如何在Linux内核中为IPv6添加一种新的扩展头
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发布时间：2022-04-23 06:21
共1个回答
热心网友
时间：2023-09-19 22:26
1、在头文件中添加新类型扩展头的定义，在linux-2.6.28/include/linux/in6.h中
/*
* NextHeader field of IPv6 header
*/
#define NEXTHDR_HOP 0 /* Hop-by-hop option header. */
#define NEXTHDR_TCP 6 /* TCP segment. */
#define NEXTHDR_UDP 17 /* UDP message. */
#define NEXTHDR_IPV6 41 /* IPv6 in IPv6 */
#define NEXTHDR_ROUTING 43 /* Routing header. */
#define NEXTHDR_FRAGMENT 44 /* Fragmentation/reassembly header. */
#define NEXTHDR_ESP 50 /* Encapsulating security payload. */
#define NEXTHDR_AUTH 51 /* Authentication header. */
#define NEXTHDR_ICMP 58 /* ICMP for IPv6. */
#define NEXTHDR_NONE 59 /* No next header */
#define NEXTHDR_DEST 60 /* Destination options header. */
#define NEXTHDR_MOBILITY 135 /* Mobility header. */
#define IPPROTO_MY 200 /*自己定义的头部类型 */
2、在linux-2.6.28/include/net/ipv6.h中定义结构体
/*
* IPV6 extension headers
*/
#define IPPROTO_HOPOPTS 0 /* IPv6 hop-by-hop options */
#define IPPROTO_ROUTING 43 /* IPv6 routing header */
#define IPPROTO_FRAGMENT 44 /* IPv6 fragmentation header */
#define IPPROTO_ICMPV6 58 /* ICMPv6 */
#define IPPROTO_NONE 59 /* IPv6 no next header */
#define IPPROTO_DSTOPTS 60 /* IPv6 destination options */
#define IPPROTO_MH 135 /* IPv6 mobility header */
自己定义新的扩展头类型如：
#define NEXTHDR_INDEX 200 /*IPv6 next header */
自己定义新的扩展头类型：
struct index_hdr{ /*index扩展头结构*/
__u8 nexthdr;
__u8 hdrlen;
__u16 reserved;
__u32 skb_index;
};
3、在需要添加头部和删除头部的源文件中添加添加和删除函数，届时直接调用这两个函数即可
static void ip6_index_add(struct sk_buff *skb,unsigned char *data,unsigned int len)
{
struct ipv6hdr *tmp_hdr;
struct ipv6hdr *old_hdr;
struct index_hdr *ih;
u8 prevhdr;
unsigned int hlen;
unsigned int ilen;
ilen=sizeof(struct index_hdr);
hlen=sizeof(struct ipv6hdr);
old_hdr=skb_network_header(skb);
prevhdr=old_hdr->nexthdr;
if(prevhdr!=200){
old_hdr->nexthdr=NEXTHDR_INDEX;
tmp_hdr = kmemp(skb_network_header(skb), hlen, GFP_ATOMIC);
__skb_pull(skb, hlen); /*使data指针下移hlen长度，将ipv6头部去掉*/
ih = (struct index_hdr*)__skb_push(skb, ilen); /*上移data指针，将index头部添加进去*/
__skb_push(skb, hlen); /*继续上移data指针，将原来的ipv6头部加进去*/
skb_reset_network_header(skb);
memcpy(skb_network_header(skb), tmp_hdr, hlen);
/*为index扩展头赋值*/
ih->nexthdr = prevhdr;
ih->hdrlen = 8;
ih->reserved = 0;
ih->skb_index = htonl(skb->xfrm_index);
skb->truesize += ilen;
ipv6_hdr(skb)->payload_len += ilen;
data = skb->data;
len = skb->len;
kfree(tmp_hdr);
}
}
static void ip6_index_del(struct sk_buff *skb,unsigned char *data,unsigned int len)
{
struct ipv6hdr *tmp_hdr;
struct ipv6hdr *old_hdr;
struct index_hdr *ih;
u8 prevhdr;
unsigned int hlen;
unsigned int ilen;
ilen=sizeof(struct index_hdr);
hlen=sizeof(struct ipv6hdr);
if(ipv6_hdr(skb)->nexthdr == 200){
tmp_hdr = kmemp(skb_network_header(skb), hlen, GFP_ATOMIC); /*保存ipv6头*/
__skb_pull(skb, hlen); /*下移data指针，去掉ipv6头*/
skb_reset_network_header(skb);
ih=(struct index_hdr *)skb_network_header(skb);
prevhdr = ih->nexthdr;
tmp_hdr->nexthdr = prevhdr;
__skb_pull(skb, ilen); /*下移data指针，去掉index扩展头*/
__skb_push(skb, hlen); /*上移data指针，将原来的ipv6头添加回去*/
skb_reset_network_header(skb);
memcpy(skb_network_header(skb), tmp_hdr, hlen);
skb_reset_network_header(skb);
skb->truesize -= ilen;
ipv6_hdr(skb)->payload_len -= ilen;
kfree(tmp_hdr);
}
}
