aboutsummaryrefslogtreecommitdiffstats
path: root/net/server_select.lua
blob: 4b156409e9598d6e365170abd1201f243d410090 (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
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
--
-- server.lua by blastbeat of the luadch project
-- Re-used here under the MIT/X Consortium License
--
-- Modifications (C) 2008-2010 Matthew Wild, Waqas Hussain
--

-- // wrapping luadch stuff // --

local use = function( what )
	return _G[ what ]
end

local log, table_concat = require ("util.logger").init("socket"), table.concat;
local out_put = function (...) return log("debug", table_concat{...}); end
local out_error = function (...) return log("warn", table_concat{...}); end

----------------------------------// DECLARATION //--

--// constants //--

local STAT_UNIT = 1 -- byte

--// lua functions //--

local type = use "type"
local pairs = use "pairs"
local ipairs = use "ipairs"
local tonumber = use "tonumber"
local tostring = use "tostring"

--// lua libs //--

local table = use "table"
local string = use "string"
local coroutine = use "coroutine"

--// lua lib methods //--

local math_min = math.min
local math_huge = math.huge
local table_concat = table.concat
local table_insert = table.insert
local string_sub = string.sub
local coroutine_wrap = coroutine.wrap
local coroutine_yield = coroutine.yield

--// extern libs //--

local has_luasec, luasec = pcall ( require , "ssl" )
local luasocket = use "socket" or require "socket"
local luasocket_gettime = luasocket.gettime
local inet = require "util.net";
local inet_pton = inet.pton;

--// extern lib methods //--

local ssl_wrap = ( has_luasec and luasec.wrap )
local socket_bind = luasocket.bind
local socket_select = luasocket.select

--// functions //--

local id
local loop
local stats
local idfalse
local closeall
local addsocket
local addserver
local listen
local addtimer
local getserver
local wrapserver
local getsettings
local closesocket
local removesocket
local removeserver
local wrapconnection
local changesettings

--// tables //--

local _server
local _readlist
local _timerlist
local _sendlist
local _socketlist
local _closelist
local _readtimes
local _writetimes
local _fullservers

--// simple data types //--

local _
local _readlistlen
local _sendlistlen
local _timerlistlen

local _sendtraffic
local _readtraffic

local _selecttimeout
local _tcpbacklog
local _accepretry

local _starttime
local _currenttime

local _maxsendlen
local _maxreadlen

local _checkinterval
local _sendtimeout
local _readtimeout

local _maxselectlen
local _maxfd

local _maxsslhandshake

----------------------------------// DEFINITION //--

_server = { } -- key = port, value = table; list of listening servers
_readlist = { } -- array with sockets to read from
_sendlist = { } -- arrary with sockets to write to
_timerlist = { } -- array of timer functions
_socketlist = { } -- key = socket, value = wrapped socket (handlers)
_readtimes = { } -- key = handler, value = timestamp of last data reading
_writetimes = { } -- key = handler, value = timestamp of last data writing/sending
_closelist = { } -- handlers to close
_fullservers = { } -- servers in a paused state while there are too many clients

_readlistlen = 0 -- length of readlist
_sendlistlen = 0 -- length of sendlist
_timerlistlen = 0 -- length of timerlist

_sendtraffic = 0 -- some stats
_readtraffic = 0

_selecttimeout = 1 -- timeout of socket.select
_tcpbacklog = 128 -- some kind of hint to the OS
_accepretry = 10 -- seconds to wait until the next attempt of a full server to accept

_maxsendlen = 51000 * 1024 -- max len of send buffer
_maxreadlen = 25000 * 1024 -- max len of read buffer

_checkinterval = 30 -- interval in secs to check idle clients
_sendtimeout = 60000 -- allowed send idle time in secs
_readtimeout = 14 * 60 -- allowed read idle time in secs

local is_windows = package.config:sub(1,1) == "\\" -- check the directory separator, to detemine whether this is Windows
_maxfd = (is_windows and math.huge) or luasocket._SETSIZE or 1024 -- max fd number, limit to 1024 by default to prevent glibc buffer overflow, but not on Windows
_maxselectlen = luasocket._SETSIZE or 1024 -- But this still applies on Windows

