RubyDNS Server

require 'rubygems'

require 'rexec'
require 'rexec/daemon'

require 'rubydns'

require 'timeout'

RUN_AS="daemon"

# Cache DNS entries for 5 minutes
CACHE_TIME=60*5

# We need to be root in order to bind to privileged port
if RExec.current_user != "root"
    $stderr.puts "Sorry, this command needs to be run as root!"
    exit 1
end

# Helper
Name = Resolv::DNS::Name

Google = '8.8.8.8'
Servers = {
    :php => '192.168.10.1',
    :ror => '192.168.10.2',
    :sql => '192.168.10.3',
    # ...
}

# The Daemon itself
class Server < RExec::Daemon::Base
    @@var_directory = File.dirname(__FILE__)

    def self.run
        # Don't buffer output (for debug purposes)
        $stderr.sync = true

        # Use upstream DNS for name resolution
        $R = Resolv::DNS.new(:nameserver => Google)

        $CACHE = {}

        # Start the RubyDNS server
        RubyDNS::run_server do
            on(:start) do
                RExec.change_user(RUN_AS)
            end

            Servers.each do |name, addr|
              match(/(.+).#{name.to_s}.dev$/, :A) do |match, transaction|
                  transaction.respond!(addr)
              end
            end

            # Default DNS handler
            otherwise do |transaction|
                transaction.passthrough!($R)
            end
        end
    end
end

# RExec daemon runner
Server.daemonize