Source code for evennia.server.portal.telnet_oob


Telnet OOB (Out of band communication)

OOB protocols allow for asynchronous communication between Evennia and
compliant telnet clients. The "text" type of send command will always
be sent "in-band", appearing in the client's main text output. OOB
commands, by contrast, can have many forms and it is up to the client
how and if they are handled.  Examples of OOB instructions could be to
instruct the client to play sounds or to update a graphical health

Note that in Evennia's Web client, all send commands are "OOB
commands", (including the "text" one), there is no equivalence to
MSDP/GMCP for the webclient since it doesn't need it.

This implements the following telnet OOB communication protocols:

- MSDP (Mud Server Data Protocol), as per
- GMCP (Generic Mud Communication Protocol) as per


import re
import json
from evennia.utils.utils import is_iter
from twisted.python.compat import _bytesChr as bchr

# General Telnet
from twisted.conch.telnet import IAC, SB, SE

# MSDP-relevant telnet cmd/opt-codes
MSDP = bchr(69)
MSDP_VAR = bchr(1)
MSDP_VAL = bchr(2)


GMCP = bchr(201)

# pre-compiled regexes
# returns 2-tuple
msdp_regex_table = re.compile(
    br"%s\s*(\w*?)\s*%s\s*%s(.*?)%s" % (MSDP_VAR, MSDP_VAL, MSDP_TABLE_OPEN, MSDP_TABLE_CLOSE)
# returns 2-tuple
msdp_regex_array = re.compile(
    br"%s\s*(\w*?)\s*%s\s*%s(.*?)%s" % (MSDP_VAR, MSDP_VAL, MSDP_ARRAY_OPEN, MSDP_ARRAY_CLOSE)
msdp_regex_var = re.compile(br"%s" % MSDP_VAR)
msdp_regex_val = re.compile(br"%s" % MSDP_VAL)

    "client_options": "Core.Supports.Get",
    "get_inputfuncs": "Core.Commands.Get",
    "get_value": "Char.Value.Get",
    "repeat": "Char.Repeat.Update",
    "monitor": "Char.Monitor.Update",

