linux c ioctl和socket 学习

#include <stdio.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <net/if.h>

unsigned char    g_eth_name[16];
unsigned char    g_macaddr[6];
unsigned int    g_subnetmask;
unsigned int    g_ipaddr;
unsigned int    g_broadcast_ipaddr;

/*初始化网络，获取当前网络设备的信息*/
void init_net(void)
{
    int i;
    int sock;
    struct sockaddr_in sin;
    struct ifreq ifr;

    sock = socket(AF_INET, SOCK_DGRAM, 0);
    if (sock == -1) {
        perror("socket");
    }

    strcpy(g_eth_name, "eth0");
        strcpy(ifr.ifr_name, g_eth_name);
    printf("eth name:\t%s\n", g_eth_name);


    // 获取并打印网卡地址
    if (ioctl(sock, SIOCGIFHWADDR, &ifr) < 0) {
        perror("ioctl");
    }
    memcpy(g_macaddr, ifr.ifr_hwaddr.sa_data, 6);

    printf("local mac:\t");
    for(i=0;i<5;i++) {
        printf("%.2x:", g_macaddr[i]);
    }
    printf("%.2x\n",g_macaddr[i]);

    // 获取并打印IP地址
    if (ioctl(sock, SIOCGIFADDR, &ifr) < 0) {
        perror("ioctl");
    }
    g_ipaddr = sin.sin_addr.s_addr;
    memcpy(&sin, &ifr.ifr_addr, sizeof(sin));
    printf("local eth0:\t%s\n", inet_ntoa(sin.sin_addr));

    // 获取并打印广播地址
    if (ioctl(sock, SIOCGIFBRDADDR, &ifr) < 0) {
        perror("ioctl");
    }
    memcpy(&sin, &ifr.ifr_addr, sizeof(sin));
    g_broadcast_ipaddr = sin.sin_addr.s_addr;
    printf("broadcast:\t%s\n", inet_ntoa(sin.sin_addr));

    // 获取并打印子网掩码
    if (ioctl(sock, SIOCGIFNETMASK, &ifr) < 0) {
        perror("ioctl");
    }
    memcpy(&sin, &ifr.ifr_addr, sizeof(sin));
    g_subnetmask = sin.sin_addr.s_addr;
    printf("subnetmask:\t%s\n", inet_ntoa(sin.sin_addr));

    close(sock);
}

int main()
{
    /*initialize...*/
    init_net();

    /*do something*/

    return 0;
}
/* result:
eth name:    eth0
local mac:    xx:xx:xx:xx:xxxx
local eth0:    192.168.10.103
broadcast:    192.168.10.255
subnetmask:    255.255.255.0

*/