aboutsummaryrefslogtreecommitdiffstats
path: root/net/server.lua
blob: 40f37345426ee08a58701d91403d95d794ae34e5 (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
--[[

		server.lua by blastbeat of the luadch project
		
		re-used here under the MIT/X Consortium License

		- this script contains the server loop of the program
		- other scripts can reg a server here

]]--

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

--// constants //--

local STAT_UNIT = 1 / ( 1024 * 1024 )    -- mb

--// lua functions //--

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

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

--// lua libs //--

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

--// lua lib methods //--

local table_concat = table.concat
local table_remove = table.remove
local string_sub = use'string'.sub
local coroutine_wrap = coroutine.wrap
local coroutine_yield = coroutine.yield
local print = print;
local out_put = function () end --print;
local out_error = print;

--// extern libs //--

local luasec = select(2, pcall(require, "ssl"))
local luasocket = require "socket"

--// extern lib methods //--

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

--// functions //--

local loop
local stats
local addtimer
local closeall
local addserver
local firetimer
local closesocket
local removesocket
local wrapserver
local wraptcpclient
local wrapsslclient

--// tables //--

local listener
local readlist
local writelist
local socketlist
local timelistener

--// simple data types //--

local _
local readlen = 0    -- length of readlist
local writelen = 0    -- lenght of writelist

local sendstat= 0
local receivestat = 0

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

listener = { }    -- key = port, value = table
readlist = { }    -- array with sockets to read from
writelist = { }    -- arrary with sockets to write to
socketlist = { }    -- key = socket, value = wrapped socket
timelistener = { }

stats = function( )
	return receivestat, sendstat
end

wrapserver = function( listener, socket, ip, serverport, mode, sslctx )    -- this function wraps a server

	local dispatch, disconnect = listener.listener, listener.disconnect    -- dangerous

	local wrapclient, err

	if sslctx then
		if not ssl_newcontext then
			return nil, "luasec not found"
		end
		if type( sslctx ) ~= "table" then
			out_error "server.lua: wrong server sslctx"
			return nil, "wrong server sslctx"
		end
		sslctx, err = ssl_newcontext( sslctx )
		if not sslctx then
			err = err or "wrong sslctx parameters"
			out_error( "server.lua: ", err )
			return nil, err
		end
		wrapclient = wrapsslclient
		wrapclient = wraptlsclient
	else
		wrapclient = wraptcpclient
	end

	local accept = socket.accept
	local close = socket.close

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

	local handler = { }

	handler.shutdown = function( ) end

	--[[handler.listener = function( data, err )
		return ondata( handler, data, err )
	end]]
	handler.ssl = function( )
		return sslctx and true or false
	end
	handler.close = function( closed )
		_ = not closed and close( socket )
		writelen = removesocket( writelist, socket, writelen )
		readlen = removesocket( readlist, socket, readlen )
		socketlist[ socket ] = nil
		handler = nil
	end
	handler.ip = function( )
		return ip
	end
	handler.serverport = function( )
		return serverport
	end
	handler.socket = function( )
		return socket
	end
	handler.receivedata = function( )
		local client, err = accept( socket )    -- try to accept
		if client then
			local ip, clientport = client:getpeername( )
			client:settimeout( 0 )
			local handler, client, err = wrapclient( listener, client, ip, serverport, clientport, mode, sslctx )    -- wrap new client socket
			if err then    -- error while wrapping ssl socket
				return false
			end
			out_put( "server.lua: accepted new client connection from ", ip, ":", clientport )
			return dispatch( handler )
		elseif err then    -- maybe timeout or something else
			out_put( "server.lua: error with new client connection: ", err )
			return false
		end
	end
	return handler
end

wrapsslclient = function( listener, socket, ip, serverport, clientport, mode, sslctx )    -- this function wraps a ssl cleint

	local dispatch, disconnect = listener.listener, listener.disconnect

	--// transform socket to ssl object //--

	local err
	socket, err = ssl_wrap( socket, sslctx )    -- wrap socket
	if err then
		out_put( "server.lua: ssl error: ", err )
		return nil, nil, err    -- fatal error
	end
	socket:settimeout( 0 )

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

	local writequeue = { }    -- buffer for messages to send

	local eol, fatal_send_error   -- end of buffer

	local sstat, rstat = 0, 0

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

	local send = socket.send
	local receive = socket.receive
	local close = socket.close
	--local shutdown = socket.shutdown

