""" This module implements the telnet protocol. This depends on a generic session module that implements the actual login procedure of the game, tracks sessions etc. """ import re from twisted.internet import protocol from twisted.internet.task import LoopingCall from twisted.conch.telnet import Telnet, StatefulTelnetProtocol from twisted.conch.telnet import IAC, NOP, LINEMODE, GA, WILL, WONT, ECHO, NULL from django.conf import settings from evennia.server.session import Session from evennia.server.portal import ttype, mssp, telnet_oob, naws, suppress_ga from evennia.server.portal.mccp import Mccp, mccp_compress, MCCP from evennia.server.portal.mxp import Mxp, mxp_parse from evennia.utils import ansi from evennia.utils.utils import to_str _RE_N = re.compile(r"\|n$") _RE_LEND = re.compile(r"\n$|\r$|\r\n$|\r\x00$|", re.MULTILINE) _RE_LINEBREAK = re.compile(r"\n\r|\r\n|\n|\r", re.DOTALL + re.MULTILINE) _RE_SCREENREADER_REGEX = re.compile(r"%s" % settings.SCREENREADER_REGEX_STRIP, re.DOTALL + re.MULTILINE) _IDLE_COMMAND = settings.IDLE_COMMAND + "\n" class TelnetServerFactory(protocol.ServerFactory): "This is only to name this better in logs" noisy = False def logPrefix(self): return "Telnet" class TelnetProtocol(Telnet, StatefulTelnetProtocol, Session): """ Each player connecting over telnet (ie using most traditional mud clients) gets a telnet protocol instance assigned to them. All communication between game and player goes through here. """ def __init__(self, *args, **kwargs): super(TelnetProtocol, self).__init__(*args, **kwargs) self.protocol_key = "telnet" def connectionMade(self): """ This is called when the connection is first established. """ # initialize the session self.line_buffer = "" client_address = self.transport.client client_address = client_address[0] if client_address else None # this number is counted down for every handshake that completes. # when it reaches 0 the portal/server syncs their data self.handshakes = 8 # suppress-go-ahead, naws, ttype, mccp, mssp, msdp, gmcp, mxp self.init_session(self.protocol_key, client_address, self.factory.sessionhandler) self.protocol_flags["ENCODING"] = settings.ENCODINGS[0] if settings.ENCODINGS else 'utf-8' # add this new connection to sessionhandler so # the Server becomes aware of it. self.sessionhandler.connect(self) # change encoding to ENCODINGS[0] which reflects Telnet default encoding # suppress go-ahead self.sga = suppress_ga.SuppressGA(self) # negotiate client size self.naws = naws.Naws(self) # negotiate ttype (client info) # Obs: mudlet ttype does not seem to work if we start mccp before ttype. /Griatch self.ttype = ttype.Ttype(self) # negotiate mccp (data compression) - turn this off for wireshark analysis self.mccp = Mccp(self) # negotiate mssp (crawler communication) self.mssp = mssp.Mssp(self) # oob communication (MSDP, GMCP) - two handshake calls! self.oob = telnet_oob.TelnetOOB(self) # mxp support self.mxp = Mxp(self) from evennia.utils.utils import delay # timeout the handshakes in case the client doesn't reply at all delay(2, callback=self.handshake_done, timeout=True) # TCP/IP keepalive watches for dead links self.transport.setTcpKeepAlive(1) # The TCP/IP keepalive is not enough for some networks; # we have to complement it with a NOP keep-alive. self.protocol_flags["NOPKEEPALIVE"] = True self.nop_keep_alive = None self.toggle_nop_keepalive() def _send_nop_keepalive(self): """Send NOP keepalive unless flag is set""" if self.protocol_flags.get("NOPKEEPALIVE"): self._write(IAC + NOP) def toggle_nop_keepalive(self): """ Allow to toggle the NOP keepalive for those sad clients that can't even handle a NOP instruction. This is turned off by the protocol_flag NOPKEEPALIVE (settable e.g. by the default `@option` command). """ if self.nop_keep_alive and self.nop_keep_alive.running: self.nop_keep_alive.stop() else: self.nop_keep_alive = LoopingCall(self._send_nop_keepalive) self.nop_keep_alive.start(30, now=False) def handshake_done(self, timeout=False): """ This is called by all telnet extensions once they are finished. When all have reported, a sync with the server is performed. The system will force-call this sync after a small time to handle clients that don't reply to handshakes at all. """ if timeout: if self.handshakes > 0: self.handshakes = 0 self.sessionhandler.sync(self) else: self.handshakes -= 1 if self.handshakes <= 0: # do the sync self.sessionhandler.sync(self) def at_login(self): """ Called when this session gets authenticated by the server. """ pass def enableRemote(self, option): """ This sets up the remote-activated options we allow for this protocol. Args: option (char): The telnet option to enable. Returns: enable (bool): If this option should be enabled. """ return (option == LINEMODE or option == ttype.TTYPE or option == naws.NAWS or option == MCCP or option == mssp.MSSP or option == suppress_ga.SUPPRESS_GA) def enableLocal(self, option): """ Call to allow the activation of options for this protocol Args: option (char): The telnet option to enable locally. Returns: enable (bool): If this option should be enabled. """ return (option == MCCP or option == ECHO or option == suppress_ga.SUPPRESS_GA) def disableLocal(self, option): """ Disable a given option locally. Args: option (char): The telnet option to disable locally. """ if option == ECHO: return True if option == MCCP: self.mccp.no_mccp(option) return True else: return super(TelnetProtocol, self).disableLocal(option) def connectionLost(self, reason): """ this is executed when the connection is lost for whatever reason. it can also be called directly, from the disconnect method Args: reason (str): Motivation for losing connection. """ self.sessionhandler.disconnect(self) self.transport.loseConnection() def applicationDataReceived(self, data): """ Telnet method called when non-telnet-command data is coming in over the telnet connection. We pass it on to the game engine directly. Args: data (str): Incoming data. """ if not data: data = [data] elif data.strip() == NULL: # this is an ancient type of keepalive used by some # legacy clients. There should never be a reason to send a # lone NULL character so this seems to be a safe thing to # support for backwards compatibility. It also stops the # NULL from continuously popping up as an unknown command. data = [_IDLE_COMMAND] else: data = _RE_LINEBREAK.split(data) if self.line_buffer and len(data) > 1: # buffer exists, it is terminated by the first line feed data[0] = self.line_buffer + data[0] self.line_buffer = "" # if the last data split is empty, it means all splits have # line breaks, if not, it is unterminated and must be # buffered. self.line_buffer += data.pop() # send all data chunks for dat in data: self.data_in(text=dat + "\n") def _write(self, data): """hook overloading the one used in plain telnet""" data = data.replace('\n', '\r\n').replace('\r\r\n', '\r\n') super(TelnetProtocol, self)._write(mccp_compress(self, data)) def sendLine(self, line): """ Hook overloading the one used by linereceiver. Args: line (str): Line to send. """ # escape IAC in line mode, and correctly add \r\n (the TELNET end-of-line) line = line.replace(IAC, IAC + IAC) line = line.replace('\n', '\r\n') if not line.endswith("\r\n") and self.protocol_flags.get("FORCEDENDLINE", True): line += "\r\n" if not self.protocol_flags.get("NOGOAHEAD", True): line += IAC + GA return self.transport.write(mccp_compress(self, line)) # Session hooks def disconnect(self, reason=""): """ generic hook for the engine to call in order to disconnect this protocol. Args: reason (str, optional): Reason for disconnecting. """ self.data_out(text=((reason,), {})) self.connectionLost(reason) def data_in(self, **kwargs): """ Data User -> Evennia Kwargs: kwargs (any): Options from the protocol. """ # from evennia.server.profiling.timetrace import timetrace # DEBUG # text = timetrace(text, "telnet.data_in") # DEBUG self.sessionhandler.data_in(self, **kwargs) def data_out(self, **kwargs): """ Data Evennia -> User Kwargs: kwargs (any): Options to the protocol """ self.sessionhandler.data_out(self, **kwargs) # send_* methods def send_text(self, *args, **kwargs): """ Send text data. This is an in-band telnet operation. Args: text (str): The first argument is always the text string to send. No other arguments are considered. Kwargs: options (dict): Send-option flags - mxp: Enforce MXP link support. - ansi: Enforce no ANSI colors. - xterm256: Enforce xterm256 colors, regardless of TTYPE. - noxterm256: Enforce no xterm256 color support, regardless of TTYPE. - nocolor: Strip all Color, regardless of ansi/xterm256 setting. - raw: Pass string through without any ansi processing (i.e. include Evennia ansi markers but do not convert them into ansi tokens) - echo: Turn on/off line echo on the client. Turn off line echo for client, for example for password. Note that it must be actively turned back on again! """ text = args[0] if args else "" if text is None: return text = to_str(text, force_string=True) # handle arguments options = kwargs.get("options", {}) flags = self.protocol_flags xterm256 = options.get("xterm256", flags.get('XTERM256', False) if flags.get("TTYPE", False) else True) useansi = options.get("ansi", flags.get('ANSI', False) if flags.get("TTYPE", False) else True) raw = options.get("raw", flags.get("RAW", False)) nocolor = options.get("nocolor", flags.get("NOCOLOR") or not (xterm256 or useansi)) echo = options.get("echo", None) mxp = options.get("mxp", flags.get("MXP", False)) screenreader = options.get("screenreader", flags.get("SCREENREADER", False)) if screenreader: # screenreader mode cleans up output text = ansi.parse_ansi(text, strip_ansi=True, xterm256=False, mxp=False) text = _RE_SCREENREADER_REGEX.sub("", text) if options.get("send_prompt"): # send a prompt instead. prompt = text if not raw: # processing prompt = ansi.parse_ansi(_RE_N.sub("", prompt) + ("||n" if prompt.endswith("|") else "|n"), strip_ansi=nocolor, xterm256=xterm256) if mxp: prompt = mxp_parse(prompt) prompt = prompt.replace(IAC, IAC + IAC).replace('\n', '\r\n') prompt += IAC + GA self.transport.write(mccp_compress(self, prompt)) else: if echo is not None: # turn on/off echo. Note that this is a bit turned around since we use # echo as if we are "turning off the client's echo" when telnet really # handles it the other way around. if echo: # by telling the client that WE WON'T echo, the client knows # that IT should echo. This is the expected behavior from # our perspective. self.transport.write(mccp_compress(self, IAC + WONT + ECHO)) else: # by telling the client that WE WILL echo, the client can # safely turn OFF its OWN echo. self.transport.write(mccp_compress(self, IAC + WILL + ECHO)) if raw: # no processing self.sendLine(text) return else: # we need to make sure to kill the color at the end in order # to match the webclient output. linetosend = ansi.parse_ansi(_RE_N.sub("", text) + ("||n" if text.endswith("|") else "|n"), strip_ansi=nocolor, xterm256=xterm256, mxp=mxp) if mxp: linetosend = mxp_parse(linetosend) self.sendLine(linetosend) def send_prompt(self, *args, **kwargs): """ Send a prompt - a text without a line end. See send_text for argument options. """ kwargs["options"].update({"send_prompt": True}) self.send_text(*args, **kwargs) def send_default(self, cmdname, *args, **kwargs): """ Send other oob data """ if not cmdname == "options": self.oob.data_out(cmdname, *args, **kwargs)