4 server.lua based on lua/libevent by blastbeat
7 -- when using luaevent, never register 2 or more EV_READ at one socket, same for EV_WRITE
8 -- you cant even register a new EV_READ/EV_WRITE callback inside another one
9 -- never call eventcallback:close( ) from inside eventcallback
10 -- to do some of the above, use timeout events or something what will called from outside
11 -- dont let garbagecollect eventcallbacks, as long they are running
12 -- when using luasec, there are 4 cases of timeout errors: wantread or wantwrite during reading or writing
16 local SCRIPT_NAME = "server_event.lua"
17 local SCRIPT_VERSION = "0.05"
18 local SCRIPT_AUTHOR = "blastbeat"
19 local LAST_MODIFIED = "2009/11/20"
22 MAX_CONNECTIONS = 100000, -- max per server connections (use "ulimit -n" on *nix)
23 MAX_HANDSHAKE_ATTEMPS = 10, -- attemps to finish ssl handshake
24 HANDSHAKE_TIMEOUT = 1, -- timout in seconds per handshake attemp
25 MAX_READ_LENGTH = 1024 * 1024 * 1024 * 1024, -- max bytes allowed to read from sockets
26 MAX_SEND_LENGTH = 1024 * 1024 * 1024 * 1024, -- max bytes size of write buffer (for writing on sockets)
27 ACCEPT_DELAY = 10, -- seconds to wait until the next attemp of a full server to accept
28 READ_TIMEOUT = 60 * 30, -- timeout in seconds for read data from socket
29 WRITE_TIMEOUT = 30, -- timeout in seconds for write data on socket
30 CONNECT_TIMEOUT = 10, -- timeout in seconds for connection attemps
31 CLEAR_DELAY = 5, -- seconds to wait for clearing interface list (and calling ondisconnect listeners)
32 DEBUG = true, -- show debug messages
35 local function use(x) return rawget(_G, x); end
36 local print = use "print"
37 local pcall = use "pcall"
38 local ipairs = use "ipairs"
39 local string = use "string"
40 local select = use "select"
41 local require = use "require"
42 local tostring = use "tostring"
43 local coroutine = use "coroutine"
44 local setmetatable = use "setmetatable"
46 local ssl = use "ssl" or require "ssl"
47 local socket = use "socket" or require "socket"
49 local log = require ("util.logger").init("socket")
51 local function debug(...)
52 return log("debug", ("%s "):rep(select('#', ...)), ...)
56 local bitor = ( function( ) -- thx Rici Lake
57 local hasbit = function( x, p )
58 return x % ( p + p ) >= p
60 return function( x, y )
63 local limit = x > y and x or y
65 if hasbit( x, p ) or hasbit( y, p ) then
74 local event = require "luaevent.core"
75 local base = event.new( )
76 local EV_READ = event.EV_READ
77 local EV_WRITE = event.EV_WRITE
78 local EV_TIMEOUT = event.EV_TIMEOUT
79 local EV_SIGNAL = event.EV_SIGNAL
81 local EV_READWRITE = bitor( EV_READ, EV_WRITE )
83 local interfacelist = ( function( ) -- holds the interfaces for sockets
86 return function( method, arg )
87 if "add" == method then
92 elseif "delete" == method then
94 return nil, "array is already empty"
96 local position = arg:_position() -- get position in array
97 if position ~= len then
98 local interface = array[ len ] -- get last interface
99 array[ position ] = interface -- copy it into free position
100 array[ len ] = nil -- free last position
101 interface:_position( position ) -- set new position in array
102 else -- free last position
113 -- Client interface methods
116 interface_mt = {}; interface_mt.__index = interface_mt;
118 local addevent = base.addevent
119 local coroutine_wrap, coroutine_yield = coroutine.wrap,coroutine.yield
120 local string_len = string.len
123 function interface_mt:_position(new_position)
124 self.position = new_position or self.position
125 return self.position;
127 function interface_mt:_close() -- regs event to start self:_destroy()
128 local callback = function( )
130 self.eventclose = nil
133 self.eventclose = addevent( base, nil, EV_TIMEOUT, callback, 0 )
137 function interface_mt:_start_connection(plainssl) -- should be called from addclient
138 local callback = function( event )
139 if EV_TIMEOUT == event then -- timout during connection
140 self.fatalerror = "connection timeout"
141 self:ontimeout() -- call timeout listener
143 debug( "new connection failed. id:", self.id, "error:", self.fatalerror )
145 if plainssl then -- start ssl session
146 self:_start_ssl( self.listener.onconnect )
147 else -- normal connection
148 self:_start_session( self.listener.onconnect )
