authconn.py

#!/usr/bin/python3

## Copyright (C) 2007, 2008, 2009, 2010, 2011, 2013, 2014 Red Hat, Inc.
## Author: Tim Waugh <twaugh@redhat.com>

## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2 of the License, or
## (at your option) any later version.

## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.

## You should have received a copy of the GNU General Public License
## along with this program; if not, write to the Free Software
## Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

import threading
import queue
import time

import config
import cups
import cupspk
import gi
from gi.repository import GLib
gi.require_version('Gdk', '3.0')
from gi.repository import Gdk
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk
import os
from errordialogs import *
from debug import *
import gettext
gettext.install(domain=config.PACKAGE, localedir=config.localedir)
N_ = lambda x: x
class WorkerTimeoutError(RuntimeError):
    pass

class WorkerUnavailableError(RuntimeError):
    pass

cups.require("1.9.60")
class AuthDialog(Gtk.Dialog):
    AUTH_FIELD={'username': N_("Username:"),
                'password': N_("Password:"),
                'domain': N_("Domain:")}

    def __init__ (self, title=None, parent=None,
                  flags=Gtk.DialogFlags.MODAL,
                  buttons=(Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
                           Gtk.STOCK_OK, Gtk.ResponseType.OK),
                  auth_info_required=None,
                  allow_remember=False):
        if title is None:
            title = _("Authentication")
        if auth_info_required is None:
            auth_info_required = ['username', 'password']
        Gtk.Dialog.__init__ (self, title, parent, flags, buttons)
        self.auth_info_required = auth_info_required
        self.set_default_response (Gtk.ResponseType.OK)
        self.set_border_width (6)
        self.set_resizable (False)
        hbox = Gtk.HBox.new (False, 12)
        hbox.set_border_width (6)
        image = Gtk.Image ()
        image.set_from_stock (Gtk.STOCK_DIALOG_AUTHENTICATION,
                              Gtk.IconSize.DIALOG)
        image.set_alignment (0.0, 0.0)
        hbox.pack_start (image, False, False, 0)
        vbox = Gtk.VBox.new (False, 12)
        self.prompt_label = Gtk.Label ()
        vbox.pack_start (self.prompt_label, False, False, 0)

        num_fields = len (auth_info_required)
        grid = Gtk.Grid()
        grid.insert_row(num_fields)
        grid.insert_column(2)
        grid.set_row_spacing (6)
        grid.set_column_spacing (6)

        self.field_entry = []
        for i in range (num_fields):
            field = auth_info_required[i]
            label = Gtk.Label (label=_(self.AUTH_FIELD.get (field, field)))
            label.set_alignment (0, 0.5)
            grid.attach (label, 0, i, 1, 1)
            entry = Gtk.Entry ()
            entry.set_visibility (field != 'password')
            grid.attach (entry, 1, i, 1, 1)
            self.field_entry.append (entry)

        self.field_entry[num_fields - 1].set_activates_default (True)
        vbox.pack_start (grid, False, False, 0)
        hbox.pack_start (vbox, False, False, 0)
        self.vbox.pack_start (hbox, False, False, 0)

        if allow_remember:
            cb = Gtk.CheckButton.new_with_label (_("Remember password"))
            cb.set_active (False)
            vbox.pack_start (cb, False, False, 0)
            self.remember_checkbox = cb

        self.vbox.show_all ()

    def set_prompt (self, prompt):
        self.prompt_label.set_markup ('<span weight="bold" size="larger">' +
                                      prompt + '</span>')
        self.prompt_label.set_use_markup (True)
        self.prompt_label.set_alignment (0, 0)
        self.prompt_label.set_line_wrap (True)

    def set_auth_info (self, auth_info):
        for i in range (len (self.field_entry)):
            self.field_entry[i].set_text (auth_info[i])

    def get_auth_info (self):
        return [x.get_text () for x in self.field_entry]

    def get_remember_password (self):
        try:
            return self.remember_checkbox.get_active ()
        except AttributeError:
            return False

    def field_grab_focus (self, field):
        i = self.auth_info_required.index (field)
        self.field_entry[i].grab_focus ()

###
### An auth-info cache.
###
class _AuthInfoCache:
    def __init__ (self):
        self.creds = dict() # by (host,port)

    def cache_auth_info (self, data, host=None, port=None):
        if port is None:
            port = 631

        self.creds[(host,port)] = data

    def lookup_auth_info (self, host=None, port=None):
        if port is None:
            port = 631

        try:
            return self.creds[(host,port)]
        except KeyError:
            return None

    def remove_auth_info (self, host=None, port=None):
        if port is None:
            port = 631

        try:
            del self.creds[(host,port)]
        except KeyError:
            return None

global_authinfocache = _AuthInfoCache ()

def _dispatch_worker_op(op, conn, args, kwds):
    """
    Execute a worker operation against the worker-owned cups.Connection
    or as a standalone callable.
    """
    if isinstance(op, str):
        fn = getattr(conn, op)
        return fn(*args, **kwds)

    if hasattr(op, '_op_name') and getattr(op, '_target_conn', None) is not None:
        fn = getattr(conn, op._op_name)
        return fn(*args, **kwds)

    if callable(op):
        if getattr(op, '_with_connection', False):
            return op(conn, *args, **kwds)
        return op(*args, **kwds)

    raise TypeError(f"Operation {op!r} is not callable or a valid method name")

class Connection:
    def __init__ (self, parent=None, try_as_root=True, lock=False,
                  host=None, port=None, encryption=None):
        if host is not None:
            cups.setServer (host)
        if port is not None:
            cups.setPort (port)
        if encryption is not None:
            cups.setEncryption (encryption)

        self._use_password = ''
        self._parent = parent
        self._try_as_root = try_as_root
        self._use_user = cups.getUser ()
        self._server = cups.getServer ()
        self._port = cups.getPort()
        self._encryption = cups.getEncryption ()
        self._prompt_allowed = True
        self._operation_stack = []
        self._lock = lock
        self._gui_event = threading.Event ()
        self._auth_lock = threading.Lock ()
        self._cancel = False
        self._cannot_auth = False
        self._worker_lock = threading.Lock()

        self._connect ()

    def cancel (self):
        self._cancel = True

    def _begin_operation (self, operation):
        debugprint ("%s: Operation += %s" % (self, operation))
        self._operation_stack.append (operation)

    def _end_operation (self):
        debugprint ("%s: Operation ended" % self)
        self._operation_stack.pop ()

    def _get_prompt_allowed (self, ):
        return self._prompt_allowed

    def _set_prompt_allowed (self, allowed):
        self._prompt_allowed = allowed

    def _set_lock (self, whether):
        self._lock = whether

    def _connect (self, allow_pk=True):
        cups.setUser (self._use_user)

        self._use_pk = (allow_pk and
                        (self._server[0] == '/' or self._server == 'localhost')
                        and os.getuid () != 0)
        if self._use_pk:
            create_object = cupspk.Connection
        else:
            create_object = cups.Connection

        self._connection = create_object (host=self._server,
                                            port=self._port,
                                            encryption=self._encryption)

        if self._use_pk:
            self._connection.set_parent(self._parent)

        self._user = self._use_user
        debugprint ("Connected as user %s" % self._user)
        methodtype_lambda = type (self._connection.getPrinters)
        methodtype_real = type (self._connection.addPrinter)
        for fname in dir (self._connection):
            if fname[0] == '_':
                continue
            fn = getattr (self._connection, fname)
            if not type (fn) in [methodtype_lambda, methodtype_real]:
                continue
            setattr (self, fname, self._make_binding (fname, fn))

    def _using_polkit (self):
        return isinstance (self._connection, cupspk.Connection)

    def _make_binding (self, fname, fn):
        binding = lambda *args, **kwds: self._authloop (fname, fn, *args, **kwds)
        binding._op_name = fname
        binding._target_conn = self
        return binding

    def run_on_worker (self, op, feedback=None, spinner=None, delay_ms=250, with_connection=False):
        """
        Returns a callable wrapper that executes the specified CUPS operation
        on the dedicated background worker thread while pumping the GLib
        main loop.

