在linux下 获取，修改网关GateWay的两个函数

//获去GateWay
QString GetGateWay()
{
FILE *fp;
char buf[512];
char cmd[128];
char gateway[30];
char *tmp;
strcpy(cmd, "ip route");
fp = popen(cmd, "r");
if(NULL == fp)
{
perror("popen error");
return "";
}
while(fgets(buf, sizeof(buf), fp) != NULL)
{
tmp =buf;
while(*tmp && isspace(*tmp))
++ tmp;
if(strncmp(tmp, "default", strlen("default")) == 0)
break;
}
sscanf(buf, "%*s%*s%s", gateway);
printf("default gateway:%s\n", gateway);
pclose(fp);

return QString(gateway);
}
//设置网关
int SetGateWay(const char *szGateWay)
{
int ret = 0;
char cmd[128];
QString DefGW = GetGateWay();
const char *strGW = DefGW.latin1();

strcpy(cmd, "route del default gw ");
strcat(cmd, strGW);
ret = system(cmd);
if(ret < 0)
{
perror("route error");
return -1;
}
strcpy(cmd, "route add default gw ");
strcat(cmd, szGateWay);

ret = system(cmd);
if(ret < 0)
{
perror("route error");
return -1;
}
return ret;
}