net/server_select.lua

   1 --
   2 -- server.lua by blastbeat of the luadch project
   3 -- Re-used here under the MIT/X Consortium License
   4 --
   5 -- Modifications (C) 2008-2010 Matthew Wild, Waqas Hussain
   6 --
   7
   8 -- // wrapping luadch stuff // --
   9
  10 local use = function( what )
  11         return _G[ what ]
  12 end
  13
  14 local log, table_concat = require ("util.logger").init("socket"), table.concat;
  15 local out_put = function (...) return log("debug", table_concat{...}); end
  16 local out_error = function (...) return log("warn", table_concat{...}); end
  17
  18 ----------------------------------// DECLARATION //--
  19
  20 --// constants //--
  21
  22 local STAT_UNIT = 1 -- byte
  23
  24 --// lua functions //--
  25
  26 local type = use "type"
  27 local pairs = use "pairs"
  28 local ipairs = use "ipairs"
  29 local tonumber = use "tonumber"
  30 local tostring = use "tostring"
  31
  32 --// lua libs //--
  33
  34 local os = use "os"
  35 local table = use "table"
  36 local string = use "string"
  37 local coroutine = use "coroutine"
  38
  39 --// lua lib methods //--
  40
  41 local os_difftime = os.difftime
  42 local math_min = math.min
  43 local math_huge = math.huge
  44 local table_concat = table.concat
  45 local string_sub = string.sub
  46 local coroutine_wrap = coroutine.wrap
  47 local coroutine_yield = coroutine.yield
  48
  49 --// extern libs //--
  50
  51 local luasec = use "ssl"
  52 local luasocket = use "socket" or require "socket"
  53 local luasocket_gettime = luasocket.gettime
  54
  55 --// extern lib methods //--
  56
  57 local ssl_wrap = ( luasec and luasec.wrap )
  58 local socket_bind = luasocket.bind
  59 local socket_sleep = luasocket.sleep
  60 local socket_select = luasocket.select
  61
  62 --// functions //--
  63
  64 local id
  65 local loop
  66 local stats
  67 local idfalse
  68 local closeall
  69 local addsocket
  70 local addserver
  71 local addtimer
  72 local getserver
  73 local wrapserver
  74 local getsettings
  75 local closesocket
  76 local removesocket
  77 local removeserver
  78 local wrapconnection
  79 local changesettings
  80
  81 --// tables //--
  82
  83 local _server
  84 local _readlist
  85 local _timerlist
  86 local _sendlist
  87 local _socketlist
  88 local _closelist
  89 local _readtimes
  90 local _writetimes
  91
  92 --// simple data types //--
  93
  94 local _
  95 local _readlistlen
  96 local _sendlistlen
  97 local _timerlistlen
  98
  99 local _sendtraffic
 100 local _readtraffic
 101
 102 local _selecttimeout
 103 local _sleeptime
 104 local _tcpbacklog
 105
 106 local _starttime
 107 local _currenttime
 108
 109 local _maxsendlen
 110 local _maxreadlen
 111
 112 local _checkinterval
 113 local _sendtimeout
 114 local _readtimeout
 115
 116 local _timer
 117
 118 local _maxselectlen
 119 local _maxfd
 120
 121 local _maxsslhandshake
 122
 123 ----------------------------------// DEFINITION //--
 124
 125 _server = { } -- key = port, value = table; list of listening servers
 126 _readlist = { } -- array with sockets to read from
 127 _sendlist = { } -- arrary with sockets to write to
 128 _timerlist = { } -- array of timer functions
 129 _socketlist = { } -- key = socket, value = wrapped socket (handlers)
 130 _readtimes = { } -- key = handler, value = timestamp of last data reading
 131 _writetimes = { } -- key = handler, value = timestamp of last data writing/sending
 132 _closelist = { } -- handlers to close
 133
 134 _readlistlen = 0 -- length of readlist
 135 _sendlistlen = 0 -- length of sendlist
 136 _timerlistlen = 0 -- lenght of timerlist
 137
 138 _sendtraffic = 0 -- some stats
 139 _readtraffic = 0
 140
 141 _selecttimeout = 1 -- timeout of socket.select
 142 _sleeptime = 0 -- time to wait at the end of every loop
 143 _tcpbacklog = 128 -- some kind of hint to the OS
 144
 145 _maxsendlen = 51000 * 1024 -- max len of send buffer
 146 _maxreadlen = 25000 * 1024 -- max len of read buffer
 147
 148 _checkinterval = 30 -- interval in secs to check idle clients
 149 _sendtimeout = 60000 -- allowed send idle time in secs
 150 _readtimeout = 6 * 60 * 60 -- allowed read idle time in secs
 151
 152 local is_windows = package.config:sub(1,1) == "\\" -- check the directory separator, to detemine whether this is Windows
 153 _maxfd = (is_windows and math.huge) or luasocket._SETSIZE or 1024 -- max fd number, limit to 1024 by default to prevent glibc buffer overflow, but not on Windows
 154 _maxselectlen = luasocket._SETSIZE or 1024 -- But this still applies on Windows
 155
 156 _maxsslhandshake = 30 -- max handshake round-trips
 157
 158 ----------------------------------// PRIVATE //--
 159
 160 wrapserver = function( listeners, socket, ip, serverport, pattern, sslctx ) -- this function wraps a server -- FIXME Make sure FD < _maxfd
 161
 162         if socket:getfd() >= _maxfd then
