Subnet contains IP

subnet.go

// SubnetContainsIP check if an IP address is part of the subnet given by the CIDR (ie. '192.168.0.0/24')
func SubnetContainsIP(CIDR, addr string) (bool, error) {
	_, ipNet, err := net.ParseCIDR(CIDR)
	if err != nil {
		return false, fmt.Errorf("Error parsing CIDR '%s'", CIDR)
	}

	host, _, err := net.SplitHostPort(addr)
	if err != nil {
		return false, fmt.Errorf("Error parsing address '%s'. %v", addr, err)
	}

	ip := net.ParseIP(host)
	if ip == nil {
		return false, fmt.Errorf("Error parsing host '%s' from address '%s'", host, addr)
	}

	return ipNet.Contains(ip), nil
}