[network]获取网络状态

=======

include <sys/types.h>

include <sys/socket.h>

include <net/if.h>

int main()
{
struct ifreq ifr;
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0)
return -1;
bzero((char)&ifr, sizeof(ifr));
strncpy(ifr.ifr_name, (char)"eth0", sizeof(ifr.ifr_name));
if(ioctl(sockfd, SIOCGIFFLAGS, &ifr) < 0)
{
return -1;
}
//check ifr.ifr_ifru.ifru_flags
.......
//
return 0
}