Diff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/net/server_event.lua	Fri Nov 20 22:58:56 2009 +0000
@@ -0,0 +1,759 @@
+--[[
+
+
+			server.lua based on lua/libevent by blastbeat
+
+			notes:
+			-- when using luaevent, never register 2 or more EV_READ at one socket, same for EV_WRITE
+			-- you cant even register a new EV_READ/EV_WRITE callback inside another one
+			-- never call eventcallback:close( ) from inside eventcallback
+			-- to do some of the above, use timeout events or something what will called from outside
+			-- dont let garbagecollect eventcallbacks, as long they are running
+			-- when using luasec, there are 4 cases of timeout errors: wantread or wantwrite during reading or writing
+
+--]]
+
+
+local SCRIPT_NAME           = "server_event.lua"
+local SCRIPT_VERSION        = "0.05"
+local SCRIPT_AUTHOR         = "blastbeat"
+local LAST_MODIFIED         = "2009/11/20"
+
+local cfg = {
+	MAX_CONNECTIONS       = 100000,  -- max per server connections (use "ulimit -n" on *nix)
+	MAX_HANDSHAKE_ATTEMPS = 10,  -- attemps to finish ssl handshake
+	HANDSHAKE_TIMEOUT     = 1,  -- timout in seconds per handshake attemp
+	MAX_READ_LENGTH       = 1024 * 1024 * 1024 * 1024,  -- max bytes allowed to read from sockets
+	MAX_SEND_LENGTH       = 1024 * 1024 * 1024 * 1024,  -- max bytes size of write buffer (for writing on sockets)
+	ACCEPT_DELAY          = 10,  -- seconds to wait until the next attemp of a full server to accept
+	READ_TIMEOUT          = 60 * 30,  -- timeout in seconds for read data from socket
+	WRITE_TIMEOUT         = 30,  -- timeout in seconds for write data on socket
+	CONNECT_TIMEOUT       = 10,  -- timeout in seconds for connection attemps
+	CLEAR_DELAY           = 5,  -- seconds to wait for clearing interface list (and calling ondisconnect listeners) 
+	DEBUG                 = true,  -- show debug messages
+}
+
+local function use(x) return rawget(_G, x); end
+local print = use "print"
+local pcall = use "pcall"
+local ipairs = use "ipairs"
+local string = use "string"
+local select = use "select"
+local require = use "require"
+local tostring = use "tostring"
+local coroutine = use "coroutine"
+local setmetatable = use "setmetatable"
+
+local ssl = use "ssl"
+local socket = use "socket"
+
+local log = require ("util.logger").init("socket")
+
+local function debug(...)
+	return log("debug", ("%s "):rep(select('#', ...)), ...)
+end
+
+local bitor = ( function( ) -- thx Rici Lake
+	local hasbit = function( x, p )
+		return x % ( p + p ) >= p
+	end
+	return function( x, y ) 
+		local p = 1
+		local z = 0
+		local limit = x > y and x or y
+		while p <= limit do 
+			if hasbit( x, p ) or hasbit( y, p ) then
+				z = z + p
+			end
+			p = p + p
+		end
+		return z
+	end
+end )( )
+
+local getid = function( )
+	return function( )
+	end
+end
+
+local event = require "luaevent.core"
+local base = event.new( )
+local EV_READ = event.EV_READ
+local EV_WRITE = event.EV_WRITE
+local EV_TIMEOUT = event.EV_TIMEOUT
+
+local EV_READWRITE = bitor( EV_READ, EV_WRITE )
+
+local interfacelist = ( function( )  -- holds the interfaces for sockets
+	local array = { }
+	local len = 0
+	return function( method, arg )
+		if "add" == method then
+			len = len + 1
+			array[ len ] = arg
+			arg:_position( len )
+			return len
+		elseif "delete" == method then
+			if len <= 0 then
+				return nil, "array is already empty"
+			end
+			local position = arg:_position()  -- get position in array
+			if position ~= len then
+				local interface = array[ len ]  -- get last interface
+				array[ position ] = interface  -- copy it into free position
+				array[ len ] = nil  -- free last position
+				interface:_position( position )  -- set new position in array
+			else  -- free last position
+				array[ len ] = nil
+			end
+			len = len - 1
+			return len    
+		else
+			return array
+		end
+	end
+end )( )
+
+-- Client interface methods
+local interface_mt
+do
+	interface_mt = {}; interface_mt.__index = interface_mt;
+	
+	local addevent = base.addevent
+	local coroutine_wrap, coroutine_yield = coroutine.wrap,coroutine.yield
+	local string_len = string.len
+	
+	-- Private methods
+	function interface_mt:_position(new_position)
+			self.position = new_position or self.position
+			return self.position;
+	end
+	function interface_mt:_close() -- regs event to start self:_destroy()
+			local callback = function( )
+				self:_destroy();
