local mysql = require "mysql"
local nmap = require "nmap"
local shortport = require "shortport"
local stdnse = require "stdnse"

local openssl = stdnse.silent_require "openssl"

description = [[
Attempts to list all users on a MySQL server.
]]

---
-- @args mysqluser The username to use for authentication. If unset it
-- attempts to use credentials found by <code>mysql-brute</code> or
-- <code>mysql-empty-password</code>.
-- @args mysqlpass The password to use for authentication. If unset it
-- attempts to use credentials found by <code>mysql-brute</code> or
-- <code>mysql-empty-password</code>.
--
-- @output
-- 3306/tcp open  mysql
-- | mysql-users:
-- |   test
-- |   root
-- |   test2
-- |   album
-- |   debian-sys-maint
-- |   horde
-- |   mediatomb
-- |_  squeezecenter


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


dependencies = {"mysql-brute", "mysql-empty-password"}

-- Version 0.1
-- Created 01/23/2010 - v0.1 - created by Patrik Karlsson <patrik@cqure.net>

portrule = shortport.port_or_service(3306, "mysql")

action = function( host, port )

  local socket = nmap.new_socket()
  local catch = function() socket:close() end
  local try = nmap.new_try(catch)
  local result, response = {}, nil
  local users = {}
  local nmap_args = nmap.registry.args
  local status, rows

  -- set a reasonable timeout value
  socket:set_timeout(5000)

  -- first, let's see if the script has any credentials as arguments?
  if nmap_args.mysqluser then
    users[nmap_args.mysqluser] = nmap_args.mysqlpass or ""
  -- next, let's see if mysql-brute or mysql-empty-password brought us anything
  elseif nmap.registry.mysqlusers then
    -- do we have root credentials?
    if nmap.registry.mysqlusers['root'] then
      users['root'] = nmap.registry.mysqlusers['root']
    else
      -- we didn't have root, so let's make sure we loop over them all
      users = nmap.registry.mysqlusers
    end
  -- last, no dice, we don't have any credentials at all
  else
    stdnse.debug1("No credentials supplied, aborting ...")
    return
  end

  --
  -- Iterates over credentials, breaks once it successfully receives results
  --
  for username, password in pairs(users) do

    try( socket:connect(host, port) )

    response = try( mysql.receiveGreeting( socket ) )
    status, response = mysql.loginRequest( socket, { authversion = "post41", charset = response.charset }, username, password, response.salt )

    if status and response.errorcode == 0 then
      status, rows = mysql.sqlQuery( socket, "SELECT DISTINCT user FROM mysql.user" )
      if status then
        result = mysql.formatResultset(rows, { noheaders = true })
      end
    end
    socket:close()
  end

  return stdnse.format_output(true, result)

end