linux下检测网卡与网线连通状态

Linux下检测网卡与网线连接状态，使用ioctl向socket发送SIOCETHTOOL 命令字。

link_stat.c
# 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>
# include < linux/ sockios. h>
# include < linux/ ethtool. h>

int get_netlink_status( const char * if_name) ;

int main( )
{
    if ( getuid( ) ! = 0)
    {
        fprintf ( stderr , "Netlink Status Check Need Root Power./n" ) ;
        return 1;
    }
    
    printf ( "Net link status: %d/n" , get_netlink_status( "eth0" ) ) ;

    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;
}