Source Code for Module mudpy.telnet

  1  # -*- coding: utf-8 -*- 
  2  u"""Telnet functions and constants for the mudpy engine.""" 
  3   
  4  # Copyright (c) 2004-2011 Jeremy Stanley <fungi@yuggoth.org>. Permission 
  5  # to use, copy, modify, and distribute this software is granted under 
  6  # terms provided in the LICENSE file distributed with this software. 
  7   
  8  # telnet options (from bsd's arpa/telnet.h since telnetlib's are ambiguous) 
  9  TELOPT_BINARY = 0 # transmit 8-bit data by the receiver (rfc 856) 
 10  TELOPT_ECHO = 1 # echo received data back to the sender (rfc 857) 
 11  TELOPT_SGA = 3 # suppress transmission of the go ahead character (rfc 858) 
 12  #TELOPT_TTYPE = 24 # exchange terminal type information (rfc 1091) 
 13  TELOPT_EOR = 25 # transmit end-of-record after transmitting data (rfc 885) 
 14  TELOPT_NAWS = 31 # negotiate about window size (rfc 1073) 
 15  TELOPT_LINEMODE = 34 # cooked line-by-line input mode (rfc 1184) 
 16   
 17  supported = ( 
 18     TELOPT_BINARY, 
 19     TELOPT_ECHO, 
 20     TELOPT_SGA, 
 21     TELOPT_EOR, 
 22     TELOPT_NAWS, 
 23     TELOPT_LINEMODE 
 24  ) 
 25   
 26  # telnet commands 
 27  EOR = 239 # end-of-record signal (rfc 885) 
 28  SE = 240 # end of subnegotiation parameters (rfc 854) 
 29  GA = 249 # go ahead signal (rfc 854) 
 30  SB = 250 # what follows is subnegotiation of the indicated option (rfc 854) 
 31  WILL = 251 # desire or confirmation of performing an option (rfc 854) 
 32  WONT = 252 # refusal or confirmation of performing an option (rfc 854) 
 33  DO = 253 # request or confirm performing an option (rfc 854) 
 34  DONT = 254 # demand or confirm no longer performing an option (rfc 854) 
 35  IAC = 255 # interpret as command escape character (rfc 854) 
 36   
 37  # RFC 1143 option negotiation states 
 38  NO = 0 # option is disabled 
 39  YES = 1 # option is enabled 
 40  WANTNO = 2 # demanded disabling option 
 41  WANTYES = 3 # requested enabling option 
 42  WANTNO_OPPOSITE = 4 # demanded disabling option but queued an enable after it 
 43  WANTYES_OPPOSITE = 5 # requested enabling option but queued a disable after it 
 44   
 45  # RFC 1143 option negotiation parties 
 46  HIM = 0 
 47  US = 1 
 48   
 49 -def telnet_proto(*arguments): 
 50     u"""Return a concatenated series of Telnet protocol commands.""" 
 51     # (this will need to be byte type during 2to3 migration) 
 52     return "".join( [chr(x) for x in arguments] ) 
 53   
 54 -def send_command(user, *command): 
 55     u"""Sends a Telnet command string to the specified user's socket.""" 
 56     user.send( telnet_proto(IAC, *command), raw=True ) 
 57   
 58 -def is_enabled(user, telopt, party, state=YES): 
 59     u"""Returns True if the indicated Telnet option is enabled, False if not.""" 
 60     if (telopt, party) in user.telopts and user.telopts[ 
 61        (telopt, party) 
 62     ] is state: return True 
 63     else: return False 
 64   
 65 -def enable(user, telopt, party): 
 66     u"""Negotiates enabling a Telnet option for the indicated user's socket.""" 
 67     if party is HIM: txpos = DO 
 68     else: txpos = WILL 
 69     if not (telopt, party) in user.telopts or user.telopts[ 
 70        (telopt, party) 
 71     ] is NO: 
 72        user.telopts[ (telopt, party) ] = WANTYES 
 73        send_command(user, txpos, telopt) 
 74     elif user.telopts[ (telopt, party) ] is WANTNO: 
 75        user.telopts[ (telopt, party) ] = WANTNO_OPPOSITE 
 76     elif user.telopts[ (telopt, party) ] is WANTYES_OPPOSITE: 
 77        user.telopts[ (telopt, party) ] = WANTYES 
 78   
 79 -def disable(user, telopt, party): 
 80     u"""Negotiates disabling a Telnet option for the indicated user's socket.""" 
