linux之ioctl函数解析

[lingyun@localhost ioctl_1]$ ls
ipconfig.c

[lingyun@localhost ioctl_1]$ cat ipconfig.c 

/*********************************************************************************

 *      Copyright:  (C) 2013 fulinux<fulinux@sina.com> 

 *                  All rights reserved.

 *

 *       Filename:  ioctl.c

 *    Description:  This file 

 *                 

 *        Version:  1.0.0(08/01/2013~)

 *         Author:  fulinux <fulinux@sina.com>

 *      ChangeLog:  1, Release initial version on "08/01/2013 03:21:50 PM"

 *                 

 ********************************************************************************/

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <errno.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <sys/ioctl.h>

#include <net/if.h>

static void usage()

{

    printf("usage: ipconfig interface\n");

    exit(0);

}

int main(int argc, char **argv)

{

    struct sockaddr_in *addr;

    struct ifreq ifr;

    char *name,*address;

    int sockfd;

    if(argc != 2)

        usage();

    else

        name = argv[1];

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);

    strncpy(ifr.ifr_name, name, IFNAMSIZ - 1);

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

        perror("ioctl error"), exit(1);

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

    address = inet_ntoa(addr->sin_addr);

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

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

        perror("ioctl error"),exit(1);

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

    address = inet_ntoa(addr->sin_addr);

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

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

        perror("ioctl error"), exit(1);

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

    address = inet_ntoa(addr->sin_addr);

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

    printf(" ");

    exit(0);

}

[lingyun@localhost ioctl_1]$ gcc -o ipconfig ipconfig.c 

[lingyun@localhost ioctl_1]$ ./ipconfig eth0

inet addr: 192.168.1.3

broad addr: 192.168.1.255

inet mask: 255.255.255.0

 [lingyun@localhost ioctl_1]$