# (c) 2014, Chris Church <chris@ninemoreminutes.com>
# Copyright (c) 2017 Ansible Project
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)

from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

DOCUMENTATION = """
    author: Ansible Core Team
    connection: winrm
    short_description: Run tasks over Microsoft's WinRM
    description:
        - Run commands or put/fetch on a target via WinRM
        - This plugin allows extra arguments to be passed that are supported by the protocol but not explicitly defined here.
          They should take the form of variables declared with the following pattern `ansible_winrm_<option>`.
    version_added: "2.0"
    requirements:
        - pywinrm (python library)
    options:
      # figure out more elegant 'delegation'
      remote_addr:
        description:
            - Address of the windows machine
        default: inventory_hostname
        vars:
            - name: ansible_host
            - name: ansible_winrm_host
      remote_user:
        keywords:
          - name: user
          - name: remote_user
        description:
            - The user to log in as to the Windows machine
        vars:
            - name: ansible_user
            - name: ansible_winrm_user
      port:
        description:
            - port for winrm to connect on remote target
            - The default is the https (5986) port, if using http it should be 5985
        vars:
          - name: ansible_port
          - name: ansible_winrm_port
        default: 5986
        keywords:
          - name: port
        type: integer
      scheme:
        description:
            - URI scheme to use
            - If not set, then will default to C(https) or C(http) if I(port) is
              C(5985).
        choices: [http, https]
        vars:
          - name: ansible_winrm_scheme
      path:
        description: URI path to connect to
        default: '/wsman'
        vars:
          - name: ansible_winrm_path
      transport:
        description:
           - List of winrm transports to attempt to to use (ssl, plaintext, kerberos, etc)
           - If None (the default) the plugin will try to automatically guess the correct list
           - The choices avialable depend on your version of pywinrm
        type: list
        vars:
          - name: ansible_winrm_transport
      kerberos_command:
        description: kerberos command to use to request a authentication ticket
        default: kinit
        vars:
          - name: ansible_winrm_kinit_cmd
      kerberos_mode:
        description:
            - kerberos usage mode.
            - The managed option means Ansible will obtain kerberos ticket.
            - While the manual one means a ticket must already have been obtained by the user.
            - If having issues with Ansible freezing when trying to obtain the
              Kerberos ticket, you can either set this to C(manual) and obtain
              it outside Ansible or install C(pexpect) through pip and try
              again.
        choices: [managed, manual]
        vars:
          - name: ansible_winrm_kinit_mode
      connection_timeout:
        description:
            - Sets the operation and read timeout settings for the WinRM
              connection.
            - Corresponds to the C(operation_timeout_sec) and
              C(read_timeout_sec) args in pywinrm so avoid setting these vars
              with this one.
            - The default value is whatever is set in the installed version of
              pywinrm.
        vars:
          - name: ansible_winrm_connection_timeout
"""

import base64
import logging
import os
import re
import traceback
import json
import tempfile
import subprocess

HAVE_KERBEROS = False
try:
    import kerberos
    HAVE_KERBEROS = True
except ImportError:
    pass

from ansible import constants as C
from ansible.errors import AnsibleError, AnsibleConnectionFailure
from ansible.errors import AnsibleFileNotFound
from ansible.module_utils.json_utils import _filter_non_json_lines
from ansible.module_utils.parsing.convert_bool import boolean
from ansible.module_utils.six.moves.urllib.parse import urlunsplit
from ansible.module_utils._text import to_bytes, to_native, to_text
from ansible.module_utils.six import binary_type, PY3
from ansible.plugins.connection import ConnectionBase
from ansible.plugins.shell.powershell import _parse_clixml
from ansible.utils.hashing import secure_hash
from ansible.utils.path import makedirs_safe
from ansible.utils.display import Display

