is inside

gistfile1.txt

func isInside(adress string, masks []string, timeout time.Duration, done chan net.IP) {
	c1 := make(chan net.IP)
	c2 := make(chan error)

	var p net.IP
	var err error

	go func() {
		ipv4 := adress
		p = net.ParseIP(ipv4).To4()
		for i := 0; i < len(masks); i++ {
			_, pc, _ := net.ParseCIDR(masks[i])
			if pc.Contains(p) {
				c1 <- p
			}
		}
		if err != nil {
			c2 <- err
		}

	}()

	select {
	case p = <-c1:
	case err = <-c2:
	case <-time.After(timeout):
		done <- nil
	}
	if err != nil {
		done <- nil
	}
	done <- p
}