/*
 * main.c
 * ----------------------------------------------
 * 2013-01-09 chrisniu1984@gmail.com
 *
 * [BUILD]
 * gcc -o main main.c -Wall
 *
 */
 
#include <stdio.h>
 
#include <netdb.h>
#include <ifaddrs.h>
 
// 系统定义的结构，贴在这里方便大家查阅，也可man getifaddrs查看。
// struct ifaddrs {
//     struct ifaddrs  *ifa_next;    /* Next item in list */
//     char            *ifa_name;    /* Name of interface */
//     unsigned int     ifa_flags;   /* Flags from SIOCGIFFLAGS */
//     struct sockaddr *ifa_addr;    /* Address of interface */
//     struct sockaddr *ifa_netmask; /* Netmask of interface */
//     union {
//         struct sockaddr *ifu_broadaddr;
//                          /* Broadcast address of interface */
//         struct sockaddr *ifu_dstaddr;
//                          /* Point-to-point destination address */
//     } ifa_ifu;
// #define              ifa_broadaddr ifa_ifu.ifu_broadaddr
// #define              ifa_dstaddr   ifa_ifu.ifu_dstaddr
//     void            *ifa_data;    /* Address-specific data */
// };
 
int main(int argc, char **argv)
{
    struct ifaddrs *ifa;
    if (getifaddrs(&ifa) != 0) {
        return -1;
    }
     
    for (; ifa!=NULL; ifa=ifa->ifa_next) {
        struct sockaddr_in *sin = (struct sockaddr_in*)ifa->ifa_addr;
        if (sin->sin_family != AF_INET) {
            continue;
        }
 
        unsigned char *b = (unsigned char *)(&sin->sin_addr.s_addr);
        printf("%s\t%u.%u.%u.%u\n", ifa->ifa_name, b[0], b[1], b[2], b[3]);
    }
 
    return 0;
}