net/server_event.lua

   1 --[[
   2
   3
   4                         server.lua based on lua/libevent by blastbeat
   5
   6                         notes:
   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                         -- to do some of the above, use timeout events or something what will called from outside
  10                         -- dont let garbagecollect eventcallbacks, as long they are running
  11                         -- when using luasec, there are 4 cases of timeout errors: wantread or wantwrite during reading or writing
  12
  13 --]]
  14 -- luacheck: ignore 212/self 431/err 211/ret
  15
  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"
  20
  21 local cfg = {
  22         MAX_CONNECTIONS       = 100000,  -- max per server connections (use "ulimit -n" on *nix)
  23         MAX_HANDSHAKE_ATTEMPTS= 1000,  -- attempts to finish ssl handshake
  24         HANDSHAKE_TIMEOUT     = 60,  -- timeout in seconds per handshake attempt
  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_QUEUE          = 128,  -- might influence the length of the pending sockets queue
  28         ACCEPT_DELAY          = 10,  -- seconds to wait until the next attempt of a full server to accept
  29         READ_TIMEOUT          = 60 * 60 * 6,  -- timeout in seconds for read data from socket
  30         WRITE_TIMEOUT         = 180,  -- timeout in seconds for write data on socket
  31         CONNECT_TIMEOUT       = 20,  -- timeout in seconds for connection attempts
  32         CLEAR_DELAY           = 5,  -- seconds to wait for clearing interface list (and calling ondisconnect listeners)
  33         DEBUG                 = true,  -- show debug messages
  34 }
  35
  36 local pairs = pairs
  37 local select = select
  38 local require = require
  39 local tostring = tostring
  40 local setmetatable = setmetatable
  41
  42 local t_insert = table.insert
  43 local t_concat = table.concat
  44 local s_sub = string.sub
  45
  46 local coroutine_wrap = coroutine.wrap
  47 local coroutine_yield = coroutine.yield
  48
  49 local has_luasec, ssl = pcall ( require , "ssl" )
  50 local socket = require "socket"
  51 local event = require "luaevent.core"
  52
  53 local socket_gettime = socket.gettime
  54 local getaddrinfo = socket.dns.getaddrinfo
  55
  56 local log = require ("util.logger").init("socket")
  57
  58 local function debug(...)
  59         return log("debug", ("%s "):rep(select('#', ...)), ...)
  60 end
  61 local vdebug = debug;
  62
  63 local bitor = ( function( ) -- thx Rici Lake
  64         local hasbit = function( x, p )
  65                 return x % ( p + p ) >= p
  66         end
  67         return function( x, y )
  68                 local p = 1
  69                 local z = 0
  70                 local limit = x > y and x or y
  71                 while p <= limit do
  72                         if hasbit( x, p ) or hasbit( y, p ) then
  73                                 z = z + p
  74                         end
  75                         p = p + p
  76                 end
  77                 return z
  78         end
  79 end )( )
  80
  81 local base = event.new( )
  82 local addevent = base.addevent
  83 local EV_READ = event.EV_READ
  84 local EV_WRITE = event.EV_WRITE
  85 local EV_TIMEOUT = event.EV_TIMEOUT
  86 local EV_SIGNAL = event.EV_SIGNAL
  87
  88 local EV_READWRITE = bitor( EV_READ, EV_WRITE )
  89
  90 local interfacelist = { }
  91
  92 -- Client interface methods
  93 local interface_mt = {}; interface_mt.__index = interface_mt;
  94
  95 -- Private methods
  96 function interface_mt:_close()
  97         return self:_destroy();
  98 end
  99
 100 function interface_mt:_start_connection(plainssl) -- should be called from addclient
 101                 local callback = function( event )
 102                         if EV_TIMEOUT == event then  -- timeout during connection
 103                                 self.fatalerror = "connection timeout"
 104                                 self:ontimeout()  -- call timeout listener
 105                                 self:_close()
 106                                 debug( "new connection failed. id:", self.id, "error:", self.fatalerror )
 107                         else
 108                                 if plainssl and has_luasec then  -- start ssl session
 109                                         self:starttls(self._sslctx, true)
 110                                 else  -- normal connection
 111                                         self:_start_session(true)
 112                                 end
 113                                 debug( "new connection established. id:", self.id )
 114                         end
 115                         self.eventconnect = nil
 116                         return -1
 117                 end
 118                 self.eventconnect = addevent( base, self.conn, EV_WRITE, callback, cfg.CONNECT_TIMEOUT )
 119                 return true
 120 end
 121 function interface_mt:_start_session(call_onconnect) -- new session, for example after startssl
 122         if self.type == "client" then
 123                 local callback = function( )
 124                         self:_lock( false,  false, false )
 125                         --vdebug( "start listening on client socket with id:", self.id )
 126                         self.eventread = addevent( base, self.conn, EV_READ, self.readcallback, cfg.READ_TIMEOUT );  -- register callback
 127                         if call_onconnect then
 128                                 self:onconnect()
 129                         end
