# -*- coding: binary -*-
module Msf

require 'msf/core/exploit/tcp'

###
#
# This module exposes methods that may be useful to exploits that deal with
# servers that speak the File Transfer Protocol (FTP).
#
###
module Exploit::Remote::Ftp

	include Exploit::Remote::Tcp

	#
	# Creates an instance of an FTP exploit module.
	#
	def initialize(info = {})
		super

		# Register the options that all FTP exploits may make use of.
		register_options(
			[
				Opt::RHOST,
				Opt::RPORT(21),
				OptString.new('FTPUSER', [ false, 'The username to authenticate as', 'anonymous']),
				OptString.new('FTPPASS', [ false, 'The password for the specified username', 'mozilla@example.com'])
			], Msf::Exploit::Remote::Ftp)

		register_advanced_options(
			[
				OptInt.new('FTPTimeout', [ true, 'The number of seconds to wait for a reply from an FTP command', 16]),
				OptBool.new('FTPDEBUG', [ false, 'Whether or not to print verbose debug statements', false ])
			], Msf::Exploit::Remote::Ftp)

		register_autofilter_ports([ 21, 2121])
		register_autofilter_services(%W{ ftp })

		@ftpbuff = ""

	end

	#
	# This method establishes an FTP connection to host and port specified by
	# the RHOST and RPORT options, respectively.  After connecting, the banner
	# message is read in and stored in the 'banner' attribute.
	#
	def connect(global = true, verbose = nil)
		verbose ||= datastore['FTPDEBUG']
		verbose ||= datastore['VERBOSE']

		print_status("Connecting to FTP server #{rhost}:#{rport}...") if verbose

		fd = super(global)

		# Wait for a banner to arrive...
		self.banner = recv_ftp_resp(fd)

		print_status("Connected to target FTP server.") if verbose

		# Return the file descriptor to the caller
		fd
	end

	#
	# This method handles establishing datasocket for data channel
	#
	def data_connect(mode = nil, nsock = self.sock)
		if mode
			res = send_cmd([ 'TYPE' , mode ], true, nsock)
			return nil if not res =~ /^200/
		end

		# force datasocket to renegotiate
		self.datasocket.shutdown if self.datasocket != nil

		res = send_cmd(['PASV'], true, nsock)
		return nil if not res =~ /^227/

		# 227 Entering Passive Mode (127,0,0,1,196,5)
		if res =~ /\((\d+)\,(\d+),(\d+),(\d+),(\d+),(\d+)/
			# convert port to FTP syntax
			datahost = "#{$1}.#{$2}.#{$3}.#{$4}"
			dataport = ($5.to_i * 256) + $6.to_i
			self.datasocket = Rex::Socket::Tcp.create('PeerHost' => datahost, 'PeerPort' => dataport)
		end
		self.datasocket
	end

	#
	# This method handles disconnecting our data channel
	#
	def data_disconnect
		self.datasocket.shutdown
		self.datasocket = nil
	end

	#
	# Connect and login to the remote FTP server using the credentials
	# that have been supplied in the exploit options.
	#
	def connect_login(global = true, verbose = nil)
		verbose ||= datastore['FTPDEBUG']
		verbose ||= datastore['VERBOSE']
		ftpsock = connect(global, verbose)

		if !(user and pass)
			print_error("No username and password were supplied, unable to login")
			return false
		end

		print_status("Authenticating as #{user} with password #{pass}...") if verbose
		res = send_user(user, ftpsock)

		if (res !~ /^(331|2)/)
			print_error("The server rejected our username") if verbose
			return false
		end

		if (pass)
			print_status("Sending password...") if verbose
			res = send_pass(pass, ftpsock)
			if (res !~ /^2/)
				print_error("The server rejected our password") if verbose
				return false
			end
		end

		return true
	end

	#
	# This method logs in as the supplied user by transmitting the FTP
	# 'USER <user>' command.
	#
	def send_user(user, nsock = self.sock)
		raw_send("USER #{user}\r\n", nsock)
		recv_ftp_resp(nsock)
	end

	#
	# This method completes user authentication by sending the supplied
	# password using the FTP 'PASS <pass>' command.
	#
	def send_pass(pass, nsock = self.sock)
		raw_send("PASS #{pass}\r\n", nsock)
		recv_ftp_resp(nsock)
	end

	#
	# This method sends a QUIT command.
	#
	def send_quit(nsock = self.sock)
		raw_send("QUIT\r\n", nsock)
		recv_ftp_resp(nsock)
	end