150 debug( "new connection established. id:", self.id )
152 self.eventconnect = nil
155 self.eventconnect = addevent( base, self.conn, EV_WRITE, callback, cfg.CONNECT_TIMEOUT )
158 function interface_mt:_start_session(onconnect) -- new session, for example after startssl
159 if self.type == "client" then
160 local callback = function( )
161 self:_lock( false, false, false )
162 --vdebug( "start listening on client socket with id:", self.id )
163 self.eventread = addevent( base, self.conn, EV_READ, self.readcallback, cfg.READ_TIMEOUT ) -- register callback
165 self.eventsession = nil
168 self.eventsession = addevent( base, nil, EV_TIMEOUT, callback, 0 )
171 --vdebug( "start listening on server socket with id:", self.id )
172 self.eventread = addevent( base, self.conn, EV_READ, self.readcallback ) -- register callback
176 function interface_mt:_start_ssl(arg) -- old socket will be destroyed, therefore we have to close read/write events first
177 --vdebug( "starting ssl session with client id:", self.id )
179 _ = self.eventread and self.eventread:close( ) -- close events; this must be called outside of the event callbacks!
180 _ = self.eventwrite and self.eventwrite:close( )
181 self.eventread, self.eventwrite = nil, nil
183 self.conn, err = ssl.wrap( self.conn, self._sslctx )
185 self.fatalerror = err
186 self.conn = nil -- cannot be used anymore
187 if "onconnect" == arg then
188 self.ondisconnect = nil -- dont call this when client isnt really connected
191 debug( "fatal error while ssl wrapping:", err )
194 self.conn:settimeout( 0 ) -- set non blocking
195 local handshakecallback = coroutine_wrap(
199 local maxattempt = cfg.MAX_HANDSHAKE_ATTEMPS
200 while attempt < 1000 do -- no endless loop
201 attempt = attempt + 1
202 debug( "ssl handshake of client with id:"..tostring(self).."attemp:"..attempt )
203 if attempt > maxattempt then
204 self.fatalerror = "max handshake attemps exceeded"
205 elseif EV_TIMEOUT == event then
206 self.fatalerror = "timeout during handshake"
208 _, err = self.conn:dohandshake( )
210 self:_lock( false, false, false ) -- unlock the interface; sending, closing etc allowed
211 self.send = self.conn.send -- caching table lookups with new client object
212 self.receive = self.conn.receive
214 if "onconnect" == arg then -- trigger listener
215 onsomething = self.onconnect
217 onsomething = self.onsslconnection
219 self:_start_session( onsomething )
220 debug( "ssl handshake done" )
221 self.eventhandshake = nil
224 debug( "error during ssl handshake:", err )
225 if err == "wantwrite" then
227 elseif err == "wantread" then
230 self.fatalerror = err
233 if self.fatalerror then
234 if "onconnect" == arg then
235 self.ondisconnect = nil -- dont call this when client isnt really connected
238 debug( "handshake failed because:", self.fatalerror )
239 self.eventhandshake = nil
242 event = coroutine_yield( event, cfg.HANDSHAKE_TIMEOUT ) -- yield this monster...
246 debug "starting handshake..."
247 self:_lock( false, true, true ) -- unlock read/write events, but keep interface locked
248 self.eventhandshake = addevent( base, self.conn, EV_READWRITE, handshakecallback, cfg.HANDSHAKE_TIMEOUT )
251 function interface_mt:_destroy() -- close this interface + events and call last listener
252 debug( "closing client with id:", self.id )
253 self:_lock( true, true, true ) -- first of all, lock the interface to avoid further actions
255 _ = self.eventread and self.eventread:close( ) -- close events; this must be called outside of the event callbacks!
256 if self.type == "client" then
257 _ = self.eventwrite and self.eventwrite:close( )
258 _ = self.eventhandshake and self.eventhandshake:close( )
259 _ = self.eventstarthandshake and self.eventstarthandshake:close( )
260 _ = self.eventconnect and self.eventconnect:close( )
261 _ = self.eventsession and self.eventsession:close( )
262 _ = self.eventwritetimeout and self.eventwritetimeout:close( )
263 _ = self.eventreadtimeout and self.eventreadtimeout:close( )
264 _ = self.ondisconnect and self:ondisconnect( self.fatalerror ) -- call ondisconnect listener (wont be the case if handshake failed on connect)
265 _ = self.conn and self.conn:close( ) -- close connection, must also be called outside of any socket registered events!
