323 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			323 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
"""passbook multi-stage authentication engine"""
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from traceback import format_tb
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from typing import Any, Dict, Optional
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from django.contrib.auth.mixins import LoginRequiredMixin
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from django.http import (
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    Http404,
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    HttpRequest,
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    HttpResponse,
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    HttpResponseRedirect,
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    JsonResponse,
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)
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from django.shortcuts import get_object_or_404, redirect, reverse
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from django.template.response import TemplateResponse
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from django.utils.decorators import method_decorator
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from django.views.decorators.clickjacking import xframe_options_sameorigin
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from django.views.generic import TemplateView, View
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from structlog import get_logger
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from passbook.audit.models import cleanse_dict
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from passbook.core.models import PASSBOOK_USER_DEBUG
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from passbook.flows.exceptions import EmptyFlowException, FlowNonApplicableException
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from passbook.flows.models import ConfigurableStage, Flow, FlowDesignation, Stage
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from passbook.flows.planner import PLAN_CONTEXT_PENDING_USER, FlowPlan, FlowPlanner
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from passbook.lib.utils.reflection import class_to_path
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from passbook.lib.utils.urls import is_url_absolute, redirect_with_qs
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from passbook.policies.http import AccessDeniedResponse
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LOGGER = get_logger()
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# Argument used to redirect user after login
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NEXT_ARG_NAME = "next"
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SESSION_KEY_PLAN = "passbook_flows_plan"
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SESSION_KEY_APPLICATION_PRE = "passbook_flows_application_pre"
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SESSION_KEY_GET = "passbook_flows_get"
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@method_decorator(xframe_options_sameorigin, name="dispatch")
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class FlowExecutorView(View):
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    """Stage 1 Flow executor, passing requests to Stage Views"""
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    flow: Flow
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    plan: Optional[FlowPlan] = None
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    current_stage: Stage
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    current_stage_view: View
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    def setup(self, request: HttpRequest, flow_slug: str):
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        super().setup(request, flow_slug=flow_slug)
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        self.flow = get_object_or_404(Flow.objects.select_related(), slug=flow_slug)
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    def handle_invalid_flow(self, exc: BaseException) -> HttpResponse:
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        """When a flow is non-applicable check if user is on the correct domain"""
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        if NEXT_ARG_NAME in self.request.GET:
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            if not is_url_absolute(self.request.GET.get(NEXT_ARG_NAME)):
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                LOGGER.debug("f(exec): Redirecting to next on fail")
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                return redirect(self.request.GET.get(NEXT_ARG_NAME))
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        message = exc.__doc__ if exc.__doc__ else str(exc)
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        return self.stage_invalid(error_message=message)
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    def dispatch(self, request: HttpRequest, flow_slug: str) -> HttpResponse:
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        # Early check if theres an active Plan for the current session
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        if SESSION_KEY_PLAN in self.request.session:
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            self.plan = self.request.session[SESSION_KEY_PLAN]
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            if self.plan.flow_pk != self.flow.pk.hex:
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                LOGGER.warning(
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                    "f(exec): Found existing plan for other flow, deleteing plan",
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                    flow_slug=flow_slug,
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                )
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                # Existing plan is deleted from session and instance
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                self.plan = None
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                self.cancel()
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            LOGGER.debug("f(exec): Continuing existing plan", flow_slug=flow_slug)
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        # Don't check session again as we've either already loaded the plan or we need to plan
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        if not self.plan:
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            LOGGER.debug(
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                "f(exec): No active Plan found, initiating planner", flow_slug=flow_slug
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            )
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            try:
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                self.plan = self._initiate_plan()
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            except FlowNonApplicableException as exc:
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                LOGGER.warning("f(exec): Flow not applicable to current user", exc=exc)
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                return to_stage_response(self.request, self.handle_invalid_flow(exc))
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            except EmptyFlowException as exc:
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                LOGGER.warning("f(exec): Flow is empty", exc=exc)
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                return to_stage_response(self.request, self.handle_invalid_flow(exc))
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        # We don't save the Plan after getting the next stage
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        # as it hasn't been successfully passed yet
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        next_stage = self.plan.next(self.request)
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        if not next_stage:
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            LOGGER.debug("f(exec): no more stages, flow is done.")
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            return self._flow_done()
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        self.current_stage = next_stage
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        LOGGER.debug(
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            "f(exec): Current stage",
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            current_stage=self.current_stage,
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            flow_slug=self.flow.slug,
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        )
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        stage_cls = self.current_stage.type
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        self.current_stage_view = stage_cls(self)
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        self.current_stage_view.args = self.args
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        self.current_stage_view.kwargs = self.kwargs
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        self.current_stage_view.request = request
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        return super().dispatch(request)
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    def get(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
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        """pass get request to current stage"""
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        LOGGER.debug(
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            "f(exec): Passing GET",
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            view_class=class_to_path(self.current_stage_view.__class__),
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            stage=self.current_stage,
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            flow_slug=self.flow.slug,
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        )
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        try:
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            stage_response = self.current_stage_view.get(request, *args, **kwargs)
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            return to_stage_response(request, stage_response)
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        except Exception as exc:  # pylint: disable=broad-except
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            LOGGER.exception(exc)
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            return to_stage_response(request, FlowErrorResponse(request, exc))
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    def post(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
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        """pass post request to current stage"""
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        LOGGER.debug(
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            "f(exec): Passing POST",
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            view_class=class_to_path(self.current_stage_view.__class__),
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            stage=self.current_stage,
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            flow_slug=self.flow.slug,
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        )
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        try:
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            stage_response = self.current_stage_view.post(request, *args, **kwargs)
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            return to_stage_response(request, stage_response)
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        except Exception as exc:  # pylint: disable=broad-except
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            LOGGER.exception(exc)
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            return to_stage_response(request, FlowErrorResponse(request, exc))
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    def _initiate_plan(self) -> FlowPlan:
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        planner = FlowPlanner(self.flow)
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        plan = planner.plan(self.request)
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        self.request.session[SESSION_KEY_PLAN] = plan
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        return plan
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    def _flow_done(self) -> HttpResponse:
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        """User Successfully passed all stages"""
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        # Since this is wrapped by the ExecutorShell, the next argument is saved in the session
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        # extract the next param before cancel as that cleans it
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        next_param = self.request.session.get(SESSION_KEY_GET, {}).get(
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            NEXT_ARG_NAME, "passbook_core:shell"
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        )
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        self.cancel()
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        return redirect_with_qs(next_param)
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    def stage_ok(self) -> HttpResponse:
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        """Callback called by stages upon successful completion.
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        Persists updated plan and context to session."""
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        LOGGER.debug(
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            "f(exec): Stage ok",
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            stage_class=class_to_path(self.current_stage_view.__class__),
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            flow_slug=self.flow.slug,
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        )
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        self.plan.pop()
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        self.request.session[SESSION_KEY_PLAN] = self.plan
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        if self.plan.stages:
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            LOGGER.debug(
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                "f(exec): Continuing with next stage",
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                reamining=len(self.plan.stages),
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                flow_slug=self.flow.slug,
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            )
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            return redirect_with_qs(
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                "passbook_flows:flow-executor", self.request.GET, **self.kwargs
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            )
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        # User passed all stages
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        LOGGER.debug(
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            "f(exec): User passed all stages",
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            flow_slug=self.flow.slug,
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            context=cleanse_dict(self.plan.context),
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        )
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        return self._flow_done()
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    def stage_invalid(self, error_message: Optional[str] = None) -> HttpResponse:
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        """Callback used stage when data is correct but a policy denies access
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        or the user account is disabled.
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        Optionally, an exception can be passed, which will be shown if the current user
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        is a superuser."""
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        LOGGER.debug("f(exec): Stage invalid", flow_slug=self.flow.slug)
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        self.cancel()
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        response = AccessDeniedResponse(
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            self.request, template="flows/denied_shell.html"
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        )
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        response.error_message = error_message
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        return to_stage_response(self.request, response)
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    def cancel(self):
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        """Cancel current execution and return a redirect"""
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        keys_to_delete = [
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            SESSION_KEY_APPLICATION_PRE,
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            SESSION_KEY_PLAN,
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            SESSION_KEY_GET,
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        ]
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        for key in keys_to_delete:
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            if key in self.request.session:
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                del self.request.session[key]
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class FlowErrorResponse(TemplateResponse):
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    """Response class when an unhandled error occurs during a stage. Normal users
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    are shown an error message, superusers are shown a full stacktrace."""
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    error: Exception
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    def __init__(self, request: HttpRequest, error: Exception) -> None:
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        # For some reason pyright complains about keyword argument usage here
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        # pyright: reportGeneralTypeIssues=false
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        super().__init__(request=request, template="flows/error.html")
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        self.error = error
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    def resolve_context(
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        self, context: Optional[Dict[str, Any]]
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    ) -> Optional[Dict[str, Any]]:
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        if not context:
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            context = {}
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        context["error"] = self.error
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        if self._request.user and self._request.user.is_authenticated:
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            if self._request.user.is_superuser or self._request.user.attributes.get(
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                PASSBOOK_USER_DEBUG, False
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            ):
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                context["tb"] = "".join(format_tb(self.error.__traceback__))
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        return context
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class FlowExecutorShellView(TemplateView):
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    """Executor Shell view, loads a dummy card with a spinner
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    that loads the next stage in the background."""
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    template_name = "flows/shell.html"
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    def get_context_data(self, **kwargs) -> Dict[str, Any]:
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        kwargs["exec_url"] = reverse("passbook_flows:flow-executor", kwargs=self.kwargs)
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        self.request.session[SESSION_KEY_GET] = self.request.GET
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        return kwargs
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class CancelView(View):
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    """View which canels the currently active plan"""
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    def get(self, request: HttpRequest) -> HttpResponse:
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        """View which canels the currently active plan"""
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        if SESSION_KEY_PLAN in request.session:
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            del request.session[SESSION_KEY_PLAN]
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            LOGGER.debug("Canceled current plan")
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        return redirect("passbook_core:shell")
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class ToDefaultFlow(View):
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    """Redirect to default flow matching by designation"""
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    designation: Optional[FlowDesignation] = None
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    def dispatch(self, request: HttpRequest) -> HttpResponse:
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        flow = Flow.with_policy(request, designation=self.designation)
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        if not flow:
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            raise Http404
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        # If user already has a pending plan, clear it so we don't have to later.
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        if SESSION_KEY_PLAN in self.request.session:
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            plan: FlowPlan = self.request.session[SESSION_KEY_PLAN]
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            if plan.flow_pk != flow.pk.hex:
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                LOGGER.warning(
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                    "f(def): Found existing plan for other flow, deleteing plan",
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                    flow_slug=flow.slug,
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                )
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                del self.request.session[SESSION_KEY_PLAN]
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        return redirect_with_qs(
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            "passbook_flows:flow-executor-shell", request.GET, flow_slug=flow.slug
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        )
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def to_stage_response(request: HttpRequest, source: HttpResponse) -> HttpResponse:
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    """Convert normal HttpResponse into JSON Response"""
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    if isinstance(source, HttpResponseRedirect) or source.status_code == 302:
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        redirect_url = source["Location"]
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        if request.path != redirect_url:
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            return JsonResponse({"type": "redirect", "to": redirect_url})
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        return source
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    if isinstance(source, TemplateResponse):
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        return JsonResponse(
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            {"type": "template", "body": source.render().content.decode("utf-8")}
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        )
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    # Check for actual HttpResponse (without isinstance as we dont want to check inheritance)
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    if source.__class__ == HttpResponse:
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        return JsonResponse(
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            {"type": "template", "body": source.content.decode("utf-8")}
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        )
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    return source
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class ConfigureFlowInitView(LoginRequiredMixin, View):
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    """Initiate planner for selected change flow and redirect to flow executor,
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    or raise Http404 if no configure_flow has been set."""
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    def get(self, request: HttpRequest, stage_uuid: str) -> HttpResponse:
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        """Initiate planner for selected change flow and redirect to flow executor,
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        or raise Http404 if no configure_flow has been set."""
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        try:
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            stage: Stage = Stage.objects.get_subclass(pk=stage_uuid)
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        except Stage.DoesNotExist as exc:
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            raise Http404 from exc
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        if not isinstance(stage, ConfigurableStage):
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            LOGGER.debug("Stage does not inherit ConfigurableStage", stage=stage)
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            raise Http404
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        if not stage.configure_flow:
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            LOGGER.debug("Stage has no configure_flow set", stage=stage)
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            raise Http404
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        plan = FlowPlanner(stage.configure_flow).plan(
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            request, {PLAN_CONTEXT_PENDING_USER: request.user}
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        )
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        request.session[SESSION_KEY_PLAN] = plan
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        return redirect_with_qs(
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            "passbook_flows:flow-executor-shell",
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            self.request.GET,
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            flow_slug=stage.configure_flow.slug,
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        )
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