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

	local handler = { }

	handler.getstats = function( )
		return rstat, sstat
	end

	handler.listener = function( data, err )
		return listener( handler, data, err )
	end
	handler.ssl = function( )
		return true
	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.close = function( closed )
		if eol and not fatal_send_error then handler._dispatchdata(); end
		close( socket )
		writelen = ( eol and removesocket( writelist, socket, writelen ) ) or writelen
		readlen = removesocket( readlist, socket, readlen )
		socketlist[ socket ] = nil
		out_put "server.lua: closed handler and removed socket from list"
	end
	handler.ip = function( )
		return ip
	end
	handler.serverport = function( )
		return serverport
	end
	handler.clientport = function( ) 
		return clientport
	end

	handler.write = function( data )
		if not eol then
			writelen = writelen + 1
			writelist[ writelen ] = socket
			eol = 0
		end
		eol = eol + 1
		writequeue[ eol ] = data
	end
	handler.writequeue = function( )
		return writequeue
	end
	handler.socket = function( )
		return socket
	end
	handler.mode = function( )
		return mode
	end
	handler._receivedata = function( )
		local data, err, part = receive( socket, mode )    -- receive data in "mode"
		if not err or ( err == "timeout" or err == "wantread" ) then    -- received something
			local data = data or part or ""
			local count = #data * STAT_UNIT
			rstat = rstat + count
			receivestat = receivestat + count
			out_put( "server.lua: read data '", data, "', error: ", err )
			return dispatch( handler, data, err )
		else    -- connections was closed or fatal error
			out_put( "server.lua: client ", ip, ":", clientport, " error: ", err )
			handler.close( )
			disconnect( handler, err )
			writequeue = nil
			handler = nil
			return false
		end
	end
	handler._dispatchdata = function( )    -- this function writes data to handlers
		local buffer = table_concat( writequeue, "", 1, eol )
		local succ, err, byte = send( socket, buffer )
		local count = ( succ or 0 ) * STAT_UNIT
		sstat = sstat + count
		sendstat = sendstat + count
		out_put( "server.lua: sended '", buffer, "', bytes: ", succ, ", error: ", err, ", part: ", byte, ", to: ", ip, ":", clientport )
		if succ then    -- sending succesful
			--writequeue = { }
			eol = nil
			writelen = removesocket( writelist, socket, writelen )    -- delete socket from writelist
			return true
		elseif byte and ( err == "timeout" or err == "wantwrite" ) then    -- want write
			buffer = string_sub( buffer, byte + 1, -1 )    -- new buffer
			writequeue[ 1 ] = buffer    -- insert new buffer in queue
			eol = 1
			return true
		else    -- connection was closed during sending or fatal error
			fatal_send_error = true;
			out_put( "server.lua: client ", ip, ":", clientport, " error: ", err )
			handler.close( )
			disconnect( handler, err )
			writequeue = nil
			handler = nil
			return false
		end
	end

	-- // COMPAT // --

	handler.getIp = handler.ip
	handler.getPort = handler.clientport

	--// handshake //--

	local wrote

	handler.handshake = coroutine_wrap( function( client )
			local err
			for i = 1, 10 do    -- 10 handshake attemps
				_, err = client:dohandshake( )
				if not err then
					out_put( "server.lua: ssl handshake done" )
					writelen = ( wrote and removesocket( writelist, socket, writelen ) ) or writelen
					handler.receivedata = handler._receivedata    -- when handshake is done, replace the handshake function with regular functions
					handler.dispatchdata = handler._dispatchdata
					return dispatch( handler )
				else
					out_put( "server.lua: error during ssl handshake: ", err )
					if err == "wantwrite" then
						if wrote == nil then
							writelen = writelen + 1
							writelist[ writelen ] = client
							wrote = true
						end
					end
					coroutine_yield( handler, nil, err )    -- handshake not finished
				end
			end
			_ = err ~= "closed" and close( socket )
			handler.close( )
			disconnect( handler, err )
			writequeue = nil
			handler = nil
			return false    -- handshake failed
		end
	)
	handler.receivedata = handler.handshake
	handler.dispatchdata = handler.handshake

	handler.handshake( socket )    -- do handshake

	socketlist[ socket ] = handler
	readlen = readlen + 1
	readlist[ readlen ] = socket