 163                 out_error("server.lua: Disallowed FD number: "..socket:getfd())
 164                 socket:close()
 165                 return nil, "fd-too-large"
 166         end
 167
 168         local connections = 0
 169
 170         local dispatch, disconnect = listeners.onconnect, listeners.ondisconnect
 171
 172         local accept = socket.accept
 173
 174         --// public methods of the object //--
 175
 176         local handler = { }
 177
 178         handler.shutdown = function( ) end
 179
 180         handler.ssl = function( )
 181                 return sslctx ~= nil
 182         end
 183         handler.sslctx = function( )
 184                 return sslctx
 185         end
 186         handler.remove = function( )
 187                 connections = connections - 1
 188                 if handler then
 189                         handler.resume( )
 190                 end
 191         end
 192         handler.close = function()
 193                 socket:close( )
 194                 _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
 195                 _readlistlen = removesocket( _readlist, socket, _readlistlen )
 196                 _server[ip..":"..serverport] = nil;
 197                 _socketlist[ socket ] = nil
 198                 handler = nil
 199                 socket = nil
 200                 --mem_free( )
 201                 out_put "server.lua: closed server handler and removed sockets from list"
 202         end
 203         handler.pause = function( hard )
 204                 if not handler.paused then
 205                         _readlistlen = removesocket( _readlist, socket, _readlistlen )
 206                         if hard then
 207                                 _socketlist[ socket ] = nil
 208                                 socket:close( )
 209                                 socket = nil;
 210                         end
 211                         handler.paused = true;
 212                 end
 213         end
 214         handler.resume = function( )
 215                 if handler.paused then
 216                         if not socket then
 217                                 socket = socket_bind( ip, serverport, _tcpbacklog );
 218                                 socket:settimeout( 0 )
 219                         end
 220                         _readlistlen = addsocket(_readlist, socket, _readlistlen)
 221                         _socketlist[ socket ] = handler
 222                         handler.paused = false;
 223                 end
 224         end
 225         handler.ip = function( )
 226                 return ip
 227         end
 228         handler.serverport = function( )
 229                 return serverport
 230         end
 231         handler.socket = function( )
 232                 return socket
 233         end
 234         handler.readbuffer = function( )
 235                 if _readlistlen >= _maxselectlen or _sendlistlen >= _maxselectlen then
 236                         handler.pause( )
 237                         out_put( "server.lua: refused new client connection: server full" )
 238                         return false
 239                 end
 240                 local client, err = accept( socket )    -- try to accept
 241                 if client then
 242                         local ip, clientport = client:getpeername( )
 243                         local handler, client, err = wrapconnection( handler, listeners, client, ip, serverport, clientport, pattern, sslctx ) -- wrap new client socket
 244                         if err then -- error while wrapping ssl socket
 245                                 return false
 246                         end
 247                         connections = connections + 1
 248                         out_put( "server.lua: accepted new client connection from ", tostring(ip), ":", tostring(clientport), " to ", tostring(serverport))
 249                         if dispatch and not sslctx then -- SSL connections will notify onconnect when handshake completes
 250                                 return dispatch( handler );
 251                         end
 252                         return;
 253                 elseif err then -- maybe timeout or something else
 254                         out_put( "server.lua: error with new client connection: ", tostring(err) )
 255                         return false
 256                 end
 257         end
 258         return handler
 259 end
 260
 261 wrapconnection = function( server, listeners, socket, ip, serverport, clientport, pattern, sslctx ) -- this function wraps a client to a handler object
 262
 263         if socket:getfd() >= _maxfd then
 264                 out_error("server.lua: Disallowed FD number: "..socket:getfd()) -- PROTIP: Switch to libevent
 265                 socket:close( ) -- Should we send some kind of error here?
