Linux 检测网卡与网线连接状态

检测网卡于网线到链接状态是使用ioctl向socket发送SIOCETHTOOL命令。

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


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

#include <linux/sockios.h>
#include <linux/ethtool.h>
int get_netlink_status(const char *if_name);


int main(int argc, char* argv[])
{
 if(argc != 2)
 {
              fprintf(stderr, "usage: %s ", argv[0]);
     return -1;
    }
    if(getuid() != 0)
    {
        fprintf(stderr, "Netlink Status Check Need Root Power.\n");
        return 1;
    }
   
    printf("Net link status: %s\n", get_netlink_status(argv[1])==1?"up":"down");
    return 0;
}
// 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(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;
}