##
# $Id$
##

##
# This file is part of the Metasploit Framework and may be subject to 
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/projects/Framework/
##


require 'msf/core'
require 'resolv'

module Msf

class Auxiliary::Server::FakeDNS < Msf::Auxiliary

	include Auxiliary::Report

	
	def initialize
		super(
			'Name'        => 'Fake DNS Service',
			'Version'     => '$Revision$',
			'Description'    => %q{
				This module provides a DNS service that redirects
			all queries to a particular address.
			},
			'Author'      => ['ddz', 'hdm'],
			'License'     => MSF_LICENSE,
			'Actions'     =>
				[
				 	[ 'Service' ]
				],
			'PassiveActions' => 
				[
					'Service'
				],
			'DefaultAction'  => 'Service'
		)

		register_options(
			[
				OptAddress.new('SRVHOST',   [ true, "The local host to listen on.", '0.0.0.0' ]),
				OptPort.new('SRVPORT',      [ true, "The local port to listen on.", 53 ]),
				OptAddress.new('TARGETHOST', [ false, "The address that all names should resolve to", nil ]),

			], self.class)

		register_advanced_options(
			[
				OptBool.new('LogConsole', [ false, "Determines whether to log all request to the console", true]),
				OptBool.new('LogDatabase', [ false, "Determines whether to log all request to the database", false]),
			], self.class)
	end

	
	def run
		
		
		@targ = datastore['TARGETHOST']
		if(@targ and @targ.strip.length == 0)
			@targ = nil
		end
		
		if(@targ)
			@targ = ::Rex::Socket.resolv_to_dotted(@targ)
		end

		@port = datastore['SRVPORT'].to_i

		@log_console  = false
		@log_database = false
		
		if (datastore['LogConsole'].to_s.match(/^(t|y|1)/i))
			@log_console = true
		end
		
		if (datastore['LogDatabase'].to_s.match(/^(t|y|1)/i))
			@log_database = true
		end
		
        # MacOS X workaround
        ::Socket.do_not_reverse_lookup = true
            
        @sock = ::UDPSocket.new()
        @sock.setsockopt(::Socket::SOL_SOCKET, ::Socket::SO_REUSEADDR, 1)
        @sock.bind(datastore['SRVHOST'], @port)
        @run = true
		
		Thread.new {
		# Wrap in exception handler
		begin
		
        while @run
            packet, addr = @sock.recvfrom(65535)
            if (packet.length == 0)
                break
            end
            request = Resolv::DNS::Message.decode(packet)
            
            #
            # XXX: Track request IDs by requesting IP address and port
            #
            # Windows XP SP1a: UDP source port constant, 
            #  sequential IDs since boot time
            # Windows XP SP2: Randomized IDs
            #
            # Debian 3.1: Static source port (32906) until timeout, 
            #  randomized IDs
            #

			lst = []
			
            request.each_question {|name, typeclass|
                tc_s = typeclass.to_s().gsub(/^Resolv::DNS::Resource::/, "")

				request.qr = 1
				request.ra = 1
					               
                lst << "#{tc_s} #{name}"
				case tc_s
				when 'IN::A'
                    
                    # Special fingerprinting name lookups:
                    #
                    # _isatap -> XP SP = 0
                    # isatap.localdomain -> XP SP >= 1
                    # teredo.ipv6.microsoft.com -> XP SP >= 2
                    #
                    # time.windows.com -> windows ???
                    # wpad.localdomain -> windows ???
                    #
                    # <hostname> SOA -> windows XP self hostname lookup
                    #

                    answer = Resolv::DNS::Resource::IN::A.new( @targ || ::Rex::Socket.source_address(addr[3].to_s) )
                    request.add_answer(name, 60, answer)
                
				when 'IN::MX'
                    mx = Resolv::DNS::Resource::IN::MX.new(10, Resolv::DNS::Name.create("mail.#{name}"))
                    ns = Resolv::DNS::Resource::IN::NS.new(Resolv::DNS::Name.create("dns.#{name}"))
					ar = Resolv::DNS::Resource::IN::A.new( @targ || ::Rex::Socket.source_address(addr[3].to_s) )
					request.add_answer(name, 60, mx)
					request.add_authority(name, 60, ns)	
					request.add_additional(Resolv::DNS::Name.create("mail.#{name}"), 60, ar)
					
				when 'IN::NS'
                    ns = Resolv::DNS::Resource::IN::NS.new(Resolv::DNS::Name.create("dns.#{name}"))
					ar = Resolv::DNS::Resource::IN::A.new( @targ || ::Rex::Socket.source_address(addr[3].to_s) )	
					request.add_answer(name, 60, ns)
					request.add_additional(name, 60, ar)
				when 'IN::PTR'
					soa = Resolv::DNS::Resource::IN::SOA.new(
						Resolv::DNS::Name.create("ns.internet.com"),
						Resolv::DNS::Name.create("root.internet.com"),
						1,
						3600,
						3600,
						3600,
						3600
					)
					ans = Resolv::DNS::Resource::IN::PTR.new(
						Resolv::DNS::Name.create("www")
					)
					
					request.add_answer(name, 60, ans)
					request.add_authority(name, 60, soa)
				else
					lst << "UNKNOWN #{tc_s}"
				end
            }
			
			if(@log_console)
				print_status("DNS #{addr[3]}:#{addr[1]} XID #{request.id} (#{lst.join(", ")})")
			end
			
			if(@log_database)
				report_note(
					:host => addr[3],
					:type => "dns_lookup",
					:data => "#{addr[3]}:#{addr[1]} XID #{request.id} (#{lst.join(", ")})"
				) if lst.length > 0
			end
			
            @sock.send(request.encode(), 0, addr[3], addr[1])
        end
		
		# Make sure the socket gets closed on exit
		rescue ::Exception => e
			print_error("fakedns: #{e.class} #{e} #{e.backtrace}")
		ensure
			@sock.close
		end
		
		}
		
	end

end
end