Diff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/net/server_select.lua	Sat Nov 21 02:36:35 2009 +0000
@@ -0,0 +1,914 @@
+-- 
+-- server.lua by blastbeat of the luadch project
+-- Re-used here under the MIT/X Consortium License
+-- 
+-- Modifications (C) 2008-2009 Matthew Wild, Waqas Hussain
+--
+
+-- // wrapping luadch stuff // --
+
+local use = function( what )
+    return _G[ what ]
+end
+local clean = function( tbl )
+    for i, k in pairs( tbl ) do
+        tbl[ i ] = nil
+    end
+end
+
+local log, table_concat = require ("util.logger").init("socket"), table.concat;
+local out_put = function (...) return log("debug", table_concat{...}); end
+local out_error = function (...) return log("warn", table_concat{...}); end
+local mem_free = collectgarbage
+
+----------------------------------// DECLARATION //--
+
+--// constants //--
+
+local STAT_UNIT = 1    -- byte
+
+--// lua functions //--
+
+local type = use "type"
+local pairs = use "pairs"
+local ipairs = use "ipairs"
+local tostring = use "tostring"
+local collectgarbage = use "collectgarbage"
+
+--// lua libs //--
+
+local os = use "os"
+local table = use "table"
+local string = use "string"
+local coroutine = use "coroutine"
+
+--// lua lib methods //--
+
+local os_time = os.time
+local os_difftime = os.difftime
+local table_concat = table.concat
+local table_remove = table.remove
+local string_len = string.len
+local string_sub = string.sub
+local coroutine_wrap = coroutine.wrap
+local coroutine_yield = coroutine.yield
+
+--// extern libs //--
+
+local luasec = select( 2, pcall( require, "ssl" ) )
+local luasocket = require "socket"
+
+--// extern lib methods //--
+
+local ssl_wrap = ( luasec and luasec.wrap )
+local socket_bind = luasocket.bind
+local socket_sleep = luasocket.sleep
+local socket_select = luasocket.select
+local ssl_newcontext = ( luasec and luasec.newcontext )
+
+--// functions //--
+
+local id
+local loop
+local stats
+local idfalse
+local addtimer
+local closeall
+local addserver
+local getserver
+local wrapserver
+local getsettings
+local closesocket
+local removesocket
+local removeserver
+local changetimeout
+local wrapconnection
+local changesettings
+
+--// tables //--
+
+local _server
+local _readlist
+local _timerlist
+local _sendlist
+local _socketlist
+local _closelist
+local _readtimes
+local _writetimes
+
+--// simple data types //--
+
+local _
+local _readlistlen
+local _sendlistlen
+local _timerlistlen
+
+local _sendtraffic
+local _readtraffic
+
+local _selecttimeout
+local _sleeptime
+
+local _starttime
+local _currenttime
+
+local _maxsendlen
+local _maxreadlen
+
+local _checkinterval
+local _sendtimeout
+local _readtimeout
+
+local _cleanqueue
+
+local _timer
+
+local _maxclientsperserver
+
+----------------------------------// DEFINITION //--
+
+_server = { }    -- key = port, value = table; list of listening servers
+_readlist = { }    -- array with sockets to read from
+_sendlist = { }    -- arrary with sockets to write to
+_timerlist = { }    -- array of timer functions
+_socketlist = { }    -- key = socket, value = wrapped socket (handlers)
+_readtimes = { }   -- key = handler, value = timestamp of last data reading
+_writetimes = { }   -- key = handler, value = timestamp of last data writing/sending
+_closelist = { }    -- handlers to close
+
+_readlistlen = 0    -- length of readlist
+_sendlistlen = 0    -- length of sendlist
+_timerlistlen = 0    -- lenght of timerlist
+
+_sendtraffic = 0    -- some stats
+_readtraffic = 0
+
+_selecttimeout = 1    -- timeout of socket.select
+_sleeptime = 0    -- time to wait at the end of every loop
+
+_maxsendlen = 51000 * 1024    -- max len of send buffer
+_maxreadlen = 25000 * 1024    -- max len of read buffer
+
+_checkinterval = 1200000    -- interval in secs to check idle clients
+_sendtimeout = 60000    -- allowed send idle time in secs
+_readtimeout = 6 * 60 * 60    -- allowed read idle time in secs
+
+_cleanqueue = false    -- clean bufferqueue after using
+
+_maxclientsperserver = 1000
+
+_maxsslhandshake = 30 -- max handshake round-trips
+----------------------------------// PRIVATE //--
+
+wrapserver = function( listeners, socket, ip, serverport, pattern, sslctx, maxconnections, startssl )    -- this function wraps a server
+
+    maxconnections = maxconnections or _maxclientsperserver
+
+    local connections = 0
+
+    local dispatch, disconnect = listeners.incoming or listeners.listener, listeners.disconnect
+
+    local err
+
+    local ssl = false
+
+    if sslctx then
