1 # -*- coding: utf-8 -*-
2 """Telnet functions and constants for the mudpy engine."""
4 # Copyright (c) 2004-2014 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.
10 # telnet options (from bsd's arpa/telnet.h since telnetlib's are ambiguous)
11 TELOPT_BINARY = 0 # transmit 8-bit data by the receiver (rfc 856)
12 TELOPT_ECHO = 1 # echo received data back to the sender (rfc 857)
13 TELOPT_SGA = 3 # suppress transmission of the go ahead character (rfc 858)
14 # TELOPT_TTYPE = 24 # exchange terminal type information (rfc 1091)
15 TELOPT_EOR = 25 # transmit end-of-record after transmitting data (rfc 885)
16 TELOPT_NAWS = 31 # negotiate about window size (rfc 1073)
17 TELOPT_LINEMODE = 34 # cooked line-by-line input mode (rfc 1184)
29 EOR = 239 # end-of-record signal (rfc 885)
30 SE = 240 # end of subnegotiation parameters (rfc 854)
31 GA = 249 # go ahead signal (rfc 854)
32 SB = 250 # what follows is subnegotiation of the indicated option (rfc 854)
33 WILL = 251 # desire or confirmation of performing an option (rfc 854)
34 WONT = 252 # refusal or confirmation of performing an option (rfc 854)
35 DO = 253 # request or confirm performing an option (rfc 854)
36 DONT = 254 # demand or confirm no longer performing an option (rfc 854)
37 IAC = 255 # interpret as command escape character (rfc 854)
39 # RFC 1143 option negotiation states
40 NO = 0 # option is disabled
41 YES = 1 # option is enabled
42 WANTNO = 2 # demanded disabling option
43 WANTYES = 3 # requested enabling option
44 WANTNO_OPPOSITE = 4 # demanded disabling option but queued an enable after it
45 WANTYES_OPPOSITE = 5 # requested enabling option but queued a disable after it
47 # RFC 1143 option negotiation parties
52 def telnet_proto(*arguments):
53 """Return a concatenated series of Telnet protocol commands."""
54 return bytes((arguments))
57 def send_command(user, *command):
58 """Sends a Telnet command string to the specified user's socket."""
59 user.send(telnet_proto(IAC, *command), raw=True)
62 def is_enabled(user, telopt, party, state=YES):
63 """Indicates whether a specified Telnet option is enabled."""
64 if (telopt, party) in user.telopts and user.telopts[
72 def enable(user, telopt, party):
73 """Negotiates enabling a Telnet option for the indicated user's socket."""
78 if not (telopt, party) in user.telopts or user.telopts[
81 user.telopts[(telopt, party)] = WANTYES
82 send_command(user, txpos, telopt)
83 elif user.telopts[(telopt, party)] is WANTNO:
84 user.telopts[(telopt, party)] = WANTNO_OPPOSITE
85 elif user.telopts[(telopt, party)] is WANTYES_OPPOSITE:
86 user.telopts[(telopt, party)] = WANTYES
89 def disable(user, telopt, party):
90 """Negotiates disabling a Telnet option for the user's socket."""
95 if not (telopt, party) in user.telopts:
96 user.telopts[(telopt, party)] = NO
97 elif user.telopts[(telopt, party)] is YES:
98 user.telopts[(telopt, party)] = WANTNO
99 send_command(user, txneg, telopt)
100 elif user.telopts[(telopt, party)] is WANTYES:
101 user.telopts[(telopt, party)] = WANTYES_OPPOSITE
102 elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
103 user.telopts[(telopt, party)] = WANTNO
106 def negotiate_telnet_options(user):
107 """Reply to and remove telnet negotiation options from partial_input."""
109 # make a local copy to play with
110 text = user.partial_input
112 # start at the begining of the input
115 # as long as we haven't checked it all
117 while position < len_text:
119 # jump to the first IAC you find
120 position = text.find(telnet_proto(IAC), position)
122 # if there wasn't an IAC in the input or it's at the end, we're done
123 if position < 0 or position >= len_text - 1:
126 # the byte following the IAC is our command
127 command = text[position+1]
129 # replace a double (literal) IAC if there's an LF later
131 if text.find("\n", position) > 0:
133 text = text[:position] + text[position + 1:]
137 # implement an RFC 1143 option negotiation queue here
138 elif len_text > position + 2 and WILL <= command <= DONT:
139 telopt = text[position+2]
140 if telopt in supported:
151 if (telopt, party) not in user.telopts:
152 user.telopts[(telopt, party)] = NO
154 if user.telopts[(telopt, party)] is NO:
155 user.telopts[(telopt, party)] = YES
156 send_command(user, txpos, telopt)
157 elif user.telopts[(telopt, party)] is WANTNO:
158 user.telopts[(telopt, party)] = NO
159 elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
160 user.telopts[(telopt, party)] = YES
161 elif user.telopts[(telopt, party)] is WANTYES_OPPOSITE:
162 user.telopts[(telopt, party)] = WANTNO
163 send_command(user, txneg, telopt)
165 user.telopts[(telopt, party)] = YES
167 if user.telopts[(telopt, party)] is YES:
168 user.telopts[(telopt, party)] = NO
169 send_command(user, txneg, telopt)
170 elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
171 user.telopts[(telopt, party)] = WANTYES
172 send_command(user, txpos, telopt)
174 user.telopts[(telopt, party)] = NO
175 elif command is WILL:
176 send_command(user, DONT, telopt)
178 send_command(user, WONT, telopt)
179 text = text[:position] + text[position + 3:]
181 # subnegotiation options
182 elif len_text > position + 4 and command is SB:
183 telopt = ord(text[position + 2])
184 if telopt is TELOPT_NAWS:
186 ord(text[position + 3]) * 256 + ord(text[position + 4]))
187 end_subnegotiation = text.find(telnet_proto(IAC, SE), position)
188 if end_subnegotiation > 0:
189 text = text[:position] + text[end_subnegotiation + 2:]
193 # otherwise, strip out a two-byte IAC command
194 elif len_text > position + 2:
195 mudpy.misc.log("Unknown Telnet IAC command %s ignored." % command)
196 text = text[:position] + text[position + 2:]
198 # and this means we got the begining of an IAC
202 # replace the input with our cleaned-up text
203 user.partial_input = text