How to generate a list of IP addresses between two addresses with Ruby

I have a user input a string of IP addresses they'd like to use. That string looks something like:

192.168.1.3-192.168.1.100

I'm trying to generate an array of IP addresses including, and between the start and end address, which would look something like:

["192.168.1.3","192.168.1.4",.....,"192.168.1.99","192.168.1.100"]

I was hoping it would be as simple as

("192.168.1.3".."192.168.1.100").step(1).to_a

but I guess it isn't.

Solution

Use IPAddr from the Ruby Stdlib.

IPAddr provides a set of methods to manipulate an IP address. Both IPv4 and IPv6 are supported.

require 'ipaddr'

# I used a smaller number to limit the output
ip_range = IPAddr.new("192.168.1.3")..IPAddr.new("192.168.1.13")
ip_range.to_a

The output is an array of IPAddr instances.

=> [#<IPAddr: IPv4:192.168.1.3/255.255.255.255>, #<IPAddr: IPv4:192.168.1.4/255.255.255.255>, #<IPAddr: IPv4:192.168.1.5/255.255.255.255>, #<IPAddr: IPv4:192.168.1.6/255.255.255.255>, #<IPAddr: IPv4:192.168.1.7/255.255.255.255>, #<IPAddr: IPv4:192.168.1.8/255.255.255.255>, #<IPAddr: IPv4:192.168.1.9/255.255.255.255>, #<IPAddr: IPv4:192.168.1.10/255.255.255.255>, #<IPAddr: IPv4:192.168.1.11/255.255.255.255>, #<IPAddr: IPv4:192.168.1.12/255.255.255.255>, #<IPAddr: IPv4:192.168.1.13/255.255.255.255>]

A word of warning though. If you are taking user input make sure to catch the potential IPAddr::InvalidAddressError that can occur.

begin 
  IPAddr.new(params[:from])..IPAddr.new(params[:to])
rescue IPAddr::InvalidAddressError
  # @todo handle error
  logger.info("Oh Noes!")
end