local _G = require "_G"
local http = require "http"
local nmap = require "nmap"
local shortport = require "shortport"
local stdnse = require "stdnse"
local string = require "string"
local table = require "table"

description = [[
Enumerates directories used by popular web applications and servers.

This parses a fingerprint file that's formatted in a way that's compatible with the Nikto Web application
scanner. This script, however, takes it one step further by building in advanced pattern matching as well
as having the ability to identify specific versions of Web applications. 

Currently, the database can be found under Nmap's directory in the nselib/data folder. The file is called
http-fingerprints and has a long description of its functionality in the file header. 

Many of the finger prints were discovered by me (Ron Bowes), and a number of them are from the Yokoso
project, used with permission from Kevin Johnson (http://seclists.org/nmap-dev/2009/q3/0685.html). 

Initially, this script attempts to access two different random files in order to detect servers
that don't return a proper 404 Not Found status. In the event that they return 200 OK, the body
has any non-static-looking data removed (URI, time, etc), and saved. If the two random attempts
return different results, the script aborts (since a 200-looking 404 cannot be distinguished from
an actual 200). This will prevent most false positives. 

In addition, if the root folder returns a 301 Moved Permanently or 401 Authentication Required, 
this script will also abort. If the root folder has disappeared or requires authentication, there
is little hope of finding anything inside it. 

By default, only pages that return 200 OK or 401 Authentication Required are displayed. If the
<code>http-enum.displayall</code> script argument is set, however, then all results will be displayed (except
for 404 Not Found and the status code returned by the random files). Entries in the http-fingerprints
database can specify their own criteria for accepting a page as valid. 

]]

---
-- @args http-enum.basepath         The base path to prepend to each request. Leading/trailing slashes are ignored. 
-- @args http-enum.displayall       Set this argument to display all status codes that may indicate a valid page, not
--                                  just 200 OK and 401 Authentication Required pages. Although this is more likely
--                                  to find certain hidden folders, it also generates far more false positives. 
-- @args http-enum.fingerprintfile  Specify a different file to read fingerprints from. 
-- @args http-enum.category         Set to a category (as defined in the fingerprints file). Some options are 'attacks',
--                                  'database', 'general', 'microsoft', 'printer', etc.
--
-- @output
-- Interesting ports on test.skullsecurity.org (208.81.2.52):
-- PORT   STATE SERVICE REASON
-- 80/tcp open  http    syn-ack
-- |  http-enum:  
-- |  |  /icons/: Icons and images
-- |  |  /images/: Icons and images
-- |  |  /robots.txt: Robots file
-- |  |  /sw/auth/login.aspx: Citrix WebTop
-- |  |  /images/outlook.jpg: Outlook Web Access
-- |  |  /nfservlets/servlet/SPSRouterServlet/: netForensics
-- |_ |_ /nfservlets/servlet/SPSRouterServlet/: netForensics

author = "Ron Bowes, Andrew Orr, Rob Nicholls"

license = "Same as Nmap--See http://nmap.org/book/man-legal.html"

categories = {"discovery", "intrusive", "vuln"}


portrule = shortport.http

-- TODO
-- o Automatically convert HEAD -> GET if the server doesn't support HEAD
-- o Add variables for common extensions, common CGI extensions, etc that expand the probes

-- File extensions (TODO: Implement this)
local cgi_ext = { 'php', 'asp', 'aspx', 'jsp', 'pl', 'cgi' }

local common_ext = { 'php', 'asp', 'aspx', 'jsp', 'pl', 'cgi', 'css', 'js', 'htm', 'html' }

---Convert the filename to backup variations. These can be valuable for a number of reasons. 
-- First, because they may not have the same access restrictions as the main version (file.php 
-- may run as a script, but file.php.bak or file.php~ might not). And second, the old versions
-- might contain old vulnerablities
--
-- At the time of the writing, these were all decided by me (Ron Bowes). 
local function get_variations(filename)
	local variations = {}

	if(filename == nil or filename == "" or filename == "/") then
		return {}
	end

	local is_directory = (string.sub(filename, #filename, #filename) == "/")
	if(is_directory) then
		filename = string.sub(filename, 1, #filename - 1)
	end

	-- Try some extensions
	table.insert(variations, filename .. ".bak")
	table.insert(variations, filename .. ".1")
	table.insert(variations, filename .. ".tmp")

