local dns = require "dns"
local nmap = require "nmap"
local shortport = require "shortport"
local stdnse = require "stdnse"
local table = require "table"

description = [[
Attempts to perform a dynamic DNS update without authentication.

Either the <code>test</code> or both the <code>hostname</code> and
<code>ip</code> script arguments are required. Note that the <code>test</code>
function will probably fail due to using a static zone name that is not the
zone configured on your target.
]]

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

---
-- @usage
-- nmap -sU -p 53 --script=dns-update --script-args=dns-update.hostname=foo.example.com,dns-update.ip=192.0.2.1 <target>
--
-- @output
-- PORT   STATE SERVICE
-- 53/udp open  domain
-- | dns-update:
-- |   Successfully added the record "nmap-test.cqure.net"
-- |_  Successfully deleted the record "nmap-test.cqure.net"
--
-- @args dns-update.hostname The name of the host to add to the zone
-- @args dns-update.ip The ip address of the host to add to the zone
-- @args dns-update.test Add and remove 4 records to determine if the target is vulnerable.
--
-- @xmloutput
-- <elem>Successfully added the record "nmap-test.cqure.net"</elem>
-- <elem>Failed to delete the record "nmap-test.cqure.net"</elem>

--
-- Examples
--
-- Adding different types of records to a server
-- * dns.update( "www.cqure.net", { host=host, port=port, dtype="A", data="10.10.10.10" } )
-- * dns.update( "alias.cqure.net", { host=host, port=port, dtype="CNAME", data="www.cqure.net" } )
-- * dns.update( "cqure.net", { host=host, port=port, dtype="MX", data={ pref=10, mx="mail.cqure.net"} })
-- * dns.update( "_ldap._tcp.cqure.net", { host=host, port=port, dtype="SRV", data={ prio=0, weight=100, port=389, target="ldap.cqure.net" } } )
--
-- Removing the above records by setting an empty data and a ttl of zero
-- * dns.update( "www.cqure.net", { host=host, port=port, dtype="A", data="", ttl=0 } )
-- * dns.update( "alias.cqure.net", { host=host, port=port, dtype="CNAME", data="", ttl=0 } )
-- * dns.update( "cqure.net", { host=host, port=port, dtype="MX", data="", ttl=0 } )
-- * dns.update( "_ldap._tcp.cqure.net", { host=host, port=port, dtype="SRV", data="", ttl=0 } )
--

-- Version 0.2

-- Created 01/09/2011 - v0.1 - created by Patrik Karlsson <patrik@cqure.net>
-- Revised 01/10/2011 - v0.2 - added test function <patrik@cqure.net>


portrule = shortport.port_or_service( 53, "dns", {"udp", "tcp"} )

local function test(host, port)

  local status, err = dns.update( "www.cqure.net", { host=host, port=port, dtype="A", data="10.10.10.10" } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end
  status, err = dns.update( "www2", { zone="cqure.net", host=host, port=port, dtype="A", data="10.10.10.10" } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end
  status, err = dns.update( "alias.cqure.net", { host=host, port=port, dtype="CNAME", data="www.cqure.net" } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end
  status, err = dns.update( "cqure.net", { host=host, port=port, dtype="MX", data={ pref=10, mx="mail.cqure.net"} })
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end
  status, err = dns.update( "_ldap._tcp.cqure.net", { host=host, port=port, dtype="SRV", data={ prio=0, weight=100, port=389, target="ldap.cqure.net" } } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end

  status, err = dns.update( "www.cqure.net", { host=host, port=port, dtype="A", data="", ttl=0 } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end
  status, err = dns.update( "www2.cqure.net", { host=host, port=port, dtype="A", data="", ttl=0 } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end
  status, err = dns.update( "alias.cqure.net", { host=host, port=port, dtype="CNAME", data="", ttl=0 } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end
  status, err = dns.update( "cqure.net", { host=host, port=port, dtype="MX", data="", ttl=0 } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end
  status, err = dns.update( "_ldap._tcp.cqure.net", { host=host, port=port, dtype="SRV", data="", ttl=0 } )
  if ( status ) then stdnse.debug1("SUCCESS") else stdnse.debug1("FAIL: " .. (err or "")) end

end

action = function(host, port)

  local t = stdnse.get_script_args('dns-update.test')
  local name, ip = stdnse.get_script_args('dns-update.hostname', 'dns-update.ip')

  if ( t ) then return test(host, port) end
  if ( not(name) or not(ip) ) then
    return stdnse.format_output(false, "Missing required script args: dns-update.hostname and dns-update.ip")
  end

  -- we really need an ip or name to continue
  -- we could attempt a random name, but we need to know at least the name of the zone
  local status, err = dns.update( name, { host=host, port=port, dtype="A", data=ip } )

  if ( status ) then
    local result = {}
    table.insert(result, ("Successfully added the record \"%s\""):format(name))
    local status = dns.update( name, { host=host, port=port, dtype="A", data="", ttl=0 } )
    if ( status ) then
      table.insert(result, ("Successfully deleted the record \"%s\""):format(name))
    else
      table.insert(result, ("Failed to delete the record \"%s\""):format(name))
    end
    nmap.set_port_state(host, port, "open")
    return result
  elseif ( err ) then
    return stdnse.format_output(false, err)
  end

end