+				self.eventclose = nil
+				return -1
+			end
+			self.eventclose = addevent( base, nil, EV_TIMEOUT, callback, 0 )
+			return true
+	end
+	
+	function interface_mt:_start_connection(plainssl) -- should be called from addclient
+			local callback = function( event )
+				if EV_TIMEOUT == event then  -- timout during connection
+					self.fatalerror = "connection timeout"
+					self.listener.ontimeout( self )  -- call timeout listener
+					self:_close()
+					debug( "new connection failed. id:", self, "error:", self.fatalerror )
+				else
+					if plainssl then  -- start ssl session
+						self:_start_ssl( self.listener.onconnect )
+					else  -- normal connection
+						self:_start_session( self.listener.onconnect )
+					end
+					debug( "new connection established. id:", self )
+				end
+				self.eventconnect = nil
+				return -1
+			end
+			self.eventconnect = addevent( base, self.conn, EV_WRITE, callback, cfg.CONNECT_TIMEOUT )
+			return true
+	end
+	function interface_mt:_start_session(onconnect) -- new session, for example after startssl
+		if self.type == "client" then
+			local callback = function( )
+				self:_lock( false,  false, false )
+				--vdebug( "start listening on client socket with id:", self )      
+				self.eventread = addevent( base, self.conn, EV_READ, self.readcallback, cfg.READ_TIMEOUT )  -- register callback
+				onconnect( self )
+				self.eventsession = nil
+				return -1
+			end
+			self.eventsession = addevent( base, nil, EV_TIMEOUT, callback, 0 )
+		else
+			self:_lock( false )
+			--vdebug( "start listening on server socket with id:", self )
+			self.eventread = addevent( base, self.conn, EV_READ, self.readcallback )  -- register callback
+		end
+		return true
+	end
+	function interface_mt:_start_ssl(arg) -- old socket will be destroyed, therefore we have to close read/write events first
+			--vdebug( "starting ssl session with client id:", self )
+			local _
+			_ = self.eventread and self.eventread:close( )  -- close events; this must be called outside of the event callbacks!
+			_ = self.eventwrite and self.eventwrite:close( )
+			self.eventread, self.eventwrite = nil, nil
+			local err
+			self.conn, err = ssl.wrap( self.conn, self.sslctx )
+			if err then
+				self.fatalerror = err
+				self.conn = nil  -- cannot be used anymore
+				if "onconnect" == arg then
+					self.ondisconnect = nil  -- dont call this when client isnt really connected
+				end
+				self:_close()
+				debug( "fatal error while ssl wrapping:", err )
+				return false
+			end
+			self.conn:settimeout( 0 )  -- set non blocking
+			local handshakecallback = coroutine_wrap(
+				function( event )
+					local _, err
+					local attempt = 0
+					local maxattempt = cfg.MAX_HANDSHAKE_ATTEMPS
+					while attempt < 1000 do  -- no endless loop
+						attempt = attempt + 1
+						debug( "ssl handshake of client with id:", self, "attemp:", attempt )
+						if attempt > maxattempt then
+							self.fatalerror = "max handshake attemps exceeded"
+						elseif EV_TIMEOUT == event then
+							self.fatalerror = "timeout during handshake"
+						else
+							_, err = self.conn:dohandshake( )
+							if not err then
+								self:_lock( false, false, false )  -- unlock the interface; sending, closing etc allowed
+								self.send = self.conn.send  -- caching table lookups with new client object
+								self.receive = self.conn.receive
+								local onsomething
+								if "onconnect" == arg then  -- trigger listener
+									onsomething = self.listener.onconnect
+								else
+									onsomething = self.listener.onsslconnection
+								end
+								self:_start_session( onsomething )
+								debug( "ssl handshake done" )
+								self.eventhandshake = nil
+								return -1
+							end
+							debug( "error during ssl handshake:", err )  
+							if err == "wantwrite" then
+								event = EV_WRITE
+							elseif err == "wantread" then
+								event = EV_READ
+							else
+								self.fatalerror = err
+							end            
+						end
+						if self.fatalerror then
+							if "onconnect" == arg then
+								self.ondisconnect = nil  -- dont call this when client isnt really connected
+							end
+							self:_close()
+							debug( "handshake failed because:", self.fatalerror )
+							self.eventhandshake = nil
+							return -1
+						end
+						event = coroutine_yield( event, cfg.HANDSHAKE_TIMEOUT )  -- yield this monster...