	-- Strip off the extension, if it has one, and try it all again. 
	-- For now, just look for three-character extensions. 
	if(string.sub(filename, #filename - 3, #filename - 3) == '.') then
		local bare = string.sub(filename, 1, #filename - 4)
		local extension = string.sub(filename, #filename - 3)

		table.insert(variations, bare .. ".bak")
		table.insert(variations, bare .. ".1")
		table.insert(variations, bare .. ".tmp")
		table.insert(variations, bare .. "_1" .. extension)
		table.insert(variations, bare .. "2" .. extension)
	end


	-- Some Windowsy things
	local onlyname = string.sub(filename, 2)
	-- If the name contains a '/', forget it
	if(string.find(onlyname, "/") == nil) then
		table.insert(variations, "/Copy of " .. onlyname)
		table.insert(variations, "/Copy (2) of " .. onlyname)
		table.insert(variations, "/Copy of Copy of " .. onlyname)

		-- Word/Excel/etc replace the first two characters with '~$', it seems
		table.insert(variations, "/~$" .. string.sub(filename, 4))
	end

	-- Some editors add a '~'
	table.insert(variations, filename .. "~")

	-- Try some directories
	table.insert(variations, "/bak" .. filename)
	table.insert(variations, "/backup" .. filename)
	table.insert(variations, "/backups" .. filename)
	table.insert(variations, "/beta" .. filename)
	table.insert(variations, "/test" .. filename)

	-- If it's a directory, add a '/' after every entry
	if(is_directory) then
		for i, v in ipairs(variations) do
			variations[i] = v .. "/"
		end
	end

	-- Some compressed formats (we don't want a trailing '/' on these, so they go after the loop)
	table.insert(variations, filename .. ".zip")
	table.insert(variations, filename .. ".tar")
	table.insert(variations, filename .. ".tar.gz")
	table.insert(variations, filename .. ".tgz")
	table.insert(variations, filename .. ".tar.bz2")



	return variations
end

---Get the list of fingerprints from files. The files are defined in <code>fingerprint_files</code>. If category
-- is non-nil, only choose scripts that are in that category.
--
--@return An array of entries, each of which have a <code>checkdir</code> field, and possibly a <code>checkdesc</code>. 
local function get_fingerprints(fingerprint_file, category)
	local entries  = {}
	local i
	local total_count = 0 -- Used for 'limit'

	-- Check if we've already read the file
	-- There might be a race condition here, where multiple scripts will read the file and set this variable, but the impact
	-- of that would be minimal (and definitely isn't security)
	if(nmap.registry.http_fingerprints ~= nil) then
		stdnse.print_debug(1, "http-enum: Using cached HTTP fingerprints")
		return nmap.registry.http_fingerprints
	end

	-- Try and find the file; if it isn't in Nmap's directories, take it as a direct path
	local filename_full = nmap.fetchfile('nselib/data/' .. fingerprint_file)
	if(not(filename_full)) then
		filename_full = fingerprint_file
	end

	stdnse.print_debug("http-enum: Loading fingerprint database: %s", filename_full)
	local env = setmetatable({fingerprints = {}}, {__index = _G})
	local file = loadfile(filename_full, "t", env)
	if(not(file)) then
		stdnse.print_debug("http-enum: Couldn't load configuration file: %s", filename_full)
		return false, "Couldn't load fingerprint file: " .. filename_full
	end

	file()

	local fingerprints = env.fingerprints

	-- Sanity check our file to ensure that all the fields were good. If any are bad, we 
	-- stop and don't load the file. 
	for i, fingerprint in pairs(fingerprints) do
		-- Make sure we have a valid index
		if(type(i) ~= 'number') then
			return false, "The 'fingerprints' table is an array, not a table; all indexes should be numeric"
		end

		-- Make sure they have either a string or a table of probes
		if(not(fingerprint.probes) or
			(type(fingerprint.probes) ~= 'table' and type(fingerprint.probes) ~= 'string') or
			(type(fingerprint.probes) == 'table' and #fingerprint.probes == 0)) then
			return false, "Invalid path found for fingerprint " .. i
		end

		-- Make sure fingerprint.path is a table
		if(type(fingerprint.probes) == 'string') then
			fingerprint.probes = {fingerprint.probes}
		end

		-- Make sure the elements in the probes array are strings or arrays
		for i, probe in pairs(fingerprint.probes) do
			-- Make sure we have a valid index
			if(type(i) ~= 'number') then
				return false, "The 'probes' table is an array, not a table; all indexes should be numeric"
			end