# MSDP/GMCP communication handler

[docs]class TelnetOOB(object): """ Implements the MSDP and GMCP protocols. """
[docs] def __init__(self, protocol): """ Initiates by storing the protocol on itself and trying to determine if the client supports MSDP. Args: protocol (Protocol): The active protocol. """ self.protocol = protocol self.protocol.protocol_flags["OOB"] = False self.MSDP = False self.GMCP = False # ask for the available protocols and assign decoders # (note that handshake_done() will be called twice!) self.protocol.negotiationMap[MSDP] = self.decode_msdp self.protocol.negotiationMap[GMCP] = self.decode_gmcp self.protocol.will(MSDP).addCallbacks(self.do_msdp, self.no_msdp) self.protocol.will(GMCP).addCallbacks(self.do_gmcp, self.no_gmcp) self.oob_reported = {}
[docs] def no_msdp(self, option): """ Client reports No msdp supported or wanted. Args: option (Option): Not used. """ # no msdp, check GMCP self.protocol.handshake_done()
[docs] def do_msdp(self, option): """ Client reports that it supports msdp. Args: option (Option): Not used. """ self.MSDP = True self.protocol.protocol_flags["OOB"] = True self.protocol.handshake_done()
[docs] def no_gmcp(self, option): """ If this is reached, it means neither MSDP nor GMCP is supported. Args: option (Option): Not used. """ self.protocol.handshake_done()
[docs] def do_gmcp(self, option): """ Called when client confirms that it can do MSDP or GMCP. Args: option (Option): Not used. """ self.GMCP = True self.protocol.protocol_flags["OOB"] = True self.protocol.handshake_done()
# encoders
[docs] def encode_msdp(self, cmdname, *args, **kwargs): """ Encode into a valid MSDP command. Args: cmdname (str): Name of send instruction. args, kwargs (any): Arguments to OOB command. Notes: The output of this encoding will be MSDP structures on these forms: :: [cmdname, [], {}] -> VAR cmdname VAL "" [cmdname, [arg], {}] -> VAR cmdname VAL arg [cmdname, [args],{}] -> VAR cmdname VAL ARRAYOPEN VAL arg VAL arg ... ARRAYCLOSE [cmdname, [], {kwargs}] -> VAR cmdname VAL TABLEOPEN VAR key VAL val ... TABLECLOSE [cmdname, [args], {kwargs}] -> VAR cmdname VAL ARRAYOPEN VAL arg VAL arg ... ARRAYCLOSE VAR cmdname VAL TABLEOPEN VAR key VAL val ... TABLECLOSE Further nesting is not supported, so if an array argument consists of an array (for example), that array will be json-converted to a string. """ msdp_cmdname = "{msdp_var}{msdp_cmdname}{msdp_val}".format( msdp_var=MSDP_VAR.decode(), msdp_cmdname=cmdname, msdp_val=MSDP_VAL.decode() ) if not (args or kwargs): return msdp_cmdname.encode() # print("encode_msdp in:", cmdname, args, kwargs) # DEBUG msdp_args = "" if args: msdp_args = msdp_cmdname if len(args) == 1: msdp_args += args[0] else: msdp_args += ( "{msdp_array_open}" "{msdp_args}" "{msdp_array_close}".format( msdp_array_open=MSDP_ARRAY_OPEN.decode(), msdp_array_close=MSDP_ARRAY_CLOSE.decode(), msdp_args="".join("%s%s" % (MSDP_VAL.decode(), val) for val in args), ) ) msdp_kwargs = "" if kwargs: msdp_kwargs = msdp_cmdname msdp_kwargs += ( "{msdp_table_open}" "{msdp_kwargs}" "{msdp_table_close}".format( msdp_table_open=MSDP_TABLE_OPEN.decode(), msdp_table_close=MSDP_TABLE_CLOSE.decode(), msdp_kwargs="".join( "%s%s%s%s" % (MSDP_VAR.decode(), key, MSDP_VAL.decode(), val) for key, val in kwargs.items() ), ) ) msdp_string = msdp_args + msdp_kwargs # print("msdp_string:", msdp_string) # DEBUG return msdp_string.encode()
[docs] def encode_gmcp(self, cmdname, *args, **kwargs): """ Encode into GMCP messages. Args: cmdname (str): GMCP OOB command name. args, kwargs (any): Arguments to OOB command. Notes: GMCP messages will be outgoing on the following form (the non-JSON cmdname at the start is what IRE games use, supposedly, and what clients appear to have adopted). A cmdname without Package will end up in the Core package, while Core package names will be stripped on the Evennia side. :: [, [], {}] -> Cmd.Name [, [arg], {}] -> Cmd.Name arg [, [args],{}] -> Cmd.Name [args] [, [], {kwargs}] -> Cmd.Name {kwargs} [cmdname, [args, {kwargs}] -> Core.Cmdname [[args],{kwargs}] Notes: There are also a few default mappings between evennia outputcmds and GMCP: :: client_options -> Core.Supports.Get get_inputfuncs -> Core.Commands.Get get_value -> Char.Value.Get repeat -> Char.Repeat.Update monitor -> Char.Monitor.Update """ if cmdname in EVENNIA_TO_GMCP: gmcp_cmdname = EVENNIA_TO_GMCP[cmdname] elif "_" in cmdname: gmcp_cmdname = ".".join(word.capitalize() for word in cmdname.split("_")) else: gmcp_cmdname = "Core.%s" % cmdname.capitalize() if not (args or kwargs): gmcp_string = gmcp_cmdname elif args: if len(args) == 1: args = args[0] if kwargs: gmcp_string = "%s %s" % (gmcp_cmdname, json.dumps([args, kwargs])) else: gmcp_string = "%s %s" % (gmcp_cmdname, json.dumps(args)) else: # only kwargs gmcp_string = "%s %s" % (gmcp_cmdname, json.dumps(kwargs)) # print("gmcp string", gmcp_string) # DEBUG return gmcp_string.encode()
