1 # -*- coding: utf-8 -*-
2 """Telnet functions and constants for the mudpy engine."""
4 # Copyright (c) 2004-2013 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 """Returns True if the indicated Telnet option is enabled, False if
65 if (telopt, party) in user.telopts and user.telopts[
73 def enable(user, telopt, party):
74 """Negotiates enabling a Telnet option for the indicated user's socket."""
79 if not (telopt, party) in user.telopts or user.telopts[
82 user.telopts[(telopt, party)] = WANTYES
83 send_command(user, txpos, telopt)
84 elif user.telopts[(telopt, party)] is WANTNO:
85 user.telopts[(telopt, party)] = WANTNO_OPPOSITE
86 elif user.telopts[(telopt, party)] is WANTYES_OPPOSITE:
87 user.telopts[(telopt, party)] = WANTYES
90 def disable(user, telopt, party):
91 """Negotiates disabling a Telnet option for the indicated user's
97 if not (telopt, party) in user.telopts:
98 user.telopts[(telopt, party)] = NO
99 elif user.telopts[(telopt, party)] is YES:
100 user.telopts[(telopt, party)] = WANTNO
101 send_command(user, txneg, telopt)
102 elif user.telopts[(telopt, party)] is WANTYES:
103 user.telopts[(telopt, party)] = WANTYES_OPPOSITE
104 elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
105 user.telopts[(telopt, party)] = WANTNO
108 def negotiate_telnet_options(user):
109 """Reply to and remove telnet negotiation options from partial_input."""
111 # make a local copy to play with
112 text = user.partial_input
114 # start at the begining of the input
117 # as long as we haven't checked it all
119 while position < len_text:
121 # jump to the first IAC you find
122 position = text.find(telnet_proto(IAC), position)
124 # if there wasn't an IAC in the input or it's at the end, we're done
125 if position < 0 or position >= len_text - 1:
128 # the byte following the IAC is our command
129 command = text[position+1]
131 # replace a double (literal) IAC if there's an LF later
133 if text.find("\n", position) > 0:
135 text = text[:position] + text[position + 1:]
139 # implement an RFC 1143 option negotiation queue here
140 elif len_text > position + 2 and WILL <= command <= DONT:
141 telopt = text[position+2]
142 if telopt in supported:
153 if (telopt, party) not in user.telopts:
154 user.telopts[(telopt, party)] = NO
156 if user.telopts[(telopt, party)] is NO:
157 user.telopts[(telopt, party)] = YES
158 send_command(user, txpos, telopt)
159 elif user.telopts[(telopt, party)] is WANTNO:
160 user.telopts[(telopt, party)] = NO
161 elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
162 user.telopts[(telopt, party)] = YES
163 elif user.telopts[(telopt, party)] is WANTYES_OPPOSITE:
164 user.telopts[(telopt, party)] = WANTNO
165 send_command(user, txneg, telopt)
167 user.telopts[(telopt, party)] = YES
169 if user.telopts[(telopt, party)] is YES:
170 user.telopts[(telopt, party)] = NO
171 send_command(user, txneg, telopt)
172 elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
173 user.telopts[(telopt, party)] = WANTYES
174 send_command(user, txpos, telopt)
176 user.telopts[(telopt, party)] = NO
177 elif command is WILL:
178 send_command(user, DONT, telopt)
180 send_command(user, WONT, telopt)
181 text = text[:position] + text[position + 3:]
183 # subnegotiation options
184 elif len_text > position + 4 and command is SB:
185 telopt = ord(text[position + 2])
186 if telopt is TELOPT_NAWS:
187 user.columns = ord(text[position + 3]) * \
188 256 + ord(text[position + 4])
189 end_subnegotiation = text.find(telnet_proto(IAC, SE), position)
190 if end_subnegotiation > 0:
191 text = text[:position] + text[end_subnegotiation + 2:]
195 # otherwise, strip out a two-byte IAC command
196 elif len_text > position + 2:
197 mudpy.misc.log("Unknown Telnet IAC command %s ignored." % command)
198 text = text[:position] + text[position + 2:]
200 # and this means we got the begining of an IAC
204 # replace the input with our cleaned-up text
205 user.partial_input = text