linux获得网卡信息

#define MAX_INTERFACE         64

int showifs()
{
    int i;
    int rc;
    int sock;
    int ifnum;
    struct ifreq ifr[MAX_INTERFACE];
//    struct arpreq arp;
    struct ifconf ifc;

    sock = socket ( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
    if ( sock == -1 )
    {
        return -1;
    }

    ifc.ifc_len = sizeof( ifr );
    ifc.ifc_buf = ( caddr_t ) ifr;
    rc = ioctl ( sock, SIOCGIFCONF, &ifc );
    if ( rc == -1 )
    {
        close( sock );
        return -1;
    }

    ifnum = ifc.ifc_len / sizeof ( struct ifreq );
    fprintf( stdout, "ifnum=[%d]
======================================
", ifnum );
    for ( i = 0; i < ifnum; i ++ )
    {
        fprintf( stdout, "ifname [%s]
", ifr[i].ifr_name );

        //status
        rc = ioctl( sock, SIOCGIFFLAGS, ifr + i );
        if ( rc != -1 )
        {
            if ( ifr[i].ifr_flags & IFF_PROMISC )
            {
                fprintf( stdout, "PROMISC=TRUE
" );
            }
            else
            {
                fprintf( stdout, "PROMISC=FALSE
" );
            }


            if ( ifr[i].ifr_flags & IFF_UP )
            {
                fprintf( stdout, "UP=TRUE
" );
            }
            else
            {
                fprintf( stdout, "UP=FALSE
" );
            }
        }

        //ip
        rc = ioctl ( sock, SIOCGIFADDR, ifr + i );
        if ( rc != -1 )
        {
            fprintf( stdout, "IP=%s
", inet_ntoa( ( ( struct sockaddr_in* )( &ifr[i].ifr_addr ) )->sin_addr ) );
        }

        //netmask
        rc = ioctl ( sock, SIOCGIFNETMASK, ifr + i );
        if ( rc != -1 )
        {
            fprintf( stdout, "NETMASK=%s
", inet_ntoa( ( ( struct sockaddr_in* )( &ifr[i].ifr_netmask  ) )->sin_addr ) );
        }

        //broadcast
        rc = ioctl ( sock, SIOCGIFBRDADDR, ifr + i );
        if ( rc != -1 )
        {
            fprintf( stdout, "BROADCAST=%s
", inet_ntoa( ( ( struct sockaddr_in* )( &ifr[i].ifr_broadaddr ) )->sin_addr ) );
        }

        //mac
        rc = ioctl ( sock, SIOCGIFHWADDR, ifr + i );
        if ( rc != -1 )
        {
            fprintf( stdout, "%02x:%02x:%02x:%02x:%02x:%02x
",
                     ( unsigned char )ifr[i].ifr_hwaddr.sa_data[0],
                     ( unsigned char )ifr[i].ifr_hwaddr.sa_data[1],
                     ( unsigned char )ifr[i].ifr_hwaddr.sa_data[2],
                     ( unsigned char )ifr[i].ifr_hwaddr.sa_data[3],
                     ( unsigned char )ifr[i].ifr_hwaddr.sa_data[4],
                     ( unsigned char )ifr[i].ifr_hwaddr.sa_data[5] );
        }
    }

    close( sock );
    return 0;
}