Rails how to validate subnet mask before ip range calculation

Question

I am using netaddr gem to validate network IP range. But I unable to find the way validated given subnet mask is valid?

  def valid_ip_range(ip, gateway, subnet_mask)
    ip_range = NetAddr::CIDR.create("#{gateway} #{subnet_mask}")

    valid_ip_range = NetAddr.range(ip_range.first, ip_range.last)
    valid_ip_range.include?(ip_ip)
  end

For Valid subnet mask

ip_range = NetAddr::CIDR.create('192.168.1.1 255.255.255.0')
=> #<NetAddr::CIDRv4:0x0000000b334720 @address_len=32, @all_f=4294967295, @hostmask=255, @ip=3232235777, @netmask=4294967040, @network=3232235776, @tag={}, @version=4, @wildcard_mask=4294967040>

For Invalid subnet mask, getting following error

ip_range = NetAddr::CIDR.create('192.168.1.1 255.128.128.0')
ip_range = NetAddr::CIDR.create('192.168.1.1 1.1.1.1')
=> NetAddr::ValidationError: 1.1.1.1 contains '1' bits within the host portion of the netmask.
from /ruby-2.1.1@customerservice-mar/gems/netaddr-1.5.1/lib/validation_shortcuts.rb:182:in `block in validate_netmask_str'

Answer 1

ruby ipaddr

require 'ipaddr'
net1 = IPAddr.new("192.168.2.0/24")
net2 = IPAddr.new("192.168.2.100")
net3 = IPAddr.new("192.168.3.0")
p net1.include?(net2)     #=> true
p net1.include?(net3)     #=> false