	return handler, socket
end

wraptlsclient = function( listener, socket, ip, serverport, clientport, mode, sslctx )    -- this function wraps a tls cleint

	local dispatch, disconnect = listener.listener, listener.disconnect

	--// transform socket to ssl object //--

	local err

	socket:settimeout( 0 )
	out_put("setting linger on "..tostring(socket))
	socket:setoption("linger", { on = true, timeout = 10 });
	--// private closures of the object //--

	local writequeue = { }    -- buffer for messages to send

	local eol, fatal_send_error   -- end of buffer

	local sstat, rstat = 0, 0

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

	local send = socket.send
	local receive = socket.receive
	local close = socket.close
	--local shutdown = socket.shutdown

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

	local handler = { }

	handler.getstats = function( )
		return rstat, sstat
	end

	handler.listener = function( data, err )
		return listener( handler, data, err )
	end
	handler.ssl = function( )
		return false
	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.close = function( closed )
		if eol and not fatal_send_error then handler._dispatchdata(); end
		close( socket )
		writelen = ( eol and removesocket( writelist, socket, writelen ) ) or writelen
		readlen = removesocket( readlist, socket, readlen )
		socketlist[ socket ] = nil
		out_put "server.lua: closed handler and removed socket from list"
	end
	handler.ip = function( )
		return ip
	end
	handler.serverport = function( )
		return serverport
	end
	handler.clientport = function( ) 
		return clientport
	end

	handler.write = function( data )
		if not eol then
			writelen = writelen + 1
			writelist[ writelen ] = socket
			eol = 0
		end
		eol = eol + 1
		writequeue[ eol ] = data
	end
	handler.writequeue = function( )
		return writequeue
	end
	handler.socket = function( )
		return socket
	end
	handler.mode = function( )
		return mode
	end
	handler._receivedata = function( )
		local data, err, part = receive( socket, mode )    -- receive data in "mode"
		if not err or ( err == "timeout" or err == "wantread" ) then    -- received something
			local data = data or part or ""
			local count = #data * STAT_UNIT
			rstat = rstat + count
			receivestat = receivestat + count
			--out_put( "server.lua: read data '", data, "', error: ", err )
			return dispatch( handler, data, err )
		else    -- connections was closed or fatal error
			out_put( "server.lua: client ", ip, ":", clientport, " error: ", err )
			handler.close( )
			disconnect( handler, err )
			writequeue = nil
			handler = nil
			return false
		end
	end
	handler._dispatchdata = function( )    -- this function writes data to handlers
		local buffer = table_concat( writequeue, "", 1, eol )
		local succ, err, byte = send( socket, buffer )
		local count = ( succ or 0 ) * STAT_UNIT
		sstat = sstat + count
		sendstat = sendstat + count
		out_put( "server.lua: sended '", buffer, "', bytes: ", succ, ", error: ", err, ", part: ", byte, ", to: ", ip, ":", clientport )
		if succ then    -- sending succesful
			--writequeue = { }
			eol = nil
			writelen = removesocket( writelist, socket, writelen )    -- delete socket from writelist
			if handler.need_tls then
				out_put("server.lua: connection is ready for tls handshake");
				handler.starttls(true);
				if handler.need_tls then
					out_put("server.lua: uh-oh... we still want tls, something must be wrong");
				end
			end
			return true
		elseif byte and ( err == "timeout" or err == "wantwrite" ) then    -- want write
			buffer = string_sub( buffer, byte + 1, -1 )    -- new buffer
			writequeue[ 1 ] = buffer    -- insert new buffer in queue
			eol = 1
			return true
		else    -- connection was closed during sending or fatal error
			fatal_send_error = true; -- :(
			out_put( "server.lua: client ", ip, ":", clientport, " error: ", err )
			handler.close( )
			disconnect( handler, err )
			writequeue = nil
			handler = nil
			return false
		end
	end

	handler.receivedata, handler.dispatchdata = handler._receivedata, handler._dispatchdata;
	-- // COMPAT // --

	handler.getIp = handler.ip
	handler.getPort = handler.clientport

	--// handshake //--

	local wrote, read
	
	handler.starttls = function (now)
		if not now then out_put("server.lua: we need to do tls, but delaying until later"); handler.need_tls = true; return; end
		out_put( "server.lua: attempting to start tls on "..tostring(socket) )
		socket, err = ssl_wrap( socket, sslctx )    -- wrap socket
		out_put("sslwrapped socket is "..tostring(socket));
		if err then
			out_put( "server.lua: ssl error: ", err )
			return nil, nil, err    -- fatal error
		end
		socket:settimeout( 1 )
		send = socket.send
		receive = socket.receive
		close = socket.close
		handler.ssl = function( )
			return true
		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.starttls = nil;
		