 81     if party is HIM: txneg = DONT 
 82     else: txneg = WONT 
 83     if not (telopt, party) in user.telopts: user.telopts[ (telopt, party) ] = NO 
 84     elif user.telopts[ (telopt, party) ] is YES: 
 85        user.telopts[ (telopt, party) ] = WANTNO 
 86        send_command(user, txneg, telopt) 
 87     elif user.telopts[ (telopt, party) ] is WANTYES: 
 88        user.telopts[ (telopt, party) ] = WANTYES_OPPOSITE 
 89     elif user.telopts[ (telopt, party) ] is WANTNO_OPPOSITE: 
 90        user.telopts[ (telopt, party) ] = WANTNO 
 91   
 92 -def negotiate_telnet_options(user): 
 93     u"""Reply to and remove telnet negotiation options from partial_input.""" 
 94     import misc 
 95   
 96     # make a local copy to play with 
 97     text = user.partial_input 
 98   
 99     # start at the begining of the input 
100     position = 0 
101   
102     # as long as we haven't checked it all 
103     len_text = len(text) 
104     while position < len_text: 
105   
106        # jump to the first IAC you find 
107        position = text.find( telnet_proto(IAC), position ) 
108   
109        # if there wasn't an IAC in the input or it's at the end, we're done 
110        if position < 0 or position >= len_text-1: break 
111   
112        # the byte following the IAC is our command 
113        # (this will need to be byte type during 2to3 migration) 
114        command = ord( text[position+1] ) 
115   
116        # replace a double (literal) IAC if there's an LF later 
117        if command is IAC: 
118           if text.find("\n", position) > 0: 
119              position += 1 
120              text = text[:position] + text[position+1:] 
121           else: position += 2 
122   
123        # implement an RFC 1143 option negotiation queue here 
124        elif len_text > position+2 and WILL <= command <= DONT: 
125           # this will need to be byte type during 2to3 migration 
126           telopt = ord( text[position+2] ) 
127           if telopt in supported: 
128              if command <= WONT: 
129                 party = HIM 
130                 rxpos = WILL 
131                 txpos = DO 
132                 txneg = DONT 
133              else: 
134                 party = US 
135                 rxpos = DO 
136                 txpos = WILL 
137                 txneg = WONT 
138              if (telopt, party) not in user.telopts: 
139                 user.telopts[ (telopt, party) ] = NO 
140              if command is rxpos: 
141                 if user.telopts[ (telopt, party) ] is NO: 
142                    user.telopts[ (telopt, party) ] = YES 
143                    send_command(user, txpos, telopt) 
144                 elif user.telopts[ (telopt, party) ] is WANTNO: 
145                    user.telopts[ (telopt, party) ] = NO 
146                 elif user.telopts[ (telopt, party) ] is WANTNO_OPPOSITE: 
147                    user.telopts[ (telopt, party) ] = YES 
148                 elif user.telopts[ (telopt, party) ] is WANTYES_OPPOSITE: 
149                    user.telopts[ (telopt, party) ] = WANTNO 
150                    send_command(user, txneg, telopt) 
151                 else: user.telopts[ (telopt, party) ] = YES 
152              else: 
153                 if user.telopts[ (telopt, party) ] is YES: 
154                    user.telopts[ (telopt, party) ] = NO 
155                    send_command(user, txneg, telopt) 
156                 elif user.telopts[ (telopt, party) ] is WANTNO_OPPOSITE: 
157                    user.telopts[ (telopt, party) ] = WANTYES 
158                    send_command(user, txpos, telopt) 
159                 else: user.telopts[ (telopt, party) ] = NO 
160           elif command is WILL: send_command(user, DONT, telopt ) 
161           else: send_command(user, WONT, telopt) 
162           text = text[:position] + text[position+3:] 
163   
164        # subnegotiation options 
165        elif len_text > position+4 and command is SB: 
166           # this will need to be byte type during 2to3 migration 
167           telopt = ord( text[position+2] ) 
168           if telopt is TELOPT_NAWS: 
169              # this will need to be byte type during 2to3 migration 
170              user.columns = ord(text[position+3])*256+ord(text[position+4]) 
171           end_subnegotiation = text.find( telnet_proto(IAC, SE), position ) 
172           if end_subnegotiation > 0: 
173              text = text[:position] + text[end_subnegotiation+2:] 
174           else: position += 1 
175   
176        # otherwise, strip out a two-byte IAC command 
177        elif len_text > position+2: 
178           misc.log(u"Unknown Telnet IAC command %s ignored." % command) 
179           text = text[:position] + text[position+2:] 
180   
181        # and this means we got the begining of an IAC 
182        else: position += 1 
183   
184     # replace the input with our cleaned-up text 
185     user.partial_input = text 
186