id = "POP3 Capabilites (nl)"

description = "retrieves POP3 server capabilites (without pop3-library dependency) "

author = "Philip Pickering <pgpickering@gmail.com>"
license = "Same as Nmap--See http://nmap.org/book/man-legal.html"

categories = {"default"}

require 'shortport'
require 'stdnse'

portrule = shortport.port_or_service({110}, "pop3")

function stat (line)
	return string.match(line, "+OK")
end

action = function(host, port)
	local socket = nmap.new_socket()

	if not socket:connect(host.ip, port.number) then return "no connection" end

	status, line = socket:receive_lines(1)
	if not stat(line) then return "no pop connection" end

	local capstr = ""

	if string.find(line, "<[%p%w]+>") then capstr = "APOP " end

	socket:send("CAPA\r\n")
	status, line = socket:receive_buf("\r\n", false)
	if stat(line) then 
		status, line = socket:receive_buf("\r\n", false)
		while line do
			if line ~= "." then
				local capability = string.sub(line, string.find(line, "[%w-]+"))
				line = string.sub(line, #capability + 1)
				capstr = capstr .. " " .. capability
				local word
				local argstr = ""
				for word in string.gmatch(line, "[%w-]+") do
					argstr = argstr .. word .. " "
				end
				if argstr ~= "" then 
					capstr = capstr .. '(' .. string.sub(argstr, 1, #argstr -1) .. ')'
				end
			else
				break 
			end
			status, line = socket:receive_buf("\r\n", false)
		end
	end
	socket:send("QUIT\r\n")
	status, line = socket:receive_buf("\r\n", false)
	socket:close()
	if capstr ~= "" then
		return capstr
	else
		return "server doesn't support CAPA"
	end
end