# getargspec is deprecated in favour of getfullargspec in Python 3 but
# getfullargspec is not available in Python 2
if PY3:
    from inspect import getfullargspec as getargspec
else:
    from inspect import getargspec

try:
    import winrm
    from winrm import Response
    from winrm.protocol import Protocol
    import requests.exceptions
    HAS_WINRM = True
except ImportError as e:
    HAS_WINRM = False
    WINRM_IMPORT_ERR = e

try:
    import xmltodict
    HAS_XMLTODICT = True
except ImportError as e:
    HAS_XMLTODICT = False
    XMLTODICT_IMPORT_ERR = e

HAS_PEXPECT = False
try:
    import pexpect
    # echo was added in pexpect 3.3+ which is newer than the RHEL package
    # we can only use pexpect for kerb auth if echo is a valid kwarg
    # https://github.com/ansible/ansible/issues/43462
    if hasattr(pexpect, 'spawn'):
        argspec = getargspec(pexpect.spawn.__init__)
        if 'echo' in argspec.args:
            HAS_PEXPECT = True
except ImportError as e:
    pass

# used to try and parse the hostname and detect if IPv6 is being used
try:
    import ipaddress
    HAS_IPADDRESS = True
except ImportError:
    HAS_IPADDRESS = False

display = Display()


class Connection(ConnectionBase):
    '''WinRM connections over HTTP/HTTPS.'''

    transport = 'winrm'
    module_implementation_preferences = ('.ps1', '.exe', '')
    allow_executable = False
    has_pipelining = True
    allow_extras = True

    def __init__(self, *args, **kwargs):

        self.always_pipeline_modules = True
        self.has_native_async = True

        self.protocol = None
        self.shell_id = None
        self.delegate = None
        self._shell_type = 'powershell'

        super(Connection, self).__init__(*args, **kwargs)

        if not C.DEFAULT_DEBUG:
            logging.getLogger('requests_credssp').setLevel(logging.INFO)
            logging.getLogger('requests_kerberos').setLevel(logging.INFO)
            logging.getLogger('urllib3').setLevel(logging.INFO)

    def _build_winrm_kwargs(self):
        # this used to be in set_options, as win_reboot needs to be able to
        # override the conn timeout, we need to be able to build the args
        # after setting individual options. This is called by _connect before
        # starting the WinRM connection
        self._winrm_host = self.get_option('remote_addr')
        self._winrm_user = self.get_option('remote_user')
        self._winrm_pass = self._play_context.password

        self._winrm_port = self.get_option('port')

        self._winrm_scheme = self.get_option('scheme')
        # old behaviour, scheme should default to http if not set and the port
        # is 5985 otherwise https
        if self._winrm_scheme is None:
            self._winrm_scheme = 'http' if self._winrm_port == 5985 else 'https'

        self._winrm_path = self.get_option('path')
        self._kinit_cmd = self.get_option('kerberos_command')
        self._winrm_transport = self.get_option('transport')
        self._winrm_connection_timeout = self.get_option('connection_timeout')

        if hasattr(winrm, 'FEATURE_SUPPORTED_AUTHTYPES'):
            self._winrm_supported_authtypes = set(winrm.FEATURE_SUPPORTED_AUTHTYPES)
        else:
            # for legacy versions of pywinrm, use the values we know are supported
            self._winrm_supported_authtypes = set(['plaintext', 'ssl', 'kerberos'])

        # calculate transport if needed
        if self._winrm_transport is None or self._winrm_transport[0] is None:
            # TODO: figure out what we want to do with auto-transport selection in the face of NTLM/Kerb/CredSSP/Cert/Basic
            transport_selector = ['ssl'] if self._winrm_scheme == 'https' else ['plaintext']

            if HAVE_KERBEROS and ((self._winrm_user and '@' in self._winrm_user)):
                self._winrm_transport = ['kerberos'] + transport_selector
            else:
                self._winrm_transport = transport_selector

        unsupported_transports = set(self._winrm_transport).difference(self._winrm_supported_authtypes)

        if unsupported_transports:
            raise AnsibleError('The installed version of WinRM does not support transport(s) %s' %
                               to_native(list(unsupported_transports), nonstring='simplerepr'))

