# Copyright (c) 2013-2018 by Ron Frederick <ronf@timeheart.net>.
# All rights reserved.
#
# This program and the accompanying materials are made available under
# the terms of the Eclipse Public License v1.0 which accompanies this
# distribution and is available at:
#
# http://www.eclipse.org/legal/epl-v10.html
#
# Contributors:
# Ron Frederick - initial implementation, API, and documentation
"""Miscellaneous utility classes and functions"""
import asyncio
import codecs
import functools
import ipaddress
import os
import platform
import socket
from collections import OrderedDict
from random import SystemRandom
import asyncssh
from .constants import DEFAULT_LANG
# Provide globals to test if we're on various Python versions
python344 = platform.python_version_tuple() >= ('3', '4', '4')
python35 = platform.python_version_tuple() >= ('3', '5', '0')
python352 = platform.python_version_tuple() >= ('3', '5', '2')
# Define a version of randrange which is based on SystemRandom(), so that
# we get back numbers suitable for cryptographic use.
_random = SystemRandom()
randrange = _random.randrange
# Avoid deprecation warning for asyncio.async()
if python344:
create_task = asyncio.ensure_future
else: # pragma: no cover
create_task = getattr(asyncio, 'async')
def hide_empty(value, prefix=', '):
"""Return a string with optional prefix if value is non-empty"""
value = str(value)
return prefix + value if value else ''
def plural(length, label, suffix='s'):
"""Return a label with an optional plural suffix"""
return '%d %s%s' % (length, label, suffix if length != 1 else '')
def to_hex(data):
"""Convert binary data to a hex string"""
return codecs.encode(data, 'hex')
def all_ints(seq):
"""Return if a sequence contains all integers"""
return all(isinstance(i, int) for i in seq)
def get_symbol_names(symbols, prefix, strip_leading=0):
"""Return a mapping from values to symbol names for logging"""
return {value: name[strip_leading:] for name, value in symbols.items()
if name.startswith(prefix)}
# Default file names in .ssh directory to read private keys from
_DEFAULT_KEY_FILES = ('id_ed25519', 'id_ecdsa', 'id_rsa', 'id_dsa')
def load_default_keypairs(passphrase=None):
"""Return a list of default keys from the user's home directory"""
result = []
for file in _DEFAULT_KEY_FILES:
try:
file = os.path.join(os.path.expanduser('~'), '.ssh', file)
result.extend(asyncssh.load_keypairs(file, passphrase))
except asyncssh.KeyImportError as exc:
# Ignore encrypted default keys if a passphrase isn't provided
if not str(exc).startswith('Passphrase'):
raise
except OSError:
pass
return result
# Punctuation to map when creating handler names
_HANDLER_PUNCTUATION = (('@', '_at_'), ('.', '_dot_'), ('-', '_'))
def map_handler_name(name):
"""Map punctuation so a string can be used as a handler name"""
for old, new in _HANDLER_PUNCTUATION:
name = name.replace(old, new)
return name
def _normalize_scoped_ip(addr):
"""Normalize scoped IP address
The ipaddress module doesn't handle scoped addresses properly,
so we strip off the CIDR suffix here and normalize scoped IP
addresses using socket.inet_pton before we pass them into
ipaddress.
"""
for family in (socket.AF_INET, socket.AF_INET6):
try:
return socket.inet_ntop(family, socket.inet_pton(family, addr))
except (ValueError, socket.error):
pass
return addr
def ip_address(addr):
"""Wrapper for ipaddress.ip_address which supports scoped addresses"""
return ipaddress.ip_address(_normalize_scoped_ip(addr))
def ip_network(addr):
"""Wrapper for ipaddress.ip_network which supports scoped addresses"""
idx = addr.find('/')
if idx >= 0:
addr, mask = addr[:idx], addr[idx:]
else:
mask = ''
return ipaddress.ip_network(_normalize_scoped_ip(addr) + mask)
if python352:
async_iterator = lambda iter: iter
else:
async_iterator = asyncio.coroutine
def async_context_manager(coro):
"""Decorator for methods returning asynchronous context managers
This function can be used as a decorator for coroutines which
return objects intended to be used as Python 3.5 asynchronous
context managers. The object returned should implement __aenter__
and __aexit__ methods to run when the async context is entered
and exited.
This wrapper also allows non-async context managers to be defined
on the returned object, as well as the use of "await" or "yield
from" on the function being decorated for backward compatibility
with the API defined by older versions of AsyncSSH.