+					end
+				end
+			)
+			debug "starting handshake..."
+			self:_lock( false, true, true )  -- unlock read/write events, but keep interface locked 
+			self.eventhandshake = addevent( base, self.conn, EV_READWRITE, handshakecallback, cfg.HANDSHAKE_TIMEOUT )
+			return true
+	end
+	function interface_mt:_destroy()  -- close this interface + events and call last listener
+			debug( "closing client with id:", self )
+			self:_lock( true, true, true )  -- first of all, lock the interface to avoid further actions
+			local _
+			_ = self.eventread and self.eventread:close( )  -- close events; this must be called outside of the event callbacks!
+			if self.type == "client" then
+				_ = self.eventwrite and self.eventwrite:close( )
+				_ = self.eventhandshake and self.eventhandshake:close( )
+				_ = self.eventstarthandshake and self.eventstarthandshake:close( )
+				_ = self.eventconnect and self.eventconnect:close( )
+				_ = self.eventsession and self.eventsession:close( )
+				_ = self.eventwritetimeout and self.eventwritetimeout:close( )
+				_ = self.eventreadtimeout and self.eventreadtimeout:close( )
+				_ = self.ondisconnect and self:ondisconnect( self.fatalerror )  -- call ondisconnect listener (wont be the case if handshake failed on connect)
+				_ = self.conn and self.conn:close( ) -- close connection, must also be called outside of any socket registered events!
+				self._server:counter(-1);
+				self.eventread, self.eventwrite = nil, nil
+				self.eventstarthandshake, self.eventhandshake, self.eventclose = nil, nil, nil
+				self.readcallback, self.writecallback = nil, nil
+			else
+				self.conn:close( )
+				self.eventread, self.eventclose = nil, nil
+				self.interface, self.readcallback = nil, nil
+			end
+			interfacelist( "delete", self )
+			return true
+	end
+	function interface_mt:_lock(nointerface, noreading, nowriting)  -- lock or unlock this interface or events
+			self.nointerface, self.noreading, self.nowriting = nointerface, noreading, nowriting
+			return nointerface, noreading, nowriting
+	end
+
+	function interface_mt:counter(c)
+		if c then
+			self._connections = self._connections - c
+		end
+		return self._connections
+	end
+	
+	-- Public methods
+	function interface_mt:write(data)
+		--vdebug( "try to send data to client, id/data:", self, data )
+		data = tostring( data )
+		local len = string_len( data )
+		local total = len + self.writebufferlen
+		if total > cfg.MAX_SEND_LENGTH then  -- check buffer length
+			local err = "send buffer exceeded"
+			debug( "error:", err )  -- to much, check your app
+			return nil, err
+		end 
+		self.writebuffer = self.writebuffer .. data -- new buffer
+		self.writebufferlen = total
+		if not self.eventwrite then  -- register new write event
+			--vdebug( "register new write event" )
+			self.eventwrite = addevent( base, self.conn, EV_WRITE, self.writecallback, cfg.WRITE_TIMEOUT )
+		end
+		return true
+	end
+	function interface_mt:close(now)
+		debug( "try to close client connection with id:", self )
+		if self.type == "client" then
+			self.fatalerror = "client to close"
+			if ( not self.eventwrite ) or now then  -- try to close immediately
+				self:_lock( true, true, true )
+				self:_close()
+				return true
+			else  -- wait for incomplete write request
+				self:_lock( true, true, false )
+				debug "closing delayed until writebuffer is empty"
+				return nil, "writebuffer not empty, waiting"
+			end
+		else
+			debug( "try to close server with id:", self, "args:", now )
+			self.fatalerror = "server to close"
+			self:_lock( true )
+			local count = 0
+			for _, item in ipairs( interfacelist( ) ) do
+				if ( item.type ~= "server" ) and ( item._server == self ) then  -- client/server match
+					if item:close( now ) then  -- writebuffer was empty
+						count = count + 1
+					end
+				end
+			end
+			local timeout = 0  -- dont wait for unfinished writebuffers of clients...