+        ssl = true
+        if not ssl_newcontext then
+            out_error "luasec not found"
+            ssl = false
+        end
+        if type( sslctx ) ~= "table" then
+            out_error "server.lua: wrong server sslctx"
+            ssl = false
+        end
+        local ctx;
+        ctx, err = ssl_newcontext( sslctx )
+        if not ctx then
+            err = err or "wrong sslctx parameters"
+            local file;
+            file = err:match("^error loading (.-) %(");
+            if file then
+            	if file == "private key" then
+            		file = sslctx.key or "your private key";
+            	elseif file == "certificate" then
+            		file = sslctx.certificate or "your certificate file";
+            	end
+	        local reason = err:match("%((.+)%)$") or "some reason";
+	        if reason == "Permission denied" then
+	        	reason = "Check that the permissions allow Prosody to read this file.";
+	        elseif reason == "No such file or directory" then
+	        	reason = "Check that the path is correct, and the file exists.";
+	        elseif reason == "system lib" then
+	        	reason = "Previous error (see logs), or other system error.";
+	        else
+	        	reason = "Reason: "..tostring(reason or "unknown"):lower();
+	        end
+	        log("error", "SSL/TLS: Failed to load %s: %s", file, reason);
+	    else
+                log("error", "SSL/TLS: Error initialising for port %d: %s", serverport, err );
+            end
+            ssl = false
+        end
+        sslctx = ctx;
+    end
+    if not ssl then
+      sslctx = false;
+      if startssl then
+         log("error", "Failed to listen on port %d due to SSL/TLS to SSL/TLS initialisation errors (see logs)", serverport )
+         return nil, "Cannot start ssl,  see log for details"
+       end
+    end
+
+    local accept = socket.accept
+
+    --// public methods of the object //--
+
+    local handler = { }
+
+    handler.shutdown = function( ) end
+
+    handler.ssl = function( )
+        return ssl
+    end
+    handler.sslctx = function( )
+        return sslctx
+    end
+    handler.remove = function( )
+        connections = connections - 1
+    end
+    handler.close = function( )
+        for _, handler in pairs( _socketlist ) do
+            if handler.serverport == serverport then
+                handler.disconnect( handler, "server closed" )
+                handler.close( true )
+            end
+        end
+        socket:close( )
+        _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
+        _readlistlen = removesocket( _readlist, socket, _readlistlen )
+        _socketlist[ socket ] = nil
+        handler = nil
+        socket = nil
+        --mem_free( )
+        out_put "server.lua: closed server handler and removed sockets from list"
+    end
+    handler.ip = function( )
+        return ip
+    end
+    handler.serverport = function( )
+        return serverport
+    end
+    handler.socket = function( )
+        return socket
+    end
+    handler.readbuffer = function( )
+        if connections > maxconnections then
+            out_put( "server.lua: refused new client connection: server full" )
+            return false
+        end
+        local client, err = accept( socket )    -- try to accept
+        if client then
+            local ip, clientport = client:getpeername( )
+            client:settimeout( 0 )
+            local handler, client, err = wrapconnection( handler, listeners, client, ip, serverport, clientport, pattern, sslctx, startssl )    -- wrap new client socket
+            if err then    -- error while wrapping ssl socket
+                return false
+            end
+            connections = connections + 1
+            out_put( "server.lua: accepted new client connection from ", tostring(ip), ":", tostring(clientport), " to ", tostring(serverport))
+            return dispatch( handler )
+        elseif err then    -- maybe timeout or something else
+            out_put( "server.lua: error with new client connection: ", tostring(err) )
+            return false
+        end
+    end
+    return handler
+end
+
+wrapconnection = function( server, listeners, socket, ip, serverport, clientport, pattern, sslctx, startssl )    -- this function wraps a client to a handler object
+
+    socket:settimeout( 0 )
+
+    --// local import of socket methods //--
+
+    local send
+    local receive
+    local shutdown
+
+    --// private closures of the object //--
+
+    local ssl
+
