aboutsummaryrefslogtreecommitdiffstats
path: root/net/server_epoll.lua
blob: 62db6c86d1c9613d3881afff2b47ae5162bfcf70 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
-- Prosody IM
-- Copyright (C) 2016-2018 Kim Alvefur
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--


local t_insert = table.insert;
local t_concat = table.concat;
local setmetatable = setmetatable;
local pcall = pcall;
local type = type;
local next = next;
local pairs = pairs;
local logger = require "util.logger";
local log = logger.init("server_epoll");
local socket = require "socket";
local luasec = require "ssl";
local gettime = require "util.time".now;
local indexedbheap = require "util.indexedbheap";
local createtable = require "util.table".create;
local inet = require "util.net";
local inet_pton = inet.pton;
local _SOCKETINVALID = socket._SOCKETINVALID or -1;
local new_id = require "util.id".medium;

local poller = require "util.poll"
local EEXIST = poller.EEXIST;
local ENOENT = poller.ENOENT;

local poll = assert(poller.new());

local _ENV = nil;
-- luacheck: std none

local default_config = { __index = {
	-- If a connection is silent for this long, close it unless onreadtimeout says not to
	read_timeout = 14 * 60;

	-- How long to wait for a socket to become writable after queuing data to send
	send_timeout = 180;

	-- How long to wait for a socket to become writable after creation
	connect_timeout = 20;

	-- Some number possibly influencing how many pending connections can be accepted
	tcp_backlog = 128;

	-- If accepting a new incoming connection fails, wait this long before trying again
	accept_retry_interval = 10;

	-- If there is still more data to read from LuaSocktes buffer, wait this long and read again
	read_retry_delay = 1e-06;

	-- Size of chunks to read from sockets
	read_size = 8192;

	-- Timeout used during between steps in TLS handshakes
	ssl_handshake_timeout = 60;

	-- Maximum and minimum amount of time to sleep waiting for events (adjusted for pending timers)
	max_wait = 86400;
	min_wait = 1e-06;

	-- EXPERIMENTAL
	-- Whether to kill connections in case of callback errors.
	fatal_errors = false;

	-- Attempt writes instantly
	opportunistic_writes = false;
}};
local cfg = default_config.__index;

local fds = createtable(10, 0); -- FD -> conn

-- Timer and scheduling --

local timers = indexedbheap.create();

local function noop() end
local function closetimer(t)
	t[1] = 0;
	t[2] = noop;
	timers:remove(t.id);
end

local function reschedule(t, time)
	t[1] = time;
	timers:reprioritize(t.id, time);
end

-- Add absolute timer
local function at(time, f)
	local timer = { time, f, close = closetimer, reschedule = reschedule, id = nil };
	timer.id = timers:insert(timer, time);
	return timer;
end

-- Add relative timer
local function addtimer(timeout, f)
	return at(gettime() + timeout, f);
end

-- Run callbacks of expired timers
-- Return time until next timeout
local function runtimers(next_delay, min_wait)
	-- Any timers at all?
	local now = gettime();
	local peek = timers:peek();
	while peek do

		if peek > now then
			next_delay = peek - now;
			break;
		end

		local _, timer, id = timers:pop();
		local ok, ret = pcall(timer[2], now);
		if ok and type(ret) == "number"  then
			local next_time = now+ret;
			timer[1] = next_time;
			timers:insert(timer, next_time);
		end

		peek = timers:peek();
	end
	if peek == nil then
		return next_delay;
	end

	if next_delay < min_wait then
		return min_wait;
	end
	return next_delay;
end

-- Socket handler interface

local interface = {};
local interface_mt = { __index = interface };

function interface_mt:__tostring()
	if self.sockname and self.peername then
		return ("FD %d (%s, %d, %s, %d)"):format(self:getfd(), self.peername, self.peerport, self.sockname, self.sockport);
	elseif self.sockname or self.peername then
		return ("FD %d (%s, %d)"):format(self:getfd(), self.sockname or self.peername, self.sockport or self.peerport);
	end
	return ("FD %d"):format(self:getfd());
end

interface.log = log;
function interface:debug(msg, ...) --luacheck: ignore 212/self
	self.log("debug", msg, ...);
end

function interface:error(msg, ...) --luacheck: ignore 212/self
	self.log("error", msg, ...);
end