+			if not now then
+				timeout = cfg.WRITE_TIMEOUT  -- ...or wait for it
+			end
+			self:_close( timeout )  -- add new event to remove the server interface
+			debug( "seconds remained until server is closed:", timeout )
+			return count  -- returns finished clients with empty writebuffer
+		end
+	end
+	
+	function interface_mt:server()
+		return self._server or self;
+	end
+	
+	function interface_mt:port()
+		return self._port
+	end
+	
+	function interface_mt:ip()
+		return self._ip
+	end
+	
+	function interface_mt:ssl()
+		return self.usingssl
+	end
+
+	function interface_mt:type()
+		return self._type or "client"
+	end
+	
+	function interface_mt:connections()
+		return self._connections
+	end
+	
+	function interface_mt:address()
+		return self.addr
+	end
+	
+			
+	
+	function interface_mt:starttls()
+		debug( "try to start ssl at client id:", self )
+		local err
+		if not self.sslctx then  -- no ssl available
+			err = "no ssl context available"
+		elseif self.usingssl then  -- startssl was already called
+			err = "ssl already active"
+		end
+		if err then
+			debug( "error:", err )
+			return nil, err      
+		end
+		self.usingssl = true
+		self.startsslcallback = function( )  -- we have to start the handshake outside of a read/write event
+			self:_start_ssl();
+			self.eventstarthandshake = nil
+			return -1
+		end
+		if not self.eventwrite then
+			self:_lock( true, true, true )  -- lock the interface, to not disturb the handshake
+			self.eventstarthandshake = addevent( base, nil, EV_TIMEOUT, self.startsslcallback, 0 )  -- add event to start handshake
+		else  -- wait until writebuffer is empty
+			self:_lock( true, true, false )
+			debug "ssl session delayed until writebuffer is empty..."
+		end
+		return true
+	end
+	
+	function interface_mt.onconnect()
+	end
+end			
+
+-- End of client interface methods
+
+local handleclient;
+do
+	local string_sub = string.sub  -- caching table lookups
+	local string_len = string.len
+	local addevent = base.addevent
+	local coroutine_wrap = coroutine.wrap
+	local socket_gettime = socket.gettime
+	local coroutine_yield = coroutine.yield
+	function handleclient( client, ip, port, server, pattern, listener, _, sslctx )  -- creates an client interface
+		--vdebug("creating client interfacce...")
+		local interface = {
+			type = "client";
+			conn = client;
+			currenttime = socket_gettime( );  -- safe the origin
+			writebuffer = "";  -- writebuffer
+			writebufferlen = 0;  -- length of writebuffer
+			send = client.send;  -- caching table lookups
+			receive = client.receive;
+			onconnect = listener.onconnect;  -- will be called when client disconnects
+			ondisconnect = listener.ondisconnect;  -- will be called when client disconnects
+			onincoming = listener.onincoming;  -- will be called when client sends data
+			eventread = false, eventwrite = false, eventclose = false,
+			eventhandshake = false, eventstarthandshake = false;  -- event handler
+			eventconnect = false, eventsession = false;  -- more event handler...
+			eventwritetimeout = false;  -- even more event handler...
