#!/usr/local/bin/ruby18 -w

# Author: Sam Roberts <sroberts@uniserve.com>

# Licence: this file is placed in the public domain

$:.unshift(File.dirname($0))

require 'getoptlong'

require 'net/dns/resolvx'

require 'net/dns'

class Resolv

class DNS

class Resource

module IN

class SRV

def inspect

"#{target}:#{port} weight=#{weight} priority=#{priority}"

end

end

class TXT

def inspect

strings.inspect

end

end

class PTR

def inspect

name.to_s

end

end

class A

def inspect

address.to_s

end

end

class HINFO

def inspect

"os=#{os.inspect}\ncpu=#{cpu.inspect}"

end

end

end

end

end

end

include Net::DNS

$stderr.sync = true

$stdout.sync = true

Addr = '224.0.0.251'

Port = 5353

$id = 1

def ask(name, type)

$id += 1

qmsg = Message.new($id)

qmsg.add_question(name, type)

@sock.send(qmsg.encode, 0, Addr,Port)

end

@sock = UDPSocket.new

ask(Name.create(ARGV.first || '_http._tcp.local'), IN::PTR)

loop do

reply, from = @sock.recvfrom(9000)

puts "++ from #{from.inspect}"

msg = Resolv::DNS::Message.decode(reply)

qr = msg.qr==0 ? 'Q' : 'R'

qrstr = msg.qr==0 ? 'Query' : 'Resp'

opcode = { 0=>'QUERY', 1=>'IQUERY', 2=>'STATUS'}[msg.opcode]

puts "#{qrstr}: id #{msg.id} qr #{qr} opcode #{opcode} aa #{msg.aa} tc #{msg.tc} rd #{msg.rd} ra #{msg.ra} rcode #{msg.rcode}"

msg.question.each do |name, type, unicast|

puts "qu #{Net::DNS.rrname type} #{name.to_s.inspect} unicast=#{unicast}"

end

msg.answer.each do |name, ttl, data, cacheflush|

puts "an #{Net::DNS.rrname data} #{name.to_s.inspect} ttl=#{ttl} cacheflush=#{cacheflush}"

puts " #{data.inspect}"

case data

when IN::PTR

ask(data.name, IN::SRV)

ask(data.name, IN::TXT)

when IN::SRV

ask(data.target, IN::A)

end

end

msg.authority.each do |name, ttl, data, cacheflush|

puts "au #{Net::DNS.rrname data} #{name.to_s.inspect} ttl=#{ttl} cacheflush=#{cacheflush.inspect}"

puts " #{data.inspect}"

end

msg.additional.each do |name, ttl, data, cacheflush|

puts "ad #{Net::DNS.rrname data} #{name.to_s.inspect} ttl=#{ttl} cacheflush=#{cacheflush.inspect}"

puts " #{data.inspect}"

end

puts

end