-- Replace the listener and tell the old one
function interface:setlistener(listeners, data)
	self:on("detach");
	self.listeners = listeners;
	self:on("attach", data);
end

-- Call a listener callback
function interface:on(what, ...)
	if not self.listeners then
		self:debug("Interface is missing listener callbacks");
		return;
	end
	local listener = self.listeners["on"..what];
	if not listener then
		-- self:debug("Missing listener 'on%s'", what); -- uncomment for development and debugging
		return;
	end
	local ok, err = pcall(listener, self, ...);
	if not ok then
		if cfg.fatal_errors then
			self:debug("Closing due to error calling on%s: %s", what, err);
			self:destroy();
		else
			self:debug("Error calling on%s: %s", what, err);
		end
		return nil, err;
	end
	return err;
end

-- Allow this one to be overridden
function interface:onincoming(...)
	return self:on("incoming", ...);
end

-- Return the file descriptor number
function interface:getfd()
	if self.conn then
		return self.conn:getfd();
	end
	return _SOCKETINVALID;
end

function interface:server()
	return self._server or self;
end

-- Get IP address
function interface:ip()
	return self.peername or self.sockname;
end

-- Get a port number, doesn't matter which
function interface:port()
	return self.sockport or self.peerport;
end

-- Get local port number
function interface:clientport()
	return self.sockport;
end

-- Get remote port
function interface:serverport()
	if self.sockport then
		return self.sockport;
	elseif self._server then
		self._server:port();
	end
end

-- Return underlying socket
function interface:socket()
	return self.conn;
end

function interface:set_mode(new_mode)
	self.read_size = new_mode;
end

function interface:setoption(k, v)
	-- LuaSec doesn't expose setoption :(
	if self.conn.setoption then
		self.conn:setoption(k, v);
	end
end

-- Timeout for detecting dead or idle sockets
function interface:setreadtimeout(t)
	if t == false then
		if self._readtimeout then
			self._readtimeout:close();
			self._readtimeout = nil;
		end
		return
	end
	t = t or cfg.read_timeout;
	if self._readtimeout then
		self._readtimeout:reschedule(gettime() + t);
	else
		self._readtimeout = addtimer(t, function ()
			if self:on("readtimeout") then
				self:debug("Read timeout, handled");
				return cfg.read_timeout;
			else
				self:debug("Read timeout, fatal");
				self:on("disconnect", "read timeout");
				self:destroy();
			end
		end);
	end
end

-- Timeout for detecting dead sockets
function interface:setwritetimeout(t)
	if t == false then
		if self._writetimeout then
			self._writetimeout:close();
			self._writetimeout = nil;
		end
		return
	end
	t = t or cfg.send_timeout;
	if self._writetimeout then
		self._writetimeout:reschedule(gettime() + t);
	else
		self._writetimeout = addtimer(t, function ()
			self:debug("Write timeout");
			self:on("disconnect", "write timeout");
			self:destroy();
		end);
	end
end

function interface:add(r, w)
	local fd = self:getfd();
	if fd < 0 then
		return nil, "invalid fd";
	end
	if r == nil then r = self._wantread; end
	if w == nil then w = self._wantwrite; end
	local ok, err, errno = poll:add(fd, r, w);
	if not ok then
		if errno == EEXIST then
			self:debug("FD already registered in poller! (EEXIST)");
			return self:set(r, w); -- So try to change its flags
		end
		self:debug("Could not register in poller: %s(%d)", err, errno);
		return ok, err;
	end
	self._wantread, self._wantwrite = r, w;
	fds[fd] = self;
	self:debug("Registered in poller");
	return true;
end