 266                 if server then
 267                         server.pause( )
 268                 end
 269                 return nil, nil, "fd-too-large"
 270         end
 271         socket:settimeout( 0 )
 272
 273         --// local import of socket methods //--
 274
 275         local send
 276         local receive
 277         local shutdown
 278
 279         --// private closures of the object //--
 280
 281         local ssl
 282
 283         local dispatch = listeners.onincoming
 284         local status = listeners.onstatus
 285         local disconnect = listeners.ondisconnect
 286         local drain = listeners.ondrain
 287         local onreadtimeout = listeners.onreadtimeout;
 288         local detach = listeners.ondetach
 289
 290         local bufferqueue = { } -- buffer array
 291         local bufferqueuelen = 0        -- end of buffer array
 292
 293         local toclose
 294         local fatalerror
 295         local needtls
 296
 297         local bufferlen = 0
 298
 299         local noread = false
 300         local nosend = false
 301
 302         local sendtraffic, readtraffic = 0, 0
 303
 304         local maxsendlen = _maxsendlen
 305         local maxreadlen = _maxreadlen
 306
 307         --// public methods of the object //--
 308
 309         local handler = bufferqueue -- saves a table ^_^
 310
 311         handler.dispatch = function( )
 312                 return dispatch
 313         end
 314         handler.disconnect = function( )
 315                 return disconnect
 316         end
 317         handler.onreadtimeout = onreadtimeout;
 318
 319         handler.setlistener = function( self, listeners )
 320                 if detach then
 321                         detach(self) -- Notify listener that it is no longer responsible for this connection
 322                 end
 323                 dispatch = listeners.onincoming
 324                 disconnect = listeners.ondisconnect
 325                 status = listeners.onstatus
 326                 drain = listeners.ondrain
 327                 handler.onreadtimeout = listeners.onreadtimeout
 328                 detach = listeners.ondetach
 329         end
 330         handler.getstats = function( )
 331                 return readtraffic, sendtraffic
 332         end
 333         handler.ssl = function( )
 334                 return ssl
 335         end
 336         handler.sslctx = function ( )
 337                 return sslctx
 338         end
 339         handler.send = function( _, data, i, j )
 340                 return send( socket, data, i, j )
 341         end
 342         handler.receive = function( pattern, prefix )
 343                 return receive( socket, pattern, prefix )
 344         end
 345         handler.shutdown = function( pattern )
 346                 return shutdown( socket, pattern )
 347         end
 348         handler.setoption = function (self, option, value)
 349                 if socket.setoption then
 350                         return socket:setoption(option, value);
 351                 end
 352                 return false, "setoption not implemented";
 353         end
 354         handler.force_close = function ( self, err )
 355                 if bufferqueuelen ~= 0 then
 356                         out_put("server.lua: discarding unwritten data for ", tostring(ip), ":", tostring(clientport))
 357                         bufferqueuelen = 0;
 358                 end
 359                 return self:close(err);
 360         end
 361         handler.close = function( self, err )
 362                 if not handler then return true; end
 363                 _readlistlen = removesocket( _readlist, socket, _readlistlen )
 364                 _readtimes[ handler ] = nil
 365                 if bufferqueuelen ~= 0 then
 366                         handler.sendbuffer() -- Try now to send any outstanding data
 367                         if bufferqueuelen ~= 0 then -- Still not empty, so we'll try again later
 368                                 if handler then
 369                                         handler.write = nil -- ... but no further writing allowed
 370                                 end
 371                                 toclose = true
 372                                 return false
 373                         end
 374                 end
 375                 if socket then
 376                         _ = shutdown and shutdown( socket )
 377                         socket:close( )
 378                         _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
 379                         _socketlist[ socket ] = nil
 380                         socket = nil
 381                 else
 382                         out_put "server.lua: socket already closed"
 383                 end
 384                 if handler then
 385                         _writetimes[ handler ] = nil
 386                         _closelist[ handler ] = nil
 387                         local _handler = handler;
 388                         handler = nil
 389                         if disconnect then
 390                                 disconnect(_handler, err or false);
 391                                 disconnect = nil
 392                         end
 393                 end
 394                 if server then
 395                         server.remove( )
 396                 end
 397                 out_put "server.lua: closed client handler and removed socket from list"
 398                 return true
 399         end
 400         handler.ip = function( )
 401                 return ip
 402         end
 403         handler.serverport = function( )
 404                 return serverport
 405         end
 406         handler.clientport = function( )
 407                 return clientport
 408         end
 409         handler.port = handler.clientport -- COMPAT server_event
 410         local write = function( self, data )
 411                 bufferlen = bufferlen + #data
 412                 if bufferlen > maxsendlen then
 413                         _closelist[ handler ] = "send buffer exceeded"   -- cannot close the client at the moment, have to wait to the end of the cycle
 414                         handler.write = idfalse -- dont write anymore
 415                         return false
 416                 elseif socket and not _sendlist[ socket ] then
 417                         _sendlistlen = addsocket(_sendlist, socket, _sendlistlen)
 418                 end
 419                 bufferqueuelen = bufferqueuelen + 1