_maxsslhandshake = 30 -- max handshake round-trips

----------------------------------// PRIVATE //--

wrapserver = function( listeners, socket, ip, serverport, pattern, sslctx, ssldirect ) -- this function wraps a server -- FIXME Make sure FD < _maxfd

	if socket:getfd() >= _maxfd then
		out_error("server.lua: Disallowed FD number: "..socket:getfd())
		socket:close()
		return nil, "fd-too-large"
	end

	local connections = 0

	local dispatch, disconnect = listeners.onconnect, listeners.ondisconnect

	local accept = socket.accept

	--// public methods of the object //--

	local handler = { }

	handler.shutdown = function( ) end

	handler.ssl = function( )
		return sslctx ~= nil
	end
	handler.sslctx = function( )
		return sslctx
	end
	handler.hosts = {} -- sni
	handler.remove = function( )
		connections = connections - 1
		if handler then
			handler.resume( )
		end
	end
	handler.close = function()
		socket:close( )
		_sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
		_readlistlen = removesocket( _readlist, socket, _readlistlen )
		_server[ip..":"..serverport] = nil;
		_socketlist[ socket ] = nil
		handler = nil
		socket = nil
		--mem_free( )
		out_put "server.lua: closed server handler and removed sockets from list"
	end
	handler.pause = function( hard )
		if not handler.paused then
			_readlistlen = removesocket( _readlist, socket, _readlistlen )
			if hard then
				_socketlist[ socket ] = nil
				socket:close( )
				socket = nil;
			end
			handler.paused = true;
			out_put("server.lua: server [", ip, "]:", serverport, " paused")
		end
	end
	handler.resume = function( )
		if handler.paused then
			if not socket then
				socket = socket_bind( ip, serverport, _tcpbacklog );
				socket:settimeout( 0 )
			end
			_readlistlen = addsocket(_readlist, socket, _readlistlen)
			_socketlist[ socket ] = handler
			_fullservers[ handler ] = nil
			handler.paused = false;
			out_put("server.lua: server [", ip, "]:", serverport, " resumed")
		end
	end
	handler.ip = function( )
		return ip
	end
	handler.serverport = function( )
		return serverport
	end
	handler.socket = function( )
		return socket
	end
	handler.readbuffer = function( )
		if _readlistlen >= _maxselectlen or _sendlistlen >= _maxselectlen then
			handler.pause( )
			_fullservers[ handler ] = _currenttime
			out_put( "server.lua: refused new client connection: server full" )
			return false
		end
		local client, err = accept( socket )	-- try to accept
		if client then
			local ip, clientport = client:getpeername( )
			local handler, client, err = wrapconnection( handler, listeners, client, ip, serverport, clientport, pattern, sslctx, ssldirect ) -- wrap new client socket
			if err then -- error while wrapping ssl socket
				return false
			end
			connections = connections + 1
			out_put( "server.lua: accepted new client connection from ", tostring(ip), ":", tostring(clientport), " to ", tostring(serverport))
			if dispatch and not ssldirect then -- SSL connections will notify onconnect when handshake completes
				return dispatch( handler );
			end
			return;
		elseif err then -- maybe timeout or something else
			out_put( "server.lua: error with new client connection: ", tostring(err) )
			handler.pause( )
			_fullservers[ handler ] = _currenttime
			return false
		end
	end
	return handler
end

wrapconnection = function( server, listeners, socket, ip, serverport, clientport, pattern, sslctx, ssldirect ) -- this function wraps a client to a handler object

	if socket:getfd() >= _maxfd then
		out_error("server.lua: Disallowed FD number: "..socket:getfd()) -- PROTIP: Switch to libevent
		socket:close( ) -- Should we send some kind of error here?
		if server then
			_fullservers[ server ] = _currenttime
			server.pause( )
		end
		return nil, nil, "fd-too-large"
	end
	socket:settimeout( 0 )