        # if kerberos is among our transports and there's a password specified, we're managing the tickets
        kinit_mode = self.get_option('kerberos_mode')
        if kinit_mode is None:
            # HACK: ideally, remove multi-transport stuff
            self._kerb_managed = "kerberos" in self._winrm_transport and (self._winrm_pass is not None and self._winrm_pass != "")
        elif kinit_mode == "managed":
            self._kerb_managed = True
        elif kinit_mode == "manual":
            self._kerb_managed = False

        # arg names we're going passing directly
        internal_kwarg_mask = set(['self', 'endpoint', 'transport', 'username', 'password', 'scheme', 'path', 'kinit_mode', 'kinit_cmd'])

        self._winrm_kwargs = dict(username=self._winrm_user, password=self._winrm_pass)
        argspec = getargspec(Protocol.__init__)
        supported_winrm_args = set(argspec.args)
        supported_winrm_args.update(internal_kwarg_mask)
        passed_winrm_args = set([v.replace('ansible_winrm_', '') for v in self.get_option('_extras')])
        unsupported_args = passed_winrm_args.difference(supported_winrm_args)

        # warn for kwargs unsupported by the installed version of pywinrm
        for arg in unsupported_args:
            display.warning("ansible_winrm_{0} unsupported by pywinrm (is an up-to-date version of pywinrm installed?)".format(arg))

        # pass through matching extras, excluding the list we want to treat specially
        for arg in passed_winrm_args.difference(internal_kwarg_mask).intersection(supported_winrm_args):
            self._winrm_kwargs[arg] = self.get_option('_extras')['ansible_winrm_%s' % arg]

    # Until pykerberos has enough goodies to implement a rudimentary kinit/klist, simplest way is to let each connection
    # auth itself with a private CCACHE.
    def _kerb_auth(self, principal, password):
        if password is None:
            password = ""

        self._kerb_ccache = tempfile.NamedTemporaryFile()
        display.vvvvv("creating Kerberos CC at %s" % self._kerb_ccache.name)
        krb5ccname = "FILE:%s" % self._kerb_ccache.name
        os.environ["KRB5CCNAME"] = krb5ccname
        krb5env = dict(KRB5CCNAME=krb5ccname)

        # stores various flags to call with kinit, we currently only use this
        # to set -f so we can get a forward-able ticket (cred delegation)
        kinit_flags = []
        if boolean(self.get_option('_extras').get('ansible_winrm_kerberos_delegation', False)):
            kinit_flags.append('-f')

        kinit_cmdline = [self._kinit_cmd]
        kinit_cmdline.extend(kinit_flags)
        kinit_cmdline.append(principal)

        # pexpect runs the process in its own pty so it can correctly send
        # the password as input even on MacOS which blocks subprocess from
        # doing so. Unfortunately it is not available on the built in Python
        # so we can only use it if someone has installed it
        if HAS_PEXPECT:
            proc_mechanism = "pexpect"
            command = kinit_cmdline.pop(0)
            password = to_text(password, encoding='utf-8',
                               errors='surrogate_or_strict')

            display.vvvv("calling kinit with pexpect for principal %s"
                         % principal)
            try:
                child = pexpect.spawn(command, kinit_cmdline, timeout=60,
                                      env=krb5env, echo=False)
            except pexpect.ExceptionPexpect as err:
                err_msg = "Kerberos auth failure when calling kinit cmd " \
                          "'%s': %s" % (command, to_native(err))
                raise AnsibleConnectionFailure(err_msg)

            try:
                child.expect(".*:")
                child.sendline(password)
            except OSError as err:
                # child exited before the pass was sent, Ansible will raise
                # error based on the rc below, just display the error here
                display.vvvv("kinit with pexpect raised OSError: %s"
                             % to_native(err))

