c语言实现rip
时间: 2023-07-13 11:13:28 浏览: 297
RIP(Routing Information Protocol)是一种基于距离向量算法的路由协议。下面是一个简单的C语言实现RIP的示例:
```
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h> //inet_ntoa()函数的头文件
#include <net/if.h> //ifreq结构体的头文件
#include <sys/ioctl.h> //ioctl()函数的头文件
#define MAX_ROUTES 100 //最大路由数
struct route {
char prefix[16]; //网络前缀
char nexthop[16]; //下一跳地址
int metric; //距离
};
int main() {
struct route routes[MAX_ROUTES]; //路由表
int num_routes = 0; //路由数
//添加初始路由
strcpy(routes[num_routes].prefix, "10.0.0.0");
strcpy(routes[num_routes].nexthop, "192.168.0.1");
routes[num_routes].metric = 1;
num_routes++;
//获取本机IP地址
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, "eth0", IFNAMSIZ-1);
ioctl(sockfd, SIOCGIFADDR, &ifr);
close(sockfd);
char *ip = inet_ntoa(((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr);
//开始监听RIP报文
while (1) {
//接收RIP报文
char buf[1024];
memset(buf, 0, sizeof(buf));
int len = recvfrom(sock, buf, sizeof(buf), 0, NULL, NULL);
//解析RIP报文
for (int i = 0; i < num_routes; i++) {
if (strcmp(routes[i].prefix, ip) == 0) {
//回复RIP响应报文
char response[1024];
memset(response, 0, sizeof(response));
int pos = 0;
response[pos++] = 0x02; //Command字段:响应
response[pos++] = 0x01; //Version字段:RIPv1
response[pos++] = 0x00; //Unused字段:0
response[pos++] = 0x00; //Unused字段:0
for (int j = 0; j < num_routes; j++) {
//添加路由项到响应报文中
response[pos++] = 0x00; //Address Family Identifier字段:IPv4
response[pos++] = 0x02; //Route Tag字段:0
memcpy(response+pos, &routes[j].prefix, 4); //IP地址字段
pos += 4;
memcpy(response+pos, &routes[j].metric, 4); //Metric字段
pos += 4;
}
//发送响应报文
sendto(sock, response, pos, 0, NULL, 0);
break;
}
}
}
return 0;
}
```
这只是一个简单的示例,实际上RIP协议的实现还需要考虑很多细节和安全问题。