C 迁移到4.1.23的Netfilter内核模块-无法检索ip标头

我们有一个2.6内核的netfilter内核模块，现在可以移植到4.1.23。我的钩子函数看起来坏了。我无法检索数据包头

下面是2.6内核的代码片段。这是生产了很长时间

    static unsigned int main_hook(unsigned int hooknum, struct sk_buff *skb, const struct net_device *in,const struct net_device *out, int (*okfn)(struct sk_buff*))
{
  //struct sk_buff *skb = (skb_p);
  struct iphdr *ih = (struct iphdr *)(skb->data);
  u32 saddr = ih->saddr;
  u32 daddr = ih->daddr;

在4.1.23中检查netfilter.h并搜索Internet得出以下结果

static unsigned int main_hook(const struct nf_hook_ops *ops, struct sk_buff *skb, const struct nf_hook_state *state)
       {
          //struct sk_buff *skb = (skb_p);
          struct iphdr *ih = (struct iphdr *)(skb->data);
          u32 saddr = ih->saddr;
          u32 daddr = ih->daddr;

注册钩子如下

  netfilter_ops.hook              =       main_hook;
  netfilter_ops.pf                =       PF_INET;
  netfilter_ops.hooknum           =       NF_INET_FORWARD;
  netfilter_ops.priority          =       NF_IP_PRI_FIRST;
  netfilter_ops.owner             =       THIS_MODULE;
  nf_register_hook(&netfilter_ops);

我没有从SADD和daddr获取源ip和目标ip

删除所有内容并尝试跟随

static unsigned int main_hook(const struct nf_hook_ops *ops, struct sk_buff *skb, const struct nf_hook_state *state)
{
  struct iphdr *ip_header = (struct iphdr *) (skb->data);
  unsigned int src_ip = (unsigned int)ip_header->saddr;
  unsigned int dest_ip = (unsigned int)ip_header->daddr;
  printk("IP addres = %pI4  DEST = %pI4\n", &src_ip, &dest_ip);
  return NF_ACCEPT;

结果如下

[37501.345997] IP addres = 0.0.0.0  DEST = 0.0.0.0
[37506.337854] IP addres = 0.0.0.0  DEST = 0.0.0.0
[37511.345295] IP addres = 0.0.0.0  DEST = 0.0.0.0
[37516.337132] IP addres = 0.0.0.0  DEST = 0.0.0.0
[37521.344589] IP addres = 0.0.0.0  DEST = 0.0.0.0
[37526.336426] IP addres = 0.0.0.0  DEST = 0.0.0.0
[37531.343866] IP addres = 0.0.0.0  DEST = 0.0.0.0

我也试过跟随，但是得到了垃圾

buff = (unsigned char *) skb->data;
for (i=0;i<60;i++) printk("%d.", buff[i]);
printk("\n");

buff=（unsigned char*）skb->data；
对于（i=0；i请尝试以下方式提取：

struct iphdr *ip_hdr = (struct iphdr *)skb_network_header(skb);

并通过以下方式访问：

printk("IP addres = %u  DEST = %u\n", ip_hdr->saddr, ip_hdr->daddr);