            # technically this is the stdout + stderr but to match the
            # subprocess error checking behaviour, we will call it stderr
            stderr = child.read()
            child.wait()
            rc = child.exitstatus
        else:
            proc_mechanism = "subprocess"
            password = to_bytes(password, encoding='utf-8',
                                errors='surrogate_or_strict')

            display.vvvv("calling kinit with subprocess for principal %s"
                         % principal)
            try:
                p = subprocess.Popen(kinit_cmdline, stdin=subprocess.PIPE,
                                     stdout=subprocess.PIPE,
                                     stderr=subprocess.PIPE,
                                     env=krb5env)

            except OSError as err:
                err_msg = "Kerberos auth failure when calling kinit cmd " \
                          "'%s': %s" % (self._kinit_cmd, to_native(err))
                raise AnsibleConnectionFailure(err_msg)

            stdout, stderr = p.communicate(password + b'\n')
            rc = p.returncode != 0

        if rc != 0:
            # one last attempt at making sure the password does not exist
            # in the output
            exp_msg = to_native(stderr.strip())
            exp_msg = exp_msg.replace(to_native(password), "<redacted>")

            err_msg = "Kerberos auth failure for principal %s with %s: %s" \
                      % (principal, proc_mechanism, exp_msg)
            raise AnsibleConnectionFailure(err_msg)

        display.vvvvv("kinit succeeded for principal %s" % principal)

    def _winrm_connect(self):
        '''
        Establish a WinRM connection over HTTP/HTTPS.
        '''
        display.vvv("ESTABLISH WINRM CONNECTION FOR USER: %s on PORT %s TO %s" %
                    (self._winrm_user, self._winrm_port, self._winrm_host), host=self._winrm_host)

        winrm_host = self._winrm_host
        if HAS_IPADDRESS:
            display.debug("checking if winrm_host %s is an IPv6 address" % winrm_host)
            try:
                ipaddress.IPv6Address(winrm_host)
            except ipaddress.AddressValueError:
                pass
            else:
                winrm_host = "[%s]" % winrm_host

        netloc = '%s:%d' % (winrm_host, self._winrm_port)
        endpoint = urlunsplit((self._winrm_scheme, netloc, self._winrm_path, '', ''))
        errors = []
        for transport in self._winrm_transport:
            if transport == 'kerberos':
                if not HAVE_KERBEROS:
                    errors.append('kerberos: the python kerberos library is not installed')
                    continue
                if self._kerb_managed:
                    self._kerb_auth(self._winrm_user, self._winrm_pass)
            display.vvvvv('WINRM CONNECT: transport=%s endpoint=%s' % (transport, endpoint), host=self._winrm_host)
            try:
                winrm_kwargs = self._winrm_kwargs.copy()
                if self._winrm_connection_timeout:
                    winrm_kwargs['operation_timeout_sec'] = self._winrm_connection_timeout
                    winrm_kwargs['read_timeout_sec'] = self._winrm_connection_timeout + 1
                protocol = Protocol(endpoint, transport=transport, **winrm_kwargs)

                # open the shell from connect so we know we're able to talk to the server
                if not self.shell_id:
                    self.shell_id = protocol.open_shell(codepage=65001)  # UTF-8
                    display.vvvvv('WINRM OPEN SHELL: %s' % self.shell_id, host=self._winrm_host)

                return protocol
            except Exception as e:
                err_msg = to_text(e).strip()
                if re.search(to_text(r'Operation\s+?timed\s+?out'), err_msg, re.I):
                    raise AnsibleError('the connection attempt timed out')
                m = re.search(to_text(r'Code\s+?(\d{3})'), err_msg)
                if m:
                    code = int(m.groups()[0])
                    if code == 401:
                        err_msg = 'the specified credentials were rejected by the server'
                    elif code == 411:
                        return protocol
                errors.append(u'%s: %s' % (transport, err_msg))
                display.vvvvv(u'WINRM CONNECTION ERROR: %s\n%s' % (err_msg, to_text(traceback.format_exc())), host=self._winrm_host)
        if errors:
            raise AnsibleConnectionFailure(', '.join(map(to_native, errors)))
        else:
            raise AnsibleError('No transport found for WinRM connection')

