-- libunbound based net.adns replacement for Prosody IM

-- Copyright (C) 2013-2015 Kim Alvefur

--

-- This file is MIT licensed.

--

-- luacheck: ignore prosody

local setmetatable = setmetatable;

local tostring = tostring;

local t_concat = table.concat;

local s_format = string.format;

local s_lower = string.lower;

local s_upper = string.upper;

local noop = function() end;

local zero = function() return 0 end;

local truop = function() return true; end;

local log = require "util.logger".init("unbound");

local net_server = require "net.server";

local libunbound = require"lunbound";

local have_promise, promise = pcall(require, "util.promise");

local gettime = require"socket".gettime;

local dns_utils = require"util.dns";

local classes, types, errors = dns_utils.classes, dns_utils.types, dns_utils.errors;

local parsers = dns_utils.parsers;

local function add_defaults(conf)

	if conf then

		for option, default in pairs(libunbound.config) do

			if conf[option] == nil then

				conf[option] = default;

			end

		end

	end

	return conf;

end

local unbound_config;

if prosody then

	local config = require"core.configmanager";

	unbound_config = add_defaults(config.get("*", "unbound"));

	prosody.events.add_handler("config-reloaded", function()

		unbound_config = add_defaults(config.get("*", "unbound"));

	end);

end

-- Note: libunbound will default to using root hints if resolvconf is unset

local function connect_server(unbound, server)

	if server.watchfd then

		return server.watchfd(unbound, function ()

			unbound:process()

		end);

	elseif server.event and server.addevent then

		local EV_READ = server.event.EV_READ;

		local function event_callback()

			unbound:process();

			return EV_READ;

		end

		return server.addevent(unbound:getfd(), EV_READ, event_callback)

	elseif server.wrapclient then

		local conn = {

			getfd = function()

				return unbound:getfd();

			end,

			send = zero,

			receive = noop,

			settimeout = noop,

			close = truop,

		}

		local function process()

			unbound:process();

		end

		local listener = {

			onincoming = process,

			onconnect = noop,

			ondisconnect = noop,

			onreadtimeout = truop,

		};

		return server.wrapclient(conn, "dns", 0, listener, "*a" );

	end

end

local unbound = libunbound.new(unbound_config);

local server_conn = connect_server(unbound, net_server);

local answer_mt = {

	__tostring = function(self)

		if self._string then return self._string end

		local h = s_format("Status: %s", errors[self.status]);

		if self.secure then

			h = h .. ", Secure";

		elseif self.bogus then

			h = h .. s_format(", Bogus: %s", self.bogus);

		end

		local t = { h };

		for i = 1, #self do

			t[i+1]=self.qname.."\t"..classes[self.qclass].."\t"..types[self.qtype].."\t"..tostring(self[i]);

		end

		local _string = t_concat(t, "\n");

		self._string = _string;

		return _string;

	end;

};

local waiting_queries = {};

local function prep_answer(a)

	if not a then return end

	local status = errors[a.rcode];

	local qclass = classes[a.qclass];

	local qtype = types[a.qtype];

	a.status, a.class, a.type = status, qclass, qtype;

	local t = s_lower(qtype);

	local rr_mt = { __index = a, __tostring = function(self) return tostring(self[t]) end };

	local parser = parsers[qtype];

	for i = 1, #a do

		if a.bogus then

			-- Discard bogus data

			a[i] = nil;

		else

			a[i] = setmetatable({[t] = parser(a[i])}, rr_mt);

		end

	end

	return setmetatable(a, answer_mt);

end

local function lookup(callback, qname, qtype, qclass)

	qtype = qtype and s_upper(qtype) or "A";

	qclass = qclass and s_upper(qclass) or "IN";

	local ntype, nclass = types[qtype], classes[qclass];

	local startedat = gettime();

	local ret;

	local function callback_wrapper(a, err)

		local gotdataat = gettime();

		waiting_queries[ret] = nil;

		if a then

			prep_answer(a);

			log("debug", "Results for %s %s %s: %s (%s, %f sec)", qname, qclass, qtype, a.rcode == 0 and (#a .. " items") or a.status,

				a.secure and "Secure" or a.bogus or "Insecure", gotdataat - startedat); -- Insecure as in unsigned

		else

			log("error", "Results for %s %s %s: %s", qname, qclass, qtype, tostring(err));

		end

		local ok, cerr = pcall(callback, a, err);

		if not ok then log("error", "Error in callback: %s", cerr); end

	end

	log("debug", "Resolve %s %s %s", qname, qclass, qtype);

	local err;

	ret, err = unbound:resolve_async(callback_wrapper, qname, ntype, nclass);

	if ret then

		waiting_queries[ret] = callback;

	else

		log("warn", err);

	end

	return ret, err;

end

local function lookup_sync(qname, qtype, qclass)

	qtype = qtype and s_upper(qtype) or "A";

	qclass = qclass and s_upper(qclass) or "IN";

	local ntype, nclass = types[qtype], classes[qclass];

	local a, err = unbound:resolve(qname, ntype, nclass);

	if not a then return a, err; end

	return prep_answer(a);

end

local function cancel(id)

	local cb = waiting_queries[id];

	unbound:cancel(id);

	if cb then

		cb(nil, "canceled");

		waiting_queries[id] = nil;

	end

	return true;

end

-- Reinitiate libunbound context, drops cache

local function purge()

	for id in pairs(waiting_queries) do cancel(id); end

	if server_conn then server_conn:close(); end

	unbound = libunbound.new(unbound_config);

	server_conn = connect_server(unbound, net_server);

	return true;

end

local function not_implemented()

	error "not implemented";

end

-- Public API

local _M = {

	lookup = lookup;

	cancel = cancel;

	new_async_socket = not_implemented;

	dns = {

		lookup = lookup_sync;

		cancel = cancel;

		cache = noop;

		socket_wrapper_set = noop;

		settimeout = noop;

		query = noop;

		purge = purge;

		random = noop;

		peek = noop;

		types = types;

		classes = classes;

	};

};

local lookup_promise;

if have_promise then

	function lookup_promise(_, qname, qtype, qclass)

		return promise.new(function (resolve, reject)

			local function callback(answer, err)

				if err then

					return reject(err);

				else

					return resolve(answer);

				end

			end

			local ret, err = lookup(callback, qname, qtype, qclass)

			if not ret then reject(err); end

		end);

	end

end

local wrapper = {

	lookup = function (_, callback, qname, qtype, qclass)

		return lookup(callback, qname, qtype, qclass)

	end;

	lookup_promise = lookup_promise;

	_resolver = {

		settimeout = function () end;

		closeall = function () end;

	};

}

function _M.resolver() return wrapper; end

return _M;