+    local dispatch = listeners.incoming or listeners.listener
+    local status = listeners.status
+    local disconnect = listeners.disconnect
+
+    local bufferqueue = { }    -- buffer array
+    local bufferqueuelen = 0    -- end of buffer array
+
+    local toclose
+    local fatalerror
+    local needtls
+
+    local bufferlen = 0
+
+    local noread = false
+    local nosend = false
+
+    local sendtraffic, readtraffic = 0, 0
+
+    local maxsendlen = _maxsendlen
+    local maxreadlen = _maxreadlen
+
+    --// public methods of the object //--
+
+    local handler = bufferqueue    -- saves a table ^_^
+
+    handler.dispatch = function( )
+        return dispatch
+    end
+    handler.disconnect = function( )
+        return disconnect
+    end
+    handler.setlistener = function( listeners )
+        dispatch = listeners.incoming
+        disconnect = listeners.disconnect
+    end
+    handler.getstats = function( )
+        return readtraffic, sendtraffic
+    end
+    handler.ssl = function( )
+        return ssl
+    end
+    handler.sslctx = function ( )
+        return sslctx
+    end
+    handler.send = function( _, data, i, j )
+        return send( socket, data, i, j )
+    end
+    handler.receive = function( pattern, prefix )
+        return receive( socket, pattern, prefix )
+    end
+    handler.shutdown = function( pattern )
+        return shutdown( socket, pattern )
+    end
+    handler.close = function( forced )
+        if not handler then return true; end
+        _readlistlen = removesocket( _readlist, socket, _readlistlen )
+        _readtimes[ handler ] = nil
+        if bufferqueuelen ~= 0 then
+            if not ( forced or fatalerror ) then
+                handler.sendbuffer( )
+                if bufferqueuelen ~= 0 then   -- try again...
+                    if handler then
+                        handler.write = nil    -- ... but no further writing allowed
+                    end
+                    toclose = true
+                    return false
+                end
+            else
+                send( socket, table_concat( bufferqueue, "", 1, bufferqueuelen ), 1, bufferlen )    -- forced send
+            end
+        end
+        if socket then
+          _ = shutdown and shutdown( socket )
+          socket:close( )
+          _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
+          _socketlist[ socket ] = nil
+          socket = nil
+        else
+          out_put "server.lua: socket already closed"
+        end
+        if handler then
+            _writetimes[ handler ] = nil
+            _closelist[ handler ] = nil
+            handler = nil
+        end
+	if server then
+		server.remove( )
+	end
+        out_put "server.lua: closed client handler and removed socket from list"
+        return true
+    end
+    handler.ip = function( )
+        return ip
+    end
+    handler.serverport = function( )
+        return serverport
+    end
+    handler.clientport = function( )
+        return clientport
+    end
+    local write = function( data )
+        bufferlen = bufferlen + string_len( data )
+        if bufferlen > maxsendlen then
+            _closelist[ handler ] = "send buffer exceeded"   -- cannot close the client at the moment, have to wait to the end of the cycle
+            handler.write = idfalse    -- dont write anymore
+            return false
+        elseif socket and not _sendlist[ socket ] then
+            _sendlistlen = addsocket(_sendlist, socket, _sendlistlen)
+        end
+        bufferqueuelen = bufferqueuelen + 1
+        bufferqueue[ bufferqueuelen ] = data
+        if handler then
+        	_writetimes[ handler ] = _writetimes[ handler ] or _currenttime
+        end
+        return true
+    end
+    handler.write = write
+    handler.bufferqueue = function( )
+        return bufferqueue
+    end
+    handler.socket = function( )
+        return socket
+    end
+    handler.pattern = function( new )
+        pattern = new or pattern
+        return pattern
+    end
+    handler.setsend = function ( newsend )
+        send = newsend or send
+        return send
+    end
+    handler.bufferlen = function( readlen, sendlen )
+        maxsendlen = sendlen or maxsendlen
+        maxreadlen = readlen or maxreadlen
+        return maxreadlen, maxsendlen
+    end
+    handler.lock = function( switch )
+        if switch == true then
+            handler.write = idfalse
+            local tmp = _sendlistlen
+            _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