 130                         self.eventsession = nil
 131                         return -1
 132                 end
 133                 self.eventsession = addevent( base, nil, EV_TIMEOUT, callback, 0 )
 134         else
 135                 self:_lock( false )
 136                 --vdebug( "start listening on server socket with id:", self.id )
 137                 self.eventread = addevent( base, self.conn, EV_READ, self.readcallback )  -- register callback
 138         end
 139         return true
 140 end
 141 function interface_mt:_start_ssl(call_onconnect) -- old socket will be destroyed, therefore we have to close read/write events first
 142                 --vdebug( "starting ssl session with client id:", self.id )
 143                 local _
 144                 _ = self.eventread and self.eventread:close( )  -- close events; this must be called outside of the event callbacks!
 145                 _ = self.eventwrite and self.eventwrite:close( )
 146                 self.eventread, self.eventwrite = nil, nil
 147                 local err
 148                 self.conn, err = ssl.wrap( self.conn, self._sslctx )
 149                 if err then
 150                         self.fatalerror = err
 151                         self.conn = nil  -- cannot be used anymore
 152                         if call_onconnect then
 153                                 self.ondisconnect = nil  -- dont call this when client isnt really connected
 154                         end
 155                         self:_close()
 156                         debug( "fatal error while ssl wrapping:", err )
 157                         return false
 158                 end
 159                 self.conn:settimeout( 0 )  -- set non blocking
 160                 local handshakecallback = coroutine_wrap(
 161                         function( event )
 162                                 local _, err
 163                                 local attempt = 0
 164                                 local maxattempt = cfg.MAX_HANDSHAKE_ATTEMPTS
 165                                 while attempt < maxattempt do  -- no endless loop
 166                                         attempt = attempt + 1
 167                                         debug( "ssl handshake of client with id:"..tostring(self)..", attempt:"..attempt )
 168                                         if attempt > maxattempt then
 169                                                 self.fatalerror = "max handshake attempts exceeded"
 170                                         elseif EV_TIMEOUT == event then
 171                                                 self.fatalerror = "timeout during handshake"
 172                                         else
 173                                                 _, err = self.conn:dohandshake( )
 174                                                 if not err then
 175                                                         self:_lock( false, false, false )  -- unlock the interface; sending, closing etc allowed
 176                                                         self.send = self.conn.send  -- caching table lookups with new client object
 177                                                         self.receive = self.conn.receive
 178                                                         if not call_onconnect then  -- trigger listener
 179                                                                 self:onstatus("ssl-handshake-complete");
 180                                                         end
 181                                                         self:_start_session( call_onconnect )
 182                                                         debug( "ssl handshake done" )
 183                                                         self.eventhandshake = nil
 184                                                         return -1
 185                                                 end
 186                                                 if err == "wantwrite" then
 187                                                         event = EV_WRITE
 188                                                 elseif err == "wantread" then
 189                                                         event = EV_READ
 190                                                 else
 191                                                         debug( "ssl handshake error:", err )
 192                                                         self.fatalerror = err
 193                                                 end
 194                                         end
 195                                         if self.fatalerror then
 196                                                 if call_onconnect then
 197                                                         self.ondisconnect = nil  -- dont call this when client isnt really connected
 198                                                 end
 199                                                 self:_close()
 200                                                 debug( "handshake failed because:", self.fatalerror )
 201                                                 self.eventhandshake = nil
 202                                                 return -1
 203                                         end
 204                                         event = coroutine_yield( event, cfg.HANDSHAKE_TIMEOUT )  -- yield this monster...
 205                                 end
 206                         end
 207                 )
 208                 debug "starting handshake..."
