#!/usr/bin/env ruby

require 'net/http'
require 'resolv'

def validate_cidr?(cidr)
  # Check for IPv4 CIDR format
  return false unless cidr =~ /^([0-9]{1,3}\.){3}[0-9]{1,3}\/[0-9]{1,2}$/

  # Parse network address and prefix length
  network_address, prefix_length = cidr.split('/')

  # Validate network address
  begin
    Resolv::DNS.new.getaddress(network_address)
  rescue Resolv::ResolvError
    return false
  end

  # Validate prefix length
  return false if prefix_length.to_i > 32

  true
end

def process_url(url)
  begin
    uri = URI(url)
    response = Net::HTTP.get(uri)
  rescue URI::InvalidURIError, Net::HTTPError => e
    puts "Error fetching URL: #{e.message}"
    return
  end

  cidrs = response.split("\n")
  cidrs.each do |cidr|
    if validate_cidr?(cidr)
      puts "Valid CIDR: #{cidr}"
    else
      puts "Invalid CIDR: #{cidr}"
    end
  end
end

# Get the URL from the user
puts "Enter the URL containing the IPv4 CIDR list:"
url = gets.chomp

# Process the URL
process_url(url)