##
# This module requires Metasploit: http//metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'
require "net/dns/resolver"
require 'rex'

class Metasploit3 < Msf::Auxiliary
  include Msf::Auxiliary::Report

  def initialize(info = {})
    super(update_info(info,
      'Name'       => 'DNS Reverse Lookup Enumeration',
      'Description' => %q{
          This module performs DNS reverse lookup against a given IP range in order to
        retrieve valid addresses and names.
      },
      'Author'    =>
        [
          'Carlos Perez <carlos_perez[at]darkoperator.com>', # Base code
          'Thanat0s <thanspam[at]trollprod.org>' # Output, Throttling & Db notes add
        ],
      'License'   => BSD_LICENSE
    ))

    register_options(
      [
        OptAddressRange.new('RANGE', [true, 'IP range to perform reverse lookup against.']),
        OptAddress.new('NS', [ false, "Specify the nameserver to use for queries, otherwise use the system DNS." ]),
        OptString.new('OUT_FILE', [ false, "Specify a CSV output file" ])
      ], self.class)

    register_advanced_options(
      [
        OptInt.new('RETRY', [ false, "Number of tries to resolve a record if no response is received.", 2]),
        OptInt.new('RETRY_INTERVAL', [ false, "Number of seconds to wait before doing a retry.", 2]),
        OptInt.new('THREADS', [ true, "The number of concurrent threads.", 1]),
        OptInt.new('THROTTLE', [ false, "Specify the resolution throttle in query per sec. 0 means unthrottled",0 ])
      ], self.class)
  end

  def run
    @res = Net::DNS::Resolver.new()

    if datastore['RETRY']
      @res.retry = datastore['RETRY'].to_i
    end

    if datastore['RETRY_INTERVAL']
      @res.retry_interval = datastore['RETRY_INTERVAL'].to_i
    end

    @threadnum = datastore['THREADS'].to_i
    switchdns() unless datastore['NS'].nil?
    reverselkp(datastore['RANGE'])
  end

  def reverselkp(iprange)
    print_status("Running reverse lookup against IP range #{iprange}")
    ar = Rex::Socket::RangeWalker.new(iprange)
    tl = []
    # Basic Throttling
    sleep_time = 0.0
    if (datastore['THROTTLE'] != 0)
      sleep_time = (1.0/datastore['THROTTLE'])*datastore['THREADS']
      print_status("Throttle set to #{datastore['THROTTLE']} queries per seconds")
    end
    # Output..
    if datastore['OUT_FILE']
      print_status("Scan result saved in #{datastore['OUT_FILE']}")
      open(datastore['OUT_FILE'], 'w') do |f|
        f.puts "; IP, Host"
      end
    end
    while (true)
      # Spawn threads for each host
      hosts = Hash.new
      while (tl.length <= @threadnum)
        ip = ar.next_ip
        break if not ip
        tl << framework.threads.spawn("Module(#{self.refname})-#{ip}", false, ip.dup) do |tip|
          begin
            Rex.sleep(sleep_time)
            query = @res.query(tip)
            query.each_ptr do |addresstp|
              print_status("Host Name: #{addresstp}, IP Address: #{tip.to_s}")
              if datastore['OUT_FILE']
                open(datastore['OUT_FILE'], 'a') do |f|
                  f.puts "#{tip.to_s},#{addresstp}"
                end
              end
              report_host(
                :host => tip.to_s,
                :name => addresstp
              )
              if !hosts[tip]
                hosts[tip] = Array.new
              end
              hosts[tip].push addresstp
            end
            unless hosts[tip].nil? or hosts[tip].empty?
              report_note(
               :host => tip.to_s,
               :type => "RDNS_Record",
               :data => hosts[tip]
              )
            end
          rescue ::Interrupt
            raise $!
          rescue ::Rex::ConnectionError
          rescue ::Exception => e
            print_error("Error: #{tip}: #{e.message}")
          end
        end
      end
      # Exit once we run out of hosts
      if(tl.length == 0)
        break
      end
      tl.first.join
      tl.delete_if { |t| not t.alive? }
    end
  end

  def switchdns()
    print_status("Using DNS server: #{datastore['NS']}")
    @res.nameserver=(datastore['NS'])
    @nsinuse = datastore['NS']
  end
end