 209                 self:_lock( false, true, true )  -- unlock read/write events, but keep interface locked
 210                 self.eventhandshake = addevent( base, self.conn, EV_READWRITE, handshakecallback, cfg.HANDSHAKE_TIMEOUT )
 211                 return true
 212 end
 213 function interface_mt:_destroy()  -- close this interface + events and call last listener
 214                 debug( "closing client with id:", self.id, self.fatalerror )
 215                 self:_lock( true, true, true )  -- first of all, lock the interface to avoid further actions
 216                 local _
 217                 _ = self.eventread and self.eventread:close( )
 218                 if self.type == "client" then
 219                         _ = self.eventwrite and self.eventwrite:close( )
 220                         _ = self.eventhandshake and self.eventhandshake:close( )
 221                         _ = self.eventstarthandshake and self.eventstarthandshake:close( )
 222                         _ = self.eventconnect and self.eventconnect:close( )
 223                         _ = self.eventsession and self.eventsession:close( )
 224                         _ = self.eventwritetimeout and self.eventwritetimeout:close( )
 225                         _ = self.eventreadtimeout and self.eventreadtimeout:close( )
 226                         _ = self.ondisconnect and self:ondisconnect( self.fatalerror ~= "client to close" and self.fatalerror)  -- call ondisconnect listener (wont be the case if handshake failed on connect)
 227                         _ = self.conn and self.conn:close( ) -- close connection
 228                         _ = self._server and self._server:counter(-1);
 229                         self.eventread, self.eventwrite = nil, nil
 230                         self.eventstarthandshake, self.eventhandshake, self.eventclose = nil, nil, nil
 231                         self.readcallback, self.writecallback = nil, nil
 232                 else
 233                         self.conn:close( )
 234                         self.eventread, self.eventclose = nil, nil
 235                         self.interface, self.readcallback = nil, nil
 236                 end
 237                 interfacelist[ self ] = nil
 238                 return true
 239 end
 240
 241 function interface_mt:_lock(nointerface, noreading, nowriting)  -- lock or unlock this interface or events
 242                 self.nointerface, self.noreading, self.nowriting = nointerface, noreading, nowriting
 243                 return nointerface, noreading, nowriting
 244 end
 245
 246 --TODO: Deprecate
 247 function interface_mt:lock_read(switch)
 248         if switch then
 249                 return self:pause();
 250         else
 251                 return self:resume();
 252         end
 253 end
 254
 255 function interface_mt:pause()
 256         return self:_lock(self.nointerface, true, self.nowriting);
 257 end
 258
 259 function interface_mt:resume()
 260         self:_lock(self.nointerface, false, self.nowriting);
 261         if not self.eventread then
 262                 self.eventread = addevent( base, self.conn, EV_READ, self.readcallback, cfg.READ_TIMEOUT );  -- register callback
 263         end
 264 end
 265
 266 function interface_mt:counter(c)
 267         if c then
 268                 self._connections = self._connections + c
 269         end
 270         return self._connections
 271 end
 272
 273 -- Public methods
 274 function interface_mt:write(data)
 275         if self.nowriting then return nil, "locked" end
 276         --vdebug( "try to send data to client, id/data:", self.id, data )
 277         data = tostring( data )
 278         local len = #data
 279         local total = len + self.writebufferlen
 280         if total > cfg.MAX_SEND_LENGTH then  -- check buffer length
 281                 local err = "send buffer exceeded"
 282                 debug( "error:", err )  -- to much, check your app
 283                 return nil, err
 284         end
 285         t_insert(self.writebuffer, data) -- new buffer
 286         self.writebufferlen = total
 287         if not self.eventwrite then  -- register new write event
 288                 --vdebug( "register new write event" )
 289                 self.eventwrite = addevent( base, self.conn, EV_WRITE, self.writecallback, cfg.WRITE_TIMEOUT )
 290         end
 291         return true
 292 end
 293 function interface_mt:close()
 294         if self.nointerface then return nil, "locked"; end
 295         debug( "try to close client connection with id:", self.id )
 296         if self.type == "client" then
 297                 self.fatalerror = "client to close"
 298                 if self.eventwrite then -- wait for incomplete write request
 299                         self:_lock( true, true, false )
 300                         debug "closing delayed until writebuffer is empty"