[docs] def decode_msdp(self, data): """ Decodes incoming MSDP data. Args: data (str or list): MSDP data. Notes: Clients should always send MSDP data on one of the following forms: :: cmdname '' -> [cmdname, [], {}] cmdname val -> [cmdname, [val], {}] cmdname array -> [cmdname, [array], {}] cmdname table -> [cmdname, [], {table}] cmdname array cmdname table -> [cmdname, [array], {table}] Observe that all MSDP_VARS are used to identify cmdnames, so if there are multiple arrays with the same cmdname given, they will be merged into one argument array, same for tables. Different MSDP_VARS (outside tables) will be identified as separate cmdnames. """ if isinstance(data, list): data = b"".join(data) # print("decode_msdp in:", data) # DEBUG tables = {} arrays = {} variables = {} # decode tables for key, table in msdp_regex_table.findall(data): key = key.decode() tables[key] = {} if key not in tables else tables[key] for varval in msdp_regex_var.split(table)[1:]: var, val = msdp_regex_val.split(varval, 1) var, val = var.decode(), val.decode() if var: tables[key][var] = val # decode arrays from all that was not a table data_no_tables = msdp_regex_table.sub(b"", data) for key, array in msdp_regex_array.findall(data_no_tables): key = key.decode() arrays[key] = [] if key not in arrays else arrays[key] parts = msdp_regex_val.split(array) parts = [part.decode() for part in parts] if len(parts) == 2: arrays[key].append(parts[1]) elif len(parts) > 1: arrays[key].extend(parts[1:]) # decode remainders from all that were not tables or arrays data_no_tables_or_arrays = msdp_regex_array.sub(b"", data_no_tables) for varval in msdp_regex_var.split(data_no_tables_or_arrays): # get remaining varvals after cleaning away tables/arrays. If mathcing # an existing key in arrays, it will be added as an argument to that command, # otherwise it will be treated as a command without argument. parts = msdp_regex_val.split(varval) parts = [part.decode() for part in parts] if len(parts) == 2: variables[parts[0]] = parts[1] elif len(parts) > 1: variables[parts[0]] = parts[1:] cmds = {} # merge matching table/array/variables together for key, table in tables.items(): args, kwargs = [], table if key in arrays: args.extend(arrays.pop(key)) if key in variables: args.append(variables.pop(key)) cmds[key] = [args, kwargs] for key, arr in arrays.items(): args, kwargs = arr, {} if key in variables: args.append(variables.pop(key)) cmds[key] = [args, kwargs] for key, var in variables.items(): cmds[key] = [[var], {}] # remap the 'generic msdp commands' to avoid colliding with builtins etc # by prepending "msdp_" lower_case = {key.lower(): key for key in cmds} for remap in ("list", "report", "reset", "send", "unreport"): if remap in lower_case: cmds["msdp_{}".format(remap)] = cmds.pop(lower_case[remap]) # print("msdp data in:", cmds) # DEBUG self.protocol.data_in(**cmds)
[docs] def decode_gmcp(self, data): """ Decodes incoming GMCP data on the form 'varname <structure>'. Args: data (str or list): GMCP data. Notes: Clients send data on the form "Module.Submodule.Cmdname <structure>". We assume the structure is valid JSON. The following is parsed into Evennia's formal structure: :: Core.Name -> [name, [], {}] Core.Name string -> [name, [string], {}] Core.Name [arg, arg,...] -> [name, [args], {}] Core.Name {key:arg, key:arg, ...} -> [name, [], {kwargs}] Core.Name [[args], {kwargs}] -> [name, [args], {kwargs}] """ if isinstance(data, list): data = b"".join(data) # print("decode_gmcp in:", data) # DEBUG if data: try: cmdname, structure = data.split(None, 1) except ValueError: cmdname, structure = data, b"" cmdname = cmdname.replace(b".", b"_") try: structure = json.loads(structure) except ValueError: # maybe the structure is not json-serialized at all pass args, kwargs = [], {} if is_iter(structure): if isinstance(structure, dict): kwargs = {key: value for key, value in structure.items() if key} else: args = list(structure) else: args = (structure,) if cmdname.lower().startswith(b"core_"): # if Core.cmdname, then use cmdname cmdname = cmdname[5:] self.protocol.data_in(**{cmdname.lower().decode(): [args, kwargs]})
# access methods
[docs] def data_out(self, cmdname, *args, **kwargs): """ Return a MSDP- or GMCP-valid subnegotiation across the protocol. Args: cmdname (str): OOB-command name. args, kwargs (any): Arguments to OOB command. """ kwargs.pop("options", None) if self.MSDP: encoded_oob = self.encode_msdp(cmdname, *args, **kwargs) self.protocol._write(IAC + SB + MSDP + encoded_oob + IAC + SE) if self.GMCP: encoded_oob = self.encode_gmcp(cmdname, *args, **kwargs) self.protocol._write(IAC + SB + GMCP + encoded_oob + IAC + SE)