function interface:set(r, w)
	local fd = self:getfd();
	if fd < 0 then
		return nil, "invalid fd";
	end
	if r == nil then r = self._wantread; end
	if w == nil then w = self._wantwrite; end
	local ok, err, errno = poll:set(fd, r, w);
	if not ok then
		self:debug("Could not update poller state: %s(%d)", err, errno);
		return ok, err;
	end
	self._wantread, self._wantwrite = r, w;
	return true;
end

function interface:del()
	local fd = self:getfd();
	if fd < 0 then
		return nil, "invalid fd";
	end
	if fds[fd] ~= self then
		return nil, "unregistered fd";
	end
	local ok, err, errno = poll:del(fd);
	if not ok and errno ~= ENOENT then
		self:debug("Could not unregister: %s(%d)", err, errno);
		return ok, err;
	end
	self._wantread, self._wantwrite = nil, nil;
	fds[fd] = nil;
	self:debug("Unregistered from poller");
	return true;
end

function interface:setflags(r, w)
	if not(self._wantread or self._wantwrite) then
		if not(r or w) then
			return true; -- no change
		end
		return self:add(r, w);
	end
	if not(r or w) then
		return self:del();
	end
	return self:set(r, w);
end

-- Called when socket is readable
function interface:onreadable()
	local data, err, partial = self.conn:receive(self.read_size or cfg.read_size);
	if data then
		self:onconnect();
		self:onincoming(data);
	else
		if err == "wantread" then
			self:set(true, nil);
			err = "timeout";
		elseif err == "wantwrite" then
			self:set(nil, true);
			err = "timeout";
		end
		if partial and partial ~= "" then
			self:onconnect();
			self:onincoming(partial, err);
		end
		if err ~= "timeout" then
			self:on("disconnect", err);
			self:destroy()
			return;
		end
	end
	if not self.conn then return; end
	if self._limit and (data or partial) then
		local cost = self._limit * #(data or partial);
		if cost > cfg.min_wait then
			self:setreadtimeout(false);
			self:pausefor(cost);
			return;
		end
	end
	if self._wantread and self.conn:dirty() then
		self:setreadtimeout(false);
		self:pausefor(cfg.read_retry_delay);
	else
		self:setreadtimeout();
	end
end

-- Called when socket is writable
function interface:onwritable()
	self:onconnect();
	if not self.conn then return; end -- could have been closed in onconnect
	local buffer = self.writebuffer;
	local data = t_concat(buffer);
	local ok, err, partial = self.conn:send(data);
	if ok then
		self:set(nil, false);
		for i = #buffer, 1, -1 do
			buffer[i] = nil;
		end
		self:setwritetimeout(false);
		self:ondrain(); -- Be aware of writes in ondrain
		return;
	elseif partial then
		buffer[1] = data:sub(partial+1);
		for i = #buffer, 2, -1 do
			buffer[i] = nil;
		end
		self:set(nil, true);
		self:setwritetimeout();
	end
	if err == "wantwrite" or err == "timeout" then
		self:set(nil, true);
	elseif err == "wantread" then
		self:set(true, nil);
	elseif err ~= "timeout" then
		self:on("disconnect", err);
		self:destroy();
	end
end

-- The write buffer has been successfully emptied
function interface:ondrain()
	return self:on("drain");
end

-- Add data to write buffer and set flag for wanting to write
function interface:write(data)
	local buffer = self.writebuffer;
	if buffer then
		t_insert(buffer, data);
	else
		self.writebuffer = { data };
	end
	if not self._write_lock then
		if cfg.opportunistic_writes then
			self:onwritable();
			return #data;
		end
		self:setwritetimeout();
		self:set(nil, true);
	end
	return #data;
end
interface.send = interface.write;