			handler.handshake = coroutine_wrap( function( client )
					local err
					for i = 1, 10 do    -- 10 handshake attemps
						_, err = client:dohandshake( )
						if not err then
							out_put( "server.lua: ssl handshake done" )
							writelen = ( wrote and removesocket( writelist, socket, writelen ) ) or writelen
							handler.receivedata = handler._receivedata    -- when handshake is done, replace the handshake function with regular functions
							handler.dispatchdata = handler._dispatchdata
							handler.need_tls = nil
							socketlist[ client ] = handler
							readlen = readlen + 1
							readlist[ readlen ] = client												
							return true;
						else
							out_put( "server.lua: error during ssl handshake: ", err )
							if err == "wantwrite" then
								if wrote == nil then
									writelen = writelen + 1
									writelist[ writelen ] = client
									wrote = true
								end
							end
							coroutine_yield( handler, nil, err )    -- handshake not finished
						end
					end
					_ = err ~= "closed" and close( socket )
					handler.close( )
					disconnect( handler, err )
					writequeue = nil
					handler = nil
					return false    -- handshake failed
				end
			)
			handler.receivedata = handler.handshake
			handler.dispatchdata = handler.handshake

			handler.handshake( socket )    -- do handshake
		end
	socketlist[ socket ] = handler
	readlen = readlen + 1
	readlist[ readlen ] = socket

	return handler, socket
end

wraptcpclient = function( listener, socket, ip, serverport, clientport, mode )    -- this function wraps a socket

	local dispatch, disconnect = listener.listener, listener.disconnect

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

	local writequeue = { }    -- list for messages to send

	local eol, fatal_send_error

	local rstat, sstat = 0, 0

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

	local send = socket.send
	local receive = socket.receive
	local close = socket.close
	local shutdown = socket.shutdown

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

	local handler = { }

	handler.getstats = function( )
		return rstat, sstat
	end

	handler.listener = function( data, err )
		return listener( handler, data, err )
	end
	handler.ssl = function( )
		return false
	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.close = function( closed )
		if eol and not fatal_send_error then handler.dispatchdata(); end
		_ = not closed and shutdown( socket )
		_ = not closed and close( socket )
		writelen = ( eol and removesocket( writelist, socket, writelen ) ) or writelen
		readlen = removesocket( readlist, socket, readlen )
		socketlist[ socket ] = nil
		out_put "server.lua: closed handler and removed socket from list"
	end
	handler.ip = function( )
		return ip
	end
	handler.serverport = function( )
		return serverport
	end
	handler.clientport = function( ) 
		return clientport
	end
	handler.write = function( data )
		if not eol then
			writelen = writelen + 1
			writelist[ writelen ] = socket
			eol = 0
		end
		eol = eol + 1
		writequeue[ eol ] = data
	end
	handler.writequeue = function( )
		return writequeue
	end
	handler.socket = function( )
		return socket
	end
	handler.mode = function( )
		return mode
	end
	
	handler.receivedata = function( )
		local data, err, part = receive( socket, mode )    -- receive data in "mode"
		if not err or ( err == "timeout" or err == "wantread" ) then    -- received something
			local data = data or part or ""
			local count = #data * STAT_UNIT
			rstat = rstat + count
			receivestat = receivestat + count
			out_put( "server.lua: read data '", data, "', error: ", err )
			return dispatch( handler, data, err )
		else    -- connections was closed or fatal error
			out_put( "server.lua: client ", ip, ":", clientport, " error: ", err )
			handler.close( )
			disconnect( handler, err )
			writequeue = nil
			handler = nil
			return false
		end
	end
	