        :param op: Either a method name string (e.g. 'getServerPPD', 'getPPD'),
                   a bound Connection method (self.cups.getServerPPD),
                   or a callable: op(*args, **kwds) or op(conn, *args, **kwds) if with_connection.
        :param feedback: Optional DelayedSpinner or WorkerFeedback instance.
        :param spinner: Optional VectorSpinner or Gtk.Spinner widget.
        :param delay_ms: Milliseconds to delay spinner appearance (default 250ms).
        :param with_connection: If True, pass the worker cups.Connection to op.
        """
        if feedback is None and spinner is not None:
            from vectorspinner import DelayedSpinner
            feedback = DelayedSpinner(spinner, delay_ms=delay_ms)

        target_op = getattr(op, '_op_name', op)
        if with_connection and callable(target_op):
            try:
                target_op._with_connection = True
            except AttributeError:
                pass

        is_conn_method = False
        if isinstance(target_op, str) and hasattr(self._connection, target_op):
            is_conn_method = True
        elif hasattr(op, '_op_name') and getattr(op, '_target_conn', None) is self:
            is_conn_method = True

        def wrapper (*args, **kwds):
            # Worker-thread re-entry: execute directly on worker connection to avoid deadlock
            if hasattr(self, '_worker_thread') and threading.current_thread() == self._worker_thread:
                conn = getattr(self, '_worker_conn', None)
                if conn is None:
                    with self._auth_lock:
                        user = self._use_user
                    cups.setUser(user)
                    conn = cups.Connection(host=self._server,
                                           port=self._port,
                                           encryption=self._encryption)
                    self._worker_conn = conn
                return _dispatch_worker_op(target_op, conn, args, kwds)

            # Execution on GTK / main thread:
            if is_conn_method:
                fn = getattr(self._connection, target_op)
                return self._authloop(target_op, fn, *args, _on_worker=True,
                                      _feedback=feedback, **kwds)
            else:
                return self._execute_in_worker(target_op, *args, _feedback=feedback, **kwds)

        return wrapper

    def _execute_in_worker(self, fname, *args, **kwds):
        timeout_val = kwds.pop('_timeout', 30.0)
        feedback = kwds.pop('_feedback', None)

        if not hasattr(self, '_worker_queue'):
            self._worker_lock = getattr(self, '_worker_lock', threading.Lock())
            self._worker_state = 'IDLE'
            self._worker_conn = None
            self._worker_queue = queue.Queue()
            self._worker_thread = threading.Thread(target=self._worker_loop, daemon=True)
            self._worker_thread.start()

        with self._worker_lock:
            if getattr(self, '_worker_unresponsive', False):
                raise WorkerUnavailableError("Worker is unavailable or busy")

        box = []
        req_state = {'completed': False, 'timed_out': False}
        self._worker_queue.put((fname, args, kwds, box, req_state))

        loop = GLib.MainLoop()
        source_id = [None]
        start_time = time.monotonic()

        if feedback is not None:
            feedback.start()

        def poll():
            with self._worker_lock:
                is_completed = req_state['completed']

            if is_completed:
                if loop.is_running():
                    loop.quit()
                source_id[0] = None
                return False

            if time.monotonic() - start_time > timeout_val:
                with self._worker_lock:
                    if req_state['completed']:
                        if loop.is_running():
                            loop.quit()
                        source_id[0] = None
                        return False

                    req_state['timed_out'] = True
                    self._worker_unresponsive = True

                if loop.is_running():
                    loop.quit()
                source_id[0] = None
                return False
            return True

