Linux C ++如何以编程方式获取LAN上所有适配器的MAC地址

How may I use C or C++ PROGRAM (no command line) to get the MAC addresses (I'll take the IP addresses too if they are "free") on my (small) local network. It's an embedded Busybox Linux so I need a minimalist answer that hopefully doesn't require porting some library. I don't have libnet or libpcap. The arp cache seems to never contain anything but the MAC if the DHCP host. (no command line