-- Close, possibly after writing is done
function interface:close()
	if self.writebuffer and self.writebuffer[1] then
		self:set(false, true); -- Flush final buffer contents
		self.write, self.send = noop, noop; -- No more writing
		self:debug("Close after writing");
		self.ondrain = interface.close;
	else
		self:debug("Closing now");
		self.write, self.send = noop, noop;
		self.close = noop;
		self:on("disconnect");
		self:destroy();
	end
end

function interface:destroy()
	self:del();
	self:setwritetimeout(false);
	self:setreadtimeout(false);
	self.onreadable = noop;
	self.onwritable = noop;
	self.destroy = noop;
	self.close = noop;
	self.on = noop;
	self.conn:close();
	self.conn = nil;
end

function interface:ssl()
	return self._tls;
end

function interface:starttls(tls_ctx)
	if tls_ctx then self.tls_ctx = tls_ctx; end
	self.starttls = false;
	if self.writebuffer and self.writebuffer[1] then
		self:debug("Start TLS after write");
		self.ondrain = interface.starttls;
		self:set(nil, true); -- make sure wantwrite is set
	else
		if self.ondrain == interface.starttls then
			self.ondrain = nil;
		end
		self.onwritable = interface.tlshandskake;
		self.onreadable = interface.tlshandskake;
		self:set(true, true);
		self:debug("Prepared to start TLS");
	end
end

function interface:tlshandskake()
	self:setwritetimeout(false);
	self:setreadtimeout(false);
	if not self._tls then
		self._tls = true;
		self:debug("Starting TLS now");
		self:del();
		local ok, conn, err = pcall(luasec.wrap, self.conn, self.tls_ctx);
		if not ok then
			conn, err = ok, conn;
			self:debug("Failed to initialize TLS: %s", err);
		end
		if not conn then
			self:on("disconnect", err);
			self:destroy();
			return conn, err;
		end
		conn:settimeout(0);
		self.conn = conn;
		if conn.sni then
			if self.servername then
				conn:sni(self.servername);
			elseif self._server and type(self._server.hosts) == "table" and next(self._server.hosts) ~= nil then
				conn:sni(self._server.hosts, true);
			end
		end
		self:on("starttls");
		self.ondrain = nil;
		self.onwritable = interface.tlshandskake;
		self.onreadable = interface.tlshandskake;
		return self:init();
	end
	local ok, err = self.conn:dohandshake();
	if ok then
		self:debug("TLS handshake complete");
		self.onwritable = nil;
		self.onreadable = nil;
		self:on("status", "ssl-handshake-complete");
		self:setwritetimeout();
		self:set(true, true);
	elseif err == "wantread" then
		self:debug("TLS handshake to wait until readable");
		self:set(true, false);
		self:setreadtimeout(cfg.ssl_handshake_timeout);
	elseif err == "wantwrite" then
		self:debug("TLS handshake to wait until writable");
		self:set(false, true);
		self:setwritetimeout(cfg.ssl_handshake_timeout);
	else
		self:debug("TLS handshake error: %s", err);
		self:on("disconnect", err);
		self:destroy();
	end
end

local function wrapsocket(client, server, read_size, listeners, tls_ctx, extra) -- luasocket object -> interface object
	client:settimeout(0);
	local conn_id = ("conn%s"):format(new_id());
	local conn = setmetatable({
		conn = client;
		_server = server;
		created = gettime();
		listeners = listeners;
		read_size = read_size or (server and server.read_size);
		writebuffer = {};
		tls_ctx = tls_ctx or (server and server.tls_ctx);
		tls_direct = server and server.tls_direct;
		id = conn_id;
		log = logger.init(conn_id);
		extra = extra;
	}, interface_mt);

	if extra then
		if extra.servername then
			conn.servername = extra.servername;
		end
	end

	conn:updatenames();
	return conn;
end

function interface:updatenames()
	local conn = self.conn;
	local ok, peername, peerport = pcall(conn.getpeername, conn);
	if ok then
		self.peername, self.peerport = peername, peerport;
	end
	local ok, sockname, sockport = pcall(conn.getsockname, conn);
	if ok then
		self.sockname, self.sockport = sockname, sockport;
	end
end