 420                 bufferqueue[ bufferqueuelen ] = data
 421                 if handler then
 422                         _writetimes[ handler ] = _writetimes[ handler ] or _currenttime
 423                 end
 424                 return true
 425         end
 426         handler.write = write
 427         handler.bufferqueue = function( self )
 428                 return bufferqueue
 429         end
 430         handler.socket = function( self )
 431                 return socket
 432         end
 433         handler.set_mode = function( self, new )
 434                 pattern = new or pattern
 435                 return pattern
 436         end
 437         handler.set_send = function ( self, newsend )
 438                 send = newsend or send
 439                 return send
 440         end
 441         handler.bufferlen = function( self, readlen, sendlen )
 442                 maxsendlen = sendlen or maxsendlen
 443                 maxreadlen = readlen or maxreadlen
 444                 return bufferlen, maxreadlen, maxsendlen
 445         end
 446         --TODO: Deprecate
 447         handler.lock_read = function (self, switch)
 448                 if switch == true then
 449                         local tmp = _readlistlen
 450                         _readlistlen = removesocket( _readlist, socket, _readlistlen )
 451                         _readtimes[ handler ] = nil
 452                         if _readlistlen ~= tmp then
 453                                 noread = true
 454                         end
 455                 elseif switch == false then
 456                         if noread then
 457                                 noread = false
 458                                 _readlistlen = addsocket(_readlist, socket, _readlistlen)
 459                                 _readtimes[ handler ] = _currenttime
 460                         end
 461                 end
 462                 return noread
 463         end
 464         handler.pause = function (self)
 465                 return self:lock_read(true);
 466         end
 467         handler.resume = function (self)
 468                 return self:lock_read(false);
 469         end
 470         handler.lock = function( self, switch )
 471                 handler.lock_read (switch)
 472                 if switch == true then
 473                         handler.write = idfalse
 474                         local tmp = _sendlistlen
 475                         _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
 476                         _writetimes[ handler ] = nil
 477                         if _sendlistlen ~= tmp then
 478                                 nosend = true
 479                         end
 480                 elseif switch == false then
 481                         handler.write = write
 482                         if nosend then
 483                                 nosend = false
 484                                 write( "" )
 485                         end
 486                 end
 487                 return noread, nosend
 488         end
 489         local _readbuffer = function( ) -- this function reads data
 490                 local buffer, err, part = receive( socket, pattern )    -- receive buffer with "pattern"
 491                 if not err or (err == "wantread" or err == "timeout") then -- received something
 492                         local buffer = buffer or part or ""
 493                         local len = #buffer
 494                         if len > maxreadlen then
 495                                 handler:close( "receive buffer exceeded" )
 496                                 return false
 497                         end
 498                         local count = len * STAT_UNIT
 499                         readtraffic = readtraffic + count
 500                         _readtraffic = _readtraffic + count
 501                         _readtimes[ handler ] = _currenttime
 502                         --out_put( "server.lua: read data '", buffer:gsub("[^%w%p ]", "."), "', error: ", err )
 503                         return dispatch( handler, buffer, err )
 504                 else    -- connections was closed or fatal error
 505                         out_put( "server.lua: client ", tostring(ip), ":", tostring(clientport), " read error: ", tostring(err) )
 506                         fatalerror = true
 507                         _ = handler and handler:force_close( err )
 508                         return false
 509                 end
 510         end
 511         local _sendbuffer = function( ) -- this function sends data
 512                 local succ, err, byte, buffer, count;
 513                 if socket then
 514                         buffer = table_concat( bufferqueue, "", 1, bufferqueuelen )
 515                         succ, err, byte = send( socket, buffer, 1, bufferlen )
 516                         count = ( succ or byte or 0 ) * STAT_UNIT
 517                         sendtraffic = sendtraffic + count
 518                         _sendtraffic = _sendtraffic + count
 519                         for i = bufferqueuelen,1,-1 do
 520                                 bufferqueue[ i ] = nil
 521                         end
 522                         --out_put( "server.lua: sended '", buffer, "', bytes: ", tostring(succ), ", error: ", tostring(err), ", part: ", tostring(byte), ", to: ", tostring(ip), ":", tostring(clientport) )
 523                 else
 524                         succ, err, count = false, "unexpected close", 0;
 525                 end
 526                 if succ then    -- sending succesful
 527                         bufferqueuelen = 0
 528                         bufferlen = 0
 529                         _sendlistlen = removesocket( _sendlist, socket, _sendlistlen ) -- delete socket from writelist
 530                         _writetimes[ handler ] = nil
 531                         if drain then
 532                                 drain(handler)
 533                         end
 534                         _ = needtls and handler:starttls(nil)
 535                         _ = toclose and handler:force_close( )
 536                         return true
 537                 elseif byte and ( err == "timeout" or err == "wantwrite" ) then -- want write
 538                         buffer = string_sub( buffer, byte + 1, bufferlen ) -- new buffer
 539                         bufferqueue[ 1 ] = buffer        -- insert new buffer in queue