"""
class AsyncContextManager:
"""Async context manager wrapper for Python 3.5 and later"""
def __init__(self, coro):
self._coro = coro
self._result = None
def __iter__(self):
return (yield from self._coro)
def __await__(self):
return (yield from self._coro)
@asyncio.coroutine
def __aenter__(self):
self._result = yield from self._coro
return (yield from self._result.__aenter__())
@asyncio.coroutine
def __aexit__(self, *exc_info):
yield from self._result.__aexit__(*exc_info)
self._result = None
@functools.wraps(coro)
def coro_wrapper(*args, **kwargs):
"""Return an async context manager wrapper for this coroutine"""
return AsyncContextManager(asyncio.coroutine(coro)(*args, **kwargs))
if python35:
return coro_wrapper
else:
return coro
class Record:
"""General-purpose record type with fixed set of fields"""
__slots__ = OrderedDict()
def __init__(self, *args, **kwargs):
for k, v in self.__slots__.items():
setattr(self, k, v)
for k, v in zip(self.__slots__, args):
setattr(self, k, v)
for k, v in kwargs.items():
setattr(self, k, v)
def __repr__(self):
return '%s(%s)' % (type(self).__name__,
', '.join('%s=%r' % (k, getattr(self, k))
for k in self.__slots__))
def __str__(self):
values = ((k, self._format(k, getattr(self, k)))
for k in self.__slots__)
return ', '.join('%s: %s' % (k, v) for k, v in values if v is not None)
def _format(self, k, v):
"""Format a field as a string"""
# pylint: disable=no-self-use,unused-argument
return str(v)
class Error(Exception):
"""General SSH error"""
def __init__(self, errtype, code, reason, lang):
super().__init__('%s Error: %s' % (errtype, reason))
self.code = code
self.reason = reason
self.lang = lang
[docs]class DisconnectError(Error):
"""SSH disconnect error
This exception is raised when a serious error occurs which causes
the SSH connection to be disconnected. Exception codes should be
taken from :ref:`disconnect reason codes <DisconnectReasons>`.
:param code:
Disconnect reason, taken from :ref:`disconnect reason
codes <DisconnectReasons>`
:param reason:
A human-readable reason for the disconnect
:param lang:
The language the reason is in
:type code: `int`
:type reason: `str`
:type lang: `str`
"""
def __init__(self, code, reason, lang=DEFAULT_LANG):
super().__init__('Disconnect', code, reason, lang)
[docs]class ChannelOpenError(Error):
"""SSH channel open error
This exception is raised by connection handlers to report
channel open failures.
:param code:
Channel open failure reason, taken from :ref:`channel open
failure reason codes <ChannelOpenFailureReasons>`
:param reason:
A human-readable reason for the channel open failure
:param lang:
The language the reason is in
:type code: `int`
:type reason: `str`
:type lang: `str`
"""
def __init__(self, code, reason, lang=DEFAULT_LANG):
super().__init__('Channel Open', code, reason, lang)
[docs]class PasswordChangeRequired(Exception):
"""SSH password change required
This exception is raised during password validation on the
server to indicate that a password change is required. It
shouuld be raised when the password provided is valid but
expired, to trigger the client to provide a new password.
:param prompt:
The prompt requesting that the user enter a new password
:param lang:
The language that the prompt is in
:type prompt: `str`
:type lang: `str`
"""
def __init__(self, prompt, lang=DEFAULT_LANG):
super().__init__('Password change required: %s' % prompt)
self.prompt = prompt
self.lang = lang
[docs]class BreakReceived(Exception):
"""SSH break request received
This exception is raised on an SSH server stdin stream when the
client sends a break on the channel.
:param msec:
The duration of the break in milliseconds
:type msec: `int`
"""
def __init__(self, msec):
super().__init__('Break for %s msec' % msec)
self.msec = msec
[docs]class SignalReceived(Exception):
"""SSH signal request received
This exception is raised on an SSH server stdin stream when the
client sends a signal on the channel.
:param signal:
The name of the signal sent by the client
:type signal: `str`
"""
def __init__(self, signal):
super().__init__('Signal: %s' % signal)
self.signal = signal
[docs]class TerminalSizeChanged(Exception):
"""SSH terminal size change notification received
This exception is raised on an SSH server stdin stream when the
client sends a terminal size change on the channel.
:param width:
The new terminal width
:param height:
The new terminal height
:param pixwidth:
The new terminal width in pixels
:param pixheight:
The new terminal height in pixels
:type width: `int`
:type height: `int`
:type pixwidth: `int`
:type pixheight: `int`
"""
def __init__(self, width, height, pixwidth, pixheight):
super().__init__('Terminal size change: (%s, %s, %s, %s)' %
(width, height, pixwidth, pixheight))
self.width = width
self.height = height
self.pixwidth = pixwidth
self.pixheight = pixheight