266 _ = self._server and self._server:counter(-1);
267 self.eventread, self.eventwrite = nil, nil
268 self.eventstarthandshake, self.eventhandshake, self.eventclose = nil, nil, nil
269 self.readcallback, self.writecallback = nil, nil
272 self.eventread, self.eventclose = nil, nil
273 self.interface, self.readcallback = nil, nil
275 interfacelist( "delete", self )
279 function interface_mt:_lock(nointerface, noreading, nowriting) -- lock or unlock this interface or events
280 self.nointerface, self.noreading, self.nowriting = nointerface, noreading, nowriting
281 return nointerface, noreading, nowriting
284 function interface_mt:counter(c)
286 self._connections = self._connections + c
288 return self._connections
292 function interface_mt:write(data)
293 if self.nowriting then return nil, "locked" end
294 --vdebug( "try to send data to client, id/data:", self.id, data )
295 data = tostring( data )
296 local len = string_len( data )
297 local total = len + self.writebufferlen
298 if total > cfg.MAX_SEND_LENGTH then -- check buffer length
299 local err = "send buffer exceeded"
300 debug( "error:", err ) -- to much, check your app
303 self.writebuffer = self.writebuffer .. data -- new buffer
304 self.writebufferlen = total
305 if not self.eventwrite then -- register new write event
306 --vdebug( "register new write event" )
307 self.eventwrite = addevent( base, self.conn, EV_WRITE, self.writecallback, cfg.WRITE_TIMEOUT )
311 function interface_mt:close(now)
312 if self.nointerface then return nil, "locked"; end
313 debug( "try to close client connection with id:", self.id )
314 if self.type == "client" then
315 self.fatalerror = "client to close"
316 if ( not self.eventwrite ) or now then -- try to close immediately
317 self:_lock( true, true, true )
320 else -- wait for incomplete write request
321 self:_lock( true, true, false )
322 debug "closing delayed until writebuffer is empty"
323 return nil, "writebuffer not empty, waiting"
326 debug( "try to close server with id:", self.id, "args:", now )
327 self.fatalerror = "server to close"
330 for _, item in ipairs( interfacelist( ) ) do
331 if ( item.type ~= "server" ) and ( item._server == self ) then -- client/server match
332 if item:close( now ) then -- writebuffer was empty
337 local timeout = 0 -- dont wait for unfinished writebuffers of clients...
339 timeout = cfg.WRITE_TIMEOUT -- ...or wait for it
341 self:_close( timeout ) -- add new event to remove the server interface
342 debug( "seconds remained until server is closed:", timeout )
343 return count -- returns finished clients with empty writebuffer
347 function interface_mt:server()
348 return self._server or self;
351 function interface_mt:port()
355 function interface_mt:serverport()
356 return self._serverport
359 function interface_mt:ip()
363 function interface_mt:ssl()
364 return self._usingssl
367 function interface_mt:type()
368 return self._type or "client"
371 function interface_mt:connections()
372 return self._connections
375 function interface_mt:address()
379 function interface_mt:set_sslctx(sslctx)
380 self._sslctx = sslctx;
382 self.starttls = nil; -- use starttls() of interface_mt
384 self.starttls = false; -- prevent starttls()
388 function interface_mt:set_send(new_send)
389 -- No-op, we always use the underlying connection's send
392 function interface_mt:starttls()
393 debug( "try to start ssl at client id:", self.id )
395 if not self._sslctx then -- no ssl available
396 err = "no ssl context available"
397 elseif self._usingssl then -- startssl was already called
398 err = "ssl already active"
401 debug( "error:", err )
404 self._usingssl = true
405 self.startsslcallback = function( ) -- we have to start the handshake outside of a read/write event
406 self.startsslcallback = nil
408 self.eventstarthandshake = nil
411 if not self.eventwrite then
412 self:_lock( true, true, true ) -- lock the interface, to not disturb the handshake
413 self.eventstarthandshake = addevent( base, nil, EV_TIMEOUT, self.startsslcallback, 0 ) -- add event to start handshake
414 else -- wait until writebuffer is empty
415 self:_lock( true, true, false )
416 debug "ssl session delayed until writebuffer is empty..."