    def _winrm_send_input(self, protocol, shell_id, command_id, stdin, eof=False):
        rq = {'env:Envelope': protocol._get_soap_header(
            resource_uri='http://schemas.microsoft.com/wbem/wsman/1/windows/shell/cmd',
            action='http://schemas.microsoft.com/wbem/wsman/1/windows/shell/Send',
            shell_id=shell_id)}
        stream = rq['env:Envelope'].setdefault('env:Body', {}).setdefault('rsp:Send', {})\
            .setdefault('rsp:Stream', {})
        stream['@Name'] = 'stdin'
        stream['@CommandId'] = command_id
        stream['#text'] = base64.b64encode(to_bytes(stdin))
        if eof:
            stream['@End'] = 'true'
        protocol.send_message(xmltodict.unparse(rq))

    def _winrm_exec(self, command, args=(), from_exec=False, stdin_iterator=None):
        if not self.protocol:
            self.protocol = self._winrm_connect()
            self._connected = True
        if from_exec:
            display.vvvvv("WINRM EXEC %r %r" % (command, args), host=self._winrm_host)
        else:
            display.vvvvvv("WINRM EXEC %r %r" % (command, args), host=self._winrm_host)
        command_id = None
        try:
            stdin_push_failed = False
            command_id = self.protocol.run_command(self.shell_id, to_bytes(command), map(to_bytes, args), console_mode_stdin=(stdin_iterator is None))

            try:
                if stdin_iterator:
                    for (data, is_last) in stdin_iterator:
                        self._winrm_send_input(self.protocol, self.shell_id, command_id, data, eof=is_last)

            except Exception as ex:
                display.warning("ERROR DURING WINRM SEND INPUT - attempting to recover: %s %s"
                                % (type(ex).__name__, to_text(ex)))
                display.debug(traceback.format_exc())
                stdin_push_failed = True

            # NB: this can hang if the receiver is still running (eg, network failed a Send request but the server's still happy).
            # FUTURE: Consider adding pywinrm status check/abort operations to see if the target is still running after a failure.
            resptuple = self.protocol.get_command_output(self.shell_id, command_id)
            # ensure stdout/stderr are text for py3
            # FUTURE: this should probably be done internally by pywinrm
            response = Response(tuple(to_text(v) if isinstance(v, binary_type) else v for v in resptuple))

            # TODO: check result from response and set stdin_push_failed if we have nonzero
            if from_exec:
                display.vvvvv('WINRM RESULT %r' % to_text(response), host=self._winrm_host)
            else:
                display.vvvvvv('WINRM RESULT %r' % to_text(response), host=self._winrm_host)

            display.vvvvvv('WINRM STDOUT %s' % to_text(response.std_out), host=self._winrm_host)
            display.vvvvvv('WINRM STDERR %s' % to_text(response.std_err), host=self._winrm_host)

            if stdin_push_failed:
                # There are cases where the stdin input failed but the WinRM service still processed it. We attempt to
                # see if stdout contains a valid json return value so we can ignore this error
                try:
                    filtered_output, dummy = _filter_non_json_lines(response.std_out)
                    json.loads(filtered_output)
                except ValueError:
                    # stdout does not contain a return response, stdin input was a fatal error
                    stderr = to_bytes(response.std_err, encoding='utf-8')
                    if stderr.startswith(b"#< CLIXML"):
                        stderr = _parse_clixml(stderr)

                    raise AnsibleError('winrm send_input failed; \nstdout: %s\nstderr %s'
                                       % (to_native(response.std_out), to_native(stderr)))

            return response
        except requests.exceptions.Timeout as exc:
            raise AnsibleConnectionFailure('winrm connection error: %s' % to_native(exc))
        finally:
            if command_id:
                self.protocol.cleanup_command(self.shell_id, command_id)

    def _connect(self):

        if not HAS_WINRM:
            raise AnsibleError("winrm or requests is not installed: %s" % to_native(WINRM_IMPORT_ERR))
        elif not HAS_XMLTODICT:
            raise AnsibleError("xmltodict is not installed: %s" % to_native(XMLTODICT_IMPORT_ERR))