        source_id[0] = GLib.timeout_add(20, poll)

        try:
            loop.run()
        finally:
            if source_id[0] is not None:
                GLib.source_remove(source_id[0])
                source_id[0] = None
            if feedback is not None:
                feedback.stop()

        if req_state['timed_out']:
            raise WorkerTimeoutError("CUPS worker timeout")

        if not box:
            raise WorkerUnavailableError("CUPS worker returned no result")

        ok, res, exc = box[0]
        if not ok:
            raise exc
        return res

    def _worker_loop(self):
        conn = None
        conn_user = None

        while True:
            item = self._worker_queue.get()
            if item is None:
                break
            fname, args, kwds, box, req_state = item

            with self._worker_lock:
                self._worker_state = 'BUSY'

            try:
                with self._auth_lock:
                    target_user = self._use_user

                if conn is None or conn_user != target_user:
                    cups.setUser(target_user)
                    conn = cups.Connection(host=self._server,
                                           port=self._port,
                                           encryption=self._encryption)
                    conn_user = target_user
                    self._worker_conn = conn

                cups.setUser(target_user)
                res = _dispatch_worker_op(fname, conn, args, kwds)

                res_tuple = (True, res, None)
            except Exception as e:
                res_tuple = (False, None, e)
            finally:
                with self._worker_lock:
                    if req_state['timed_out']:
                        # Clean up temporary files if a file path was returned
                        if (res_tuple[0] and isinstance(res_tuple[1], str) and
                                os.path.isabs(res_tuple[1]) and os.path.exists(res_tuple[1])):
                            try:
                                os.unlink(res_tuple[1])
                            except OSError:
                                pass
                        conn = None
                        conn_user = None
                        self._worker_conn = None
                        self._worker_unresponsive = False
                    else:
                        req_state['completed'] = True
                        box.append(res_tuple)
                    self._worker_state = 'IDLE'

                # Clear references to avoid retaining connection or data
                fn = None
                res = None
                res_tuple = None
                item = None
                args = None
                kwds = None
                box = None
                req_state = None
                fname = None

                self._worker_queue.task_done()

        self._worker_conn = None

    def _authloop (self, fname, fn, *args, _on_worker=False, _feedback=None, **kwds):
        self._passes = 0
        # remove signature if dbus is not being used and signature is provided
        if not self._using_polkit():
            kwds.pop('signature', None)

        c = self._connection
        retry = False
        while True:
            try:
                auth_stat = self._perform_authentication ()
                if auth_stat == 0:
                    break
                if auth_stat < 0 or self._cancel:
                    if self._cancel and not self._cannot_auth:
                        raise cups.IPPError (0, _("Operation canceled"))
                    break

                if c != self._connection:
                    # We have reconnected.
                    fn = getattr (self._connection, fname)
                    c = self._connection

                cups.setUser (self._use_user)

                if _on_worker:
                    result = self._execute_in_worker (fname, *args, _feedback=_feedback, **kwds)
                else:
                    if fn is None:
                        fn = getattr (self._connection, fname)
                    result = fn.__call__ (*args, **kwds)

                if fname == 'adminGetServerSettings':
                    # Special case for a rubbish bit of API.
                    if result == {}:
                        # Authentication failed, but we aren't told that.
                        raise cups.IPPError (cups.IPP_NOT_AUTHORIZED, '')
                break
            except cups.IPPError as e:
                (e, m) = e.args
                if self._use_pk and m == 'pkcancel':
                    raise cups.IPPError (0, _("Operation canceled"))

                if not self._cancel and (e == cups.IPP_NOT_AUTHORIZED or
                                         e == cups.IPP_FORBIDDEN or
                                         e == cups.IPP_AUTHENTICATION_CANCELED):
                    self._failed (e == cups.IPP_FORBIDDEN)
                elif not self._cancel and e == cups.IPP_SERVICE_UNAVAILABLE:
                    debugprint ("Got IPP_SERVICE_UNAVAILABLE")
                    debugprint (m)
                    if self._lock:
                        self._gui_event.clear ()
                        GLib.timeout_add (1, self._ask_retry_server_error, m)
                        self._gui_event.wait ()
                    else:
                        self._ask_retry_server_error (m)