-- A server interface has new incoming connections waiting
-- This replaces the onreadable callback
function interface:onacceptable()
	local conn, err = self.conn:accept();
	if not conn then
		self:debug("Error accepting new client: %s, server will be paused for %ds", err, cfg.accept_retry_interval);
		self:pausefor(cfg.accept_retry_interval);
		return;
	end
	local client = wrapsocket(conn, self, nil, self.listeners);
	client:debug("New connection %s on server %s", client, self);
	client:init();
	if self.tls_direct then
		client:starttls(self.tls_ctx);
	else
		client:onconnect();
	end
end

-- Initialization
function interface:init()
	self:setwritetimeout(cfg.connect_timeout);
	return self:add(true, true);
end

function interface:pause()
	self:debug("Pause reading");
	return self:set(false);
end

function interface:resume()
	self:debug("Resume reading");
	return self:set(true);
end

-- Pause connection for some time
function interface:pausefor(t)
	self:debug("Pause for %fs", t);
	if self._pausefor then
		self._pausefor:close();
	end
	if t == false then return; end
	self:set(false);
	self._pausefor = addtimer(t, function ()
		self._pausefor = nil;
		self:set(true);
		if self.conn and self.conn:dirty() then
			self:onreadable();
		end
	end);
end

function interface:setlimit(Bps)
	if Bps > 0 then
		self._limit = 1/Bps;
	else
		self._limit = nil;
	end
end

function interface:pause_writes()
	if self._write_lock then
		return
	end
	self:debug("Pause writes");
	self._write_lock = true;
	self:setwritetimeout(false);
	self:set(nil, false);
end

function interface:resume_writes()
	if not self._write_lock then
		return
	end
	self:debug("Resume writes");
	self._write_lock = nil;
	if self.writebuffer[1] then
		self:setwritetimeout();
		self:set(nil, true);
	end
end

-- Connected!
function interface:onconnect()
	self:debug("Connected");
	self:updatenames();
	self.onconnect = noop;
	self:on("connect");
end

local function listen(addr, port, listeners, config)
	local conn, err = socket.bind(addr, port, cfg.tcp_backlog);
	if not conn then return conn, err; end
	conn:settimeout(0);
	local server = setmetatable({
		conn = conn;
		created = gettime();
		listeners = listeners;
		read_size = config and config.read_size;
		onreadable = interface.onacceptable;
		tls_ctx = config and config.tls_ctx;
		tls_direct = config and config.tls_direct;
		hosts = config and config.sni_hosts;
		sockname = addr;
		sockport = port;
		log = logger.init(("serv%s"):format(new_id()));
	}, interface_mt);
	server:debug("Server %s created", server);
	server:add(true, false);
	return server;
end

-- COMPAT
local function addserver(addr, port, listeners, read_size, tls_ctx)
	return listen(addr, port, listeners, {
		read_size = read_size;
		tls_ctx = tls_ctx;
		tls_direct = tls_ctx and true or false;
	});
end

-- COMPAT
local function wrapclient(conn, addr, port, listeners, read_size, tls_ctx, extra)
	local client = wrapsocket(conn, nil, read_size, listeners, tls_ctx, extra);
	if not client.peername then
		client.peername, client.peerport = addr, port;
	end
	local ok, err = client:init();
	if not ok then return ok, err; end
	if tls_ctx then
		client:starttls(tls_ctx);
	end
	return client;
end