	--// local import of socket methods //--

	local send
	local receive
	local shutdown

	--// private closures of the object //--

	local ssl

	local dispatch = listeners.onincoming
	local status = listeners.onstatus
	local disconnect = listeners.ondisconnect
	local drain = listeners.ondrain
	local onreadtimeout = listeners.onreadtimeout;
	local detach = listeners.ondetach

	local bufferqueue = { } -- buffer array
	local bufferqueuelen = 0	-- end of buffer array

	local toclose
	local needtls

	local bufferlen = 0

	local noread = false
	local nosend = false

	local sendtraffic, readtraffic = 0, 0

	local maxsendlen = _maxsendlen
	local maxreadlen = _maxreadlen

	--// public methods of the object //--

	local handler = bufferqueue -- saves a table ^_^

	handler.dispatch = function( )
		return dispatch
	end
	handler.disconnect = function( )
		return disconnect
	end
	handler.onreadtimeout = onreadtimeout;

	handler.setlistener = function( self, listeners, data )
		if detach then
			detach(self) -- Notify listener that it is no longer responsible for this connection
		end
		dispatch = listeners.onincoming
		disconnect = listeners.ondisconnect
		status = listeners.onstatus
		drain = listeners.ondrain
		handler.onreadtimeout = listeners.onreadtimeout
		detach = listeners.ondetach
		if listeners.onattach then
			listeners.onattach(self, data)
		end
	end
	handler.getstats = function( )
		return readtraffic, sendtraffic
	end
	handler.ssl = function( )
		return ssl
	end
	handler.sslctx = function ( )
		return sslctx
	end
	handler.send = function( _, data, i, j )
		return send( socket, data, i, j )
	end
	handler.receive = function( pattern, prefix )
		return receive( socket, pattern, prefix )
	end
	handler.shutdown = function( pattern )
		return shutdown( socket, pattern )
	end
	handler.setoption = function (self, option, value)
		if socket.setoption then
			return socket:setoption(option, value);
		end
		return false, "setoption not implemented";
	end
	handler.force_close = function ( self, err )
		if bufferqueuelen ~= 0 then
			out_put("server.lua: discarding unwritten data for ", tostring(ip), ":", tostring(clientport))
			bufferqueuelen = 0;
		end
		return self:close(err);
	end
	handler.close = function( self, err )
		if not handler then return true; end
		_readlistlen = removesocket( _readlist, socket, _readlistlen )
		_readtimes[ handler ] = nil
		if bufferqueuelen ~= 0 then
			handler.sendbuffer() -- Try now to send any outstanding data
			if bufferqueuelen ~= 0 then -- Still not empty, so we'll try again later
				if handler then
					handler.write = nil -- ... but no further writing allowed
				end
				toclose = true
				return false
			end
		end
		if socket then
			_ = shutdown and shutdown( socket )
			socket:close( )
			_sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
			_socketlist[ socket ] = nil
			socket = nil
		else
			out_put "server.lua: socket already closed"
		end
		if handler then
			_writetimes[ handler ] = nil
			_closelist[ handler ] = nil
			local _handler = handler;
			handler = nil
			if disconnect then
				disconnect(_handler, err or false);
				disconnect = nil
			end
		end
		if server then
			server.remove( )
		end
		out_put "server.lua: closed client handler and removed socket from list"
		return true
	end
	handler.server = function ( )
		return server
	end
	handler.ip = function( )
		return ip
	end
	handler.serverport = function( )
		return serverport
	end
	handler.clientport = function( )
		return clientport
	end
	handler.port = handler.clientport -- COMPAT server_event
	local write = function( self, data )
		if not handler then return false end
		bufferlen = bufferlen + #data
		if bufferlen > maxsendlen then
			_closelist[ handler ] = "send buffer exceeded"	 -- cannot close the client at the moment, have to wait to the end of the cycle
			return false
		elseif not nosend and socket and not _sendlist[ socket ] then
			_sendlistlen = addsocket(_sendlist, socket, _sendlistlen)
		end
		bufferqueuelen = bufferqueuelen + 1
		bufferqueue[ bufferqueuelen ] = data
		if handler then
			_writetimes[ handler ] = _writetimes[ handler ] or _currenttime
		end
		return true
	end
	handler.write = write
	handler.bufferqueue = function( self )
		return bufferqueue
	end
	handler.socket = function( self )
		return socket
	end
	handler.set_mode = function( self, new )
		pattern = new or pattern
		return pattern
	end
	handler.set_send = function ( self, newsend )
		send = newsend or send
		return send
	end
	handler.bufferlen = function( self, readlen, sendlen )
		maxsendlen = sendlen or maxsendlen
		maxreadlen = readlen or maxreadlen
		return bufferlen, maxreadlen, maxsendlen
	end
	handler.lock_read = function (self, switch)
		out_error( "server.lua, lock_read() is deprecated, use pause() and resume()" )
		if switch == true then
			return self:pause()
		elseif switch == false then
			return self:resume()
		end
		return noread
	end
	handler.pause = function (self)
		local tmp = _readlistlen
		_readlistlen = removesocket( _readlist, socket, _readlistlen )
		_readtimes[ handler ] = nil
		if _readlistlen ~= tmp then
			noread = true
		end
		return noread;
	end
	handler.resume = function (self)
		if noread then
			noread = false
			_readlistlen = addsocket(_readlist, socket, _readlistlen)
			_readtimes[ handler ] = _currenttime
		end
		return noread;
	end
	handler.lock = function( self, switch )
		out_error( "server.lua, lock() is deprecated" )
		handler.lock_read (self, switch)
		if switch == true then
			handler.pause_writes (self)
		elseif switch == false then
			handler.resume_writes (self)
		end
		return noread, nosend
	end
	handler.pause_writes = function (self)
		local tmp = _sendlistlen
		_sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
		_writetimes[ handler ] = nil
		if _sendlistlen ~= tmp then
			nosend = true
		end
	end
	handler.resume_writes = function (self)
		if nosend then
			nosend = false
			write( "" )
		end
	end

