[C/C++] 目前網路連線狀態

說明:
目前網路連線狀態

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/if.h>
#include <linux/sockios.h>
#include <linux/ethtool.h>

typedef unsigned short u16;
typedef unsigned int u32;
typedef unsigned char u8;

// if_name like "ath0", "eth0". Notice: call this function
// need root privilege.
// return value:
// -1 -- error , details can check errno
// 1 -- interface link up
// 0 -- interface link down.
int get_netlink_status_fun(const char *if_name)
{
    int skfd;
    struct ifreq ifr;
    struct ethtool_value edata;
    edata.cmd = ETHTOOL_GLINK;
    edata.data = 0;
    memset(&ifr, 0, sizeof(ifr));
    strncpy(ifr.ifr_name, if_name, sizeof(ifr.ifr_name) - 1);
    ifr.ifr_data = (char *) &edata;
    
    if (( skfd = socket( AF_INET, SOCK_DGRAM, 0 )) == 0)
        return -1;
    
    if(ioctl( skfd, SIOCETHTOOL, &ifr ) == -1)
    {
        close(skfd);
        return -1;
    }
    
    close(skfd);
    return edata.data;
}


int main(int argc, char *argv[])
{
    printf("eth0 : %s\n", get_netlink_status_fun("eth0")==1?"up":"down");
    return 0;
}

Result:

eth0 : up