 540                         bufferqueuelen = 1
 541                         bufferlen = bufferlen - byte
 542                         _writetimes[ handler ] = _currenttime
 543                         return true
 544                 else    -- connection was closed during sending or fatal error
 545                         out_put( "server.lua: client ", tostring(ip), ":", tostring(clientport), " write error: ", tostring(err) )
 546                         fatalerror = true
 547                         _ = handler and handler:force_close( err )
 548                         return false
 549                 end
 550         end
 551
 552         -- Set the sslctx
 553         local handshake;
 554         function handler.set_sslctx(self, new_sslctx)
 555                 sslctx = new_sslctx;
 556                 local read, wrote
 557                 handshake = coroutine_wrap( function( client ) -- create handshake coroutine
 558                                 local err
 559                                 for i = 1, _maxsslhandshake do
 560                                         _sendlistlen = ( wrote and removesocket( _sendlist, client, _sendlistlen ) ) or _sendlistlen
 561                                         _readlistlen = ( read and removesocket( _readlist, client, _readlistlen ) ) or _readlistlen
 562                                         read, wrote = nil, nil
 563                                         _, err = client:dohandshake( )
 564                                         if not err then
 565                                                 out_put( "server.lua: ssl handshake done" )
 566                                                 handler.readbuffer = _readbuffer        -- when handshake is done, replace the handshake function with regular functions
 567                                                 handler.sendbuffer = _sendbuffer
 568                                                 _ = status and status( handler, "ssl-handshake-complete" )
 569                                                 if self.autostart_ssl and listeners.onconnect then
 570                                                         listeners.onconnect(self);
 571                                                 end
 572                                                 _readlistlen = addsocket(_readlist, client, _readlistlen)
 573                                                 return true
 574                                         else
 575                                                 if err == "wantwrite" then
 576                                                         _sendlistlen = addsocket(_sendlist, client, _sendlistlen)
 577                                                         wrote = true
 578                                                 elseif err == "wantread" then
 579                                                         _readlistlen = addsocket(_readlist, client, _readlistlen)
 580                                                         read = true
 581                                                 else
 582                                                         break;
 583                                                 end
 584                                                 err = nil;
 585                                                 coroutine_yield( ) -- handshake not finished
 586                                         end
 587                                 end
 588                                 out_put( "server.lua: ssl handshake error: ", tostring(err or "handshake too long") )
 589                                 _ = handler and handler:force_close("ssl handshake failed")
 590                                 return false, err -- handshake failed
 591                         end
 592                 )
 593         end
 594         if luasec then
 595                 handler.starttls = function( self, _sslctx)
 596                         if _sslctx then
 597                                 handler:set_sslctx(_sslctx);
 598                         end
 599                         if bufferqueuelen > 0 then
 600                                 out_put "server.lua: we need to do tls, but delaying until send buffer empty"
 601                                 needtls = true
 602                                 return
 603                         end
 604                         out_put( "server.lua: attempting to start tls on " .. tostring( socket ) )
 605                         local oldsocket, err = socket
 606                         socket, err = ssl_wrap( socket, sslctx )        -- wrap socket
 607                         if not socket then
 608                                 out_put( "server.lua: error while starting tls on client: ", tostring(err or "unknown error") )
 609                                 return nil, err -- fatal error
 610                         end
 611
 612                         socket:settimeout( 0 )
 613
 614                         -- add the new socket to our system
 615                         send = socket.send
 616                         receive = socket.receive
 617                         shutdown = id
 618                         _socketlist[ socket ] = handler
 619                         _readlistlen = addsocket(_readlist, socket, _readlistlen)
 620
 621                         -- remove traces of the old socket
 622                         _readlistlen = removesocket( _readlist, oldsocket, _readlistlen )
 623                         _sendlistlen = removesocket( _sendlist, oldsocket, _sendlistlen )
 624                         _socketlist[ oldsocket ] = nil
 625
 626                         handler.starttls = nil
 627                         needtls = nil
 628
 629                         -- Secure now (if handshake fails connection will close)
 630                         ssl = true
 631
 632                         handler.readbuffer = handshake
 633                         handler.sendbuffer = handshake
 634                         return handshake( socket ) -- do handshake
 635                 end
 636         end
 637
 638         handler.readbuffer = _readbuffer
 639         handler.sendbuffer = _sendbuffer
 640         send = socket.send
 641         receive = socket.receive
 642         shutdown = ( ssl and id ) or socket.shutdown
 643
 644         _socketlist[ socket ] = handler
 645         _readlistlen = addsocket(_readlist, socket, _readlistlen)
 646
 647         if sslctx and luasec then
 648                 out_put "server.lua: auto-starting ssl negotiation..."
