Generate bgp filter for dn42

bgp-filter.rb

#!/usr/bin/env ruby
# Author: Mic92 <joerg@higgsboson.tk>
# License: WTFPL (C) 2015
#
# TODO
# - support openbgp

require "optparse"

if (RUBY_VERSION.split(/\./) <=> ["1","9","0"]) == -1
  abort "This script needs at least ruby 1.9"
end

def blank?(s)
  s.nil? || s =~ /^\s*$/
end

options = { }
parser = OptionParser.new do |opts|
  opts.banner = "Usage: #{$0} [options]"

  opts.on("--format [FORMAT]", [:bird, :quagga], "syntax format (bird, quagga)") do |format|
    options[:format] = format
  end
end
parser.parse!

if ARGV.size == 0
  source = $stdin
else
  begin
    source = File.open(ARGV[0])
  rescue SystemCallError => e
    abort e.to_s
  end
end

peers = []
source.map do |line|
  # Line-Format:  Nr Action Prefix MinLen MaxLen
  next unless line =~ %r!(\d+)\s+(\w+)\s+([a-fA-F0-9.:]+)/(\d+)\s+(\d+)\s+(\d+)!
  peer = [$1, $2, $3, $4, $5, $6]
  line =~ /#(.*)$/
  peer << $1
  peers << peer
end

case options[:format]
when :bird
  puts "function is_valid_network() {"
  puts "  return net ~ ["

  permitted_peers = peers.find_all {|peer| peer[1] == "permit" }
  permitted_peers.each_with_index do |peer, i|
    _, _, prefix, prefixlen, minlen, maxlen, comment = peer
    print "    #{prefix}/#{prefixlen}{#{minlen},#{maxlen}}"
    print "," unless (permitted_peers.size - 1) == i
    if blank?(comment)
      puts
    else
      puts " ##{comment}"
    end
  end
  puts "  ];\n}"
else # :quagga
  peers.each do |peer|
    number, action, prefix, prefixlen, minlen, maxlen, comment = peer
    print "ip prefix-list dn42-in seq #{number} #{action} #{prefix}/#{prefixlen}"
    if prefixlen != maxlen
      print " ge #{maxlen}"
    end
    if prefixlen != minlen
      print " le #{minlen}"
    end
    if blank?(comment)
      puts
    else
      puts " ##{comment}"
    end
  end
end