                    if self._retry_response == Gtk.ResponseType.OK:
                        debugprint ("retrying operation...")
                        retry = True
                        self._passes -= 1
                        self._has_failed = True
                    else:
                        self._cancel = True
                        raise
                else:
                    if self._cancel and not self._cannot_auth:
                        raise cups.IPPError (0, _("Operation canceled"))

                    debugprint ("%s: %s" % (e, repr (m)))
                    raise
            except cups.HTTPError as e:
                (s,) = e.args
                if not self._cancel:
                    self._failed (s == cups.HTTP_FORBIDDEN)
                else:
                    raise

        return result

    def _ask_retry_server_error (self, message):
        try:
            msg = (_("CUPS server error (%s)") % self._operation_stack[0])
        except IndexError:
            msg = _("CUPS server error")

        d = Gtk.MessageDialog (transient_for=self._parent,
                               modal=True, destroy_with_parent=True,
                               message_type=Gtk.MessageType.ERROR,
                               buttons=Gtk.ButtonsType.NONE,
                               text=msg)

        d.format_secondary_text (_("There was an error during the "
                                   "CUPS operation: '%s'.") % message)
        d.add_buttons (Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
                       _("Retry"), Gtk.ResponseType.OK)
        d.set_default_response (Gtk.ResponseType.OK)
        if self._lock:
            d.connect ("response", self._on_retry_server_error_response)
        else:
            self._retry_response = d.run ()
            d.destroy ()

    def _on_retry_server_error_response (self, dialog, response):
        self._retry_response = response
        dialog.destroy ()
        self._gui_event.set ()

    def _failed (self, forbidden=False):
        self._has_failed = True
        self._forbidden = forbidden

    def _password_callback (self, prompt):
        debugprint ("Got password callback")
        if self._cancel or self._auth_called:
            return ''

        self._auth_called = True
        self._prompt = prompt
        with self._auth_lock:
            return self._use_password

    def _perform_authentication (self):
        self._passes += 1

        creds = global_authinfocache.lookup_auth_info (host=self._server, port=self._port)
        if creds is not None:
            if (creds[0] != 'root' or self._try_as_root):
                (self._use_user, self._use_password) = creds
            del creds

        debugprint ("Authentication pass: %d" % self._passes)
        if self._passes == 1:
            # Haven't yet tried the operation.  Set the password
            # callback and return > 0 so we try it for the first time.
            self._has_failed = False
            self._forbidden = False
            self._auth_called = False
            self._cancel = False
            self._cannot_auth = False
            self._dialog_shown = False
            cups.setPasswordCB (self._password_callback)
            debugprint ("Authentication: password callback set")
            return 1

        debugprint ("Forbidden: %s" % self._forbidden)
        if not self._has_failed:
            # Tried the operation and it worked.  Return 0 to signal to
            # break out of the loop.
            debugprint ("Authentication: Operation successful")
            return 0

        # Reset failure flag.
        self._has_failed = False

        if self._passes >= 2:
            # Tried the operation without a password and it failed.
            if (self._try_as_root and
                self._user != 'root' and
                (self._server[0] == '/' or self._forbidden)):
                # This is a UNIX domain socket connection so we should
                # not have needed a password (or it is not a UDS but
                # we got an HTTP_FORBIDDEN response), and so the
                # operation must not be something that the current
                # user is authorised to do.  They need to try as root,
                # and supply the password.  However, to get the right
                # prompt, we need to try as root but with no password
                # first.
                debugprint ("Authentication: Try as root")
                self._use_user = 'root'
                self._auth_called = False
                try:
                    self._connect (allow_pk=False)
                except RuntimeError:
                    raise cups.IPPError (cups.IPP_SERVICE_UNAVAILABLE,
                                         'server-error-service-unavailable')

                return 1

        if not self._prompt_allowed:
            debugprint ("Authentication: prompting not allowed")
            self._cancel = True
            return 1

        if not self._auth_called:
            # We aren't even getting a chance to supply credentials.
            debugprint ("Authentication: giving up")
            self._cancel = True
            self._cannot_auth = True
            return 1

