Linux环境下通过ioctl设置默认网关

#include <errno.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>
#include <net/route.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <unistd.h>


int main()
{
   int sockfd;
   struct rtentry rt;

   sockfd = socket(AF_INET, SOCK_DGRAM, 0);
   if (sockfd == -1)
   {
      perror("socket creation failed\n");
      return -1;
   }

   struct sockaddr_in *sockinfo = (struct sockaddr_in *)&rt.rt_gateway;
   sockinfo->sin_family = AF_INET;
   sockinfo->sin_addr.s_addr = inet_addr("192.168.0.1");

   sockinfo = (struct sockaddr_in *)&rt.rt_dst;
   sockinfo->sin_family = AF_INET;
   sockinfo->sin_addr.s_addr = INADDR_ANY;

   sockinfo = (struct sockaddr_in *)&rt.rt_genmask;
   sockinfo->sin_family = AF_INET;
   sockinfo->sin_addr.s_addr = INADDR_ANY;

   rt.rt_flags = RTF_UP | RTF_GATEWAY;
   rt.rt_dev = "eth0";

   if(ioctl(sockfd, SIOCADDRT, &rt) < 0 )
       perror("ioctl");

   return 0;
}