net_func.go

package main

import (
	"log"
	"net"
)

func dupIP(ip net.IP) net.IP {
	dup := make(net.IP, len(ip))
	copy(dup, ip)
	return dup
}

func inc(ip net.IP) {
	for j := len(ip) - 1; j >= 0; j-- {
		ip[j]++
		if ip[j] > 0 {
			break
		}
	}
}

func NetGetNetworkIPs() (ip []net.IP, err error) {
	var ipList []net.IP

	ifaces, err := net.Interfaces()
	if err != nil {
		return nil, err
	}

	// scan all interfaces
	for _, iface := range ifaces {
		if iface.Flags&net.FlagUp != 0 && iface.Flags&net.FlagBroadcast != 0 {
			addrs, err := iface.Addrs()
			if err != nil {
				log.Printf("Error reading interface address %v : %v", iface, err)
			} else {
				for _, addr := range addrs {
					ip, ipnet, err := net.ParseCIDR(addr.String())
					if err != nil {
						log.Printf("Error parsing CIDR %s : %v", addr.String(), err)
					} else {
						ip = ip.To4()  // make sure that the IP is IPv4
						if ip != nil { // will be nill if IPv6
							log.Printf("Scanning network interface '%v' with CIDR = %v, IP = %v\n", iface.Name, addr.String(), ip)
							for xip := ip.Mask(ipnet.Mask); ipnet.Contains(xip); inc(xip) {
								ipList = append(ipList, dupIP(xip))
							}
						}
					}
				}
			}
		}
	}

	return ipList, nil

}