Well, to get the CIDR notation of a range, you need an IP and the number of network bits (calculated from the netmask).
To enumerate the addresses of a given range, you can use the NetAddr
(< 2.x) gem.
p NetAddr::CIDR.create('192.168.1.0/24').enumerate
=> ['192.168.1.0', '192.168.1.1', '192.168.1.2'... '192.168.1.255']
You can also calculate the bits from the netmask on the fly:
mask_int = NetAddr.netmask_to_i('255.255.255.0')
p NetAddr.mask_to_bits(mask_int)
=> 24
And to create a range based on two IPs:
lower = NetAddr::CIDR.create('192.168.1.1')
upper = NetAddr::CIDR.create('192.168.1.10')
p NetAddr.range(lower, upper)
=> ['192.168.1.2', '192.168.1.3'... '192.168.1.9']
So now that you can create a CIDR range, you can check to see if an IP is a part of it:
cidr = NetAddr::CIDR.create('192.168.1.0/24')
p cidr.contains?('192.168.1.10')
=> true