/*


main.c



2013-01-09 chrisniu1984@gmail.com
*
[BUILD]
gcc -o main main.c -Wall
/

include <stdio.h>
include <netdb.h>
include <ifaddrs.h>
// 系統定義的結構，貼在這里方便大家查閱，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;

}</pre>