mitogen/mitogen/sudo.py

# Copyright 2017, David Wilson
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
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# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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import logging
import os
import time

import mitogen.core
import mitogen.parent


LOG = logging.getLogger(__name__)
PASSWORD_PROMPT = 'password'


class PasswordError(mitogen.core.Error):
    pass


class Stream(mitogen.parent.Stream):
    create_child = staticmethod(mitogen.parent.tty_create_child)
    sudo_path = 'sudo'
    password = None

    def construct(self, username=None, sudo_path=None, password=None,
                  **kwargs):
        """
        Get the named sudo context, creating it if it does not exist.

        :param mitogen.core.Broker broker:
            The broker that will own the context.

        :param str username:
            Username to pass to sudo as the ``-u`` parameter, defaults to
            ``root``.

        :param str sudo_path:
            Filename or complete path to the sudo binary. ``PATH`` will be
            searched if given as a filename. Defaults to ``sudo``.

        :param str python_path:
            Filename or complete path to the Python binary. ``PATH`` will be
            searched if given as a filename. Defaults to
            :py:data:`sys.executable`.

        :param str password:
            The password to use when authenticating to sudo. Depending on the
            sudo configuration, this is either the current account password or
            the target account password. :py:class:`mitogen.sudo.PasswordError`
            will be raised if sudo requests a password but none is provided.
        """
        super(Stream, self).construct(**kwargs)
        self.username = username or 'root'
        if sudo_path:
            self.sudo_path = sudo_path
        if password:
            self.password = password

    def connect(self):
        super(Stream, self).connect()
        self.name = 'sudo.' + self.username

    def get_boot_command(self):
        bits = [self.sudo_path, '-u', self.username]
        bits = bits + super(Stream, self).get_boot_command()
        LOG.debug('sudo command line: %r', bits)
        return bits

    password_incorrect_msg = 'sudo password is incorrect'
    password_required_msg = 'sudo password is required'

    def _connect_bootstrap(self):
        password_sent = False
        for buf in mitogen.parent.iter_read(self.receive_side.fd,
                                            time.time() + 10.0):
            LOG.debug('%r: received %r', self, buf)
            if buf.endswith('EC0\n'):
                self._ec0_received()
                return
            elif PASSWORD_PROMPT in buf.lower():
                if self.password is None:
                    raise PasswordError(self.password_required_msg)
                if password_sent:
                    raise PasswordError(self.password_incorrect_msg)
                LOG.debug('sending password')
                os.write(self.transmit_side.fd, self.password + '\n')
                password_sent = True
        raise mitogen.core.StreamError('bootstrap failed')