用C语言写个IPv6 TCP header checksum计算代码
时间: 2023-04-08 14:03:13 浏览: 74
我可以回答这个问题。以下是一个示例代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/ip6.h>
#include <netinet/tcp.h>
unsigned short calculate_tcp_checksum(struct ip6_hdr *ip6hdr, struct tcphdr *tcphdr) {
unsigned short *buf;
unsigned int length = sizeof(struct tcphdr);
unsigned int sum = 0;
buf = (unsigned short *)tcphdr;
while (length > 1) {
sum += *buf++;
length -= 2;
}
if (length == 1) {
sum += *((unsigned char *)buf);
}
buf = (unsigned short *)&ip6hdr->ip6_src;
length = sizeof(struct in6_addr) * 2;
while (length > 1) {
sum += *buf++;
length -= 2;
}
if (length == 1) {
sum += *((unsigned char *)buf);
}
buf = (unsigned short *)&ip6hdr->ip6_dst;
length = sizeof(struct in6_addr) * 2;
while (length > 1) {
sum += *buf++;
length -= 2;
}
if (length == 1) {
sum += *((unsigned char *)buf);
}
sum += htons(IPPROTO_TCP + ntohs(tcphdr->th_len));
length = (unsigned int)ntohs(tcphdr->th_sum);
sum = ~((sum & 0xffff) + (sum >> 16));
sum += length;
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return (unsigned short)(~sum);
}
int main() {
struct ip6_hdr ip6hdr;
struct tcphdr tcphdr;
memset(&ip6hdr, 0, sizeof(ip6hdr));
memset(&tcphdr, 0, sizeof(tcphdr));
// 填充 IPv6 头部和 TCP 头部
unsigned short checksum = calculate_tcp_checksum(&ip6hdr, &tcphdr);
printf("TCP checksum: 0x%x\n", checksum);
return 0;
}
```
这个代码使用了 `netinet/ip6.h` 和 `netinet/tcp.h` 头文件中定义的结构体,计算 TCP 头部的校验和。