local brute = require "brute"
local creds = require "creds"
local nmap = require "nmap"
local shortport = require "shortport"
local stdnse = require "stdnse"
local string = require "string"

description = [[
Performs brute force password auditing against FTP servers.

Based on old ftp-brute.nse script by Diman Todorov, Vlatko Kosturjak and Ron Bowes.
]]

---
-- @usage
-- nmap --script ftp-brute -p 21 <host>
--
-- This script uses brute library to perform password
-- guessing.
-- 
-- @output
-- PORT   STATE SERVICE
-- 21/tcp open  ftp
-- | my-ftp-brute:
-- |   Accounts
-- |     root:root - Valid credentials
-- |   Statistics
-- |_    Performed 510 guesses in 610 seconds, average tps: 0
--
-- @args ftp-brute.timeout the amount of time to wait for a response on the socket.
--       Lowering this value may result in a higher throughput for servers
--       having a delayed response on incorrect login attempts. (default: 5s)

author = "Aleksandar Nikolic"
license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
categories = {"intrusive", "brute"}

portrule = shortport.port_or_service(21, "ftp")

local arg_timeout = stdnse.parse_timespec(stdnse.get_script_args(SCRIPT_NAME .. ".timeout"))
arg_timeout = (arg_timeout or 5) * 1000

Driver = {

	new = function(self, host, port)
		local o = {}
       	setmetatable(o, self)
        self.__index = self
		o.host = host
		o.port = port
		return o
	end,

	connect = function( self )
		self.socket = nmap.new_socket()
		local status, err = self.socket:connect(self.host, self.port)
		self.socket:set_timeout(arg_timeout)
		if(not(status)) then
			return false, brute.Error:new( "Couldn't connect to host: " .. err )
		end
		return true
	end,
	
	login = function (self, user, pass)
		local status, err
		local res = ""


		status, err = self.socket:send("USER " .. user .. "\r\n")
		if(not(status)) then
			return false, brute.Error:new("Couldn't send login: " .. err)
		end

		status, err = self.socket:send("PASS " .. pass .. "\n\n")
		if(not(status)) then
			return false, brute.Error:new("Couldn't send login: " .. err)
		end

		-- Create a buffer and receive the first line
		local buffer = stdnse.make_buffer(self.socket, "\r?\n")
		local line = buffer()

		-- Loop over the lines
		while(line)do
			stdnse.print_debug("Received: %s", line)
			if(string.match(line, "^230")) then
				stdnse.print_debug(1, "ftp-brute: Successful login: %s/%s", user, pass)
				return true, brute.Account:new( user, pass, creds.State.VALID)
			elseif(string.match(line, "^530")) then
				return false,  brute.Error:new( "Incorrect password" )
			elseif(string.match(line, "^220")) then
			elseif(string.match(line, "^331")) then
			else
				stdnse.print_debug(1, "ftp-brute: WARNING: Unhandled response: %s", line)
				local err = brute.Error:new("Unhandled response")
				err:setRetry(true)
				return false, err
			end

			line = buffer()
		end


		return false, brute.Error:new("Login didn't return a proper response")
	end,

	disconnect = function( self ) 
		self.socket:close()
		return true
	end
	

}

action = function( host, port )

	local status, result 
	local engine = brute.Engine:new(Driver, host, port)
	engine.options.script_name = SCRIPT_NAME


	status, result = engine:start()
	
	return result
end
