--- /dev/null
+"""Telnet functions and constants for the mudpy engine."""
+
+# Copyright (c) 2004-2015 Jeremy Stanley <fungi@yuggoth.org>. Permission
+# to use, copy, modify, and distribute this software is granted under
+# terms provided in the LICENSE file distributed with this software.
+
+import mudpy
+
+# telnet options (from bsd's arpa/telnet.h since telnetlib's are ambiguous)
+TELOPT_BINARY = 0 # transmit 8-bit data by the receiver (rfc 856)
+TELOPT_ECHO = 1 # echo received data back to the sender (rfc 857)
+TELOPT_SGA = 3 # suppress transmission of the go ahead character (rfc 858)
+# TELOPT_TTYPE = 24 # exchange terminal type information (rfc 1091)
+TELOPT_EOR = 25 # transmit end-of-record after transmitting data (rfc 885)
+TELOPT_NAWS = 31 # negotiate about window size (rfc 1073)
+TELOPT_LINEMODE = 34 # cooked line-by-line input mode (rfc 1184)
+
+supported = (
+ TELOPT_BINARY,
+ TELOPT_ECHO,
+ TELOPT_SGA,
+ TELOPT_EOR,
+ TELOPT_NAWS,
+ TELOPT_LINEMODE
+)
+
+# telnet commands
+EOR = 239 # end-of-record signal (rfc 885)
+SE = 240 # end of subnegotiation parameters (rfc 854)
+GA = 249 # go ahead signal (rfc 854)
+SB = 250 # what follows is subnegotiation of the indicated option (rfc 854)
+WILL = 251 # desire or confirmation of performing an option (rfc 854)
+WONT = 252 # refusal or confirmation of performing an option (rfc 854)
+DO = 253 # request or confirm performing an option (rfc 854)
+DONT = 254 # demand or confirm no longer performing an option (rfc 854)
+IAC = 255 # interpret as command escape character (rfc 854)
+
+# RFC 1143 option negotiation states
+NO = 0 # option is disabled
+YES = 1 # option is enabled
+WANTNO = 2 # demanded disabling option
+WANTYES = 3 # requested enabling option
+WANTNO_OPPOSITE = 4 # demanded disabling option but queued an enable after it
+WANTYES_OPPOSITE = 5 # requested enabling option but queued a disable after it
+
+# RFC 1143 option negotiation parties
+HIM = 0
+US = 1
+
+
+def telnet_proto(*arguments):
+ """Return a concatenated series of Telnet protocol commands."""
+ return bytes((arguments))
+
+
+def send_command(user, *command):
+ """Sends a Telnet command string to the specified user's socket."""
+ user.send(telnet_proto(IAC, *command), raw=True)
+
+
+def is_enabled(user, telopt, party, state=YES):
+ """Indicates whether a specified Telnet option is enabled."""
+ if (telopt, party) in user.telopts and user.telopts[
+ (telopt, party)
+ ] is state:
+ return True
+ else:
+ return False
+
+
+def enable(user, telopt, party):
+ """Negotiates enabling a Telnet option for the indicated user's socket."""
+ if party is HIM:
+ txpos = DO
+ else:
+ txpos = WILL
+ if not (telopt, party) in user.telopts or user.telopts[
+ (telopt, party)
+ ] is NO:
+ user.telopts[(telopt, party)] = WANTYES
+ send_command(user, txpos, telopt)
+ elif user.telopts[(telopt, party)] is WANTNO:
+ user.telopts[(telopt, party)] = WANTNO_OPPOSITE
+ elif user.telopts[(telopt, party)] is WANTYES_OPPOSITE:
+ user.telopts[(telopt, party)] = WANTYES
+
+
+def disable(user, telopt, party):
+ """Negotiates disabling a Telnet option for the user's socket."""
