gro_complete   =       tcp6_gro_complete,
2102         .flags          =       INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
2103 };

1033 static struct inet6_protocol udpv6_protocol = {
1034         .handler        =       udpv6_rcv,
1035         .err_handler    =       udpv6_err,
1036         .flags          =       INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
1037 };
         //esp协议头处理
561 static struct inet6_protocol esp6_protocol = {
562         .handler        =       xfrm6_rcv,
563         .err_handler    =       esp6_err,
564         .flags          =       INET6_PROTO_NOPOLICY,
565 };
           //管道协议头处理
136 static struct inet6_protocol tunnel6_protocol = {
137         .handler        = tunnel6_rcv,
138         .err_handler    = tunnel6_err,
139         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
140 };
141 
           
142 static struct inet6_protocol tunnel46_protocol = {
143         .handler        = tunnel46_rcv,
144         .err_handler    = tunnel6_err,
145         .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
146 };