        super(Connection, self)._connect()
        if not self.protocol:
            self._build_winrm_kwargs()  # build the kwargs from the options set
            self.protocol = self._winrm_connect()
            self._connected = True
        return self

    def reset(self):
        self.protocol = None
        self.shell_id = None
        self._connect()

    def _wrapper_payload_stream(self, payload, buffer_size=200000):
        payload_bytes = to_bytes(payload)
        byte_count = len(payload_bytes)
        for i in range(0, byte_count, buffer_size):
            yield payload_bytes[i:i + buffer_size], i + buffer_size >= byte_count

    def exec_command(self, cmd, in_data=None, sudoable=True):
        super(Connection, self).exec_command(cmd, in_data=in_data, sudoable=sudoable)
        cmd_parts = self._shell._encode_script(cmd, as_list=True, strict_mode=False, preserve_rc=False)

        # TODO: display something meaningful here
        display.vvv("EXEC (via pipeline wrapper)")

        stdin_iterator = None

        if in_data:
            stdin_iterator = self._wrapper_payload_stream(in_data)

        result = self._winrm_exec(cmd_parts[0], cmd_parts[1:], from_exec=True, stdin_iterator=stdin_iterator)

        result.std_out = to_bytes(result.std_out)
        result.std_err = to_bytes(result.std_err)

        # parse just stderr from CLIXML output
        if result.std_err.startswith(b"#< CLIXML"):
            try:
                result.std_err = _parse_clixml(result.std_err)
            except Exception:
                # unsure if we're guaranteed a valid xml doc- use raw output in case of error
                pass

        return (result.status_code, result.std_out, result.std_err)

    # FUTURE: determine buffer size at runtime via remote winrm config?
    def _put_file_stdin_iterator(self, in_path, out_path, buffer_size=250000):
        in_size = os.path.getsize(to_bytes(in_path, errors='surrogate_or_strict'))
        offset = 0
        with open(to_bytes(in_path, errors='surrogate_or_strict'), 'rb') as in_file:
            for out_data in iter((lambda: in_file.read(buffer_size)), b''):
                offset += len(out_data)
                self._display.vvvvv('WINRM PUT "%s" to "%s" (offset=%d size=%d)' % (in_path, out_path, offset, len(out_data)), host=self._winrm_host)
                # yes, we're double-encoding over the wire in this case- we want to ensure that the data shipped to the end PS pipeline is still b64-encoded
                b64_data = base64.b64encode(out_data) + b'\r\n'
                # cough up the data, as well as an indicator if this is the last chunk so winrm_send knows to set the End signal
                yield b64_data, (in_file.tell() == in_size)

            if offset == 0:  # empty file, return an empty buffer + eof to close it
                yield "", True

    def put_file(self, in_path, out_path):
        super(Connection, self).put_file(in_path, out_path)
        out_path = self._shell._unquote(out_path)
        display.vvv('PUT "%s" TO "%s"' % (in_path, out_path), host=self._winrm_host)
        if not os.path.exists(to_bytes(in_path, errors='surrogate_or_strict')):
            raise AnsibleFileNotFound('file or module does not exist: "%s"' % to_native(in_path))

        script_template = u'''
            begin {{
                $path = '{0}'

                $DebugPreference = "Continue"
                $ErrorActionPreference = "Stop"
                Set-StrictMode -Version 2

                $fd = [System.IO.File]::Create($path)

                $sha1 = [System.Security.Cryptography.SHA1CryptoServiceProvider]::Create()

                $bytes = @() #initialize for empty file case
            }}
            process {{
               $bytes = [System.Convert]::FromBase64String($input)
               $sha1.TransformBlock($bytes, 0, $bytes.Length, $bytes, 0) | Out-Null
               $fd.Write($bytes, 0, $bytes.Length)
            }}
            end {{
                $sha1.TransformFinalBlock($bytes, 0, 0) | Out-Null

                $hash = [System.BitConverter]::ToString($sha1.Hash).Replace("-", "").ToLowerInvariant()

                $fd.Close()