 301                         return nil, "writebuffer not empty, waiting"
 302                 else -- close now
 303                         self:_lock( true, true, true )
 304                         self:_close()
 305                         return true
 306                 end
 307         else
 308                 debug( "try to close server with id:", tostring(self.id))
 309                 self.fatalerror = "server to close"
 310                 self:_lock( true )
 311                 self:_close( 0 )
 312                 return true
 313         end
 314 end
 315
 316 function interface_mt:socket()
 317         return self.conn
 318 end
 319
 320 function interface_mt:server()
 321         return self._server or self;
 322 end
 323
 324 function interface_mt:port()
 325         return self._port
 326 end
 327
 328 function interface_mt:serverport()
 329         return self._serverport
 330 end
 331
 332 function interface_mt:ip()
 333         return self._ip
 334 end
 335
 336 function interface_mt:ssl()
 337         return self._usingssl
 338 end
 339 interface_mt.clientport = interface_mt.port -- COMPAT server_select
 340
 341 function interface_mt:type()
 342         return self._type or "client"
 343 end
 344
 345 function interface_mt:connections()
 346         return self._connections
 347 end
 348
 349 function interface_mt:address()
 350         return self.addr
 351 end
 352
 353 function interface_mt:set_sslctx(sslctx)
 354         self._sslctx = sslctx;
 355         if sslctx then
 356                 self.starttls = nil; -- use starttls() of interface_mt
 357         else
 358                 self.starttls = false; -- prevent starttls()
 359         end
 360 end
 361
 362 function interface_mt:set_mode(pattern)
 363         if pattern then
 364                 self._pattern = pattern;
 365         end
 366         return self._pattern;
 367 end
 368
 369 function interface_mt:set_send(new_send) -- luacheck: ignore 212
 370         -- No-op, we always use the underlying connection's send
 371 end
 372
 373 function interface_mt:starttls(sslctx, call_onconnect)
 374         debug( "try to start ssl at client id:", self.id )
 375         local err
 376         self._sslctx = sslctx;
 377         if self._usingssl then  -- startssl was already called
 378                 err = "ssl already active"
 379         end
 380         if err then
 381                 debug( "error:", err )
 382                 return nil, err
 383         end
 384         self._usingssl = true
 385         self.startsslcallback = function( )  -- we have to start the handshake outside of a read/write event
 386                 self.startsslcallback = nil
 387                 self:_start_ssl(call_onconnect);
 388                 self.eventstarthandshake = nil
 389                 return -1
 390         end
 391         if not self.eventwrite then
 392                 self:_lock( true, true, true )  -- lock the interface, to not disturb the handshake
 393                 self.eventstarthandshake = addevent( base, nil, EV_TIMEOUT, self.startsslcallback, 0 )  -- add event to start handshake
 394         else  -- wait until writebuffer is empty
 395                 self:_lock( true, true, false )
 396                 debug "ssl session delayed until writebuffer is empty..."
 397         end
 398         self.starttls = false;
 399         return true
 400 end
 401
 402 function interface_mt:setoption(option, value)
 403         if self.conn.setoption then
 404                 return self.conn:setoption(option, value);
 405         end
 406         return false, "setoption not implemented";
 407 end
 408
 409 function interface_mt:setlistener(listener)
 410         self:ondetach(); -- Notify listener that it is no longer responsible for this connection
 411         self.onconnect, self.ondisconnect, self.onincoming, self.ontimeout,
 412         self.onreadtimeout, self.onstatus, self.ondetach
 413                 = listener.onconnect, listener.ondisconnect, listener.onincoming, listener.ontimeout,
 414                   listener.onreadtimeout, listener.onstatus, listener.ondetach;
 415 end
 416
 417 -- Stub handlers
 418 function interface_mt:onconnect()
 419 end
 420 function interface_mt:onincoming()
 421 end
 422 function interface_mt:ondisconnect()
 423 end
 424 function interface_mt:ontimeout()
 425 end
 426 function interface_mt:onreadtimeout()
 427         self.fatalerror = "timeout during receiving"
 428         debug( "connection failed:", self.fatalerror )
 429         self:_close()
 430         self.eventread = nil
 431 end
 432 function interface_mt:ondrain()
 433 end
 434 function interface_mt:ondetach()
 435 end
 436 function interface_mt:onstatus()
 437 end
 438
 439 -- End of client interface methods
 440
 441 local function handleclient( client, ip, port, server, pattern, listener, sslctx )  -- creates an client interface
 442         --vdebug("creating client interfacce...")