+            _writetimes[ handler ] = nil
+            if _sendlistlen ~= tmp then
+                nosend = true
+            end
+            tmp = _readlistlen
+            _readlistlen = removesocket( _readlist, socket, _readlistlen )
+            _readtimes[ handler ] = nil
+            if _readlistlen ~= tmp then
+                noread = true
+            end
+        elseif switch == false then
+            handler.write = write
+            if noread then
+                noread = false
+                _readlistlen = addsocket(_readlist, socket, _readlistlen)
+                _readtimes[ handler ] = _currenttime
+            end
+            if nosend then
+                nosend = false
+                write( "" )
+            end
+        end
+        return noread, nosend
+    end
+    local _readbuffer = function( )    -- this function reads data
+        local buffer, err, part = receive( socket, pattern )    -- receive buffer with "pattern"
+        if not err or ( err == "timeout" or err == "wantread" ) then    -- received something
+            local buffer = buffer or part or ""
+            local len = string_len( buffer )
+            if len > maxreadlen then
+                disconnect( handler, "receive buffer exceeded" )
+                handler.close( true )
+                return false
+            end
+            local count = len * STAT_UNIT
+            readtraffic = readtraffic + count
+            _readtraffic = _readtraffic + count
+            _readtimes[ handler ] = _currenttime
+            --out_put( "server.lua: read data '", buffer:gsub("[^%w%p ]", "."), "', error: ", err )
+            return dispatch( handler, buffer, err )
+        else    -- connections was closed or fatal error
+            out_put( "server.lua: client ", tostring(ip), ":", tostring(clientport), " read error: ", tostring(err) )
+            fatalerror = true
+            disconnect( handler, err )
+	    _ = handler and handler.close( )
+            return false
+        end
+    end
+    local _sendbuffer = function( )    -- this function sends data
+    	local succ, err, byte, buffer, count;
+    	local count;
+    	if socket then
+            buffer = table_concat( bufferqueue, "", 1, bufferqueuelen )
+            succ, err, byte = send( socket, buffer, 1, bufferlen )
+            count = ( succ or byte or 0 ) * STAT_UNIT
+            sendtraffic = sendtraffic + count
+            _sendtraffic = _sendtraffic + count
+            _ = _cleanqueue and clean( bufferqueue )
+            --out_put( "server.lua: sended '", buffer, "', bytes: ", tostring(succ), ", error: ", tostring(err), ", part: ", tostring(byte), ", to: ", tostring(ip), ":", tostring(clientport) )
+        else
+            succ, err, count = false, "closed", 0;
+        end
+        if succ then    -- sending succesful
+            bufferqueuelen = 0
+            bufferlen = 0
+            _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )    -- delete socket from writelist
+            _ = needtls and handler.starttls(true)
+            _writetimes[ handler ] = nil
+	    _ = toclose and handler.close( )
+            return true
+        elseif byte and ( err == "timeout" or err == "wantwrite" ) then    -- want write
+            buffer = string_sub( buffer, byte + 1, bufferlen )    -- new buffer
+            bufferqueue[ 1 ] = buffer    -- insert new buffer in queue
+            bufferqueuelen = 1
+            bufferlen = bufferlen - byte
+            _writetimes[ handler ] = _currenttime
+            return true
+        else    -- connection was closed during sending or fatal error
+            out_put( "server.lua: client ", tostring(ip), ":", tostring(clientport), " write error: ", tostring(err) )
+            fatalerror = true
+            disconnect( handler, err )
+            _ = handler and handler.close( )
+            return false
+        end
+    end
+
+    -- Set the sslctx
+    local handshake;
+    function handler.set_sslctx(new_sslctx)
+        ssl = true
+        sslctx = new_sslctx;
+        local wrote
+        local read
+        handshake = coroutine_wrap( function( client )    -- create handshake coroutine
+                local err
+                for i = 1, _maxsslhandshake do
+                    _sendlistlen = ( wrote and removesocket( _sendlist, client, _sendlistlen ) ) or _sendlistlen
+                    _readlistlen = ( read and removesocket( _readlist, client, _readlistlen ) ) or _readlistlen