	local _readbuffer = function( ) -- this function reads data
		local buffer, err, part = receive( socket, pattern )	-- receive buffer with "pattern"
		if not err or (err == "wantread" or err == "timeout") then -- received something
			local buffer = buffer or part or ""
			local len = #buffer
			if len > maxreadlen then
				handler:close( "receive buffer exceeded" )
				return false
			end
			local count = len * STAT_UNIT
			readtraffic = readtraffic + count
			_readtraffic = _readtraffic + count
			_readtimes[ handler ] = _currenttime
			--out_put( "server.lua: read data '", buffer:gsub("[^%w%p ]", "."), "', error: ", err )
			return dispatch( handler, buffer, err )
		else	-- connections was closed or fatal error
			out_put( "server.lua: client ", tostring(ip), ":", tostring(clientport), " read error: ", tostring(err) )
			_ = handler and handler:force_close( err )
			return false
		end
	end
	local _sendbuffer = function( ) -- this function sends data
		local succ, err, byte, buffer, count;
		if socket then
			buffer = table_concat( bufferqueue, "", 1, bufferqueuelen )
			succ, err, byte = send( socket, buffer, 1, bufferlen )
			count = ( succ or byte or 0 ) * STAT_UNIT
			sendtraffic = sendtraffic + count
			_sendtraffic = _sendtraffic + count
			for i = bufferqueuelen,1,-1 do
				bufferqueue[ i ] = nil
			end
			--out_put( "server.lua: sended '", buffer, "', bytes: ", tostring(succ), ", error: ", tostring(err), ", part: ", tostring(byte), ", to: ", tostring(ip), ":", tostring(clientport) )
		else
			succ, err, count = false, "unexpected close", 0;
		end
		if succ then	-- sending successful
			bufferqueuelen = 0
			bufferlen = 0
			_sendlistlen = removesocket( _sendlist, socket, _sendlistlen ) -- delete socket from writelist
			_writetimes[ handler ] = nil
			if drain then
				drain(handler)
			end
			_ = needtls and handler:starttls(nil)
			_ = toclose and handler:force_close( )
			return true
		elseif byte and ( err == "timeout" or err == "wantwrite" ) then -- want write
			buffer = string_sub( buffer, byte + 1, bufferlen ) -- new buffer
			bufferqueue[ 1 ] = buffer	 -- insert new buffer in queue
			bufferqueuelen = 1
			bufferlen = bufferlen - byte
			_writetimes[ handler ] = _currenttime
			return true
		else	-- connection was closed during sending or fatal error
			out_put( "server.lua: client ", tostring(ip), ":", tostring(clientport), " write error: ", tostring(err) )
			_ = handler and handler:force_close( err )
			return false
		end
	end