418 self.starttls = false;
422 function interface_mt:setoption(option, value)
423 return self.conn:setoption(option, value);
427 function interface_mt:onconnect()
429 function interface_mt:onincoming()
431 function interface_mt:ondisconnect()
433 function interface_mt:ontimeout()
437 -- End of client interface methods
441 local string_sub = string.sub -- caching table lookups
442 local string_len = string.len
443 local addevent = base.addevent
444 local coroutine_wrap = coroutine.wrap
445 local socket_gettime = socket.gettime
446 local coroutine_yield = coroutine.yield
447 function handleclient( client, ip, port, server, pattern, listener, _, sslctx ) -- creates an client interface
448 --vdebug("creating client interfacce...")
452 currenttime = socket_gettime( ); -- safe the origin
453 writebuffer = ""; -- writebuffer
454 writebufferlen = 0; -- length of writebuffer
455 send = client.send; -- caching table lookups
456 receive = client.receive;
457 onconnect = listener.onconnect; -- will be called when client disconnects
458 ondisconnect = listener.ondisconnect; -- will be called when client disconnects
459 onincoming = listener.onincoming; -- will be called when client sends data
460 ontimeout = listener.ontimeout; -- called when fatal socket timeout occurs
461 eventread = false, eventwrite = false, eventclose = false,
462 eventhandshake = false, eventstarthandshake = false; -- event handler
463 eventconnect = false, eventsession = false; -- more event handler...
464 eventwritetimeout = false; -- even more event handler...
465 eventreadtimeout = false;
466 fatalerror = false; -- error message
467 writecallback = false; -- will be called on write events
468 readcallback = false; -- will be called on read events
469 nointerface = true; -- lock/unlock parameter of this interface
470 noreading = false, nowriting = false; -- locks of the read/writecallback
471 startsslcallback = false; -- starting handshake callback
472 position = false; -- position of client in interfacelist
475 _ip = ip, _port = port, _server = server, _pattern = pattern,
476 _serverport = (server and server:port() or nil),
477 _sslctx = sslctx; -- parameters
478 _usingssl = false; -- client is using ssl;
481 interface.starttls = false -- don't allow TLS
483 interface.id = tostring(interface):match("%x+$");
484 interface.writecallback = function( event ) -- called on write events
485 --vdebug( "new client write event, id/ip/port:", interface, ip, port )
486 if interface.nowriting or ( interface.fatalerror and ( "client to close" ~= interface.fatalerror ) ) then -- leave this event
487 --vdebug( "leaving this event because:", interface.nowriting or interface.fatalerror )
488 interface.eventwrite = false
491 if EV_TIMEOUT == event then -- took too long to write some data to socket -> disconnect
492 interface.fatalerror = "timeout during writing"
493 debug( "writing failed:", interface.fatalerror )
495 interface.eventwrite = false
498 if interface._usingssl then -- handle luasec
499 if interface.eventreadtimeout then -- we have to read first
500 local ret = interface.readcallback( ) -- call readcallback
501 --vdebug( "tried to read in writecallback, result:", ret )
503 if interface.eventwritetimeout then -- luasec only
504 interface.eventwritetimeout:close( ) -- first we have to close timeout event which where regged after a wantread error
505 interface.eventwritetimeout = false
508 local succ, err, byte = interface.conn:send( interface.writebuffer, 1, interface.writebufferlen )
509 --vdebug( "write data:", interface.writebuffer, "error:", err, "part:", byte )
510 if succ then -- writing succesful
511 interface.writebuffer = ""
512 interface.writebufferlen = 0
513 if interface.fatalerror then
514 debug "closing client after writing"
515 interface:_close() -- close interface if needed
516 elseif interface.startsslcallback then -- start ssl connection if needed
517 debug "starting ssl handshake after writing"
518 interface.eventstarthandshake = addevent( base, nil, EV_TIMEOUT, interface.startsslcallback, 0 )
519 elseif interface.eventreadtimeout then
520 return EV_WRITE, EV_TIMEOUT
522 interface.eventwrite = nil
524 elseif byte then -- want write again
525 --vdebug( "writebuffer is not empty:", err )
526 interface.writebuffer = string_sub( interface.writebuffer, byte + 1, interface.writebufferlen ) -- new buffer
527 interface.writebufferlen = interface.writebufferlen - byte
528 if "wantread" == err then -- happens only with luasec