+                    read, wrote = nil, nil
+                    _, err = client:dohandshake( )
+                    if not err then
+                        out_put( "server.lua: ssl handshake done" )
+                        handler.readbuffer = _readbuffer    -- when handshake is done, replace the handshake function with regular functions
+                        handler.sendbuffer = _sendbuffer
+                        _ = status and status( handler, "ssl-handshake-complete" )
+                        _readlistlen = addsocket(_readlist, client, _readlistlen)
+                        return true
+                    else
+                       out_put( "server.lua: error during ssl handshake: ", tostring(err) )
+                       if err == "wantwrite" and not wrote then
+                           _sendlistlen = addsocket(_sendlist, client, _sendlistlen)
+                           wrote = true
+                       elseif err == "wantread" and not read then
+                           _readlistlen = addsocket(_readlist, client, _readlistlen)
+                           read = true
+                       else
+                           break;
+                       end
+                       --coroutine_yield( handler, nil, err )    -- handshake not finished
+                       coroutine_yield( )
+                    end
+                end
+                disconnect( handler, "ssl handshake failed" )
+                _ = handler and handler.close( true )    -- forced disconnect
+                return false    -- handshake failed
+            end
+        )
+    end
+    if sslctx then    -- ssl?
+    	handler.set_sslctx(sslctx);
+        if startssl then    -- ssl now?
+            --out_put("server.lua: ", "starting ssl handshake")
+	    local err
+            socket, err = ssl_wrap( socket, sslctx )    -- wrap socket
+            if err then
+                out_put( "server.lua: ssl error: ", tostring(err) )
+                --mem_free( )
+                return nil, nil, err    -- fatal error
+            end
+            socket:settimeout( 0 )
+            handler.readbuffer = handshake
+            handler.sendbuffer = handshake
+            handshake( socket ) -- do handshake
+            if not socket then
+                return nil, nil, "ssl handshake failed";
+            end
+        else
+            -- We're not automatically doing SSL, so we're not secure (yet)
+            ssl = false
+            handler.starttls = function( now )
+                if not now then
+                    --out_put "server.lua: we need to do tls, but delaying until later"
+                    needtls = true
+                    return
+                end
+                --out_put( "server.lua: attempting to start tls on " .. tostring( socket ) )
+                local oldsocket, err = socket
+                socket, err = ssl_wrap( socket, sslctx )    -- wrap socket
+                --out_put( "server.lua: sslwrapped socket is " .. tostring( socket ) )
+                if err then
+                    out_put( "server.lua: error while starting tls on client: ", tostring(err) )
+                    return nil, err    -- fatal error
+                end
+
+                socket:settimeout( 0 )
+
+                -- add the new socket to our system
+
+                send = socket.send
+                receive = socket.receive
+                shutdown = id
+
+                _socketlist[ socket ] = handler
+                _readlistlen = addsocket(_readlist, socket, _readlistlen)
+
+                -- remove traces of the old socket
+
+                _readlistlen = removesocket( _readlist, oldsocket, _readlistlen )
+                _sendlistlen = removesocket( _sendlist, oldsocket, _sendlistlen )
+                _socketlist[ oldsocket ] = nil
+
+                handler.starttls = nil
+                needtls = nil
+                
+                -- Secure now
+                ssl = true
+
+                handler.readbuffer = handshake
+                handler.sendbuffer = handshake
+                handshake( socket )    -- do handshake
+            end
+            handler.readbuffer = _readbuffer
+            handler.sendbuffer = _sendbuffer
+        end
+    else    -- normal connection
+        ssl = false
+        handler.readbuffer = _readbuffer
+        handler.sendbuffer = _sendbuffer
+    end
+
+    send = socket.send
+    receive = socket.receive
+    shutdown = ( ssl and id ) or socket.shutdown
+
+    _socketlist[ socket ] = handler