+			eventreadtimeout = false;
+			fatalerror = false;  -- error message
+			writecallback = false;  -- will be called on write events
+			readcallback = false;  -- will be called on read events
+			nointerface = true;  -- lock/unlock parameter of this interface
+			noreading = false, nowriting = false;  -- locks of the read/writecallback
+			startsslcallback = false;  -- starting handshake callback
+			position = false;  -- position of client in interfacelist
+			
+			-- Properties
+			_ip = ip, _port = port, _server = server, _pattern = pattern,
+			_sslctx = sslctx; -- parameters
+			_usingssl = false;  -- client is using ssl;
+		}
+		interface.writecallback = function( event )  -- called on write events
+			--vdebug( "new client write event, id/ip/port:", interface, ip, port )
+			if interface.nowriting or ( interface.fatalerror and ( "client to close" ~= interface.fatalerror ) ) then  -- leave this event
+				--vdebug( "leaving this event because:", interface.nowriting or interface.fatalerror )
+				interface.eventwrite = false
+				return -1
+			end
+			if EV_TIMEOUT == event then  -- took too long to write some data to socket -> disconnect
+				interface.fatalerror = "timeout during writing"
+				debug( "writing failed:", interface.fatalerror ) 
+				interface:_close()
+				interface.eventwrite = false
+				return -1
+			else  -- can write :)
+				if interface.usingssl then  -- handle luasec
+					if interface.eventreadtimeout then  -- we have to read first
+						local ret = interface.readcallback( )  -- call readcallback
+						--vdebug( "tried to read in writecallback, result:", ret )
+					end
+					if interface.eventwritetimeout then  -- luasec only
+						interface.eventwritetimeout:close( )  -- first we have to close timeout event which where regged after a wantread error
+						interface.eventwritetimeout = false
+					end
+				end
+				local succ, err, byte = interface.send( interface.conn, interface.writebuffer, 1, interface.writebufferlen )
+				--vdebug( "write data:", interface.writebuffer, "error:", err, "part:", byte )
+				if succ then  -- writing succesful
+					interface.writebuffer = ""
+					interface.writebufferlen = 0
+					if interface.fatalerror then
+						debug "closing client after writing"
+						interface:_close()  -- close interface if needed
+					elseif interface.startsslcallback then  -- start ssl connection if needed
+						debug "starting ssl handshake after writing"
+						interface.eventstarthandshake = addevent( base, nil, EV_TIMEOUT, interface.startsslcallback, 0 )
+					elseif interface.eventreadtimeout then
+						return EV_WRITE, EV_TIMEOUT
+					end
+					interface.eventwrite = nil
+					return -1
+				elseif byte then  -- want write again
+					--vdebug( "writebuffer is not empty:", err )
+					interface.writebuffer = string_sub( interface.writebuffer, byte + 1, interface.writebufferlen )  -- new buffer
+					interface.writebufferlen = interface.writebufferlen - byte            
+					if "wantread" == err then  -- happens only with luasec
+						local callback = function( )
+							interface:_close()
+							interface.eventwritetimeout = nil
+							return evreturn, evtimeout
+						end
+						interface.eventwritetimeout = addevent( base, nil, EV_TIMEOUT, callback, cfg.WRITE_TIMEOUT )  -- reg a new timeout event
+						debug( "wantread during write attemp, reg it in readcallback but dont know what really happens next..." )
+						-- hopefully this works with luasec; its simply not possible to use 2 different write events on a socket in luaevent
+						return -1
+					end
+					return EV_WRITE, cfg.WRITE_TIMEOUT 
+				else  -- connection was closed during writing or fatal error
+					interface.fatalerror = err or "fatal error"
+					debug( "connection failed in write event:", interface.fatalerror ) 
+					interface:_close()
+					interface.eventwrite = nil
+					return -1
+				end
+			end
+		end
+		local usingssl, receive = interface._usingssl, interface.receive;
+		interface.readcallback = function( event )  -- called on read events
