# Copyright (c) Twisted Matrix Laboratories. # See LICENSE for details. """TELNET implementation, with line-oriented command handling. """ import warnings warnings.warn( "As of Twisted 2.1, twisted.protocols.telnet is deprecated. " "See twisted.conch.telnet for the current, supported API.", DeprecationWarning, stacklevel=2) # System Imports try: from cStringIO import StringIO except ImportError: from StringIO import StringIO # Twisted Imports from twisted import copyright from twisted.internet import protocol # Some utility chars. ESC = chr(27) # ESC for doing fanciness BOLD_MODE_ON = ESC+"[1m" # turn bold on BOLD_MODE_OFF= ESC+"[m" # no char attributes # Characters gleaned from the various (and conflicting) RFCs. Not all of these are correct. NULL = chr(0) # No operation. LF = chr(10) # Moves the printer to the # next print line, keeping the # same horizontal position. CR = chr(13) # Moves the printer to the left # margin of the current line. BEL = chr(7) # Produces an audible or # visible signal (which does # NOT move the print head). BS = chr(8) # Moves the print head one # character position towards # the left margin. HT = chr(9) # Moves the printer to the # next horizontal tab stop. # It remains unspecified how # either party determines or # establishes where such tab # stops are located. VT = chr(11) # Moves the printer to the # next vertical tab stop. It # remains unspecified how # either party determines or # establishes where such tab # stops are located. FF = chr(12) # Moves the printer to the top # of the next page, keeping # the same horizontal position. SE = chr(240) # End of subnegotiation parameters. NOP= chr(241) # No operation. DM = chr(242) # "Data Mark": The data stream portion # of a Synch. This should always be # accompanied by a TCP Urgent # notification. BRK= chr(243) # NVT character Break. IP = chr(244) # The function Interrupt Process. AO = chr(245) # The function Abort Output AYT= chr(246) # The function Are You There. EC = chr(247) # The function Erase Character. EL = chr(248) # The function Erase Line GA = chr(249) # The Go Ahead signal. SB = chr(250) # Indicates that what follows is # subnegotiation of the indicated # option. WILL = chr(251) # Indicates the desire to begin # performing, or confirmation that # you are now performing, the # indicated option. WONT = chr(252) # Indicates the refusal to perform, # or continue performing, the # indicated option. DO = chr(253) # Indicates the request that the # other party perform, or # confirmation that you are expecting # the other party to perform, the # indicated option. DONT = chr(254) # Indicates the demand that the # other party stop performing, # or confirmation that you are no # longer expecting the other party # to perform, the indicated option. IAC = chr(255) # Data Byte 255. # features ECHO = chr(1) # User-to-Server: Asks the server to send # Echos of the transmitted data. # Server-to User: States that the server is # sending echos of the transmitted data. # Sent only as a reply to ECHO or NO ECHO. SUPGA = chr(3) # Supress Go Ahead...? "Modern" telnet servers # are supposed to do this. LINEMODE = chr(34) # I don't care that Jon Postel is dead. HIDE = chr(133) # The intention is that a server will send # this signal to a user system which is # echoing locally (to the user) when the user # is about to type something secret (e.g. a # password). In this case, the user system # is to suppress local echoing or overprint # the input (or something) until the server # sends a NOECHO signal. In situations where # the user system is not echoing locally, # this signal must not be sent by the server. NOECHO= chr(131) # User-to-Server: Asks the server not to # return Echos of the transmitted data. # # Server-to-User: States that the server is # not sending echos of the transmitted data. # Sent only as a reply to ECHO or NO ECHO, # or to end the hide your input. iacBytes = { DO: 'DO', DONT: 'DONT', WILL: 'WILL', WONT: 'WONT', IP: 'IP' } def multireplace(st, dct): for k, v in dct.items(): st = st.replace(k, v) return st class Telnet(protocol.Protocol): """I am a Protocol for handling Telnet connections. I have two sets of special methods, telnet_* and iac_*. telnet_* methods get called on every line sent to me. The method to call is decided by the current mode. The