+    _readlistlen = addsocket(_readlist, socket, _readlistlen)
+
+    return handler, socket
+end
+
+id = function( )
+end
+
+idfalse = function( )
+    return false
+end
+
+addsocket = function( list, socket, len )
+    if not list[ socket ] then
+      len = len + 1
+      list[ len ] = socket
+      list[ socket ] = len
+    end
+    return len;
+end
+
+removesocket = function( list, socket, len )    -- this function removes sockets from a list ( copied from copas )
+    local pos = list[ socket ]
+    if pos then
+        list[ socket ] = nil
+        local last = list[ len ]
+        list[ len ] = nil
+        if last ~= socket then
+            list[ last ] = pos
+            list[ pos ] = last
+        end
+        return len - 1
+    end
+    return len
+end
+
+closesocket = function( socket )
+    _sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
+    _readlistlen = removesocket( _readlist, socket, _readlistlen )
+    _socketlist[ socket ] = nil
+    socket:close( )
+    --mem_free( )
+end
+
+----------------------------------// PUBLIC //--
+
+addserver = function( listeners, port, addr, pattern, sslctx, maxconnections, startssl )    -- this function provides a way for other scripts to reg a server
+    local err
+    --out_put("server.lua: autossl on ", port, " is ", startssl)
+    if type( listeners ) ~= "table" then
+        err = "invalid listener table"
+    end
+    if not type( port ) == "number" or not ( port >= 0 and port <= 65535 ) then
+        err = "invalid port"
+    elseif _server[ port ] then
+        err =  "listeners on port '" .. port .. "' already exist"
+    elseif sslctx and not luasec then
+        err = "luasec not found"
+    end
+    if err then
+        out_error( "server.lua, port ", port, ": ", err )
+        return nil, err
+    end
+    addr = addr or "*"
+    local server, err = socket_bind( addr, port )
+    if err then
+        out_error( "server.lua, port ", port, ": ", err )
+        return nil, err
+    end
+    local handler, err = wrapserver( listeners, server, addr, port, pattern, sslctx, maxconnections, startssl )    -- wrap new server socket
+    if not handler then
+        server:close( )
+        return nil, err
+    end
+    server:settimeout( 0 )
+    _readlistlen = addsocket(_readlist, server, _readlistlen)
+    _server[ port ] = handler
+    _socketlist[ server ] = handler
+    out_put( "server.lua: new server listener on '", addr, ":", port, "'" )
+    return handler
+end
+
+getserver = function ( port )
+	return _server[ port ];
+end
+
+removeserver = function( port )
+    local handler = _server[ port ]
+    if not handler then
+        return nil, "no server found on port '" .. tostring( port ) .. "'"
+    end
+    handler.close( )
+    _server[ port ] = nil
+    return true
+end
+
+closeall = function( )
+    for _, handler in pairs( _socketlist ) do
+        handler.close( )
+        _socketlist[ _ ] = nil
+    end
+    _readlistlen = 0
+    _sendlistlen = 0
+    _timerlistlen = 0
+    _server = { }
+    _readlist = { }
+    _sendlist = { }
+    _timerlist = { }
+    _socketlist = { }
+    --mem_free( )
+end
+
+getsettings = function( )
+    return  _selecttimeout, _sleeptime, _maxsendlen, _maxreadlen, _checkinterval, _sendtimeout, _readtimeout, _cleanqueue, _maxclientsperserver, _maxsslhandshake
+end
+
+changesettings = function( new )
+    if type( new ) ~= "table" then
+        return nil, "invalid settings table"
+    end
+    _selecttimeout = tonumber( new.timeout ) or _selecttimeout
+    _sleeptime = tonumber( new.sleeptime ) or _sleeptime
+    _maxsendlen = tonumber( new.maxsendlen ) or _maxsendlen
+    _maxreadlen = tonumber( new.maxreadlen ) or _maxreadlen
+    _checkinterval = tonumber( new.checkinterval ) or _checkinterval
+    _sendtimeout = tonumber( new.sendtimeout ) or _sendtimeout
+    _readtimeout = tonumber( new.readtimeout ) or _readtimeout
+    _cleanqueue = new.cleanqueue
+    _maxclientsperserver = new._maxclientsperserver or _maxclientsperserver
+    _maxsslhandshake = new._maxsslhandshake or _maxsslhandshake
+    return true
+end
+
+addtimer = function( listener )
+    if type( listener ) ~= "function" then
+        return nil, "invalid listener function"
+    end
+    _timerlistlen = _timerlistlen + 1
+    _timerlist[ _timerlistlen ] = listener
+    return true
+end
+
+stats = function( )
+    return _readtraffic, _sendtraffic, _readlistlen, _sendlistlen, _timerlistlen
+end
+
+local dontstop = true; -- thinking about tomorrow, ...