	-- Set the sslctx
	local handshake;
	function handler.set_sslctx(self, new_sslctx)
		sslctx = new_sslctx;
		local read, wrote
		handshake = coroutine_wrap( function( client ) -- create handshake coroutine
				local err
				for _ = 1, _maxsslhandshake do
					_sendlistlen = ( wrote and removesocket( _sendlist, client, _sendlistlen ) ) or _sendlistlen
					_readlistlen = ( read and removesocket( _readlist, client, _readlistlen ) ) or _readlistlen
					read, wrote = nil, nil
					_, err = client:dohandshake( )
					if not err then
						out_put( "server.lua: ssl handshake done" )
						handler.readbuffer = _readbuffer	-- when handshake is done, replace the handshake function with regular functions
						handler.sendbuffer = _sendbuffer
						_ = status and status( handler, "ssl-handshake-complete" )
						if self.autostart_ssl and listeners.onconnect then
							listeners.onconnect(self);
							if bufferqueuelen ~= 0 then
								_sendlistlen = addsocket(_sendlist, client, _sendlistlen)
							end
						end
						_readlistlen = addsocket(_readlist, client, _readlistlen)
						return true
					else
						if err == "wantwrite" then
							_sendlistlen = addsocket(_sendlist, client, _sendlistlen)
							wrote = true
						elseif err == "wantread" then
							_readlistlen = addsocket(_readlist, client, _readlistlen)
							read = true
						else
							break;
						end
						err = nil;
						coroutine_yield( ) -- handshake not finished
					end
				end
				err = "ssl handshake error: " .. ( err or "handshake too long" );
				out_put( "server.lua: ", err );
				_ = handler and handler:force_close(err)
				return false, err -- handshake failed
			end
		)
	end
	if has_luasec then
		handler.starttls = function( self, _sslctx)
			if _sslctx then
				handler:set_sslctx(_sslctx);
			end
			if bufferqueuelen > 0 then
				out_put "server.lua: we need to do tls, but delaying until send buffer empty"
				needtls = true
				return
			end
			out_put( "server.lua: attempting to start tls on " .. tostring( socket ) )
			local oldsocket, err = socket
			socket, err = ssl_wrap( socket, sslctx )	-- wrap socket

			if not socket then
				out_put( "server.lua: error while starting tls on client: ", tostring(err or "unknown error") )
				return nil, err -- fatal error
			end

			if socket.sni then
				if self.servername then
					socket:sni(self.servername);
				elseif self._server and type(self._server.hosts) == "table" and next(self._server.hosts) ~= nil then
					socket:sni(self.server().hosts, true);
				end
			end

			socket:settimeout( 0 )

			-- add the new socket to our system
			send = socket.send
			receive = socket.receive
			shutdown = id
			_socketlist[ socket ] = handler
			_readlistlen = addsocket(_readlist, socket, _readlistlen)

			-- remove traces of the old socket
			_readlistlen = removesocket( _readlist, oldsocket, _readlistlen )
			_sendlistlen = removesocket( _sendlist, oldsocket, _sendlistlen )
			_socketlist[ oldsocket ] = nil

			handler.starttls = nil
			needtls = nil

			-- Secure now (if handshake fails connection will close)
			ssl = true

			handler.readbuffer = handshake
			handler.sendbuffer = handshake
			return handshake( socket ) -- do handshake
		end
	end

	handler.readbuffer = _readbuffer
	handler.sendbuffer = _sendbuffer
	send = socket.send
	receive = socket.receive
	shutdown = ( ssl and id ) or socket.shutdown

	_socketlist[ socket ] = handler
	_readlistlen = addsocket(_readlist, socket, _readlistlen)

	if sslctx and ssldirect and has_luasec then
		out_put "server.lua: auto-starting ssl negotiation..."
		handler.autostart_ssl = true;
		local ok, err = handler:starttls(sslctx);
		if ok == false then
			return nil, nil, err
		end
	end

	return handler, socket
end

id = function( )
end

idfalse = function( )
	return false
end

addsocket = function( list, socket, len )
	if not list[ socket ] then
		len = len + 1
		list[ len ] = socket
		list[ socket ] = len
	end
	return len;
end

removesocket = function( list, socket, len )	-- this function removes sockets from a list ( copied from copas )
	local pos = list[ socket ]
	if pos then
		list[ socket ] = nil
		local last = list[ len ]
		list[ len ] = nil
		if last ~= socket then
			list[ last ] = pos
			list[ pos ] = last
		end
		return len - 1
	end
	return len
end

