getmask

#include "stdio.h"

#include "stdlib.h"

#include "string.h"



#include "net/if.h"

#include "arpa/inet.h"

#include "linux/sockios.h"



int main(int argc,char *argv[])

{

    struct sockaddr_in *addr;

    struct ifreq ifr;

    char*address;

    int sockfd;



    char *name = "eth0";

    if( strlen(name) >= IFNAMSIZ)

        printf("device name is error.\n"), exit(0);

        

    strcpy( ifr.ifr_name, name);

        

    sockfd = socket(AF_INET,SOCK_DGRAM,0);



    //get inet addr

    if( ioctl( sockfd, SIOCGIFADDR, &ifr) == -1)

        printf("ioctl error.\n"), exit(0);



    addr = (struct sockaddr_in *)&(ifr.ifr_addr);

    address = inet_ntoa(addr->sin_addr);



    printf("inet addr: %s\n",address);



    //get Mask

    if( ioctl( sockfd, SIOCGIFNETMASK, &ifr) == -1)

        printf("ioctl error.\n"), exit(0);



    addr = (struct sockaddr_in *)&ifr.ifr_addr;

    address = inet_ntoa(addr->sin_addr);



    printf("Mask: %s\n",address);



    //get HWaddr 

    u_int8_t hd[6];

    if(ioctl(sockfd, SIOCGIFHWADDR, &ifr) == -1)

        printf("hwaddr error.\n"), exit(0);



    memcpy( hd, ifr.ifr_hwaddr.sa_data, sizeof(hd));

    printf("HWaddr: %02X:%02X:%02X:%02X:%02X:%02X\n", hd[0], hd[1], hd[2], hd[3], hd[4], hd[5]);

    

    exit(0);

}