-- libunbound based net.adns replacement for Prosody IM

-- Copyright (C) 2012-2015 Kim Alvefur

-- Copyright (C) 2012 Waqas Hussain

--

-- This file is MIT licensed.

local setmetatable = setmetatable;

local table = table;

local t_concat = table.concat;

local t_insert = table.insert;

local s_byte = string.byte;

local s_format = string.format;

local s_sub = string.sub;

local iana_data = require "util.dnsregistry";

local tohex = require "util.hex".encode;

local inet_ntop = require "util.net".ntop;

-- Simplified versions of Waqas DNS parsers

-- Only the per RR parsers are needed and only feed a single RR

local parsers = {};

-- No support for pointers, but libunbound appears to take care of that.

local function readDnsName(packet, pos)

	if s_byte(packet, pos) == 0 then return ".", pos+1; end

	local pack_len, r, len = #packet, {};

	pos = pos or 1;

	repeat

		len = s_byte(packet, pos) or 0;

		t_insert(r, s_sub(packet, pos + 1, pos + len));

		pos = pos + len + 1;

	until len == 0 or pos >= pack_len;

	return t_concat(r, "."), pos;

end

-- These are just simple names.

parsers.CNAME = readDnsName;

parsers.NS = readDnsName

parsers.PTR = readDnsName;

local soa_mt = {

	__tostring = function(rr)

		return s_format("%s %s %d %d %d %d %d", rr.mname, rr.rname, rr.serial, rr.refresh, rr.retry, rr.expire, rr.minimum);

	end;

};

function parsers.SOA(packet)

	local mname, rname, offset;

	mname, offset = readDnsName(packet, 1);

	rname, offset = readDnsName(packet, offset);

	-- Extract all the bytes of these fields in one call

	local

		s1, s2, s3, s4, -- serial

		r1, r2, r3, r4, -- refresh

		t1, t2, t3, t4, -- retry

		e1, e2, e3, e4, -- expire

		m1, m2, m3, m4  -- minimum

			= s_byte(packet, offset, offset + 19);

	return setmetatable({

		mname = mname;

		rname = rname;

		serial  = s1*0x1000000 + s2*0x10000 + s3*0x100 + s4;

		refresh = r1*0x1000000 + r2*0x10000 + r3*0x100 + r4;