529 local callback = function( )
531 interface.eventwritetimeout = nil
532 return evreturn, evtimeout
534 interface.eventwritetimeout = addevent( base, nil, EV_TIMEOUT, callback, cfg.WRITE_TIMEOUT ) -- reg a new timeout event
535 debug( "wantread during write attemp, reg it in readcallback but dont know what really happens next..." )
536 -- hopefully this works with luasec; its simply not possible to use 2 different write events on a socket in luaevent
539 return EV_WRITE, cfg.WRITE_TIMEOUT
540 else -- connection was closed during writing or fatal error
541 interface.fatalerror = err or "fatal error"
542 debug( "connection failed in write event:", interface.fatalerror )
544 interface.eventwrite = nil
550 interface.readcallback = function( event ) -- called on read events
551 --vdebug( "new client read event, id/ip/port:", tostring(interface.id), tostring(ip), tostring(port) )
552 if interface.noreading or interface.fatalerror then -- leave this event
553 --vdebug( "leaving this event because:", tostring(interface.noreading or interface.fatalerror) )
554 interface.eventread = nil
557 if EV_TIMEOUT == event then -- took too long to get some data from client -> disconnect
558 interface.fatalerror = "timeout during receiving"
559 debug( "connection failed:", interface.fatalerror )
561 interface.eventread = nil
564 if interface._usingssl then -- handle luasec
565 if interface.eventwritetimeout then -- ok, in the past writecallback was regged
566 local ret = interface.writecallback( ) -- call it
567 --vdebug( "tried to write in readcallback, result:", tostring(ret) )
569 if interface.eventreadtimeout then
570 interface.eventreadtimeout:close( )
571 interface.eventreadtimeout = nil
574 local buffer, err, part = interface.conn:receive( pattern ) -- receive buffer with "pattern"
575 --vdebug( "read data:", tostring(buffer), "error:", tostring(err), "part:", tostring(part) )
576 buffer = buffer or part or ""
577 local len = string_len( buffer )
578 if len > cfg.MAX_READ_LENGTH then -- check buffer length
579 interface.fatalerror = "receive buffer exceeded"
580 debug( "fatal error:", interface.fatalerror )
582 interface.eventread = nil
585 interface.onincoming( interface, buffer, err ) -- send new data to listener
586 if err and ( err ~= "timeout" and err ~= "wantread" ) then
587 if "wantwrite" == err then -- need to read on write event
588 if not interface.eventwrite then -- register new write event if needed
589 interface.eventwrite = addevent( base, interface.conn, EV_WRITE, interface.writecallback, cfg.WRITE_TIMEOUT )
591 interface.eventreadtimeout = addevent( base, nil, EV_TIMEOUT,
594 end, cfg.READ_TIMEOUT
596 debug( "wantwrite during read attemp, reg it in writecallback but dont know what really happens next..." )
597 -- to be honest i dont know what happens next, if it is allowed to first read, the write etc...
598 else -- connection was closed or fatal error
599 interface.fatalerror = err
600 debug( "connection failed in read event:", interface.fatalerror )
602 interface.eventread = nil
606 return EV_READ, cfg.READ_TIMEOUT
610 client:settimeout( 0 ) -- set non blocking
611 setmetatable(interface, interface_mt)
612 interfacelist( "add", interface ) -- add to interfacelist
619 function handleserver( server, addr, port, pattern, listener, sslctx, startssl ) -- creates an server interface
620 debug "creating server interface..."
625 onconnect = listener.onconnect; -- will be called when new client connected
626 eventread = false; -- read event handler
627 eventclose = false; -- close event handler
628 readcallback = false; -- read event callback
629 fatalerror = false; -- error message
630 nointerface = true; -- lock/unlock parameter
632 _ip = addr, _port = port, _pattern = pattern,
635 interface.id = tostring(interface):match("%x+$");
636 interface.readcallback = function( event ) -- server handler, called on incoming connections
637 --vdebug( "server can accept, id/addr/port:", interface, addr, port )
638 if interface.fatalerror then
639 --vdebug( "leaving this event because:", self.fatalerror )
640 interface.eventread = nil
643 local delay = cfg.ACCEPT_DELAY
644 if EV_TIMEOUT == event then
645 if interface._connections >= cfg.MAX_CONNECTIONS then -- check connection count
646 debug( "to many connections, seconds to wait for next accept:", delay )
647 return EV_TIMEOUT, delay -- timeout...
649 return EV_READ -- accept again
652 --vdebug("max connection check ok, accepting...")
