gateway 默认路由获取与设置

来源：互联网发布：办公软件技巧大全编辑：程序博客网时间：2024/05/17 23:05

//Route add -net default gw 192.168.22.1
//在有IP没有默认路由的时候设置

/*cat /proc/net/route
Iface   Destination     Gateway         Flags   RefCnt Use     Metric Mask            MTU     Window IRTT
eth0    0016A8C0        00000000        0001    0       0       0       00FFFFFF        0       0       0
eth0    00000000        0116A8C0        0003    0       0       0       00000000        0       0       0
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/route.h>
#include <net/if.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>

int network_get_gatway(int sock_id,char *interface_name, char *gateway)
{
FILE *fp;
char buf[256]; // 128 is enough for linux
char iface[16];
unsigned long dest_addr,net_addr,gate_addr;
struct in_addr addr;
unsigned long *p;

fp = fopen("/proc/net/route", "r");
if (fp == NULL)
  return -1;
/* Skip title line */
fgets(buf, sizeof(buf), fp);
while (fgets(buf, sizeof(buf), fp))
{
  if (sscanf(buf, "%s\t%lX\t%lX", iface,&dest_addr, &gate_addr)!= 3||dest_addr != 0||!strcpy(iface,interface_name))
   continue;
  break;
}

fclose(fp);
printf("gate_addr:%lx\n",gate_addr);
memcpy(&addr,&gate_addr,4);
strcpy( gateway,inet_ntoa(addr));
printf("gateway=%s\n",gateway);
return 0;

}

int network_set_getway(int sock_id,char *interface_name, char *gateway)
{
struct rtentry rt;
u_int32_t dstaddr, gwaddr;

dstaddr = inet_addr("0.0.0.0");
gwaddr = inet_addr(gateway);

memset (&rt, 0, sizeof (rt));

/*set Destination addr*/
memset ((char *) &(rt.rt_dst),0, sizeof(rt.rt_dst));
rt.rt_dst.sa_family = AF_INET;
((struct sockaddr_in *)&(rt.rt_dst))->sin_addr.s_addr= dstaddr;

/*set gw addr*/
memset ((char *) &(rt.rt_gateway),0, sizeof(rt.rt_gateway));
rt.rt_gateway.sa_family = AF_INET;
((struct sockaddr_in *)&(rt.rt_gateway))->sin_addr.s_addr= gwaddr;

/*set genmask addr*/
memset ((char *) &(rt.rt_genmask),0, sizeof(rt.rt_genmask));
rt.rt_genmask.sa_family = AF_INET;
((struct sockaddr_in *)&(rt.rt_genmask))->sin_addr.s_addr= 0L;

rt.rt_dev = interface_name;
rt.rt_flags = RTF_GATEWAY;

if (ioctl(sock_id, SIOCADDRT, &rt) < 0)
{
printf("SIOCADDRT failed: %s %d\n", strerror(errno),RTF_GATEWAY);
return -1;
}

return 0;
}

int main()
{
int sock_id;
char ifname[]="eth0";
char getway[16]="192.168.22.1";
char getway1[16];

sock_id=socket(AF_INET,SOCK_DGRAM,0);
if (sock_id < 0)
{
printf("socket failed: %s\n", strerror(errno));
return -1;
}

network_set_getway(sock_id,ifname, getway);
network_get_gatway(sock_id,ifname, getway1);

return 0;
}

0 0