	handler.dispatchdata = function( )    -- this function writes data to handlers
		local buffer = table_concat( writequeue, "", 1, eol )
		local succ, err, byte = send( socket, buffer )
		local count = ( succ or 0 ) * STAT_UNIT
		sstat = sstat + count
		sendstat = sendstat + count
		out_put( "server.lua: sended '", buffer, "', bytes: ", succ, ", error: ", err, ", part: ", byte, ", to: ", ip, ":", clientport )
		if succ then    -- sending succesful
			--writequeue = { }
			eol = nil
			writelen = removesocket( writelist, socket, writelen )    -- delete socket from writelist
			return true
		elseif byte and ( err == "timeout" or err == "wantwrite" ) then    -- want write
			buffer = string_sub( buffer, byte + 1, -1 )    -- new buffer
			writequeue[ 1 ] = buffer    -- insert new buffer in queue
			eol = 1
			return true
		else    -- connection was closed during sending or fatal error
			fatal_send_error = true; -- :'-(
			out_put( "server.lua: client ", ip, ":", clientport, " error: ", err )
			handler.close( )
			disconnect( handler, err )
			writequeue = nil
			handler = nil
			return false
		end
	end

	-- // COMPAT // --

	handler.getIp = handler.ip
	handler.getPort = handler.clientport

	socketlist[ socket ] = handler
	readlen = readlen + 1
	readlist[ readlen ] = socket

	return handler, socket
end

addtimer = function( listener )
	timelistener[ #timelistener + 1 ] = listener
end

firetimer = function( listener )
	for i, listener in ipairs( timelistener ) do
		listener( )
	end
end

addserver = function( listeners, port, addr, mode, sslctx )    -- this function provides a way for other scripts to reg a server
	local err
	if type( listeners ) ~= "table" then
		err = "invalid listener table"
	else
		for name, func in pairs( listeners ) do
			if type( func ) ~= "function" then
				--err = "invalid listener function"
				break
			end
		end
	end
	if not type( port ) == "number" or not ( port >= 0 and port <= 65535 ) then
		err = "invalid port"
	elseif listener[ port ] then
		err=  "listeners on port '" .. port .. "' already exist"
	elseif sslctx and not luasec then
		err = "luasec not found"
	end
	if err then
		out_error( "server.lua: ", err )
		return nil, err
	end
	addr = addr or "*"
	local server, err = socket_bind( addr, port )
	if err then
		out_error( "server.lua: ", err )
		return nil, err
	end
	local handler, err = wrapserver( listeners, server, addr, port, mode, sslctx )    -- wrap new server socket
	if not handler then
		server:close( )
		return nil, err
	end
	server:settimeout( 0 )
	readlen = readlen + 1
	readlist[ readlen ] = server
	listener[ port ] = listeners
	socketlist[ server ] = handler
	out_put( "server.lua: new server listener on ", addr, ":", port )
	return true
end

removesocket = function( tbl, socket, len )    -- this function removes sockets from a list
	for i, target in ipairs( tbl ) do
		if target == socket then
			len = len - 1
			table_remove( tbl, i )
			return len
		end
	end
	return len
end

closeall = function( )
	for sock, handler in pairs( socketlist ) do
		handler.shutdown( )
		handler.close( )
		socketlist[ sock ] = nil
	end
	writelist, readlist, socketlist = { }, { }, { }
end

closesocket = function( socket )
	writelen = removesocket( writelist, socket, writelen )
	readlen = removesocket( readlist, socket, readlen )
	socketlist[ socket ] = nil
	socket:close( )
end

loop = function( )    -- this is the main loop of the program
	--signal_set( "hub", "run" )
	repeat
		--[[print(readlen, writelen)
		for _, s in ipairs(readlist) do print("R:", tostring(s)) end
		for _, s in ipairs(writelist) do print("W:", tostring(s)) end
		out_put("select()"..os.time())]]
		local read, write, err = socket_select( readlist, writelist, 1 )    -- 1 sec timeout, nice for timers
		for i, socket in ipairs( write ) do    -- send data waiting in writequeues
			local handler = socketlist[ socket ]
			if handler then
				handler.dispatchdata( )
			else
				closesocket( socket )
				out_put "server.lua: found no handler and closed socket (writelist)"    -- this should not happen
			end
		end
		for i, socket in ipairs( read ) do    -- receive data
			local handler = socketlist[ socket ]
			if handler then
				handler.receivedata( )
			else
				closesocket( socket )
				out_put "server.lua: found no handler and closed socket (readlist)"    -- this can happen
			end
		end
		firetimer( )
	until false
	return
end

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

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

return {

	add = addserver,
	loop = loop,
	stats = stats,
	closeall = closeall,
	addtimer = addtimer,
	wraptlsclient = wraptlsclient,
}