653 local client, err = server:accept() -- try to accept; TODO: check err
655 if interface._connections >= cfg.MAX_CONNECTIONS then
656 client:close( ) -- refuse connection
657 debug( "maximal connections reached, refuse client connection; accept delay:", delay )
658 return EV_TIMEOUT, delay -- delay for next accept attemp
660 local ip, port = client:getpeername( )
661 interface._connections = interface._connections + 1 -- increase connection count
662 local clientinterface = handleclient( client, ip, port, interface, pattern, listener, nil, sslctx )
663 --vdebug( "client id:", clientinterface, "startssl:", startssl )
665 clientinterface:_start_ssl( clientinterface.onconnect )
667 clientinterface:_start_session( clientinterface.onconnect )
669 debug( "accepted incoming client connection from:", ip, port )
670 client, err = server:accept() -- try to accept again
675 server:settimeout( 0 )
676 setmetatable(interface, interface_mt)
677 interfacelist( "add", interface )
678 interface:_start_session()
683 local addserver = ( function( )
684 return function( addr, port, listener, pattern, sslcfg, startssl ) -- TODO: check arguments
685 --vdebug( "creating new tcp server with following parameters:", addr or "nil", port or "nil", sslcfg or "nil", startssl or "nil")
686 local server, err = socket.bind( addr, port, cfg.ACCEPT_QUEUE ) -- create server socket
688 debug( "creating server socket failed because:", err )
694 debug "fatal error: luasec not found"
695 return nil, "luasec not found"
697 sslctx, err = ssl.newcontext( sslcfg )
699 debug( "error while creating new ssl context for server socket:", err )
703 local interface = handleserver( server, addr, port, pattern, listener, sslctx, startssl ) -- new server handler
704 debug( "new server created with id:", tostring(interface))
709 local addclient, wrapclient
711 function wrapclient( client, ip, port, listeners, pattern, sslctx, startssl )
712 local interface = handleclient( client, ip, port, nil, pattern, listeners, sslctx )
713 interface:_start_session()
715 --function handleclient( client, ip, port, server, pattern, listener, _, sslctx ) -- creates an client interface
718 function addclient( addr, serverport, listener, pattern, localaddr, localport, sslcfg, startssl )
719 local client, err = socket.tcp() -- creating new socket
721 debug( "cannot create socket:", err )
724 client:settimeout( 0 ) -- set nonblocking
726 local res, err = client:bind( localaddr, localport, -1 )
728 debug( "cannot bind client:", err )
733 if sslcfg then -- handle ssl/new context
735 debug "need luasec, but not available"
736 return nil, "luasec not found"
738 sslctx, err = ssl.newcontext( sslcfg )
740 debug( "cannot create new ssl context:", err )
744 local res, err = client:connect( addr, serverport ) -- connect
745 if res or ( err == "timeout" ) then
746 local ip, port = client:getsockname( )
747 local server = function( )
748 return nil, "this is a dummy server interface"
750 local interface = wrapclient( client, ip, serverport, listeners, pattern, sslctx, startssl )
751 interface:_start_connection( startssl )
752 debug( "new connection id:", interface.id )
753 return interface, err
755 debug( "new connection failed:", err )
762 local loop = function( ) -- starts the event loop
767 local newevent = ( function( )
768 local add = base.addevent
769 return function( ... )
770 return add( base, ... )
774 local closeallservers = function( arg )
775 for _, item in ipairs( interfacelist( ) ) do
776 if item.type == "server" then
782 local function setquitting(yes)
790 function get_backend()
791 return base:method();
794 -- We need to hold onto the events to stop them
795 -- being garbage-collected
796 local signal_events = {}; -- [signal_num] -> event object
797 function hook_signal(signal_num, handler)
798 local function _handler(event)
799 local ret = handler();
800 if ret ~= false then -- Continue handling this signal?
801 return EV_SIGNAL; -- Yes
803 return -1; -- Close this event
805 signal_events[signal_num] = base:addevent(signal_num, EV_SIGNAL, _handler);
806 return signal_events[signal_num];
817 addserver = addserver,
818 addclient = addclient,
819 wrapclient = wrapclient,
820 setquitting = setquitting,
821 closeall = closeallservers,
822 get_backend = get_backend,
823 hook_signal = hook_signal,
825 __NAME = SCRIPT_NAME,
826 __DATE = LAST_MODIFIED,
827 __AUTHOR = SCRIPT_AUTHOR,
828 __VERSION = SCRIPT_VERSION,