initial mode is 'User'; this means that telnet_User is the first telnet_* method to be called. All telnet_* methods should return a string which specifies the mode to go into next; thus dictating which telnet_* method to call next. For example, the default telnet_User method returns 'Password' to go into Password mode, and the default telnet_Password method returns 'Command' to go into Command mode. The iac_* methods are less-used; they are called when an IAC telnet byte is received. You can define iac_DO, iac_DONT, iac_WILL, iac_WONT, and iac_IP methods to do what you want when one of these bytes is received.""" gotIAC = 0 iacByte = None lastLine = None buffer = '' echo = 0 delimiters = ['\r\n', '\r\000'] mode = "User" def write(self, data): """Send the given data over my transport.""" self.transport.write(data) def connectionMade(self): """I will write a welcomeMessage and loginPrompt to the client.""" self.write(self.welcomeMessage() + self.loginPrompt()) def welcomeMessage(self): """Override me to return a string which will be sent to the client before login.""" x = self.factory.__class__ return ("\r\n" + x.__module__ + '.' + x.__name__ + '\r\nTwisted %s\r\n' % copyright.version ) def loginPrompt(self): """Override me to return a 'login:'-type prompt.""" return "username: " def iacSBchunk(self, chunk): pass def iac_DO(self, feature): pass def iac_DONT(self, feature): pass def iac_WILL(self, feature): pass def iac_WONT(self, feature): pass def iac_IP(self, feature): pass def processLine(self, line): """I call a method that looks like 'telnet_*' where '*' is filled in by the current mode. telnet_* methods should return a string which will become the new mode. If None is returned, the mode will not change. """ mode = getattr(self, "telnet_"+self.mode)(line) if mode is not None: self.mode = mode def telnet_User(self, user): """I take a username, set it to the 'self.username' attribute, print out a password prompt, and switch to 'Password' mode. If you want to do something else when the username is received (ie, create a new user if the user doesn't exist), override me.""" self.username = user self.write(IAC+WILL+ECHO+"password: ") return "Password" def telnet_Password(self, paswd): """I accept a password as an argument, and check it with the checkUserAndPass method. If the login is successful, I call loggedIn().""" self.write(IAC+WONT+ECHO+"*****\r\n") try: checked = self.checkUserAndPass(self.username, paswd) except: return "Done" if not checked: return "Done" self.loggedIn() return "Command" def telnet_Command(self, cmd): """The default 'command processing' mode. You probably want to override me.""" return "Command" def processChunk(self, chunk): """I take a chunk of data and delegate out to telnet_* methods by way of processLine. If the current mode is 'Done', I'll close the connection. """ self.buffer = self.buffer + chunk #yech. for delim in self.delimiters: idx = self.buffer.find(delim) if idx != -1: break while idx != -1: buf, self.buffer = self.buffer[:idx], self.buffer[idx+2:] self.processLine(buf) if self.mode == 'Done': self.transport.loseConnection() for delim in self.delimiters: idx = self.buffer.find(delim) if idx != -1: break def dataReceived(self, data): chunk = StringIO() # silly little IAC state-machine for char in data: if self.gotIAC: # working on an IAC request state if self.iacByte: # we're in SB mode, getting a chunk if self.iacByte == SB: if char == SE: self.iacSBchunk(chunk.getvalue()) chunk = StringIO() del self.iacByte del self.gotIAC else: chunk.write(char) else: # got all I need to know state try: getattr(self, 'iac_%s' % iacBytes[self.iacByte])(char) except KeyError: pass del self.iacByte del self.gotIAC else: # got IAC, this is my W/W/D/D (or perhaps sb) self.iacByte = char elif char == IAC: # Process what I've got so far before going into # the IAC state; don't want to process characters # in an inconsistent state with what they were # received in. c = chunk.getvalue() if c: why = self.processChunk(c) if why: return why chunk = StringIO() self.gotIAC = 1 else: chunk.write(char) # chunks are of a relatively indeterminate size. c = chunk.getvalue() if c: why = self.processChunk(c) if why: return why def loggedIn(self): """Called after the user succesfully logged in. Override in subclasses. """ pass