	#
	# This method sends one command with zero or more parameters
	#
	def send_cmd(args, recv = true, nsock = self.sock)
		cmd = args.join(" ") + "\r\n"
		ret = raw_send(cmd, nsock)
		if (recv)
			return recv_ftp_resp(nsock)
		end
		return ret
	end

	#
	# This method transmits the command in args and receives / uploads DATA via data channel
	# For commands not needing data, it will fall through to the original send_cmd
	#
	# For commands that send data only, the return will be the server response.
	# For commands returning both data and a server response, an array will be returned.
	#
	# NOTE: This function always waits for a response from the server.
	#
	def send_cmd_data(args, data, mode = 'a', nsock = self.sock)
		type = nil
		# implement some aliases for various commands
		if (args[0] =~ /^DIR$/i || args[0] =~ /^LS$/i)
			# TODO || args[0] =~ /^MDIR$/i || args[0] =~ /^MLS$/i
			args[0] = "LIST"
			type = "get"
		elsif (args[0] =~ /^GET$/i)
			args[0] = "RETR"
			type = "get"
		elsif (args[0] =~ /^PUT$/i)
			args[0] = "STOR"
			type = "put"
		end

		# fall back if it's not a supported data command
		if not type
			return send_cmd(args, true, nsock)
		end

		# Set the transfer mode and connect to the remove server
		return nil if not data_connect(mode)

		# Our pending command should have got a connection now.
		res = send_cmd(args, true, nsock)
		# make sure could open port
		return nil unless res =~ /^(150|125) /

		# dispatch to the proper method
		if (type == "get")
			# failed listings jsut disconnect..
			begin
				data = self.datasocket.get_once(-1, ftp_timeout)
			rescue ::EOFError
				data = nil
			end
		else
			sent = self.datasocket.put(data)
		end

		# close data channel so command channel updates
		data_disconnect

		# get status of transfer
		ret = nil
		if (type == "get")
			ret = recv_ftp_resp(nsock)
			ret = [ ret, data ]
		else
			ret = recv_ftp_resp(nsock)
		end

		ret
	end

	#
	# This method transmits a FTP command and waits for a response.  If one is
	# received, it is returned to the caller.
	#
	def raw_send_recv(cmd, nsock = self.sock)
		nsock.put(cmd)
		nsock.get_once(-1, ftp_timeout)
	end

	#
	# This method reads an FTP response based on FTP continuation stuff
	#
	def recv_ftp_resp(nsock = self.sock)
		found_end = false
		resp = ""
		left = ""
		if !@ftpbuff.empty?
			left << @ftpbuff
			@ftpbuff = ""
		end
		while true
			data = nsock.get_once(-1, ftp_timeout)
			if not data
				@ftpbuff << resp
				@ftpbuff << left
				return data
			end

			got = left + data
			left = ""

			# handle the end w/o newline case
			enlidx = got.rindex(0x0a.chr)
			if enlidx != (got.length-1)
				if not enlidx
					left << got
					next
				else
					left << got.slice!((enlidx+1)..got.length)
				end
			end

			# split into lines
			rarr = got.split(/\r?\n/)
			rarr.each do |ln|
				if not found_end
					resp << ln
					resp << "\r\n"
					if ln.length > 3 and ln[3,1] == ' '
						found_end = true
					end
				else
					left << ln
					left << "\r\n"
				end
			end
			if found_end
				@ftpbuff << left
				print_status("FTP recv: #{resp.inspect}") if datastore['FTPDEBUG']
				return resp
			end
		end
	end

	#
	# This method transmits a FTP command and does not wait for a response
	#
	def raw_send(cmd, nsock = self.sock)
		print_status("FTP send: #{cmd.inspect}") if datastore['FTPDEBUG']
		nsock.put(cmd)
	end

	##
	#
	# Wrappers for getters
	#
	##

	#
	# Returns the user string from the 'FTPUSER' option.
	#
	def user
		datastore['FTPUSER']
	end

	#
	# Returns the user string from the 'FTPPASS' option.
	#
	def pass
		datastore['FTPPASS']
	end

	#
	# Returns the number of seconds to wait for a FTP reply
	#
	def ftp_timeout
		(datastore['FTPTimeout'] || 10).to_i
	end

protected

	#
	# This attribute holds the banner that was read in after a successful call
	# to connect or connect_login.
	#
	attr_accessor :banner, :datasocket

end

end