 649                 handler.autostart_ssl = true;
 650                 local ok, err = handler:starttls(sslctx);
 651                 if ok == false then
 652                         return nil, nil, err
 653                 end
 654         end
 655
 656         return handler, socket
 657 end
 658
 659 id = function( )
 660 end
 661
 662 idfalse = function( )
 663         return false
 664 end
 665
 666 addsocket = function( list, socket, len )
 667         if not list[ socket ] then
 668                 len = len + 1
 669                 list[ len ] = socket
 670                 list[ socket ] = len
 671         end
 672         return len;
 673 end
 674
 675 removesocket = function( list, socket, len )    -- this function removes sockets from a list ( copied from copas )
 676         local pos = list[ socket ]
 677         if pos then
 678                 list[ socket ] = nil
 679                 local last = list[ len ]
 680                 list[ len ] = nil
 681                 if last ~= socket then
 682                         list[ last ] = pos
 683                         list[ pos ] = last
 684                 end
 685                 return len - 1
 686         end
 687         return len
 688 end
 689
 690 closesocket = function( socket )
 691         _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
 692         _readlistlen = removesocket( _readlist, socket, _readlistlen )
 693         _socketlist[ socket ] = nil
 694         socket:close( )
 695         --mem_free( )
 696 end
 697
 698 local function link(sender, receiver, buffersize)
 699         local sender_locked;
 700         local _sendbuffer = receiver.sendbuffer;
 701         function receiver.sendbuffer()
 702                 _sendbuffer();
 703                 if sender_locked and receiver.bufferlen() < buffersize then
 704                         sender:lock_read(false); -- Unlock now
 705                         sender_locked = nil;
 706                 end
 707         end
 708
 709         local _readbuffer = sender.readbuffer;
 710         function sender.readbuffer()
 711                 _readbuffer();
 712                 if not sender_locked and receiver.bufferlen() >= buffersize then
 713                         sender_locked = true;
 714                         sender:lock_read(true);
 715                 end
 716         end
 717         sender:set_mode("*a");
 718 end
 719
 720 ----------------------------------// PUBLIC //--
 721
 722 addserver = function( addr, port, listeners, pattern, sslctx ) -- this function provides a way for other scripts to reg a server
 723         local err
 724         if type( listeners ) ~= "table" then
 725                 err = "invalid listener table"
 726         end
 727         if type( port ) ~= "number" or not ( port >= 0 and port <= 65535 ) then
 728                 err = "invalid port"
 729         elseif _server[ addr..":"..port ] then
 730                 err = "listeners on '[" .. addr .. "]:" .. port .. "' already exist"
 731         elseif sslctx and not luasec then
 732                 err = "luasec not found"
 733         end
 734         if err then
 735                 out_error( "server.lua, [", addr, "]:", port, ": ", err )
 736                 return nil, err
 737         end
 738         addr = addr or "*"
 739         local server, err = socket_bind( addr, port, _tcpbacklog )
 740         if err then
 741                 out_error( "server.lua, [", addr, "]:", port, ": ", err )
 742                 return nil, err
 743         end
 744         local handler, err = wrapserver( listeners, server, addr, port, pattern, sslctx ) -- wrap new server socket
 745         if not handler then
 746                 server:close( )
 747                 return nil, err
 748         end
 749         server:settimeout( 0 )
 750         _readlistlen = addsocket(_readlist, server, _readlistlen)
 751         _server[ addr..":"..port ] = handler
 752         _socketlist[ server ] = handler
 753         out_put( "server.lua: new "..(sslctx and "ssl " or "").."server listener on '[", addr, "]:", port, "'" )
 754         return handler
 755 end
 756
 757 getserver = function ( addr, port )
 758         return _server[ addr..":"..port ];
 759 end
 760
 761 removeserver = function( addr, port )
 762         local handler = _server[ addr..":"..port ]
 763         if not handler then
 764                 return nil, "no server found on '[" .. addr .. "]:" .. tostring( port ) .. "'"
 765         end
 766         handler:close( )
 767         _server[ addr..":"..port ] = nil
 768         return true
 769 end
 770
 771 closeall = function( )
 772         for _, handler in pairs( _socketlist ) do
 773                 handler:close( )
 774                 _socketlist[ _ ] = nil
 775         end
 776         _readlistlen = 0
 777         _sendlistlen = 0
 778         _timerlistlen = 0
 779         _server = { }
 780         _readlist = { }
 781         _sendlist = { }
 782         _timerlist = { }
 783         _socketlist = { }
 784         --mem_free( )
 785 end
 786
 787 getsettings = function( )
 788         return {
