307 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			307 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
"""passbook SAML IDP Views"""
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from typing import Optional
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from django.contrib.auth import logout
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from django.contrib.auth.mixins import AccessMixin
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from django.core.exceptions import ValidationError
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from django.core.validators import URLValidator
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from django.http import HttpRequest, HttpResponse
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from django.shortcuts import get_object_or_404, redirect, render, reverse
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from django.utils.datastructures import MultiValueDictKeyError
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from django.utils.decorators import method_decorator
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from django.utils.html import mark_safe
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from django.utils.translation import gettext as _
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from django.views import View
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from django.views.decorators.csrf import csrf_exempt
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from signxml.util import strip_pem_header
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from structlog import get_logger
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from passbook.audit.models import Event, EventAction
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from passbook.core.models import Application, Provider
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from passbook.lib.utils.template import render_to_string
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from passbook.lib.views import bad_request_message
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from passbook.policies.engine import PolicyEngine
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from passbook.providers.saml.exceptions import CannotHandleAssertion
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from passbook.providers.saml.models import SAMLProvider
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from passbook.providers.saml.processors.types import SAMLResponseParams
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LOGGER = get_logger()
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URL_VALIDATOR = URLValidator(schemes=("http", "https"))
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SESSION_KEY_SAML_REQUEST = "SAMLRequest"
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SESSION_KEY_SAML_RESPONSE = "SAMLResponse"
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SESSION_KEY_RELAY_STATE = "RelayState"
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SESSION_KEY_PARAMS = "SAMLParams"
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class AccessRequiredView(AccessMixin, View):
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    """Mixin class for Views using a provider instance"""
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    _provider: Optional[SAMLProvider] = None
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    @property
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    def provider(self) -> SAMLProvider:
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        """Get provider instance"""
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        if not self._provider:
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            application = get_object_or_404(
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                Application, slug=self.kwargs["application"]
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            )
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            provider: SAMLProvider = get_object_or_404(
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                SAMLProvider, pk=application.provider_id
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            )
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            self._provider = provider
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            return self._provider
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        return self._provider
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    def _has_access(self) -> bool:
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        """Check if user has access to application"""
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        policy_engine = PolicyEngine(
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            self.provider.application.policies.all(), self.request.user, self.request
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        )
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        policy_engine.build()
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        passing = policy_engine.passing
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        LOGGER.debug(
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            "saml_has_access",
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            user=self.request.user,
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            app=self.provider.application,
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            passing=passing,
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        )
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        return passing
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    def dispatch(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
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        if not request.user.is_authenticated:
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            return self.handle_no_permission()
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        if not self._has_access():
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            return render(
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                request,
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                "login/denied.html",
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                {"title": _("You don't have access to this application"),},
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            )
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        return super().dispatch(request, *args, **kwargs)
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class LoginBeginView(AccessRequiredView):
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    """Receives a SAML 2.0 AuthnRequest from a Service Provider and
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    stores it in the session prior to enforcing login."""
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    def handler(self, source, application: str) -> HttpResponse:
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        """Handle SAML Request whether its a POST or a Redirect binding"""
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        # