Esempio n. 1
0
class CommonRequestHandler(RequestHandler):
    """Encapsulates shared RequestHandler functionality.

    """

    # Whether the login cookie duration has to be refreshed when
    # this handler is called. Useful to filter asynchronous
    # requests.
    refresh_cookie = True

    def __init__(self, *args, **kwargs):
        super(CommonRequestHandler, self).__init__(*args, **kwargs)
        self.timestamp = None
        self.sql_session = None
        self.r_params = None
        self.contest = None
        self.url = None

    def prepare(self):
        """This method is executed at the beginning of each request.

        """
        super(CommonRequestHandler, self).prepare()
        self.timestamp = make_datetime()
        self.set_header("Cache-Control", "no-cache, must-revalidate")
        self.sql_session = Session()
        self.sql_session.expire_all()
        self.url = create_url_builder(get_url_root(self.request.path))

    def finish(self, *args, **kwargs):
        """Finish this response, ending the HTTP request.

        We override this method in order to properly close the database.

        TODO - Now that we have greenlet support, this method could be
        refactored in terms of context manager or something like
        that. So far I'm leaving it to minimize changes.

        """
        if self.sql_session is not None:
            try:
                self.sql_session.close()
            except Exception as error:
                logger.warning("Couldn't close SQL connection: %r", error)
        try:
            super(CommonRequestHandler, self).finish(*args, **kwargs)
        except IOError:
            # When the client closes the connection before we reply,
            # Tornado raises an IOError exception, that would pollute
            # our log with unnecessarily critical messages
            logger.debug("Connection closed before our reply.")

    @property
    def service(self):
        return self.application.service
Esempio n. 2
0
File: util.py Progetto: cms-dev/cms
class CommonRequestHandler(RequestHandler):
    """Encapsulates shared RequestHandler functionality.

    """

    # Whether the login cookie duration has to be refreshed when
    # this handler is called. Useful to filter asynchronous
    # requests.
    refresh_cookie = True

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.timestamp = make_datetime()
        self.sql_session = Session()
        self.r_params = None
        self.contest = None
        self.url = None

    def prepare(self):
        """This method is executed at the beginning of each request.

        """
        super().prepare()
        self.url = Url(get_url_root(self.request.path))
        self.set_header("Cache-Control", "no-cache, must-revalidate")

    def finish(self, *args, **kwargs):
        """Finish this response, ending the HTTP request.

        We override this method in order to properly close the database.

        TODO - Now that we have greenlet support, this method could be
        refactored in terms of context manager or something like
        that. So far I'm leaving it to minimize changes.

        """
        if self.sql_session is not None:
            try:
                self.sql_session.close()
            except Exception as error:
                logger.warning("Couldn't close SQL connection: %r", error)
        try:
            super().finish(*args, **kwargs)
        except OSError:
            # When the client closes the connection before we reply,
            # Tornado raises an OSError exception, that would pollute
            # our log with unnecessarily critical messages
            logger.debug("Connection closed before our reply.")

    @property
    def service(self):
        return self.application.service
Esempio n. 3
0
File: base.py Progetto: hydai/cms
class BaseHandler(CommonRequestHandler):
    """Base RequestHandler for this application.

    All the RequestHandler classes in this application should be a
    child of this class.

    """

    def try_commit(self):
        """Try to commit the current session.

        If not successful display a warning in the webpage.

        return (bool): True if commit was successful, False otherwise.

        """
        try:
            self.sql_session.commit()
        except IntegrityError as error:
            self.application.service.add_notification(
                make_datetime(),
                "Operation failed.", "%s" % error)
            return False
        else:
            self.application.service.add_notification(
                make_datetime(),
                "Operation successful.", "")
            return True

    def safe_get_item(self, cls, ident, session=None):
        """Get item from database of class cls and id ident, using
        session if given, or self.sql_session if not given. If id is
        not found, raise a 404.

        cls (type): class of object to retrieve.
        ident (string): id of object.
        session (Session|None): session to use.

        return (object): the object with the given id.

        raise (HTTPError): 404 if not found.

        """
        if session is None:
            session = self.sql_session
        entity = cls.get_from_id(ident, session)
        if entity is None:
            raise tornado.web.HTTPError(404)
        return entity

    def prepare(self):
        """This method is executed at the beginning of each request.

        """
        # Attempt to update the contest and all its references
        # If this fails, the request terminates.
        self.set_header("Cache-Control", "no-cache, must-revalidate")

        self.sql_session = Session()
        self.sql_session.expire_all()
        self.contest = None

    def render_params(self):
        """Return the default render params used by almost all handlers.

        return (dict): default render params

        """
        params = {}
        params["timestamp"] = make_datetime()
        params["contest"] = self.contest
        params["url_root"] = get_url_root(self.request.path)
        if self.contest is not None:
            params["phase"] = self.contest.phase(params["timestamp"])
            # Keep "== None" in filter arguments. SQLAlchemy does not
            # understand "is None".
            params["unanswered"] = self.sql_session.query(Question)\
                .join(Participation)\
                .filter(Participation.contest_id == self.contest.id)\
                .filter(Question.reply_timestamp == None)\
                .filter(Question.ignored == False)\
                .count()  # noqa
        # TODO: not all pages require all these data.
        params["contest_list"] = self.sql_session.query(Contest).all()
        params["task_list"] = self.sql_session.query(Task).all()
        params["user_list"] = self.sql_session.query(User).all()
        return params

    def finish(self, *args, **kwds):
        """Finish this response, ending the HTTP request.

        We override this method in order to properly close the database.

        TODO - Now that we have greenlet support, this method could be
        refactored in terms of context manager or something like
        that. So far I'm leaving it to minimize changes.

        """
        self.sql_session.close()
        try:
            tornado.web.RequestHandler.finish(self, *args, **kwds)
        except IOError:
            # When the client closes the connection before we reply,
            # Tornado raises an IOError exception, that would pollute
            # our log with unnecessarily critical messages
            logger.debug("Connection closed before our reply.")

    def write_error(self, status_code, **kwargs):
        if "exc_info" in kwargs and \
                kwargs["exc_info"][0] != tornado.web.HTTPError:
            exc_info = kwargs["exc_info"]
            logger.error(
                "Uncaught exception (%r) while processing a request: %s",
                exc_info[1], ''.join(traceback.format_exception(*exc_info)))

        # Most of the handlers raise a 404 HTTP error before r_params
        # is defined. If r_params is not defined we try to define it
        # here, and if it fails we simply return a basic textual error notice.
        if self.r_params is None:
            try:
                self.r_params = self.render_params()
            except:
                self.write("A critical error has occurred :-(")
                self.finish()
                return
        self.render("error.html", status_code=status_code, **self.r_params)

    get_string = argument_reader(lambda a: a, empty="")

    # When a checkbox isn't active it's not sent at all, making it
    # impossible to distinguish between missing and False.
    def get_bool(self, dest, name):
        """Parse a boolean.

        dest (dict): a place to store the result.
        name (string): the name of the argument and of the item.

        """
        value = self.get_argument(name, False)
        try:
            dest[name] = bool(value)
        except:
            raise ValueError("Can't cast %s to bool." % value)

    get_int = argument_reader(parse_int)

    get_timedelta_sec = argument_reader(parse_timedelta_sec)

    get_timedelta_min = argument_reader(parse_timedelta_min)

    get_datetime = argument_reader(parse_datetime)

    get_ip_address_or_subnet = argument_reader(parse_ip_address_or_subnet)

    def get_submission_format(self, dest):
        """Parse the submission format.

        Using the two arguments "submission_format_choice" and
        "submission_format" set the "submission_format" item of the
        given dictionary.

        dest (dict): a place to store the result.

        """
        choice = self.get_argument("submission_format_choice", "other")
        if choice == "simple":
            filename = "%s.%%l" % dest["name"]
            format_ = [SubmissionFormatElement(filename)]
        elif choice == "other":
            value = self.get_argument("submission_format", "[]")
            if value == "":
                value = "[]"
            format_ = []
            try:
                for filename in json.loads(value):
                    format_ += [SubmissionFormatElement(filename)]
            except ValueError:
                raise ValueError("Submission format not recognized.")
        else:
            raise ValueError("Submission format not recognized.")
        dest["submission_format"] = format_

    def get_time_limit(self, dest, field):
        """Parse the time limit.

        Read the argument with the given name and use its value to set
        the "time_limit" item of the given dictionary.

        dest (dict): a place to store the result.
        field (string): the name of the argument to use.

        """
        value = self.get_argument(field, None)
        if value is None:
            return
        if value == "":
            dest["time_limit"] = None
        else:
            try:
                value = float(value)
            except:
                raise ValueError("Can't cast %s to float." % value)
            if not 0 <= value < float("+inf"):
                raise ValueError("Time limit out of range.")
            dest["time_limit"] = value

    def get_memory_limit(self, dest, field):
        """Parse the memory limit.

        Read the argument with the given name and use its value to set
        the "memory_limit" item of the given dictionary.

        dest (dict): a place to store the result.
        field (string): the name of the argument to use.

        """
        value = self.get_argument(field, None)
        if value is None:
            return
        if value == "":
            dest["memory_limit"] = None
        else:
            try:
                value = int(value)
            except:
                raise ValueError("Can't cast %s to float." % value)
            if not 0 < value:
                raise ValueError("Invalid memory limit.")
            dest["memory_limit"] = value

    def get_task_type(self, dest, name, params):
        """Parse the task type.

        Parse the arguments to get the task type and its parameters,
        and fill them in the "task_type" and "task_type_parameters"
        items of the given dictionary.

        dest (dict): a place to store the result.
        name (string): the name of the argument that holds the task
            type name.
        params (string): the prefix of the names of the arguments that
            hold the parameters.

        """
        name = self.get_argument(name, None)
        if name is None:
            raise ValueError("Task type not found.")
        try:
            class_ = get_task_type_class(name)
        except KeyError:
            raise ValueError("Task type not recognized: %s." % name)
        params = json.dumps(class_.parse_handler(self, params + name + "_"))
        dest["task_type"] = name
        dest["task_type_parameters"] = params

    def get_score_type(self, dest, name, params):
        """Parse the score type.

        Parse the arguments to get the score type and its parameters,
        and fill them in the "score_type" and "score_type_parameters"
        items of the given dictionary.

        dest (dict): a place to store the result.
        name (string): the name of the argument that holds the score
            type name.
        params (string): the name of the argument that hold the
            parameters.

        """
        name = self.get_argument(name, None)
        if name is None:
            raise ValueError("Score type not found.")
        try:
            get_score_type_class(name)
        except KeyError:
            raise ValueError("Score type not recognized: %s." % name)
        params = self.get_argument(params, None)
        if params is None:
            raise ValueError("Score type parameters not found.")
        dest["score_type"] = name
        dest["score_type_parameters"] = params
Esempio n. 4
0
File: base.py Progetto: giomasce/cms
class BaseHandler(CommonRequestHandler):
    """Base RequestHandler for this application.

    All the RequestHandler classes in this application should be a
    child of this class.

    """
    def try_commit(self):
        """Try to commit the current session.

        If not successful display a warning in the webpage.

        return (bool): True if commit was successful, False otherwise.

        """
        try:
            self.sql_session.commit()
        except IntegrityError as error:
            self.application.service.add_notification(make_datetime(),
                                                      "Operation failed.",
                                                      "%s" % error)
            return False
        else:
            self.application.service.add_notification(make_datetime(),
                                                      "Operation successful.",
                                                      "")
            return True

    def safe_get_item(self, cls, ident, session=None):
        """Get item from database of class cls and id ident, using
        session if given, or self.sql_session if not given. If id is
        not found, raise a 404.

        cls (type): class of object to retrieve.
        ident (string): id of object.
        session (Session|None): session to use.

        return (object): the object with the given id.

        raise (HTTPError): 404 if not found.

        """
        if session is None:
            session = self.sql_session
        entity = cls.get_from_id(ident, session)
        if entity is None:
            raise tornado.web.HTTPError(404)
        return entity

    def prepare(self):
        """This method is executed at the beginning of each request.

        """
        # Attempt to update the contest and all its references
        # If this fails, the request terminates.
        self.set_header("Cache-Control", "no-cache, must-revalidate")

        self.sql_session = Session()
        self.sql_session.expire_all()
        self.contest = None

    def render_params(self):
        """Return the default render params used by almost all handlers.

        return (dict): default render params

        """
        params = {}
        params["timestamp"] = make_datetime()
        params["contest"] = self.contest
        params["url_root"] = get_url_root(self.request.path)
        if self.contest is not None:
            params["phase"] = self.contest.phase(params["timestamp"])
            # Keep "== None" in filter arguments. SQLAlchemy does not
            # understand "is None".
            params["unanswered"] = self.sql_session.query(Question)\
                .join(Participation)\
                .filter(Participation.contest_id == self.contest.id)\
                .filter(Question.reply_timestamp == None)\
                .filter(Question.ignored == False)\
                .count()  # noqa
        # TODO: not all pages require all these data.
        params["contest_list"] = self.sql_session.query(Contest).all()
        params["task_list"] = self.sql_session.query(Task).all()
        params["user_list"] = self.sql_session.query(User).all()
        params["team_list"] = self.sql_session.query(Team).all()
        return params

    def finish(self, *args, **kwds):
        """Finish this response, ending the HTTP request.

        We override this method in order to properly close the database.

        TODO - Now that we have greenlet support, this method could be
        refactored in terms of context manager or something like
        that. So far I'm leaving it to minimize changes.

        """
        self.sql_session.close()
        try:
            tornado.web.RequestHandler.finish(self, *args, **kwds)
        except IOError:
            # When the client closes the connection before we reply,
            # Tornado raises an IOError exception, that would pollute
            # our log with unnecessarily critical messages
            logger.debug("Connection closed before our reply.")

    def write_error(self, status_code, **kwargs):
        if "exc_info" in kwargs and \
                kwargs["exc_info"][0] != tornado.web.HTTPError:
            exc_info = kwargs["exc_info"]
            logger.error(
                "Uncaught exception (%r) while processing a request: %s",
                exc_info[1], ''.join(traceback.format_exception(*exc_info)))

        # Most of the handlers raise a 404 HTTP error before r_params
        # is defined. If r_params is not defined we try to define it
        # here, and if it fails we simply return a basic textual error notice.
        if self.r_params is None:
            try:
                self.r_params = self.render_params()
            except:
                self.write("A critical error has occurred :-(")
                self.finish()
                return
        self.render("error.html", status_code=status_code, **self.r_params)

    get_string = argument_reader(lambda a: a, empty="")

    # When a checkbox isn't active it's not sent at all, making it
    # impossible to distinguish between missing and False.
    def get_bool(self, dest, name):
        """Parse a boolean.

        dest (dict): a place to store the result.
        name (string): the name of the argument and of the item.

        """
        value = self.get_argument(name, False)
        try:
            dest[name] = bool(value)
        except:
            raise ValueError("Can't cast %s to bool." % value)

    get_int = argument_reader(parse_int)

    get_timedelta_sec = argument_reader(parse_timedelta_sec)

    get_timedelta_min = argument_reader(parse_timedelta_min)

    get_datetime = argument_reader(parse_datetime)

    get_ip_address_or_subnet = argument_reader(parse_ip_address_or_subnet)

    def get_submission_format(self, dest):
        """Parse the submission format.

        Using the two arguments "submission_format_choice" and
        "submission_format" set the "submission_format" item of the
        given dictionary.

        dest (dict): a place to store the result.

        """
        choice = self.get_argument("submission_format_choice", "other")
        if choice == "simple":
            filename = "%s.%%l" % dest["name"]
            format_ = [SubmissionFormatElement(filename)]
        elif choice == "other":
            value = self.get_argument("submission_format", "[]")
            if value == "":
                value = "[]"
            format_ = []
            try:
                for filename in json.loads(value):
                    format_ += [SubmissionFormatElement(filename)]
            except ValueError:
                raise ValueError("Submission format not recognized.")
        else:
            raise ValueError("Submission format not recognized.")
        dest["submission_format"] = format_

    def get_time_limit(self, dest, field):
        """Parse the time limit.

        Read the argument with the given name and use its value to set
        the "time_limit" item of the given dictionary.

        dest (dict): a place to store the result.
        field (string): the name of the argument to use.

        """
        value = self.get_argument(field, None)
        if value is None:
            return
        if value == "":
            dest["time_limit"] = None
        else:
            try:
                value = float(value)
            except:
                raise ValueError("Can't cast %s to float." % value)
            if not 0 <= value < float("+inf"):
                raise ValueError("Time limit out of range.")
            dest["time_limit"] = value

    def get_memory_limit(self, dest, field):
        """Parse the memory limit.

        Read the argument with the given name and use its value to set
        the "memory_limit" item of the given dictionary.

        dest (dict): a place to store the result.
        field (string): the name of the argument to use.

        """
        value = self.get_argument(field, None)
        if value is None:
            return
        if value == "":
            dest["memory_limit"] = None
        else:
            try:
                value = int(value)
            except:
                raise ValueError("Can't cast %s to float." % value)
            if not 0 < value:
                raise ValueError("Invalid memory limit.")
            dest["memory_limit"] = value

    def get_task_type(self, dest, name, params):
        """Parse the task type.

        Parse the arguments to get the task type and its parameters,
        and fill them in the "task_type" and "task_type_parameters"
        items of the given dictionary.

        dest (dict): a place to store the result.
        name (string): the name of the argument that holds the task
            type name.
        params (string): the prefix of the names of the arguments that
            hold the parameters.

        """
        name = self.get_argument(name, None)
        if name is None:
            raise ValueError("Task type not found.")
        try:
            class_ = get_task_type_class(name)
        except KeyError:
            raise ValueError("Task type not recognized: %s." % name)
        params = json.dumps(class_.parse_handler(self, params + name + "_"))
        dest["task_type"] = name
        dest["task_type_parameters"] = params

    def get_score_type(self, dest, name, params):
        """Parse the score type.

        Parse the arguments to get the score type and its parameters,
        and fill them in the "score_type" and "score_type_parameters"
        items of the given dictionary.

        dest (dict): a place to store the result.
        name (string): the name of the argument that holds the score
            type name.
        params (string): the name of the argument that hold the
            parameters.

        """
        name = self.get_argument(name, None)
        if name is None:
            raise ValueError("Score type not found.")
        try:
            get_score_type_class(name)
        except KeyError:
            raise ValueError("Score type not recognized: %s." % name)
        params = self.get_argument(params, None)
        if params is None:
            raise ValueError("Score type parameters not found.")
        dest["score_type"] = name
        dest["score_type_parameters"] = params

    def render_params_for_submissions(self, query, page, page_size=50):
        """Add data about the requested submissions to r_params.

        submission_query (sqlalchemy.orm.query.Query): the query
            giving back all interesting submissions.
        page (int): the index of the page to display.
        page_size(int): the number of submissions per page.

        """
        query = query\
            .options(joinedload(Submission.task))\
            .options(joinedload(Submission.participation))\
            .options(joinedload(Submission.files))\
            .options(joinedload(Submission.token))\
            .options(joinedload(Submission.results)
                     .joinedload(SubmissionResult.evaluations))\
            .order_by(Submission.timestamp.desc())

        offset = page * page_size
        count = query.count()

        if self.r_params is None:
            self.r_params = self.render_params()

        # A page showing paginated submissions can use these
        # parameters: total number of submissions, submissions to
        # display in this page, index of the current page, total
        # number of pages.
        self.r_params["submission_count"] = count
        self.r_params["submissions"] = \
            query.slice(offset, offset + page_size).all()
        self.r_params["submission_page"] = page
        self.r_params["submission_pages"] = \
            (count + page_size - 1) // page_size
Esempio n. 5
0
class BaseHandler(CommonRequestHandler):
    """Base RequestHandler for this application.

    All the RequestHandler classes in this application should be a
    child of this class.

    """

    # Whether the login cookie duration has to be refreshed when
    # this handler is called. Useful to filter asynchronous
    # requests.
    refresh_cookie = True

    def __init__(self, *args, **kwargs):
        super(BaseHandler, self).__init__(*args, **kwargs)
        self.timestamp = None
        self.cookie_lang = None
        self.browser_lang = None
        self.langs = None
        self._ = None

    def prepare(self):
        """This method is executed at the beginning of each request.

        """
        self.timestamp = make_datetime()

        self.set_header("Cache-Control", "no-cache, must-revalidate")

        self.sql_session = Session()
        self.contest = Contest.get_from_id(self.application.service.contest,
                                           self.sql_session)

        self._ = self.locale.translate

        self.r_params = self.render_params()

    def get_current_user(self):
        """The name is get_current_user because tornado wants it that
        way, but this is really a get_current_participation.

        Gets the current participation from cookies.

        If a valid cookie is retrieved, return a Participation tuple
        (specifically: the Participation involving the username
        specified in the cookie and the current contest).

        Otherwise (e.g. the user exists but doesn't participate in the
        current contest), return None.

        """
        remote_ip = self.request.remote_ip
        if self.contest.ip_autologin:
            self.clear_cookie("login")
            participations = self.sql_session.query(Participation)\
                .filter(Participation.contest == self.contest)\
                .filter(Participation.ip == remote_ip)\
                .all()
            if len(participations) == 1:
                return participations[0]

            if len(participations) > 1:
                logger.error("Multiple users have IP %s." % (remote_ip))
            else:
                logger.error("No user has IP %s" % (remote_ip))

            # If IP autologin is set, we do not allow password logins.
            return None

        if self.get_secure_cookie("login") is None:
            return None

        # Parse cookie.
        try:
            cookie = pickle.loads(self.get_secure_cookie("login"))
            username = cookie[0]
            password = cookie[1]
            last_update = make_datetime(cookie[2])
        except:
            self.clear_cookie("login")
            return None

        # Check if the cookie is expired.
        if self.timestamp - last_update > \
                timedelta(seconds=config.cookie_duration):
            self.clear_cookie("login")
            return None

        # Load user from DB.
        user = self.sql_session.query(User)\
            .filter(User.username == username)\
            .first()

        # Check if user exists.
        if user is None:
            self.clear_cookie("login")
            return None

        # Load participation from DB.
        participation = self.sql_session.query(Participation)\
            .filter(Participation.contest == self.contest)\
            .filter(Participation.user == user)\
            .first()

        # Check if participaton exists.
        if participation is None:
            self.clear_cookie("login")
            return None

        # If a contest-specific password is defined, use that. If it's
        # not, use the user's main password.
        if participation.password is None:
            correct_password = user.password
        else:
            correct_password = participation.password

        # Check if user is allowed to login.
        if password != correct_password:
            self.clear_cookie("login")
            return None

        # Check if user is using the right IP (or is on the right subnet)
        if self.contest.ip_restriction and participation.ip is not None \
                and not check_ip(self.request.remote_ip, participation.ip):
            self.clear_cookie("login")
            return None

        # Check if user is hidden
        if participation.hidden and self.contest.block_hidden_participations:
            self.clear_cookie("login")
            return None

        if self.refresh_cookie:
            self.set_secure_cookie("login",
                                   pickle.dumps((user.username,
                                                 password,
                                                 make_timestamp())),
                                   expires_days=None)

        return participation

    def get_user_locale(self):
        self.langs = self.application.service.langs
        lang_codes = self.langs.keys()

        if len(self.contest.allowed_localizations) > 0:
            lang_codes = filter_language_codes(
                lang_codes, self.contest.allowed_localizations)

        # TODO We fallback on "en" if no language matches: we could
        # return 406 Not Acceptable instead.
        # Select the one the user likes most.
        http_langs = [lang_code.replace("_", "-") for lang_code in lang_codes]
        self.browser_lang = parse_accept_header(
            self.request.headers.get("Accept-Language", ""),
            LanguageAccept).best_match(http_langs, "en")

        self.cookie_lang = self.get_cookie("language", None)

        if self.cookie_lang in http_langs:
            lang_code = self.cookie_lang
        else:
            lang_code = self.browser_lang

        self.set_header("Content-Language", lang_code)
        return self.langs[lang_code.replace("-", "_")]

    @staticmethod
    def _get_token_status(obj):
        """Return the status of the tokens for the given object.

        obj (Contest or Task): an object that has the token_* attributes.
        return (int): one of 0 (disabled), 1 (enabled/finite) and 2
                      (enabled/infinite).

        """
        if obj.token_mode == "disabled":
            return 0
        elif obj.token_mode == "finite":
            return 1
        elif obj.token_mode == "infinite":
            return 2
        else:
            raise RuntimeError("Unknown token_mode value.")

    def render_params(self):
        """Return the default render params used by almost all handlers.

        return (dict): default render params

        """
        ret = {}
        ret["timestamp"] = self.timestamp
        ret["contest"] = self.contest
        ret["url_root"] = get_url_root(self.request.path)

        ret["phase"] = self.contest.phase(self.timestamp)

        ret["printing_enabled"] = (config.printer is not None)

        if self.current_user is not None:
            participation = self.current_user

            res = compute_actual_phase(
                self.timestamp, self.contest.start, self.contest.stop,
                self.contest.per_user_time, participation.starting_time,
                participation.delay_time, participation.extra_time)

            ret["actual_phase"], ret["current_phase_begin"], \
                ret["current_phase_end"], ret["valid_phase_begin"], \
                ret["valid_phase_end"] = res

            if ret["actual_phase"] == 0:
                ret["phase"] = 0

            # set the timezone used to format timestamps
            ret["timezone"] = get_timezone(participation.user, self.contest)

        # some information about token configuration
        ret["tokens_contest"] = self._get_token_status(self.contest)

        t_tokens = sum(self._get_token_status(t) for t in self.contest.tasks)
        if t_tokens == 0:
            ret["tokens_tasks"] = 0  # all disabled
        elif t_tokens == 2 * len(self.contest.tasks):
            ret["tokens_tasks"] = 2  # all infinite
        else:
            ret["tokens_tasks"] = 1  # all finite or mixed

        # TODO Now all language names are shown in the active language.
        # It would be better to show them in the corresponding one.
        ret["lang_names"] = {}
        for lang_code, trans in self.langs.iteritems():
            language_name = None
            try:
                language_name = translate_language_country_code(
                    lang_code, trans)
            except ValueError:
                language_name = translate_language_code(
                    lang_code, trans)
            ret["lang_names"][lang_code.replace("_", "-")] = language_name

        ret["cookie_lang"] = self.cookie_lang
        ret["browser_lang"] = self.browser_lang

        return ret

    def finish(self, *args, **kwds):
        """Finish this response, ending the HTTP request.

        We override this method in order to properly close the database.

        TODO - Now that we have greenlet support, this method could be
        refactored in terms of context manager or something like
        that. So far I'm leaving it to minimize changes.

        """
        if hasattr(self, "sql_session"):
            try:
                self.sql_session.close()
            except Exception as error:
                logger.warning("Couldn't close SQL connection: %r", error)
        try:
            tornado.web.RequestHandler.finish(self, *args, **kwds)
        except IOError:
            # When the client closes the connection before we reply,
            # Tornado raises an IOError exception, that would pollute
            # our log with unnecessarily critical messages
            logger.debug("Connection closed before our reply.")

    def write_error(self, status_code, **kwargs):
        if "exc_info" in kwargs and \
                kwargs["exc_info"][0] != tornado.web.HTTPError:
            exc_info = kwargs["exc_info"]
            logger.error(
                "Uncaught exception (%r) while processing a request: %s",
                exc_info[1], ''.join(traceback.format_exception(*exc_info)))

        # We assume that if r_params is defined then we have at least
        # the data we need to display a basic template with the error
        # information. If r_params is not defined (i.e. something went
        # *really* bad) we simply return a basic textual error notice.
        if hasattr(self, 'r_params'):
            self.render("error.html", status_code=status_code, **self.r_params)
        else:
            self.write("A critical error has occurred :-(")
            self.finish()