--
-- server.lua by blastbeat of the luadch project
-- Re-used here under the MIT/X Consortium License
--
-- Modifications (C) 2008-2010 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
----------------------------------// DECLARATION //--
--// constants //--
local STAT_UNIT = 1 -- byte
--// lua functions //--
local type = use "type"
local pairs = use "pairs"
local ipairs = use "ipairs"
local tonumber = use "tonumber"
local tostring = use "tostring"
--// lua libs //--
local os = use "os"
local table = use "table"
local string = use "string"
local coroutine = use "coroutine"
--// lua lib methods //--
local os_difftime = os.difftime
local math_min = math.min
local math_huge = math.huge
local table_concat = table.concat
local string_len = string.len
local string_sub = string.sub
local coroutine_wrap = coroutine.wrap
local coroutine_yield = coroutine.yield
--// extern libs //--
local luasec = use "ssl"
local luasocket = use "socket" or require "socket"
local luasocket_gettime = luasocket.gettime
--// 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
--// functions //--
local id
local loop
local stats
local idfalse
local closeall
local addsocket
local addserver
local getserver
local wrapserver
local getsettings
local closesocket
local removesocket
local removeserver
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
local _maxsslhandshake
----------------------------------// 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 ) -- this function wraps a server
maxconnections = maxconnections or _maxclientsperserver
local connections = 0
local dispatch, disconnect = listeners.onconnect, listeners.ondisconnect
local accept = socket.accept
--// public methods of the object //--
local handler = { }
handler.shutdown = function( ) end
handler.ssl = function( )
return sslctx ~= nil
end
handler.sslctx = function( )
return sslctx
end
handler.remove = function( )
connections = connections - 1
end
handler.close = function()
socket:close( )
_sendlistlen = removesocket( _sendlist, socket, _sendlistlen )
_readlistlen = removesocket( _readlist, socket, _readlistlen )
_server[ip..":"..serverport] = nil;
_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 ) -- 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))
if dispatch then
return dispatch( handler );
end
return;
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 ) -- 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.onincoming
local status = listeners.onstatus
local disconnect = listeners.ondisconnect
local drain = listeners.ondrain
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( self, listeners )
dispatch = listeners.onincoming
disconnect = listeners.ondisconnect
status = listeners.onstatus
drain = listeners.ondrain
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.setoption = function (self, option, value)
if socket.setoption then
return socket:setoption(option, value);
end
return false, "setoption not implemented";
end
handler.force_close = function ( self, err )
if bufferqueuelen ~= 0 then
out_put("server.lua: discarding unwritten data for ", tostring(ip), ":", tostring(clientport))
for i = bufferqueuelen, 1, -1 do
bufferqueue[i] = nil;
end
bufferqueuelen = 0;
end
return self:close(err);
end
handler.close = function( self, err )
if not handler then return true; end
_readlistlen = removesocket( _readlist, socket, _readlistlen )
_readtimes[ handler ] = nil
if bufferqueuelen ~= 0 then
handler.sendbuffer() -- Try now to send any outstanding data
if bufferqueuelen ~= 0 then -- Still not empty, so we'll try again later
if handler then
handler.write = nil -- ... but no further writing allowed
end
toclose = true
return false
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
local _handler = handler;
handler = nil
if disconnect then
disconnect(_handler, err or false);
disconnect = nil
end