+ if party is HIM:
+ txneg = DONT
+ else:
+ txneg = WONT
+ if not (telopt, party) in user.telopts:
+ user.telopts[(telopt, party)] = NO
+ elif user.telopts[(telopt, party)] is YES:
+ user.telopts[(telopt, party)] = WANTNO
+ send_command(user, txneg, telopt)
+ elif user.telopts[(telopt, party)] is WANTYES:
+ user.telopts[(telopt, party)] = WANTYES_OPPOSITE
+ elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
+ user.telopts[(telopt, party)] = WANTNO
+
+
+def negotiate_telnet_options(user):
+ """Reply to and remove telnet negotiation options from partial_input."""
+
+ # make a local copy to play with
+ text = user.partial_input
+
+ # start at the begining of the input
+ position = 0
+
+ # as long as we haven't checked it all
+ len_text = len(text)
+ while position < len_text:
+
+ # jump to the first IAC you find
+ position = text.find(telnet_proto(IAC), position)
+
+ # if there wasn't an IAC in the input or it's at the end, we're done
+ if position < 0 or position >= len_text - 1:
+ break
+
+ # the byte following the IAC is our command
+ command = text[position+1]
+
+ # replace a double (literal) IAC if there's an LF later
+ if command is IAC:
+ if text.find("\n", position) > 0:
+ position += 1
+ text = text[:position] + text[position + 1:]
+ else:
+ position += 2
+
+ # implement an RFC 1143 option negotiation queue here
+ elif len_text > position + 2 and WILL <= command <= DONT:
+ telopt = text[position+2]
+ if telopt in supported:
+ if command <= WONT:
+ party = HIM
+ rxpos = WILL
+ txpos = DO
+ txneg = DONT
+ else:
+ party = US
+ rxpos = DO
+ txpos = WILL
+ txneg = WONT
+ if (telopt, party) not in user.telopts:
+ user.telopts[(telopt, party)] = NO
+ if command is rxpos:
+ if user.telopts[(telopt, party)] is NO:
+ user.telopts[(telopt, party)] = YES
+ send_command(user, txpos, telopt)
+ elif user.telopts[(telopt, party)] is WANTNO:
+ user.telopts[(telopt, party)] = NO
+ elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
+ user.telopts[(telopt, party)] = YES
+ elif user.telopts[(telopt, party)] is WANTYES_OPPOSITE:
+ user.telopts[(telopt, party)] = WANTNO
+ send_command(user, txneg, telopt)
+ else:
+ user.telopts[(telopt, party)] = YES
+ else:
+ if user.telopts[(telopt, party)] is YES:
+ user.telopts[(telopt, party)] = NO
+ send_command(user, txneg, telopt)
+ elif user.telopts[(telopt, party)] is WANTNO_OPPOSITE:
+ user.telopts[(telopt, party)] = WANTYES
+ send_command(user, txpos, telopt)
+ else:
+ user.telopts[(telopt, party)] = NO
+ elif command is WILL:
+ send_command(user, DONT, telopt)
+ else:
+ send_command(user, WONT, telopt)
+ text = text[:position] + text[position + 3:]
+
+ # subnegotiation options
+ elif len_text > position + 4 and command is SB:
+ telopt = ord(text[position + 2])
+ if telopt is TELOPT_NAWS:
+ user.columns = (
+ ord(text[position + 3]) * 256 + ord(text[position + 4]))
+ end_subnegotiation = text.find(telnet_proto(IAC, SE), position)
+ if end_subnegotiation > 0:
+ text = text[:position] + text[end_subnegotiation + 2:]
+ else:
+ position += 1
+
+ # otherwise, strip out a two-byte IAC command
+ elif len_text > position + 2:
+ mudpy.misc.log("Unknown Telnet IAC command %s ignored." % command)
+ text = text[:position] + text[position + 2:]
+
+ # and this means we got the begining of an IAC
+ else:
+ position += 1
+
+ # replace the input with our cleaned-up text
+ user.partial_input = text
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