Exscript/emulators/vdevice.py
#
# Copyright (C) 2010-2017 Samuel Abels
# The MIT License (MIT)
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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"""
Defines the behavior of a device, as needed by :class:`Exscript.servers`.
"""
from __future__ import absolute_import, unicode_literals
from builtins import range
from builtins import object
from builtins import str
from . import CommandSet
class VirtualDevice(object):
"""
An object that emulates a remote device.
"""
LOGIN_TYPE_PASSWORDONLY, \
LOGIN_TYPE_USERONLY, \
LOGIN_TYPE_BOTH, \
LOGIN_TYPE_NONE = list(range(1, 5))
PROMPT_STAGE_USERNAME, \
PROMPT_STAGE_PASSWORD, \
PROMPT_STAGE_CUSTOM = list(range(1, 4))
def __init__(self,
hostname,
echo=True,
login_type=LOGIN_TYPE_BOTH,
strict=True,
banner=None):
"""
:type hostname: str
:param hostname: The hostname, used for the prompt.
:param echo: bool
:keyword echo: whether to echo the command in a response.
:param login_type: int
:keyword login_type: integer constant, one of LOGIN_TYPE_PASSWORDONLY,
LOGIN_TYPE_USERONLY, LOGIN_TYPE_BOTH, LOGIN_TYPE_NONE.
:param strict: bool
:keyword strict: Whether to raise when a given command has no handler.
:param banner: str
:keyword banner: A string to show as soon as the connection is opened.
"""
self.hostname = str(hostname)
self.banner = str(banner or 'Welcome to %s!\n' % hostname)
self.echo = echo
self.login_type = int(login_type)
self.prompt = str(hostname + '> ')
self.logged_in = False
self.commands = CommandSet(strict=strict)
self.user_prompt = 'User: '
self.password_prompt = 'Password: '
self.init()
def _get_prompt(self):
if self.prompt_stage == self.PROMPT_STAGE_USERNAME:
if self.login_type == self.LOGIN_TYPE_USERONLY:
self.prompt_stage = self.PROMPT_STAGE_CUSTOM
else:
self.prompt_stage = self.PROMPT_STAGE_PASSWORD
return self.user_prompt
elif self.prompt_stage == self.PROMPT_STAGE_PASSWORD:
self.prompt_stage = self.PROMPT_STAGE_CUSTOM
return self.password_prompt
elif self.prompt_stage == self.PROMPT_STAGE_CUSTOM:
self.logged_in = True
return self.prompt
else:
raise Exception('invalid prompt stage')
def _create_autoprompt_handler(self, handler):
if hasattr(handler, '__call__'):
return lambda x: handler(x) + '\n' + self._get_prompt()
else:
return lambda x: handler + '\n' + self._get_prompt()
def get_prompt(self):
"""
Returns the prompt of the device.
:rtype: str
:return: The current command line prompt.
"""
return self.prompt
def set_prompt(self, prompt):
"""
Change the prompt of the device.
:type prompt: str
:param prompt: The new command line prompt.
"""
self.prompt = prompt
def add_command(self, command, handler, prompt=True):
"""
Registers a command.
The command may be either a string (which is then automatically
compiled into a regular expression), or a pre-compiled regular
expression object.
If the given response handler is a string, it is sent as the
response to any command that matches the given regular expression.
If the given response handler is a function, it is called
with the command passed as an argument.
:type command: str|regex
:param command: A string or a compiled regular expression.
:type handler: function|str
:param handler: A string, or a response handler.
:type prompt: bool
:param prompt: Whether to show a prompt after completing the command.
"""
if prompt:
thehandler = self._create_autoprompt_handler(handler)
else:
thehandler = handler
self.commands.add(command, thehandler)
def add_commands_from_file(self, filename, autoprompt=True):
"""
Wrapper around add_command_handler that reads the handlers from the
file with the given name. The file is a Python script containing
a list named 'commands' of tuples that map command names to
handlers.
:type filename: str
:param filename: The name of the file containing the tuples.
:type autoprompt: bool
:param autoprompt: Whether to append a prompt to each response.
"""
if autoprompt:
deco = self._create_autoprompt_handler
else:
deco = None
self.commands.add_from_file(filename, deco)
def init(self):
"""
Init or reset the virtual device.
:rtype: str
:return: The initial response of the virtual device.
"""
self.logged_in = False
if self.login_type == self.LOGIN_TYPE_PASSWORDONLY:
self.prompt_stage = self.PROMPT_STAGE_PASSWORD
elif self.login_type == self.LOGIN_TYPE_NONE:
self.prompt_stage = self.PROMPT_STAGE_CUSTOM
else:
self.prompt_stage = self.PROMPT_STAGE_USERNAME
return self.banner + self._get_prompt()
def do(self, command):
"""
"Executes" the given command on the virtual device, and returns
the response.
:type command: str
:param command: The command to be executed.
:rtype: str
:return: The response of the virtual device.
"""
echo = self.echo and command or ''
if not self.logged_in:
return echo + '\n' + self._get_prompt()
response = self.commands.eval(command)
if response is None:
return echo + '\n' + self._get_prompt()
return echo + response