 789                 select_timeout = _selecttimeout;
 790                 select_sleep_time = _sleeptime;
 791                 tcp_backlog = _tcpbacklog;
 792                 max_send_buffer_size = _maxsendlen;
 793                 max_receive_buffer_size = _maxreadlen;
 794                 select_idle_check_interval = _checkinterval;
 795                 send_timeout = _sendtimeout;
 796                 read_timeout = _readtimeout;
 797                 max_connections = _maxselectlen;
 798                 max_ssl_handshake_roundtrips = _maxsslhandshake;
 799                 highest_allowed_fd = _maxfd;
 800         }
 801 end
 802
 803 changesettings = function( new )
 804         if type( new ) ~= "table" then
 805                 return nil, "invalid settings table"
 806         end
 807         _selecttimeout = tonumber( new.select_timeout ) or _selecttimeout
 808         _sleeptime = tonumber( new.select_sleep_time ) or _sleeptime
 809         _maxsendlen = tonumber( new.max_send_buffer_size ) or _maxsendlen
 810         _maxreadlen = tonumber( new.max_receive_buffer_size ) or _maxreadlen
 811         _checkinterval = tonumber( new.select_idle_check_interval ) or _checkinterval
 812         _tcpbacklog = tonumber( new.tcp_backlog ) or _tcpbacklog
 813         _sendtimeout = tonumber( new.send_timeout ) or _sendtimeout
 814         _readtimeout = tonumber( new.read_timeout ) or _readtimeout
 815         _maxselectlen = new.max_connections or _maxselectlen
 816         _maxsslhandshake = new.max_ssl_handshake_roundtrips or _maxsslhandshake
 817         _maxfd = new.highest_allowed_fd or _maxfd
 818         return true
 819 end
 820
 821 addtimer = function( listener )
 822         if type( listener ) ~= "function" then
 823                 return nil, "invalid listener function"
 824         end
 825         _timerlistlen = _timerlistlen + 1
 826         _timerlist[ _timerlistlen ] = listener
 827         return true
 828 end
 829
 830 stats = function( )
 831         return _readtraffic, _sendtraffic, _readlistlen, _sendlistlen, _timerlistlen
 832 end
 833
 834 local quitting;
 835
 836 local function setquitting(quit)
 837         quitting = not not quit;
 838 end
 839
 840 loop = function(once) -- this is the main loop of the program
 841         if quitting then return "quitting"; end
 842         if once then quitting = "once"; end
 843         local next_timer_time = math_huge;
 844         repeat
 845                 local read, write, err = socket_select( _readlist, _sendlist, math_min(_selecttimeout, next_timer_time) )
 846                 for i, socket in ipairs( write ) do -- send data waiting in writequeues
 847                         local handler = _socketlist[ socket ]
 848                         if handler then
 849                                 handler.sendbuffer( )
 850                         else
 851                                 closesocket( socket )
 852                                 out_put "server.lua: found no handler and closed socket (writelist)"    -- this should not happen
 853                         end
 854                 end
 855                 for i, socket in ipairs( read ) do -- receive data
 856                         local handler = _socketlist[ socket ]
 857                         if handler then
 858                                 handler.readbuffer( )
 859                         else
 860                                 closesocket( socket )
 861                                 out_put "server.lua: found no handler and closed socket (readlist)" -- this can happen
 862                         end
 863                 end
 864                 for handler, err in pairs( _closelist ) do
 865                         handler.disconnect( )( handler, err )
 866                         handler:force_close()    -- forced disconnect
 867                         _closelist[ handler ] = nil;
 868                 end
 869                 _currenttime = luasocket_gettime( )
 870
 871                 -- Check for socket timeouts
 872                 local difftime = os_difftime( _currenttime - _starttime )
 873                 if difftime > _checkinterval then
 874                         _starttime = _currenttime
 875                         for handler, timestamp in pairs( _writetimes ) do
 876                                 if os_difftime( _currenttime - timestamp ) > _sendtimeout then
 877                                         handler.disconnect( )( handler, "send timeout" )
 878                                         handler:force_close()    -- forced disconnect
 879                                 end
 880                         end
 881                         for handler, timestamp in pairs( _readtimes ) do
 882                                 if os_difftime( _currenttime - timestamp ) > _readtimeout then
 883                                         if not(handler.onreadtimeout) or handler:onreadtimeout() ~= true then
 884                                                 handler.disconnect( )( handler, "read timeout" )
 885                                                 handler:close( )        -- forced disconnect?