			-- Convert the probe to a table if it's a string
			if(type(probe) == 'string') then
				fingerprint.probes[i] = {path=fingerprint.probes[i]}
				probe = fingerprint.probes[i]
			end

			-- Make sure the probes table has a 'path'
			if(not(probe['path'])) then
				return false, "The 'probes' table requires each element to have a 'path'."
			end

			-- If they didn't set a method, set it to 'GET'
			if(not(probe['method'])) then
				probe['method'] = 'GET'
			end

			-- Make sure the method's a string
			if(type(probe['method']) ~= 'string') then
				return false, "The 'method' in the probes file has to be a string"
			end
		end

		-- Ensure that matches is an array
		if(type(fingerprint.matches) ~= 'table') then
			return false, "'matches' field has to be a table"
		end

		-- Loop through the matches
		for i, match in pairs(fingerprint.matches) do
			-- Make sure we have a valid index
			if(type(i) ~= 'number') then
				return false, "The 'matches' table is an array, not a table; all indexes should be numeric"
			end

			-- Check that every element in the table is an array
			if(type(match) ~= 'table') then
				return false, "Every element of 'matches' field has to be a table"
			end

			-- Check the output field
			if(match['output'] == nil or type(match['output']) ~= 'string') then
				return false, "The 'output' field in 'matches' has to be present and a string"
			end

			-- Check the 'match' and 'dontmatch' fields, if present
			if((match['match'] and type(match['match']) ~= 'string') or (match['dontmatch'] and type(match['dontmatch']) ~= 'string')) then
				return false, "The 'match' and 'dontmatch' fields in 'matches' have to be strings, if they exist"
			end

			-- Change blank 'match' strings to '.*' so they match everything
			if(not(match['match']) or match['match'] == '') then
				match['match'] = '(.*)'
			end
		end

		-- Make sure the severity is an integer between 1 and 4. Default it to 1. 
		if(fingerprint.severity and (type(fingerprint.severity) ~= 'number' or fingerprint.severity < 1 or fingerprint.severity > 4)) then
			return false, "The 'severity' field has to be an integer between 1 and 4"
		else
			fingerprint.severity = 1
		end

		-- Make sure ignore_404 is a boolean. Default it to false. 
		if(fingerprint.ignore_404 and type(fingerprint.ignore_404) ~= 'boolean') then
			return false, "The 'ignore_404' field has to be a boolean"
		else
			fingerprint.ignore_404 = false
		end
	end

	-- Make sure we have some fingerprints fingerprints
	if(#fingerprints == 0) then
		return false, "No fingerprints were loaded"
	end

	-- If the user wanted to filter by category, do it
	if(category) then
		local filtered_fingerprints = {}
		for _, fingerprint in pairs(fingerprints) do
			if(fingerprint.category == category) then
				table.insert(filtered_fingerprints, fingerprint)
			end
		end

		fingerprints = filtered_fingerprints

		-- Make sure we still have fingerprints after the category filter
		if(#fingerprints == 0) then
			return false, "No fingerprints matched the given category (" .. category .. ")"
		end
	end


--	-- If the user wants to try variations, add them
--	if(try_variations) then
--		-- Get a list of all variations for this directory
--		local variations = get_variations(entry['checkdir'])
--
--		-- Make a copy of the entry for each of them
--		for _, variation in ipairs(variations) do
--			new_entry = {}
--			for k, v in pairs(entry) do
--				new_entry[k] = v
--			end
--			new_entry['checkdesc'] = new_entry['checkdesc'] .. " (variation)"
--			new_entry['checkdir'] = variation
--			table.insert(entries, new_entry)
--			count = count + 1
--		end
--	end

	-- Cache the fingerprints for other scripts, so we aren't reading the files every time
--	nmap.registry.http_fingerprints = fingerprints

	return true, fingerprints
end

action = function(host, port)
	local response = {}

	-- Read the script-args, keeping the old ones for reverse compatibility
	local basepath         = stdnse.get_script_args({'http-enum.basepath',        'path'})         or '/'
	local displayall       = stdnse.get_script_args({'http-enum.displayall',      'displayall'})   or false
	local fingerprint_file = stdnse.get_script_args({'http-enum.fingerprintfile', 'fingerprints'}) or 'http-fingerprints.lua'
	local category         = stdnse.get_script_args('http-enum.category')
--	local try_variations   = stdnse.get_script_args({'http-enum.tryvariations',   'variations'})   or false
--	local limit            = tonumber(stdnse.get_script_args({'http-enum.limit', 'limit'})) or -1