 443         local interface = {
 444                 type = "client";
 445                 conn = client;
 446                 currenttime = socket_gettime( );  -- safe the origin
 447                 writebuffer = {};  -- writebuffer
 448                 writebufferlen = 0;  -- length of writebuffer
 449                 send = client.send;  -- caching table lookups
 450                 receive = client.receive;
 451                 onconnect = listener.onconnect;  -- will be called when client disconnects
 452                 ondisconnect = listener.ondisconnect;  -- will be called when client disconnects
 453                 onincoming = listener.onincoming;  -- will be called when client sends data
 454                 ontimeout = listener.ontimeout; -- called when fatal socket timeout occurs
 455                 onreadtimeout = listener.onreadtimeout; -- called when socket inactivity timeout occurs
 456                 ondrain = listener.ondrain; -- called when writebuffer is empty
 457                 ondetach = listener.ondetach; -- called when disassociating this listener from this connection
 458                 onstatus = listener.onstatus; -- called for status changes (e.g. of SSL/TLS)
 459                 eventread = false, eventwrite = false, eventclose = false,
 460                 eventhandshake = false, eventstarthandshake = false;  -- event handler
 461                 eventconnect = false, eventsession = false;  -- more event handler...
 462                 eventwritetimeout = false;  -- even more event handler...
 463                 eventreadtimeout = false;
 464                 fatalerror = false;  -- error message
 465                 writecallback = false;  -- will be called on write events
 466                 readcallback = false;  -- will be called on read events
 467                 nointerface = true;  -- lock/unlock parameter of this interface
 468                 noreading = false, nowriting = false;  -- locks of the read/writecallback
 469                 startsslcallback = false;  -- starting handshake callback
 470                 position = false;  -- position of client in interfacelist
 471
 472                 -- Properties
 473                 _ip = ip, _port = port, _server = server, _pattern = pattern,
 474                 _serverport = (server and server:port() or nil),
 475                 _sslctx = sslctx; -- parameters
 476                 _usingssl = false;  -- client is using ssl;
 477         }
 478         if not has_luasec then interface.starttls = false; end
 479         interface.id = tostring(interface):match("%x+$");
 480         interface.writecallback = function( event )  -- called on write events
 481                 --vdebug( "new client write event, id/ip/port:", interface, ip, port )
 482                 if interface.nowriting or ( interface.fatalerror and ( "client to close" ~= interface.fatalerror ) ) then  -- leave this event
 483                         --vdebug( "leaving this event because:", interface.nowriting or interface.fatalerror )
 484                         interface.eventwrite = false
 485                         return -1
 486                 end
 487                 if EV_TIMEOUT == event then  -- took too long to write some data to socket -> disconnect
 488                         interface.fatalerror = "timeout during writing"
 489                         debug( "writing failed:", interface.fatalerror )
 490                         interface:_close()
 491                         interface.eventwrite = false
 492                         return -1
 493                 else  -- can write :)
 494                         if interface._usingssl then  -- handle luasec
 495                                 if interface.eventreadtimeout then  -- we have to read first
 496                                         local ret = interface.readcallback( )  -- call readcallback
 497                                         --vdebug( "tried to read in writecallback, result:", ret )
 498                                 end
 499                                 if interface.eventwritetimeout then  -- luasec only
 500                                         interface.eventwritetimeout:close( )  -- first we have to close timeout event which where regged after a wantread error
 501                                         interface.eventwritetimeout = false
 502                                 end
 503                         end
 504                         interface.writebuffer = { t_concat(interface.writebuffer) }
 505                         local succ, err, byte = interface.conn:send( interface.writebuffer[1], 1, interface.writebufferlen )
 506                         --vdebug( "write data:", interface.writebuffer, "error:", err, "part:", byte )
 507                         if succ then  -- writing succesful
 508                                 interface.writebuffer[1] = nil
 509                                 interface.writebufferlen = 0
 510                                 interface:ondrain();
 511                                 if interface.fatalerror then
 512                                         debug "closing client after writing"
 513                                         interface:_close()  -- close interface if needed
 514                                 elseif interface.startsslcallback then  -- start ssl connection if needed
 515                                         debug "starting ssl handshake after writing"
 516                                         interface.eventstarthandshake = addevent( base, nil, EV_TIMEOUT, interface.startsslcallback, 0 )