 886                                         end
 887                                 end
 888                         end
 889                 end
 890
 891                 -- Fire timers
 892                 if _currenttime - _timer >= math_min(next_timer_time, 1) then
 893                         next_timer_time = math_huge;
 894                         for i = 1, _timerlistlen do
 895                                 local t = _timerlist[ i ]( _currenttime ) -- fire timers
 896                                 if t then next_timer_time = math_min(next_timer_time, t); end
 897                         end
 898                         _timer = _currenttime
 899                 else
 900                         next_timer_time = next_timer_time - (_currenttime - _timer);
 901                 end
 902
 903                 -- wait some time (0 by default)
 904                 socket_sleep( _sleeptime )
 905         until quitting;
 906         if once and quitting == "once" then quitting = nil; return; end
 907         return "quitting"
 908 end
 909
 910 local function step()
 911         return loop(true);
 912 end
 913
 914 local function get_backend()
 915         return "select";
 916 end
 917
 918 --// EXPERIMENTAL //--
 919
 920 local wrapclient = function( socket, ip, serverport, listeners, pattern, sslctx )
 921         local handler, socket, err = wrapconnection( nil, listeners, socket, ip, serverport, "clientport", pattern, sslctx )
 922         if not handler then return nil, err end
 923         _socketlist[ socket ] = handler
 924         if not sslctx then
 925                 _sendlistlen = addsocket(_sendlist, socket, _sendlistlen)
 926                 if listeners.onconnect then
 927                         -- When socket is writeable, call onconnect
 928                         local _sendbuffer = handler.sendbuffer;
 929                         handler.sendbuffer = function ()
 930                                 handler.sendbuffer = _sendbuffer;
 931                                 listeners.onconnect(handler);
 932                                 return _sendbuffer(); -- Send any queued outgoing data
 933                         end
 934                 end
 935         end
 936         return handler, socket
 937 end
 938
 939 local addclient = function( address, port, listeners, pattern, sslctx )
 940         local client, err = luasocket.tcp( )
 941         if err then
 942                 return nil, err
 943         end
 944         client:settimeout( 0 )
 945         _, err = client:connect( address, port )
 946         if err then -- try again
 947                 return wrapclient( client, address, port, listeners, pattern, sslctx )
 948         else
 949                 return wrapconnection( nil, listeners, client, address, port, "clientport", pattern, sslctx )
 950         end
 951 end
 952
 953 --// EXPERIMENTAL //--
 954
 955 ----------------------------------// BEGIN //--
 956
 957 use "setmetatable" ( _socketlist, { __mode = "k" } )
 958 use "setmetatable" ( _readtimes, { __mode = "k" } )
 959 use "setmetatable" ( _writetimes, { __mode = "k" } )
 960
 961 _timer = luasocket_gettime( )
 962 _starttime = luasocket_gettime( )
 963
 964 local function setlogger(new_logger)
 965         local old_logger = log;
 966         if new_logger then
 967                 log = new_logger;
 968         end
 969         return old_logger;
 970 end
 971
 972 ----------------------------------// PUBLIC INTERFACE //--
 973
 974 return {
 975         _addtimer = addtimer,
 976
 977         addclient = addclient,
 978         wrapclient = wrapclient,
 979
 980         loop = loop,
 981         link = link,
 982         step = step,
 983         stats = stats,
 984         closeall = closeall,
 985         addserver = addserver,
 986         getserver = getserver,
 987         setlogger = setlogger,
 988         getsettings = getsettings,
 989         setquitting = setquitting,
 990         removeserver = removeserver,
 991         get_backend = get_backend,
 992         changesettings = changesettings,
 993 }