local shortport = require "shortport"
local socks = require "socks"
local table = require "table"

description = [[
Determines the supported authentication mechanisms of a remote SOCKS
proxy server.  Starting with SOCKS version 5 socks servers may support
authentication.  The script checks for the following authentication
types:
  0 - No authentication
  1 - GSSAPI
  2 - Username and password
]]

---
-- @usage
-- nmap -p 1080 <ip> --script socks-auth-info
--
-- @output
-- PORT     STATE SERVICE
-- 1080/tcp open  socks
-- | socks-auth-info:
-- |   No authentication
-- |_  Username and password
--
-- @xmloutput
-- <table>
--   <elem key="method">0</elem>
--   <elem key="name">No authentication</elem>
-- </table>
-- <table>
--   <elem key="method">2</elem>
--   <elem key="name">Username and password</elem>
-- </table>

author = "Patrik Karlsson"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
categories = {"discovery", "safe", "default"}

portrule = shortport.port_or_service({1080, 9050}, {"socks", "socks5", "tor-socks"})

action = function(host, port)

  local helper = socks.Helper:new(host, port)
  local auth_methods = {}

  -- iterate over all authentication methods as the server only responds with
  -- a single supported one if we send a list.
  local mt = { __tostring = function(t) return t.name end }
  for _, method in pairs(socks.AuthMethod) do
    local status, response = helper:connect( method )
    if ( status ) then
      local out = {
        method = response.method,
        name = helper:authNameByNumber(response.method)
      }
      setmetatable(out, mt)
      table.insert(auth_methods, out)
    end
  end

  helper:close()
  if ( 0 == #auth_methods ) then return end
  return auth_methods
end