+
+setquitting = function (quit)
+	dontstop = not quit;
+	return;
+end
+
+loop = function( )    -- this is the main loop of the program
+    while dontstop do
+        local read, write, err = socket_select( _readlist, _sendlist, _selecttimeout )
+        for i, socket in ipairs( write ) do    -- send data waiting in writequeues
+            local handler = _socketlist[ socket ]
+            if handler then
+                handler.sendbuffer( )
+            else
+                closesocket( socket )
+                out_put "server.lua: found no handler and closed socket (writelist)"    -- this should not happen
+            end
+        end
+        for i, socket in ipairs( read ) do    -- receive data
+            local handler = _socketlist[ socket ]
+            if handler then
+                handler.readbuffer( )
+            else
+                closesocket( socket )
+                out_put "server.lua: found no handler and closed socket (readlist)"    -- this can happen
+            end
+        end
+        for handler, err in pairs( _closelist ) do
+            handler.disconnect( )( handler, err )
+            handler.close( true )    -- forced disconnect
+        end
+        clean( _closelist )
+        _currenttime = os_time( )
+        if os_difftime( _currenttime - _timer ) >= 1 then
+            for i = 1, _timerlistlen do
+                _timerlist[ i ]( _currenttime )    -- fire timers
+            end
+            _timer = _currenttime
+        end
+        socket_sleep( _sleeptime )    -- wait some time
+        --collectgarbage( )
+    end
+    return "quitting"
+end
+
+--// EXPERIMENTAL //--
+
+local wrapclient = function( socket, ip, serverport, listeners, pattern, sslctx, startssl )
+    local handler = wrapconnection( nil, listeners, socket, ip, serverport, "clientport", pattern, sslctx, startssl )
+    _socketlist[ socket ] = handler
+    _sendlistlen = addsocket(_sendlist, socket, _sendlistlen)
+    return handler, socket
+end
+
+local addclient = function( address, port, listeners, pattern, sslctx, startssl )
+    local client, err = luasocket.tcp( )
+    if err then
+        return nil, err
+    end
+    client:settimeout( 0 )
+    _, err = client:connect( address, port )
+    if err then    -- try again
+        local handler = wrapclient( client, address, port, listeners )
+    else
+        wrapconnection( nil, listeners, client, address, port, "clientport", pattern, sslctx, startssl )
+    end
+end
+
+--// EXPERIMENTAL //--
+
+----------------------------------// BEGIN //--
+
+use "setmetatable" ( _socketlist, { __mode = "k" } )
+use "setmetatable" ( _readtimes, { __mode = "k" } )
+use "setmetatable" ( _writetimes, { __mode = "k" } )
+
+_timer = os_time( )
+_starttime = os_time( )
+
+addtimer( function( )
+        local difftime = os_difftime( _currenttime - _starttime )
+        if difftime > _checkinterval then
+            _starttime = _currenttime
+            for handler, timestamp in pairs( _writetimes ) do
+                if os_difftime( _currenttime - timestamp ) > _sendtimeout then
+                    --_writetimes[ handler ] = nil
+                    handler.disconnect( )( handler, "send timeout" )
+                    handler.close( true )    -- forced disconnect
+                end
+            end
+            for handler, timestamp in pairs( _readtimes ) do
+                if os_difftime( _currenttime - timestamp ) > _readtimeout then
+                    --_readtimes[ handler ] = nil
+                    handler.disconnect( )( handler, "read timeout" )
+                    handler.close( )    -- forced disconnect?
+                end
+            end
+        end
+    end
+)
+
+----------------------------------// PUBLIC INTERFACE //--
+
+return {
+
+    addclient = addclient,
+    wrapclient = wrapclient,
+    
+    loop = loop,
+    stats = stats,
+    closeall = closeall,
+    addtimer = addtimer,
+    addserver = addserver,
+    getserver = getserver,
+    getsettings = getsettings,
+    setquitting = setquitting,
+    removeserver = removeserver,
+    changesettings = changesettings,
+}