 517                                 elseif interface.eventreadtimeout then
 518                                         return EV_WRITE, EV_TIMEOUT
 519                                 end
 520                                 interface.eventwrite = nil
 521                                 return -1
 522                         elseif byte and (err == "timeout" or err == "wantwrite") then  -- want write again
 523                                 --vdebug( "writebuffer is not empty:", err )
 524                                 interface.writebuffer[1] = s_sub( interface.writebuffer[1], byte + 1, interface.writebufferlen )  -- new buffer
 525                                 interface.writebufferlen = interface.writebufferlen - byte
 526                                 if "wantread" == err then  -- happens only with luasec
 527                                         local callback = function( )
 528                                                 interface:_close()
 529                                                 interface.eventwritetimeout = nil
 530                                                 return -1;
 531                                         end
 532                                         interface.eventwritetimeout = addevent( base, nil, EV_TIMEOUT, callback, cfg.WRITE_TIMEOUT )  -- reg a new timeout event
 533                                         debug( "wantread during write attempt, reg it in readcallback but dont know what really happens next..." )
 534                                         -- hopefully this works with luasec; its simply not possible to use 2 different write events on a socket in luaevent
 535                                         return -1
 536                                 end
 537                                 return EV_WRITE, cfg.WRITE_TIMEOUT
 538                         else  -- connection was closed during writing or fatal error
 539                                 interface.fatalerror = err or "fatal error"
 540                                 debug( "connection failed in write event:", interface.fatalerror )
 541                                 interface:_close()
 542                                 interface.eventwrite = nil
 543                                 return -1
 544                         end
 545                 end
 546         end
 547
 548         interface.readcallback = function( event )  -- called on read events
 549                 --vdebug( "new client read event, id/ip/port:", tostring(interface.id), tostring(ip), tostring(port) )
 550                 if interface.noreading or interface.fatalerror then  -- leave this event
 551                         --vdebug( "leaving this event because:", tostring(interface.noreading or interface.fatalerror) )
 552                         interface.eventread = nil
 553                         return -1
 554                 end
 555                 if EV_TIMEOUT == event and interface:onreadtimeout() ~= true then
 556                         return -1 -- took too long to get some data from client -> disconnect
 557                 end
 558                 if interface._usingssl then  -- handle luasec
 559                         if interface.eventwritetimeout then  -- ok, in the past writecallback was regged
 560                                 local ret = interface.writecallback( )  -- call it
 561                                 --vdebug( "tried to write in readcallback, result:", tostring(ret) )
 562                         end
 563                         if interface.eventreadtimeout then
 564                                 interface.eventreadtimeout:close( )
 565                                 interface.eventreadtimeout = nil
 566                         end
 567                 end
 568                 local buffer, err, part = interface.conn:receive( interface._pattern )  -- receive buffer with "pattern"
 569                 --vdebug( "read data:", tostring(buffer), "error:", tostring(err), "part:", tostring(part) )
 570                 buffer = buffer or part
 571                 if buffer and #buffer > cfg.MAX_READ_LENGTH then  -- check buffer length
 572                         interface.fatalerror = "receive buffer exceeded"
 573                         debug( "fatal error:", interface.fatalerror )
 574                         interface:_close()
 575                         interface.eventread = nil
 576                         return -1
 577                 end
 578                 if err and ( err ~= "timeout" and err ~= "wantread" ) then
 579                         if "wantwrite" == err then -- need to read on write event
 580                                 if not interface.eventwrite then  -- register new write event if needed
 581                                         interface.eventwrite = addevent( base, interface.conn, EV_WRITE, interface.writecallback, cfg.WRITE_TIMEOUT )
 582                                 end
 583                                 interface.eventreadtimeout = addevent( base, nil, EV_TIMEOUT,
 584                                         function( )
 585                                                 interface:_close()
 586                                         end, cfg.READ_TIMEOUT
 587                                 )
 588                                 debug( "wantwrite during read attempt, reg it in writecallback but dont know what really happens next..." )
 589                                 -- to be honest i dont know what happens next, if it is allowed to first read, the write etc...
