rubydns.rb

require 'rubygems'
require 'rubydns'
require 'rubydns/system'

# You can specify other DNS servers easily
# $R = Resolv::DNS.new(:nameserver => ["xx.xx.1.1", "xx.xx.2.2"])

R = RubyDNS::Resolver.new(RubyDNS::System::nameservers)
Name = Resolv::DNS::Name
IN = Resolv::DNS::Resource::IN

RubyDNS::run_server do
  # % dig +nocmd +noall +answer @localhost ANY dev.mydomain.org
	# dev.mydomain.org.	16000	IN	A	10.0.0.80
	# dev.mydomain.org.	16000	IN	MX	10 mail.mydomain.org.
	match(/dev.mydomain.org/, IN::ANY) do |match_data, transaction|
		transaction.append_question!

		[IN::A, IN::CNAME, IN::MX].each do |resource_class|
			logger.debug "Appending query for #{resource_class}..."
			transaction.append_query!(transaction.name, resource_class)
		end
	end

	# For this exact address record, return an IP address
	match("dev.mydomain.org", IN::A) do |transaction|
		transaction.respond!("10.0.0.80")
	end

	match("80.0.0.10.in-addr.arpa", IN::PTR) do |transaction|
		transaction.respond!(Name.create("dev.mydomain.org."))
	end

	match("dev.mydomain.org", IN::MX) do |transaction|
		transaction.respond!(10, Name.create("mail.mydomain.org."))
	end

	match(/^test([0-9]+).mydomain.org$/, IN::A) do |match_data, transaction|
		offset = match_data[1].to_i

		if offset > 0 && offset < 10
			logger.info "Responding with address #{"10.0.0." + (90 + offset).to_s}..."
			transaction.respond!("10.0.0." + (90 + offset).to_s)
		else
			logger.info "Address out of range: #{offset}!"
			false
		end
	end

	# Default DNS handler
	otherwise do |transaction|
		logger.info "Passing DNS request upstream..."
		transaction.passthrough!(R)
	end