net/adns.lua

-- Prosody IM
-- Copyright (C) 2008-2009 Matthew Wild
-- Copyright (C) 2008-2009 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;

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()));
				dns.query(qname, qtype, qclass);
				coroutine.yield({ qclass or "IN", qtype or "A", qname, coroutine.running()}); -- Wait for reply
				log("debug", "Reply for %s (%s)", qname, tostring(coroutine.running()));
				local ok, err = pcall(handler, dns.peek(qname, qtype, qclass));
				if not ok then
					log("debug", "Error in DNS response handler: %s", tostring(err));
				end
			end)(dns.peek(qname, qtype, qclass));
end

function cancel(handle, call_handler)
	log("warn", "Cancelling DNS lookup for %s", tostring(handle[3]));
	dns.cancel(handle);
	if call_handler then
		coroutine.resume(handle[4]);
	end
end

function new_async_socket(sock, resolver)
	local newconn, peername = {}, "<unknown>";
	local listener = {};
	function listener.incoming(conn, data)
		dns.feed(sock, data);
	end
	function listener.disconnect(conn, err)
		log("warn", "DNS socket for %s disconnected: %s", peername, err);
		local servers = resolver.server;
		if resolver.socketset[newconn.handler] == 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
	newconn.handler, newconn._socket = server.wrapclient(sock, "dns", 53, listener);
	if not newconn.handler then
		log("warn", "handler is nil");
	end
	if not newconn._socket then
		log("warn", "socket is nil");
	end
	newconn.handler.settimeout = function () end
	newconn.handler.setsockname = function (_, ...) return sock:setsockname(...); end
	newconn.handler.setpeername = function (_, ...) peername = (...); local ret = sock:setpeername(...); _.setsend(sock.send); return ret; end
	newconn.handler.connect = function (_, ...) return sock:connect(...) end	
	newconn.handler.send = function (_, data) _.write(data); return _.sendbuffer(); end	
	return newconn.handler;
end

dns:socket_wrapper_set(new_async_socket);

return _M;