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( self, 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( self )
return bufferqueue
end
handler.socket = function( self )
return socket
end
handler.set_mode = function( self, new )
pattern = new or pattern
return pattern
end
handler.set_send = function ( self, newsend )
send = newsend or send
return send
end
handler.bufferlen = function( self, readlen, sendlen )
maxsendlen = sendlen or maxsendlen
maxreadlen = readlen or maxreadlen
return bufferlen, maxreadlen, maxsendlen
end
--TODO: Deprecate
handler.lock_read = function (self, switch)
if switch == true then
local tmp = _readlistlen
_readlistlen = removesocket( _readlist, socket, _readlistlen )
_readtimes[ handler ] = nil
if _readlistlen ~= tmp then
noread = true
end
elseif switch == false then
if noread then
noread = false
_readlistlen = addsocket(_readlist, socket, _readlistlen)
_readtimes[ handler ] = _currenttime
end
end
return noread
end
handler.pause = function (self)
return self:lock_read(true);
end
handler.resume = function (self)
return self:lock_read(false);
end
handler.lock = function( self, switch )
handler.lock_read (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
elseif switch == false then
handler.write = write
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 == "wantread" or err == "timeout") then -- received something
local buffer = buffer or part or ""
local len = string_len( buffer )
if len > maxreadlen then
handler:close( "receive buffer exceeded" )
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
_ = handler and handler:force_close( err )
return false
end
end
local _sendbuffer = function( ) -- this function sends data
local succ, err, byte, buffer, 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, "unexpected close", 0;
end
if succ then -- sending succesful
bufferqueuelen = 0
bufferlen = 0
_sendlistlen = removesocket( _sendlist, socket, _sendlistlen ) -- delete socket from writelist
_writetimes[ handler ] = nil
if drain then
drain(handler)
end
_ = needtls and handler:starttls(nil)
_ = toclose and handler:force_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
_ = handler and handler:force_close( err )
return false
end
end
-- Set the sslctx
local handshake;
function handler.set_sslctx(self, new_sslctx)
sslctx = new_sslctx;
local read, wrote
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" )
if self.autostart_ssl and listeners.onconnect then
listeners.onconnect(self);
end
_readlistlen = addsocket(_readlist, client, _readlistlen)
return true
else
if err == "wantwrite" then
_sendlistlen = addsocket(_sendlist, client, _sendlistlen)
wrote = true
elseif err == "wantread" then
_readlistlen = addsocket(_readlist, client, _readlistlen)
read = true
else
break;
end
err = nil;
coroutine_yield( ) -- handshake not finished
end
end
out_put( "server.lua: ssl handshake error: ", tostring(err or "handshake too long") )
_ = handler and handler:force_close("ssl handshake failed")
return false, err -- handshake failed
end
)
end
if luasec then
handler.starttls = function( self, _sslctx)
if _sslctx then
handler:set_sslctx(_sslctx);
end
if bufferqueuelen > 0 then
out_put "server.lua: we need to do tls, but delaying until send buffer empty"
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
if not socket then
out_put( "server.lua: error while starting tls on client: ", tostring(err or "unknown error") )
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 (if handshake fails connection will close)
ssl = true
handler.readbuffer = handshake
handler.sendbuffer = handshake
return handshake( socket ) -- do handshake
end
end
handler.readbuffer = _readbuffer
handler.sendbuffer = _sendbuffer
send = socket.send
receive = socket.receive
shutdown = ( ssl and id ) or socket.shutdown
_socketlist[ socket ] = handler
_readlistlen = addsocket(_readlist, socket, _readlistlen)
if sslctx and luasec then
out_put "server.lua: auto-starting ssl negotiation..."
