require 'msf/core'
require 'rex/proto/natpmp'

class Metasploit3 < Msf::Auxiliary

	include Msf::Auxiliary::Report
	include Msf::Auxiliary::Scanner

	def initialize
		super(
			'Name'        => 'NAT-PMP External Address Scanner',
			'Description' => 'Scan NAT devices for their external address using NAT-PMP',
			'Author'      => 'Jon Hart <jhart[at]spoofed.org>',
			'License'     => MSF_LICENSE
		)

		register_options(
			[
				Opt::RPORT(Rex::Proto::NATPMP::DefaultPort),
				Opt::CHOST
			],
			self.class
		)
	end

	def run_host(host)
		begin
			udp_sock = Rex::Socket::Udp.create({
				'LocalHost' => datastore['CHOST'] || nil,
				'Context'   => {'Msf' => framework, 'MsfExploit' => self}
			})
			add_socket(udp_sock)
			vprint_status "#{host}:#{datastore['RPORT']} - NATPMP - Probing for external address"

			udp_sock.sendto(Rex::Proto::NATPMP.external_address_request, host, datastore['RPORT'].to_i, 0)
			while (r = udp_sock.recvfrom(12, 1.0) and r[1])
				handle_reply(host, r)
			end
		rescue ::Interrupt
			raise $!
		rescue ::Rex::HostUnreachable, ::Rex::ConnectionTimeout, ::Rex::ConnectionRefused
			nil
		rescue ::Exception => e
			print_error("#{host}:#{datastore['RPORT']} Unknown error: #{e.class} #{e}")
		end
	end

	def handle_reply(host, pkt)
		return if not pkt[1]

		if(pkt[1] =~ /^::ffff:/)
			pkt[1] = pkt[1].sub(/^::ffff:/, '')
		end

		(ver, op, result, epoch, external_address) = Rex::Proto::NATPMP.parse_external_address_response(pkt[0])

		if (result == 0)
			print_status("#{host} -- external address #{external_address}")
		end

		# report the host we scanned as alive
		report_host(
			:host   => host,
			:state => Msf::HostState::Alive
		)

		# also report its external address as alive
		if inside_workspace_boundary(external_address)
			report_host(
				:host   => external_address,
				:state => Msf::HostState::Alive
			)
		end

		# report NAT-PMP as being open
		report_service(
			:host   => host,
			:port   => pkt[2],
			:proto  => 'udp',
			:name   => 'natpmp',
			:state  => Msf::ServiceState::Open
		)
	end
end