-- New outgoing TCP connection
local function addclient(addr, port, listeners, read_size, tls_ctx, typ, extra)
	local create;
	if not typ then
		local n = inet_pton(addr);
		if not n then return nil, "invalid-ip"; end
		if #n == 16 then
			typ = "tcp6";
		else
			typ = "tcp4";
		end
	end
	if typ then
		create = socket[typ];
	end
	if type(create) ~= "function" then
		return nil, "invalid socket type";
	end
	local conn, err = create();
	if not conn then return conn, err; end
	local ok, err = conn:settimeout(0);
	if not ok then return ok, err; end
	local ok, err = conn:setpeername(addr, port);
	if not ok and err ~= "timeout" then return ok, err; end
	local client = wrapsocket(conn, nil, read_size, listeners, tls_ctx, extra)
	local ok, err = client:init();
	if not ok then return ok, err; end
	if tls_ctx then
		client:starttls(tls_ctx);
	end
	client:debug("Client %s created", client);
	return client, conn;
end

local function watchfd(fd, onreadable, onwritable)
	local conn = setmetatable({
		conn = fd;
		onreadable = onreadable;
		onwritable = onwritable;
		close = function (self)
			self:del();
		end
	}, interface_mt);
	if type(fd) == "number" then
		conn.getfd = function ()
			return fd;
		end;
		-- Otherwise it'll need to be something LuaSocket-compatible
	end
	conn.log = logger.init(("fdwatch%s"):format(new_id()));
	conn:add(onreadable, onwritable);
	return conn;
end;

-- Dump all data from one connection into another
local function link(from, to, read_size)
	from:debug("Linking to %s", to.id);
	function from:onincoming(data)
		self:pause();
		to:write(data);
	end
	function to:ondrain() -- luacheck: ignore 212/self
		from:resume();
	end
	from:set_mode(read_size);
	from:set(true, nil);
	to:set(nil, true);
end

-- COMPAT
-- net.adns calls this but then replaces :send so this can be a noop
function interface:set_send(new_send) -- luacheck: ignore 212
end

-- Close all connections and servers
local function closeall()
	for fd, conn in pairs(fds) do -- luacheck: ignore 213/fd
		conn:close();
	end
end

local quitting = nil;

-- Signal main loop about shutdown via above upvalue
local function setquitting(quit)
	if quit then
		quitting = "quitting";
		closeall();
	else
		quitting = nil;
	end
end

-- Main loop
local function loop(once)
	repeat
		local t = runtimers(cfg.max_wait, cfg.min_wait);
		local fd, r, w = poll:wait(t);
		if fd then
			local conn = fds[fd];
			if conn then
				if r then
					conn:onreadable();
				end
				if w then
					conn:onwritable();
				end
			else
				log("debug", "Removing unknown fd %d", fd);
				poll:del(fd);
			end
		elseif r ~= "timeout" and r ~= "signal" then
			log("debug", "epoll_wait error: %s[%d]", r, w);
		end
	until once or (quitting and next(fds) == nil);
	return quitting;
end

return {
	get_backend = function () return "epoll"; end;
	addserver = addserver;
	addclient = addclient;
	add_task = addtimer;
	listen = listen;
	at = at;
	loop = loop;
	closeall = closeall;
	setquitting = setquitting;
	wrapclient = wrapclient;
	watchfd = watchfd;
	link = link;
	set_config = function (newconfig)
		cfg = setmetatable(newconfig, default_config);
	end;

	-- libevent emulation
	event = { EV_READ = "r", EV_WRITE = "w", EV_READWRITE = "rw", EV_LEAVE = -1 };
	addevent = function (fd, mode, callback)
		log("warn", "Using deprecated libevent emulation, please update code to use watchfd API instead");
		local function onevent(self)
			local ret = self:callback();
			if ret == -1 then
				self:set(false, false);
			elseif ret then
				self:set(mode == "r" or mode == "rw", mode == "w" or mode == "rw");
			end
		end

		local conn = setmetatable({
			getfd = function () return fd; end;
			callback = callback;
			onreadable = onevent;
			onwritable = onevent;
			close = function (self)
				self:del();
				fds[fd] = nil;
			end;
		}, interface_mt);
		conn.log = logger.init(("fdwatch%d"):format(conn:getfd()));
		local ok, err = conn:add(mode == "r" or mode == "rw", mode == "w" or mode == "rw");
		if not ok then return ok, err; end
		return conn;
	end;
};