/* Copyright mcmanus@ducksong.com 2009, Under terms of GPLv2 */

#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <net/if.h>


int main()
{
    struct sockaddr_nl addr;
    int nls,len,rtl;
    char buffer[4096];
    struct nlmsghdr *nlh;
    struct ifaddrmsg *ifa;
    struct rtattr *rth;
    
    if ((nls = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) == -1)   perror ("socket failure\n");
    
    memset (&addr,0,sizeof(addr));
    addr.nl_family = AF_NETLINK;
    addr.nl_groups = RTMGRP_IPV4_IFADDR;
    
    if (bind(nls, (struct sockaddr *)&addr, sizeof(addr)) == -1)    perror ("bind failure\n");

    nlh = (struct nlmsghdr *)buffer;
    while ((len = recv (nls,nlh,4096,0)) > 0)
    {
        for (;(NLMSG_OK (nlh, len)) && (nlh->nlmsg_type != NLMSG_DONE); nlh = NLMSG_NEXT(nlh, len))
        {
            if (nlh->nlmsg_type != RTM_NEWADDR) continue; /* some other kind of announcement */
            
            ifa = (struct ifaddrmsg *) NLMSG_DATA (nlh);
            
            rth = IFA_RTA (ifa);
            rtl = IFA_PAYLOAD (nlh);
            for (;rtl && RTA_OK (rth, rtl); rth = RTA_NEXT (rth,rtl))
            {
                char name[IFNAMSIZ];
                uint32_t ipaddr;
                
                if (rth->rta_type != IFA_LOCAL) continue;
                
                ipaddr = * ((uint32_t *)RTA_DATA(rth));
                ipaddr = htonl(ipaddr);
                
                fprintf (stdout,"%s is now %X\n",if_indextoname(ifa->ifa_index,name),ipaddr);
            }
        }
    }
}