 590                         else  -- connection was closed or fatal error
 591                                 interface.fatalerror = err
 592                                 debug( "connection failed in read event:", interface.fatalerror )
 593                                 interface:_close()
 594                                 interface.eventread = nil
 595                                 return -1
 596                         end
 597                 else
 598                         interface.onincoming( interface, buffer, err )  -- send new data to listener
 599                 end
 600                 if interface.noreading then
 601                         interface.eventread = nil;
 602                         return -1;
 603                 end
 604                 return EV_READ, cfg.READ_TIMEOUT
 605         end
 606
 607         client:settimeout( 0 )  -- set non blocking
 608         setmetatable(interface, interface_mt)
 609         interfacelist[ interface ] = true  -- add to interfacelist
 610         return interface
 611 end
 612
 613 local function handleserver( server, addr, port, pattern, listener, sslctx )  -- creates an server interface
 614         debug "creating server interface..."
 615         local interface = {
 616                 _connections = 0;
 617
 618                 conn = server;
 619                 onconnect = listener.onconnect;  -- will be called when new client connected
 620                 eventread = false;  -- read event handler
 621                 eventclose = false; -- close event handler
 622                 readcallback = false; -- read event callback
 623                 fatalerror = false; -- error message
 624                 nointerface = true;  -- lock/unlock parameter
 625
 626                 _ip = addr, _port = port, _pattern = pattern,
 627                 _sslctx = sslctx;
 628         }
 629         interface.id = tostring(interface):match("%x+$");
 630         interface.readcallback = function( event )  -- server handler, called on incoming connections
 631                 --vdebug( "server can accept, id/addr/port:", interface, addr, port )
 632                 if interface.fatalerror then
 633                         --vdebug( "leaving this event because:", self.fatalerror )
 634                         interface.eventread = nil
 635                         return -1
 636                 end
 637                 local delay = cfg.ACCEPT_DELAY
 638                 if EV_TIMEOUT == event then
 639                         if interface._connections >= cfg.MAX_CONNECTIONS then  -- check connection count
 640                                 debug( "to many connections, seconds to wait for next accept:", delay )
 641                                 return EV_TIMEOUT, delay  -- timeout...
 642                         else
 643                                 return EV_READ  -- accept again
 644                         end
 645                 end
 646                 --vdebug("max connection check ok, accepting...")
 647                 local client, err = server:accept()    -- try to accept; TODO: check err
 648                 while client do
 649                         if interface._connections >= cfg.MAX_CONNECTIONS then
 650                                 client:close( )  -- refuse connection
 651                                 debug( "maximal connections reached, refuse client connection; accept delay:", delay )
 652                                 return EV_TIMEOUT, delay  -- delay for next accept attempt
 653                         end
 654                         local client_ip, client_port = client:getpeername( )
 655                         interface._connections = interface._connections + 1  -- increase connection count
 656                         local clientinterface = handleclient( client, client_ip, client_port, interface, pattern, listener, sslctx )
 657                         --vdebug( "client id:", clientinterface, "startssl:", startssl )
 658                         if has_luasec and sslctx then
 659                                 clientinterface:starttls(sslctx, true)
 660                         else
 661                                 clientinterface:_start_session( true )
 662                         end
 663                         debug( "accepted incoming client connection from:", client_ip or "<unknown IP>", client_port or "<unknown port>", "to", port or "<unknown port>");
 664
 665                         client, err = server:accept()    -- try to accept again
 666                 end
 667                 return EV_READ
 668         end
 669
 670         server:settimeout( 0 )
 671         setmetatable(interface, interface_mt)
 672         interfacelist[ interface ] = true
 673         interface:_start_session()
 674         return interface
 675 end
 676
 677 local function addserver( addr, port, listener, pattern, sslctx, startssl )  -- TODO: check arguments
 678         --vdebug( "creating new tcp server with following parameters:", addr or "nil", port or "nil", sslctx or "nil", startssl or "nil")
 679         if sslctx and not has_luasec then
 680                 debug "fatal error: luasec not found"
 681                 return nil, "luasec not found"
 682         end