closesocket = function( socket )
	_sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
	_readlistlen = removesocket( _readlist, socket, _readlistlen )
	_socketlist[ socket ] = nil
	socket:close( )
	--mem_free( )
end

local function link(sender, receiver, buffersize)
	local sender_locked;
	local _sendbuffer = receiver.sendbuffer;
	function receiver.sendbuffer()
		_sendbuffer();
		if sender_locked and receiver.bufferlen() < buffersize then
			sender:lock_read(false); -- Unlock now
			sender_locked = nil;
		end
	end

	local _readbuffer = sender.readbuffer;
	function sender.readbuffer()
		_readbuffer();
		if not sender_locked and receiver.bufferlen() >= buffersize then
			sender_locked = true;
			sender:lock_read(true);
		end
	end
	sender:set_mode("*a");
end

----------------------------------// PUBLIC //--

listen = function ( addr, port, listeners, config )
	addr = addr or "*"
	config = config or {}
	local err
	local sslctx = config.tls_ctx;
	local ssldirect = config.tls_direct;
	local pattern = config.read_size;
	if type( listeners ) ~= "table" then
		err = "invalid listener table"
	elseif type ( addr ) ~= "string" then
		err = "invalid address"
	elseif type( port ) ~= "number" or not ( port >= 0 and port <= 65535 ) then
		err = "invalid port"
	elseif _server[ addr..":"..port ] then
		err = "listeners on '[" .. addr .. "]:" .. port .. "' already exist"
	elseif sslctx and not has_luasec then
		err = "luasec not found"
	end
	if err then
		out_error( "server.lua, [", addr, "]:", port, ": ", err )
		return nil, err
	end
	local server, err = socket_bind( addr, port, _tcpbacklog )
	if err then
		out_error( "server.lua, [", addr, "]:", port, ": ", err )
		return nil, err
	end
	local handler, err = wrapserver( listeners, server, addr, port, pattern, sslctx, ssldirect ) -- wrap new server socket
	if not handler then
		server:close( )
		return nil, err
	end
	server:settimeout( 0 )
	_readlistlen = addsocket(_readlist, server, _readlistlen)
	_server[ addr..":"..port ] = handler
	_socketlist[ server ] = handler
	out_put( "server.lua: new "..(sslctx and "ssl " or "").."server listener on '[", addr, "]:", port, "'" )
	return handler
end

addserver = function( addr, port, listeners, pattern, sslctx ) -- this function provides a way for other scripts to reg a server
	return listen(addr, port, listeners, {
		read_size = pattern;
		tls_ctx = sslctx;
		tls_direct = sslctx and true or false;
	});
end

getserver = function ( addr, port )
	return _server[ addr..":"..port ];
end

removeserver = function( addr, port )
	local handler = _server[ addr..":"..port ]
	if not handler then
		return nil, "no server found on '[" .. addr .. "]:" .. tostring( port ) .. "'"
	end
	handler:close( )
	_server[ addr..":"..port ] = nil
	return true
end

closeall = function( )
	for _, handler in pairs( _socketlist ) do
		handler:close( )
		_socketlist[ _ ] = nil
	end
	_readlistlen = 0
	_sendlistlen = 0
	_timerlistlen = 0
	_server = { }
	_readlist = { }
	_sendlist = { }
	_timerlist = { }
	_socketlist = { }
	--mem_free( )
end

getsettings = function( )
	return {
		select_timeout = _selecttimeout;
		tcp_backlog = _tcpbacklog;
		max_send_buffer_size = _maxsendlen;
		max_receive_buffer_size = _maxreadlen;
		select_idle_check_interval = _checkinterval;
		send_timeout = _sendtimeout;
		read_timeout = _readtimeout;
		max_connections = _maxselectlen;
		max_ssl_handshake_roundtrips = _maxsslhandshake;
		highest_allowed_fd = _maxfd;
		accept_retry_interval = _accepretry;
	}
end