	-- Add URLs from external files
	local status, fingerprints = get_fingerprints(fingerprint_file, category)
	if(not(status)) then
		return stdnse.format_output(false, fingerprints)
	end
	stdnse.print_debug(1, "http-enum: Loaded %d fingerprints", #fingerprints)

	-- Check what response we get for a 404
	local result, result_404, known_404 = http.identify_404(host, port)
	if(result == false) then
		return stdnse.format_output(false, result_404)
	end

	-- Queue up the checks
	local all = {}

	-- Remove trailing slash, if it exists
	if(#basepath > 1 and string.sub(basepath, #basepath, #basepath) == '/') then
		basepath = string.sub(basepath, 1, #basepath - 1)
	end

	-- Add a leading slash, if it doesn't exist
	if(#basepath <= 1) then
		basepath = ''
	else
		if(string.sub(basepath, 1, 1) ~= '/') then
			basepath = '/' .. basepath
		end
	end
  
  local results_nopipeline = {}
	-- Loop through the fingerprints
	stdnse.print_debug(1, "http-enum: Searching for entries under path '%s' (change with 'http-enum.basepath' argument)", basepath)
	for i = 1, #fingerprints, 1 do
		-- Add each path. The order very much matters here. 
		for j = 1, #fingerprints[i].probes, 1 do
      if fingerprints[i].probes[j].nopipeline then
        local res = http.generic_request(host, port, fingerprints[i].probes[j].method or 'GET', basepath .. fingerprints[i].probes[j].path, nil)
        if res.status then
          table.insert(results_nopipeline, res)
        else
          table.insert(results_nopipeline, false)
        end
      else
        all = http.pipeline_add(basepath .. fingerprints[i].probes[j].path, nil, all, fingerprints[i].probes[j].method or 'GET')
      end
    end
	end

	-- Perform all the requests. 
	local results = http.pipeline_go(host, port, all, nil)

	-- Check for http.pipeline error
	if(results == nil) then
		stdnse.print_debug(1, "http-enum: http.pipeline_go encountered an error")
		return stdnse.format_output(false, "http.pipeline_go encountered an error")
	end

	-- Loop through the fingerprints. Note that for each fingerprint, we may have multiple results
	local j = 1
  local j_nopipeline = 1
	for i, fingerprint in ipairs(fingerprints) do

		-- Loop through the paths for each fingerprint in the same order we did the requests. Each of these will
		-- have one result, so increment the result value at each iteration
		for _, probe in ipairs(fingerprint.probes) do
      local result
      if probe.nopipeline then
        result = results_nopipeline[j_nopipeline]
        j_nopipeline = j_nopipeline + 1
      else
        result = results[j]
        j = j + 1
      end
			if(result) then
				local path = basepath .. probe['path']
				local good = true
				local output = nil
				-- Unless this check said to ignore 404 messages, check if we got a valid page back using a known 404 message. 
				if(fingerprint.ignore_404 ~= true and not(http.page_exists(result, result_404, known_404, path, displayall))) then
					good = false
				else
					-- Loop through our matches table and see if anything matches our result
					for _, match in ipairs(fingerprint.matches) do
						if(match.match) then
							local result, matches = http.response_contains(result, match.match)
							if(result) then
								output = match.output
								good = true
								for k, value in ipairs(matches) do
									output = string.gsub(output, '\\' .. k, matches[k])
									end
							end
						else
							output = match.output
						end

						-- If nothing matched, turn off the match
						if(not(output)) then
							good = false
						end

						-- If we match the 'dontmatch' line, we're not getting a match
						if(match.dontmatch and match.dontmatch ~= '' and http.response_contains(result, match.dontmatch)) then
							output = nil
							good = false
						end

						-- Break the loop if we found it
						if(output) then
							break
						end
					end
				end

				if(good) then
					-- Save the path in the registry
					http.save_path(stdnse.get_hostname(host), port.number, path, result.status)

					-- Add the path to the output
					output = string.format("%s: %s", path, output)

					-- Build the status code, if it isn't a 200
					if(result.status ~= 200) then
						output = output .. " (" .. http.get_status_string(result) .. ")"
					end

					stdnse.print_debug(1, "Found a valid page! %s", output)

					table.insert(response, output)	
				end
			end
		end
	end

	return stdnse.format_output(true, response)
end