+			--vdebug( "new client read event, id/ip/port:", interface, ip, port )
+			if interface.noreading or interface.fatalerror then  -- leave this event
+				--vdebug( "leaving this event because:", interface.noreading or interface.fatalerror )
+				interface.eventread = nil
+				return -1
+			end
+			if EV_TIMEOUT == event then  -- took too long to get some data from client -> disconnect
+				interface.fatalerror = "timeout during receiving"
+				debug( "connection failed:", interface.fatalerror ) 
+				interface:_close()
+				interface.eventread = nil
+				return -1
+			else -- can read
+				if usingssl then  -- handle luasec
+					if interface.eventwritetimeout then  -- ok, in the past writecallback was regged
+						local ret = interface.writecallback( )  -- call it
+						--vdebug( "tried to write in readcallback, result:", ret )
+					end
+					if interface.eventreadtimeout then
+						interface.eventreadtimeout:close( )
+						interface.eventreadtimeout = nil
+					end
+				end
+				local buffer, err, part = receive( client, pattern )  -- receive buffer with "pattern"
+				--vdebug( "read data:", buffer, "error:", err, "part:", part )        
+				buffer = buffer or part or ""
+				local len = string_len( buffer )
+				if len > cfg.MAX_READ_LENGTH then  -- check buffer length
+					interface.fatalerror = "receive buffer exceeded"
+					debug( "fatal error:", interface.fatalerror )
+					interface:_close()
+					interface.eventread = nil
+					return -1
+				end
+				if err and ( "timeout" ~= err ) then
+					if "wantwrite" == err then -- need to read on write event
+						if not interface.eventwrite then  -- register new write event if needed
+							interface.eventwrite = addevent( base, interface.conn, EV_WRITE, interface.writecallback, cfg.WRITE_TIMEOUT )
+						end
+						interface.eventreadtimeout = addevent( base, nil, EV_TIMEOUT,
+							function( )
+								interface:_close()
+							end, cfg.READ_TIMEOUT
+						)             
+						debug( "wantwrite during read attemp, reg it in writecallback but dont know what really happens next..." )
+						-- to be honest i dont know what happens next, if it is allowed to first read, the write etc...
+					else  -- connection was closed or fatal error            
+						interface.fatalerror = err
+						debug( "connection failed in read event:", interface.fatalerror ) 
+						interface:_close()
+						interface.eventread = nil
+						return -1
+					end
+				end
+				interface.onincoming( interface, buffer, err )  -- send new data to listener
+				return EV_READ, cfg.READ_TIMEOUT
+			end
+		end
+
+		client:settimeout( 0 )  -- set non blocking
+		setmetatable(interface, interface_mt)
+		interfacelist( "add", interface )  -- add to interfacelist
+		return interface
+	end
+end
+
+local handleserver
+do
+	function handleserver( server, addr, port, pattern, listener, sslctx, startssl )  -- creates an server interface
+		debug "creating server interface..."
+		local interface = {
+			_connections = 0;
+			
+			conn = server;
+			onconnect = listener.onconnect;  -- will be called when new client connected
+			eventread = false;  -- read event handler
+			eventclose = false; -- close event handler
+			readcallback = false; -- read event callback
+			fatalerror = false; -- error message
+			nointerface = true;  -- lock/unlock parameter
+		}
+		interface.readcallback = function( event )  -- server handler, called on incoming connections
+			--vdebug( "server can accept, id/addr/port:", interface, addr, port )
+			if interface.fatalerror then
+				--vdebug( "leaving this event because:", self.fatalerror )
+				interface.eventread = nil
+				return -1
+			end
+			local delay = cfg.ACCEPT_DELAY
+			if EV_TIMEOUT == event then
+				if interface._connections >= cfg.MAX_CONNECTIONS then  -- check connection count
+					debug( "to many connections, seconds to wait for next accept:", delay )
+					return EV_TIMEOUT, delay  -- timeout...
+				else
+					return EV_READ  -- accept again
+				end
+			end
+			--vdebug("max connection check ok, accepting...")