 683         local server, err = socket.bind( addr, port, cfg.ACCEPT_QUEUE )  -- create server socket
 684         if not server then
 685                 debug( "creating server socket on "..addr.." port "..port.." failed:", err )
 686                 return nil, err
 687         end
 688         local interface = handleserver( server, addr, port, pattern, listener, sslctx, startssl )  -- new server handler
 689         debug( "new server created with id:", tostring(interface))
 690         return interface
 691 end
 692
 693 local function wrapclient( client, ip, port, listeners, pattern, sslctx )
 694         local interface = handleclient( client, ip, port, nil, pattern, listeners, sslctx )
 695         interface:_start_connection(sslctx)
 696         return interface, client
 697         --function handleclient( client, ip, port, server, pattern, listener, _, sslctx )  -- creates an client interface
 698 end
 699
 700 local function addclient( addr, serverport, listener, pattern, sslctx, typ )
 701         if sslctx and not has_luasec then
 702                 debug "need luasec, but not available"
 703                 return nil, "luasec not found"
 704         end
 705         if not typ then
 706                 local addrinfo, err = getaddrinfo(addr)
 707                 if not addrinfo then return nil, err end
 708                 if addrinfo[1] and addrinfo[1].family == "inet6" then
 709                         typ = "tcp6"
 710                 else
 711                         typ = "tcp"
 712                 end
 713         end
 714         local create = socket[typ]
 715         if type( create ) ~= "function"  then
 716                 return nil, "invalid socket type"
 717         end
 718         local client, err = create()  -- creating new socket
 719         if not client then
 720                 debug( "cannot create socket:", err )
 721                 return nil, err
 722         end
 723         client:settimeout( 0 )  -- set nonblocking
 724         local res, err = client:connect( addr, serverport )  -- connect
 725         if res or ( err == "timeout" ) then
 726                 local ip, port = client:getsockname( )
 727                 local interface = wrapclient( client, ip, serverport, listener, pattern, sslctx )
 728                 interface:_start_connection( startssl )
 729                 debug( "new connection id:", interface.id )
 730                 return interface, err
 731         else
 732                 debug( "new connection failed:", err )
 733                 return nil, err
 734         end
 735 end
 736
 737 local function loop( )  -- starts the event loop
 738         base:loop( )
 739         return "quitting";
 740 end
 741
 742 local function newevent( ... )
 743         return addevent( base, ... )
 744 end
 745
 746 local function closeallservers ( arg )
 747         for item in pairs( interfacelist ) do
 748                 if item.type == "server" then
 749                         item:close( arg )
 750                 end
 751         end
 752 end
 753
 754 local function setquitting(yes)
 755         if yes then
 756                  -- Quit now
 757                  closeallservers();
 758                  base:loopexit();
 759         end
 760 end
 761
 762 local function get_backend()
 763         return base:method();
 764 end
 765
 766 -- We need to hold onto the events to stop them
 767 -- being garbage-collected
 768 local signal_events = {}; -- [signal_num] -> event object
 769 local function hook_signal(signal_num, handler)
 770         local function _handler(event)
 771                 local ret = handler();
 772                 if ret ~= false then -- Continue handling this signal?
 773                         return EV_SIGNAL; -- Yes
 774                 end
 775                 return -1; -- Close this event
 776         end
 777         signal_events[signal_num] = base:addevent(signal_num, EV_SIGNAL, _handler);
 778         return signal_events[signal_num];
 779 end
 780
 781 local function link(sender, receiver, buffersize)
 782         local sender_locked;
 783
 784         function receiver:ondrain()
 785                 if sender_locked then
 786                         sender:resume();
 787                         sender_locked = nil;
 788                 end
 789         end
 790
 791         function sender:onincoming(data)
 792                 receiver:write(data);
 793                 if receiver.writebufferlen >= buffersize then
 794                         sender_locked = true;
 795                         sender:pause();
 796                 end
 797         end
 798         sender:set_mode("*a");
 799 end
 800
 801 return {
 802         cfg = cfg,
 803         base = base,
 804         loop = loop,
 805         link = link,
 806         event = event,
 807         event_base = base,
 808         addevent = newevent,
 809         addserver = addserver,
 810         addclient = addclient,
 811         wrapclient = wrapclient,
 812         setquitting = setquitting,
 813         closeall = closeallservers,
 814         get_backend = get_backend,
 815         hook_signal = hook_signal,
 816
 817         __NAME = SCRIPT_NAME,
 818         __DATE = LAST_MODIFIED,
 819         __AUTHOR = SCRIPT_AUTHOR,
 820         __VERSION = SCRIPT_VERSION,
 821
 822 }