net/adns.lua

-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

-- 

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local server = require "net.server";

local dns = require "net.dns";

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

local t_insert, t_remove = table.insert, table.remove;

local coroutine, tostring, pcall = coroutine, tostring, pcall;

local function dummy_send(sock, data, i, j) return (j-i)+1; end

module "adns"

function lookup(handler, qname, qtype, qclass)

	return coroutine.wrap(function (peek)

				if peek then

					log("debug", "Records for %s already cached, using those...", qname);

					handler(peek);

					return;

				end

				log("debug", "Records for %s not in cache, sending query (%s)...", qname, tostring(coroutine.running()));

				local ok, err = dns.query(qname, qtype, qclass);

				if ok then

					coroutine.yield({ qclass or "IN", qtype or "A", qname, coroutine.running()}); -- Wait for reply

					log("debug", "Reply for %s (%s)", qname, tostring(coroutine.running()));

				end

				if ok then

					ok, err = pcall(handler, dns.peek(qname, qtype, qclass));

				else

					log("error", "Error sending DNS query: %s", err);

					ok, err = pcall(handler, nil, err);

				end

				if not ok then

					log("error", "Error in DNS response handler: %s", tostring(err));

				end

			end)(dns.peek(qname, qtype, qclass));

end

function cancel(handle, call_handler, reason)

	log("warn", "Cancelling DNS lookup for %s", tostring(handle[3]));

	dns.cancel(handle[1], handle[2], handle[3], handle[4], call_handler);

end

function new_async_socket(sock, resolver)

	local peername = "<unknown>";

	local listener = {};

	local handler = {};

	function listener.onincoming(conn, data)

		if data then

			dns.feed(handler, data);

		end

	end

	function listener.ondisconnect(conn, err)

		if err then

			log("warn", "DNS socket for %s disconnected: %s", peername, err);

			local servers = resolver.server;

			if resolver.socketset[conn] == resolver.best_server and resolver.best_server == #servers then

				log("error", "Exhausted all %d configured DNS servers, next lookup will try %s again", #servers, servers[1]);

			end

			resolver:servfail(conn); -- Let the magic commence

		end

	end

	handler = server.wrapclient(sock, "dns", 53, listener);

	if not handler then

		log("warn", "handler is nil");

	end

	handler.settimeout = function () end

	handler.setsockname = function (_, ...) return sock:setsockname(...); end

	handler.setpeername = function (_, ...) peername = (...); local ret = sock:setpeername(...); _:set_send(dummy_send); return ret; end

	handler.connect = function (_, ...) return sock:connect(...) end

	--handler.send = function (_, data) _:write(data);  return _.sendbuffer and _.sendbuffer(); end

	handler.send = function (_, data) return sock:send(data); end

	return handler;

end

dns.socket_wrapper_set(new_async_socket);

return _M;