        # Reset the flag indicating whether we were given an auth callback.
        self._auth_called = False

        # If we're previously prompted, explain why we're prompting again.
        if self._dialog_shown:
            if self._lock:
                self._gui_event.clear ()
                GLib.timeout_add (1, self._show_not_authorized_dialog)
                self._gui_event.wait ()
            else:
                self._show_not_authorized_dialog ()

        if self._lock:
            self._gui_event.clear ()
            GLib.timeout_add (1, self._perform_authentication_with_dialog)
            self._gui_event.wait ()
        else:
            self._perform_authentication_with_dialog ()

        if self._cancel:
            debugprint ("cancelled")
            return -1

        cups.setUser (self._use_user)
        debugprint ("Authentication: Reconnect")
        try:
            self._connect (allow_pk=False)
        except RuntimeError:
            raise cups.IPPError (cups.IPP_SERVICE_UNAVAILABLE,
                                 'server-error-service-unavailable')

        return 1

    def _show_not_authorized_dialog (self):
        d = Gtk.MessageDialog (transient_for=self._parent,
                               modal=True, destroy_with_parent=True,
                               message_type=Gtk.MessageType.ERROR,
                               buttons=Gtk.ButtonsType.CLOSE)
        d.set_title (_("Not authorized"))
        d.set_markup ('<span weight="bold" size="larger">' +
                      _("Not authorized") + '</span>\n\n' +
                      _("The password may be incorrect."))
        if self._lock:
            d.connect ("response", self._on_not_authorized_dialog_response)
            d.show_all ()
            d.show_now ()
        else:
            d.run ()
            d.destroy ()

    def _on_not_authorized_dialog_response (self, dialog, response):
        self._gui_event.set ()
        dialog.destroy ()

    def _perform_authentication_with_dialog (self):
        # Prompt.
        if len (self._operation_stack) > 0:
            try:
                title = (_("Authentication (%s)") % self._operation_stack[0])
            except IndexError:
                title = _("Authentication")

            d = AuthDialog (title=title,
                            parent=self._parent)
        else:
            d = AuthDialog (parent=self._parent)

        d.set_prompt ('')
        d.set_auth_info (['', ''])
        d.field_grab_focus ('username')
        d.set_keep_above (True)
        d.show_all ()
        d.show_now ()
        self._dialog_shown = True
        if self._lock:
            d.connect ("response", self._on_authentication_response)
        else:
            response = d.run ()
            self._on_authentication_response (d, response)

    def _on_authentication_response (self, dialog, response):
        (user, password) = dialog.get_auth_info ()
        with self._auth_lock:
            if user != '':
                self._use_user = user
            self._use_password = password
        global_authinfocache.cache_auth_info ((self._use_user,
                                               self._use_password),
                                              host=self._server,
                                              port=self._port)
        dialog.destroy ()

        if (response == Gtk.ResponseType.CANCEL or
            response == Gtk.ResponseType.DELETE_EVENT):
            self._cancel = True

        if self._lock:
            self._gui_event.set ()

if __name__ == '__main__':
    # Test it out.
    from timedops import TimedOperation
    set_debugging (True)
    c = TimedOperation (Connection, args=(None,)).run ()
    debugprint ("Connected")
    c._set_lock (True)
    print(TimedOperation (c.getFile,
                          args=('/admin/conf/cupsd.conf',
                                '/dev/stdout')).run ())