+			local client, err = server:accept()    -- try to accept; TODO: check err
+			while client do
+				if interface._connections >= cfg.MAX_CONNECTIONS then
+					client:close( )  -- refuse connection
+					debug( "maximal connections reached, refuse client connection; accept delay:", delay )
+					return EV_TIMEOUT, delay  -- delay for next accept attemp
+				end
+				local ip, port = client:getpeername( )
+				interface._connections = interface._connections + 1  -- increase connection count
+				local clientinterface = handleclient( client, ip, port, interface, pattern, listener, nil, sslctx )
+				--vdebug( "client id:", clientinterface, "startssl:", startssl )
+				if startssl then
+					clientinterface:_start_ssl( clientinterface.onconnect )
+				else
+					clientinterface:_start_session( clientinterface.onconnect )
+				end
+				debug( "accepted incoming client connection from:", ip, port )
+				client, err = server:accept()    -- try to accept again
+			end
+			return EV_READ
+		end
+		
+		server:settimeout( 0 )
+		setmetatable(interface, interface_mt)
+		interfacelist( "add", interface )
+		interface:_start_session()
+		return interface
+	end
+end
+
+local addserver = ( function( )
+	return function( addr, port, listener, pattern, backlog, sslcfg, startssl )  -- TODO: check arguments
+		debug( "creating new tcp server with following parameters:", addr or "nil", port or "nil", sslcfg or "nil", startssl or "nil")
+		local server, err = socket.bind( addr, port, backlog )  -- create server socket
+		if not server then
+			debug( "creating server socket failed because:", err )
+			return nil, err
+		end
+		local sslctx
+		if sslcfg then
+			if not ssl then
+				debug "fatal error: luasec not found"
+				return nil, "luasec not found"
+			end
+			sslctx, err = ssl.newcontext( sslcfg )
+			if err then
+				debug( "error while creating new ssl context for server socket:", err )
+				return nil, err
+			end
+		end      
+		local interface = handleserver( server, addr, port, pattern, listener, sslctx, startssl )  -- new server handler
+		debug( "new server created with id:", tostring(interface))
+		return interface
+	end
+end )( )
+
+local wrapclient = ( function( )
+	return function( client, addr, serverport, listener, pattern, localaddr, localport, sslcfg, startssl )
+		debug( "try to connect to:", addr, serverport, "with parameters:", pattern, localaddr, localport, sslcfg, startssl )
+		local sslctx
+		if sslcfg then  -- handle ssl/new context
+			if not ssl then
+				debug "need luasec, but not available" 
+				return nil, "luasec not found"
+			end
+			sslctx, err = ssl.newcontext( sslcfg )
+			if err then
+				debug( "cannot create new ssl context:", err )
+				return nil, err
+			end
+		end
+	end
+end )( )
+
+local addclient = ( function( )
+	return function( addr, serverport, listener, pattern, localaddr, localport, sslcfg, startssl )
+		local client, err = socket.tcp()  -- creating new socket
+		if not client then
+			debug( "cannot create socket:", err ) 
+			return nil, err
+		end
+		client:settimeout( 0 )  -- set nonblocking
+		if localaddr then
+			local res, err = client:bind( localaddr, localport, -1 )
+			if not res then
+				debug( "cannot bind client:", err )
+				return nil, err
+			end
+		end
+		local res, err = client:connect( addr, serverport )  -- connect
+		if res or ( err == "timeout" ) then
+			local ip, port = client:getsockname( )
+			local server = function( )
+				return nil, "this is a dummy server interface"
+			end
+			local interface = handleclient( client, ip, port, server, pattern, listener, sslctx )
+			interface:_start_connection( startssl )
+			debug( "new connection id:", interface )
+			return interface, err
+		else
+			debug( "new connection failed:", err )
+			return nil, err
+		end
+		return wrapclient( client, addr, serverport, listener, pattern, localaddr, localport, sslcfg, startssl )    
+	end
+end )( )
+
+local loop = function( )  -- starts the event loop
+	return base:loop( )
+end
+
+local newevent = ( function( )
+	local add = base.addevent
+	return function( ... )
+		return add( base, ... )
+	end
+end )( )
+
+local closeallservers = function( arg )
+	for _, item in ipairs( interfacelist( ) ) do
+		if item "type" == "server" then
+			item( "close", arg )
+		end
+	end
+end
+
+return {
+
+	cfg = cfg,
+	base = base,
+	loop = loop,
+	event = event,
+	addevent = newevent,
+	addserver = addserver,
+	addclient = addclient,
+	wrapclient = wrapclient,
+	closeallservers = closeallservers,
+
+	__NAME = SCRIPT_NAME,
+	__DATE = LAST_MODIFIED,
+	__AUTHOR = SCRIPT_AUTHOR,
+	__VERSION = SCRIPT_VERSION,
+
+}