                Write-Output "{{""sha1"":""$hash""}}"
            }}
        '''

        script = script_template.format(self._shell._escape(out_path))
        cmd_parts = self._shell._encode_script(script, as_list=True, strict_mode=False, preserve_rc=False)

        result = self._winrm_exec(cmd_parts[0], cmd_parts[1:], stdin_iterator=self._put_file_stdin_iterator(in_path, out_path))
        # TODO: improve error handling
        if result.status_code != 0:
            raise AnsibleError(to_native(result.std_err))

        put_output = json.loads(result.std_out)
        remote_sha1 = put_output.get("sha1")

        if not remote_sha1:
            raise AnsibleError("Remote sha1 was not returned")

        local_sha1 = secure_hash(in_path)

        if not remote_sha1 == local_sha1:
            raise AnsibleError("Remote sha1 hash {0} does not match local hash {1}".format(to_native(remote_sha1), to_native(local_sha1)))

    def fetch_file(self, in_path, out_path):
        super(Connection, self).fetch_file(in_path, out_path)
        in_path = self._shell._unquote(in_path)
        out_path = out_path.replace('\\', '/')
        display.vvv('FETCH "%s" TO "%s"' % (in_path, out_path), host=self._winrm_host)
        buffer_size = 2**19  # 0.5MB chunks
        makedirs_safe(os.path.dirname(out_path))
        out_file = None
        try:
            offset = 0
            while True:
                try:
                    script = '''
                        $path = "%(path)s"
                        If (Test-Path -Path $path -PathType Leaf)
                        {
                            $buffer_size = %(buffer_size)d
                            $offset = %(offset)d

                            $stream = New-Object -TypeName IO.FileStream($path, [IO.FileMode]::Open, [IO.FileAccess]::Read, [IO.FileShare]::ReadWrite)
                            $stream.Seek($offset, [System.IO.SeekOrigin]::Begin) > $null
                            $buffer = New-Object -TypeName byte[] $buffer_size
                            $bytes_read = $stream.Read($buffer, 0, $buffer_size)
                            if ($bytes_read -gt 0) {
                                $bytes = $buffer[0..($bytes_read - 1)]
                                [System.Convert]::ToBase64String($bytes)
                            }
                            $stream.Close() > $null
                        }
                        ElseIf (Test-Path -Path $path -PathType Container)
                        {
                            Write-Host "[DIR]";
                        }
                        Else
                        {
                            Write-Error "$path does not exist";
                            Exit 1;
                        }
                    ''' % dict(buffer_size=buffer_size, path=self._shell._escape(in_path), offset=offset)
                    display.vvvvv('WINRM FETCH "%s" to "%s" (offset=%d)' % (in_path, out_path, offset), host=self._winrm_host)
                    cmd_parts = self._shell._encode_script(script, as_list=True, preserve_rc=False)
                    result = self._winrm_exec(cmd_parts[0], cmd_parts[1:])
                    if result.status_code != 0:
                        raise IOError(to_native(result.std_err))
                    if result.std_out.strip() == '[DIR]':
                        data = None
                    else:
                        data = base64.b64decode(result.std_out.strip())
                    if data is None:
                        makedirs_safe(out_path)
                        break
                    else:
                        if not out_file:
                            # If out_path is a directory and we're expecting a file, bail out now.
                            if os.path.isdir(to_bytes(out_path, errors='surrogate_or_strict')):
                                break
                            out_file = open(to_bytes(out_path, errors='surrogate_or_strict'), 'wb')
                        out_file.write(data)
                        if len(data) < buffer_size:
                            break
                        offset += len(data)
                except Exception:
                    traceback.print_exc()
                    raise AnsibleError('failed to transfer file to "%s"' % to_native(out_path))
        finally:
            if out_file:
                out_file.close()

    def close(self):
        if self.protocol and self.shell_id:
            display.vvvvv('WINRM CLOSE SHELL: %s' % self.shell_id, host=self._winrm_host)
            self.protocol.close_shell(self.shell_id)
        self.shell_id = None
        self.protocol = None
        self._connected = False