changesettings = function( new )
	if type( new ) ~= "table" then
		return nil, "invalid settings table"
	end
	_selecttimeout = tonumber( new.select_timeout ) or _selecttimeout
	_maxsendlen = tonumber( new.max_send_buffer_size ) or _maxsendlen
	_maxreadlen = tonumber( new.max_receive_buffer_size ) or _maxreadlen
	_checkinterval = tonumber( new.select_idle_check_interval ) or _checkinterval
	_tcpbacklog = tonumber( new.tcp_backlog ) or _tcpbacklog
	_sendtimeout = tonumber( new.send_timeout ) or _sendtimeout
	_readtimeout = tonumber( new.read_timeout ) or _readtimeout
	_accepretry = tonumber( new.accept_retry_interval ) or _accepretry
	_maxselectlen = new.max_connections or _maxselectlen
	_maxsslhandshake = new.max_ssl_handshake_roundtrips or _maxsslhandshake
	_maxfd = new.highest_allowed_fd or _maxfd
	return true
end

addtimer = function( listener )
	if type( listener ) ~= "function" then
		return nil, "invalid listener function"
	end
	_timerlistlen = _timerlistlen + 1
	_timerlist[ _timerlistlen ] = listener
	return true
end

local add_task do
	local data = {};
	local new_data = {};

	function add_task(delay, callback)
		local current_time = luasocket_gettime();
		delay = delay + current_time;
		if delay >= current_time then
			table_insert(new_data, {delay, callback});
		else
			local r = callback(current_time);
			if r and type(r) == "number" then
				return add_task(r, callback);
			end
		end
	end

	addtimer(function(current_time)
		if #new_data > 0 then
			for _, d in pairs(new_data) do
				table_insert(data, d);
			end
			new_data = {};
		end

		local next_time = math_huge;
		for i, d in pairs(data) do
			local t, callback = d[1], d[2];
			if t <= current_time then
				data[i] = nil;
				local r = callback(current_time);
				if type(r) == "number" then
					add_task(r, callback);
					next_time = math_min(next_time, r);
				end
			else
				next_time = math_min(next_time, t - current_time);
			end
		end
		return next_time;
	end);
end

stats = function( )
	return _readtraffic, _sendtraffic, _readlistlen, _sendlistlen, _timerlistlen
end

local quitting;

local function setquitting(quit)
	quitting = quit;
end

loop = function(once) -- this is the main loop of the program
	if quitting then return "quitting"; end
	if once then quitting = "once"; end
	_currenttime = luasocket_gettime( )
	repeat
		-- Fire timers
	local next_timer_time = math_huge;
		for i = 1, _timerlistlen do
			local t = _timerlist[ i ]( _currenttime ) -- fire timers
			if t then next_timer_time = math_min(next_timer_time, t); end
		end

		local read, write, err = socket_select( _readlist, _sendlist, math_min(_selecttimeout, next_timer_time) )
		for _, socket in ipairs( read ) do -- receive data
			local handler = _socketlist[ socket ]
			if handler then
				handler.readbuffer( )
			else
				closesocket( socket )
				out_put "server.lua: found no handler and closed socket (readlist)" -- this can happen
			end
		end
		for _, socket in ipairs( write ) do -- send data waiting in writequeues
			local handler = _socketlist[ socket ]
			if handler then
				handler.sendbuffer( )
			else
				closesocket( socket )
				out_put "server.lua: found no handler and closed socket (writelist)"	-- this should not happen
			end
		end
		for handler, err in pairs( _closelist ) do
			handler.disconnect( )( handler, err )
			handler:force_close()	 -- forced disconnect
			_closelist[ handler ] = nil;
		end
		_currenttime = luasocket_gettime( )

		-- Check for socket timeouts
		if _currenttime - _starttime > _checkinterval then
			_starttime = _currenttime
			for handler, timestamp in pairs( _writetimes ) do
				if _currenttime - timestamp > _sendtimeout then
					handler.disconnect( )( handler, "send timeout" )
					handler:force_close()	 -- forced disconnect
				end
			end
			for handler, timestamp in pairs( _readtimes ) do
				if _currenttime - timestamp > _readtimeout then
					if not(handler.onreadtimeout) or handler:onreadtimeout() ~= true then
						handler.disconnect( )( handler, "read timeout" )
						handler:close( )	-- forced disconnect?
					else
						_readtimes[ handler ] = _currenttime -- reset timer
					end
				end
			end
		end

		for server, paused_time in pairs( _fullservers ) do
			if _currenttime - paused_time > _accepretry then
				_fullservers[ server ] = nil;
				server.resume();
			end
		end
	until quitting;
	if quitting == "once" then quitting = nil; return; end
	closeall();
	return "quitting"
end