handler.autostart_ssl = true;
local ok, err = handler:starttls(sslctx);
if ok == false then
return nil, nil, err
end
end
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
local function link(sender, receiver, buffersize)
local sender_locked;
local _sendbuffer = receiver.sendbuffer;
function receiver.sendbuffer()
_sendbuffer();
if sender_locked and receiver.bufferlen() < buffersize then
sender:lock_read(false); -- Unlock now
sender_locked = nil;
end
end
local _readbuffer = sender.readbuffer;
function sender.readbuffer()
_readbuffer();
if not sender_locked and receiver.bufferlen() >= buffersize then
sender_locked = true;
sender:lock_read(true);
end
end
end
----------------------------------// PUBLIC //--
addserver = function( addr, port, listeners, pattern, sslctx ) -- this function provides a way for other scripts to reg a server
local err
if type( listeners ) ~= "table" then
err = "invalid listener table"
end
if type( port ) ~= "number" or not ( port >= 0 and port <= 65535 ) then
err = "invalid port"
elseif _server[ addr..":"..port ] then
err = "listeners on '[" .. addr .. "]:" .. port .. "' already exist"
elseif sslctx and not luasec then
err = "luasec not found"
end
if err then
out_error( "server.lua, [", addr, "]:", port, ": ", err )
return nil, err
end
addr = addr or "*"
local server, err = socket_bind( addr, port )
if err then
out_error( "server.lua, [", addr, "]:", port, ": ", err )
return nil, err
end
local handler, err = wrapserver( listeners, server, addr, port, pattern, sslctx, _maxclientsperserver ) -- wrap new server socket
if not handler then
server:close( )
return nil, err
end
server:settimeout( 0 )
_readlistlen = addsocket(_readlist, server, _readlistlen)
_server[ addr..":"..port ] = handler
_socketlist[ server ] = handler
out_put( "server.lua: new "..(sslctx and "ssl " or "").."server listener on '[", addr, "]:", port, "'" )
return handler
end
getserver = function ( addr, port )
return _server[ addr..":"..port ];
end
removeserver = function( addr, port )
local handler = _server[ addr..":"..port ]
if not handler then
return nil, "no server found on '[" .. addr .. "]:" .. tostring( port ) .. "'"
end
handler:close( )
_server[ addr..":"..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 quitting;
local function setquitting(quit)
quitting = not not quit;
end
loop = function(once) -- this is the main loop of the program
if quitting then return "quitting"; end
if once then quitting = "once"; end
local next_timer_time = math_huge;
repeat
local read, write, err = socket_select( _readlist, _sendlist, math_min(_selecttimeout, next_timer_time) )
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:force_close() -- forced disconnect
end
clean( _closelist )
_currenttime = luasocket_gettime( )
if _currenttime - _timer >= math_min(next_timer_time, 1) then
next_timer_time = math_huge;
for i = 1, _timerlistlen do
local t = _timerlist[ i ]( _currenttime ) -- fire timers
if t then next_timer_time = math_min(next_timer_time, t); end
end
_timer = _currenttime
else
next_timer_time = next_timer_time - (_currenttime - _timer);
end
socket_sleep( _sleeptime ) -- wait some time
--collectgarbage( )
until quitting;
if once and quitting == "once" then quitting = nil; return; end
return "quitting"
end
local function step()
return loop(true);
end
local function get_backend()
return "select";
end
--// EXPERIMENTAL //--
local wrapclient = function( socket, ip, serverport, listeners, pattern, sslctx )
local handler = wrapconnection( nil, listeners, socket, ip, serverport, "clientport", pattern, sslctx )
_socketlist[ socket ] = handler
if not sslctx then
_sendlistlen = addsocket(_sendlist, socket, _sendlistlen)
if listeners.onconnect then
-- When socket is writeable, call onconnect
local _sendbuffer = handler.sendbuffer;
handler.sendbuffer = function ()
_sendlistlen = removesocket( _sendlist, socket, _sendlistlen );
handler.sendbuffer = _sendbuffer;
listeners.onconnect(handler);
-- If there was data with the incoming packet, handle it now.
if #handler:bufferqueue() > 0 then
return _sendbuffer();
end
end
end
end
return handler, socket
end
local addclient = function( address, port, listeners, pattern, sslctx )
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 )
end
end
--// EXPERIMENTAL //--
----------------------------------// BEGIN //--
use "setmetatable" ( _socketlist, { __mode = "k" } )
use "setmetatable" ( _readtimes, { __mode = "k" } )
use "setmetatable" ( _writetimes, { __mode = "k" } )
_timer = luasocket_gettime( )
_starttime = luasocket_gettime( )
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:force_close() -- 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
)
local function setlogger(new_logger)
local old_logger = log;
if new_logger then
log = new_logger;
end
return old_logger;
end
----------------------------------// PUBLIC INTERFACE //--
return {
_addtimer = addtimer,
addclient = addclient,
wrapclient = wrapclient,
loop = loop,
link = link,
step = step,
stats = stats,
closeall = closeall,
addserver = addserver,
getserver = getserver,
setlogger = setlogger,
getsettings = getsettings,
setquitting = setquitting,
removeserver = removeserver,
get_backend = get_backend,
changesettings = changesettings,
}