Liunx C获取IP、MAC地址

#include 
#include 
#include 
#include 
#include 
#include 



//获取地址
//返回IP地址字符串
//返回：0=成功，-1=失败
int getlocalip(char* outip)
{
    int i=0;
    int sockfd;
    struct ifconf ifconf;
    char buf[512];
    struct ifreq *ifreq;
    char* ip;
    //初始化ifconf
    ifconf.ifc_len = 512;
    ifconf.ifc_buf = buf;

    if((sockfd = socket(AF_INET, SOCK_DGRAM, 0))<0)
    {
        return -1;
    }
    ioctl(sockfd, SIOCGIFCONF, &ifconf);    //获取所有接口信息
    close(sockfd);
    //接下来一个一个的获取IP地址
    ifreq = (struct ifreq*)buf;

    for(i=(ifconf.ifc_len/sizeof(struct ifreq)); i>0; i--)
    {
        ip = inet_ntoa(((struct sockaddr_in*)&(ifreq->ifr_addr))->sin_addr);
        //排除127.0.0.1，继续下一个
        if(strcmp(ip,"127.0.0.1")==0)
        {
            ifreq++;
            continue;
        }
        strcpy(outip,ip);
        return 0;
    }

    return -1;
}

//获取地址
//返回MAC地址字符串
//返回：0=成功，-1=失败
int get_mac(char* mac)
{
    struct ifreq tmp;
    int sock_mac;
    char mac_addr[30];
    sock_mac = socket(AF_INET, SOCK_STREAM, 0);
    if( sock_mac == -1)
    {
        perror("create socket fail\n");
        return -1;
    }
    memset(&tmp,0,sizeof(tmp));
    strncpy(tmp.ifr_name,"eth0",sizeof(tmp.ifr_name)-1 );
    if( (ioctl( sock_mac, SIOCGIFHWADDR, &tmp)) < 0 )
    {
        printf("mac ioctl error\n");
        return -1;
    }
    sprintf(mac_addr, "%02x:%02x:%02x:%02x:%02x:%02x",
            (unsigned char)tmp.ifr_hwaddr.sa_data[0],
            (unsigned char)tmp.ifr_hwaddr.sa_data[1],
            (unsigned char)tmp.ifr_hwaddr.sa_data[2],
            (unsigned char)tmp.ifr_hwaddr.sa_data[3],
            (unsigned char)tmp.ifr_hwaddr.sa_data[4],
            (unsigned char)tmp.ifr_hwaddr.sa_data[5]
            );
    close(sock_mac);
    memcpy(mac,mac_addr,strlen(mac_addr));
    return 0;
}

int main(void)
{
    char ip[20];
    char mac[17];

    if ( getlocalip( ip ) == 0 )
    {
        printf("本机IP地址是： %s\n", ip );
    }
    else
    {
        printf("无法获取本机IP地址");
    }

    if(get_mac(mac) == 0)
    {
        printf("本机MAC地址是： %s\n", mac);
    }
    else
    {
        printf("无法获取本机MAC地址");
    }
    return 0;
}