local function step()
	return loop(true);
end

local function get_backend()
	return "select";
end

--// EXPERIMENTAL //--

local wrapclient = function( socket, ip, serverport, listeners, pattern, sslctx )
	local handler, socket, err = wrapconnection( nil, listeners, socket, ip, serverport, "clientport", pattern, sslctx, sslctx)
	if not handler then return nil, err end
	_socketlist[ socket ] = handler
	if not sslctx then
		_readlistlen = addsocket(_readlist, socket, _readlistlen)
		_sendlistlen = addsocket(_sendlist, socket, _sendlistlen)
		if listeners.onconnect then
			-- When socket is writeable, call onconnect
			local _sendbuffer = handler.sendbuffer;
			handler.sendbuffer = function ()
				handler.sendbuffer = _sendbuffer;
				listeners.onconnect(handler);
				return _sendbuffer(); -- Send any queued outgoing data
			end
		end
	end
	return handler, socket
end

local addclient = function( address, port, listeners, pattern, sslctx, typ )
	local err
	if type( listeners ) ~= "table" then
		err = "invalid listener table"
	elseif type ( address ) ~= "string" then
		err = "invalid address"
	elseif type( port ) ~= "number" or not ( port >= 0 and port <= 65535 ) then
		err = "invalid port"
	elseif sslctx and not has_luasec then
		err = "luasec not found"
	end
	if not typ then
		local n = inet_pton(address);
		if not n then return nil, "invalid-ip"; end
		if #n == 16 then
			typ = "tcp6";
		elseif #n == 4 then
			typ = "tcp4";
		end
	end
	local create = luasocket[typ];
	if type( create ) ~= "function"  then
		err = "invalid socket type"
	end

	if err then
		out_error( "server.lua, addclient: ", err )
		return nil, err
	end

	local client, err = create( )
	if err then
		return nil, err
	end
	client:settimeout( 0 )
	local ok, err = client:setpeername( address, port )
	if ok or err == "timeout" or err == "Operation already in progress" then
		return wrapclient( client, address, port, listeners, pattern, sslctx )
	else
		return nil, err
	end
end

local closewatcher = function (handler)
	local socket = handler.conn;
	_sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
	_readlistlen = removesocket( _readlist, socket, _readlistlen )
	_socketlist[ socket ] = nil
end;

local addremove = function (handler, read, send)
	local socket = handler.conn
	_socketlist[ socket ] = handler
	if read ~= nil then
		if read then
			_readlistlen = addsocket( _readlist, socket, _readlistlen )
		else
			_sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
		end
	end
	if send ~= nil then
		if send then
			_sendlistlen = addsocket( _sendlist, socket, _sendlistlen )
		else
			_readlistlen = removesocket( _readlist, socket, _readlistlen )
		end
	end
end

local watchfd = function ( fd, onreadable, onwriteable )
	local socket = fd
	if type(fd) == "number" then
		socket = { getfd = function () return fd; end }
	end
	local handler = {
		conn = socket;
		readbuffer = onreadable or id;
		sendbuffer = onwriteable or id;
		close = closewatcher;
		setflags = addremove;
	};
	addremove( handler, onreadable, onwriteable )
	return handler
end

----------------------------------// BEGIN //--

use "setmetatable" ( _socketlist, { __mode = "k" } )
use "setmetatable" ( _readtimes, { __mode = "k" } )
use "setmetatable" ( _writetimes, { __mode = "k" } )

_starttime = luasocket_gettime( )

local function setlogger(new_logger)
	local old_logger = log;
	if new_logger then
		log = new_logger;
	end
	return old_logger;
end

----------------------------------// PUBLIC INTERFACE //--

return {
	_addtimer = addtimer,
	add_task = add_task;

	addclient = addclient,
	wrapclient = wrapclient,
	watchfd = watchfd,

	loop = loop,
	link = link,
	step = step,
	stats = stats,
	closeall = closeall,
	addserver = addserver,
	listen = listen,
	getserver = getserver,
	setlogger = setlogger,
	getsettings = getsettings,
	setquitting = setquitting,
	removeserver = removeserver,
	get_backend = get_backend,
	changesettings = changesettings,
}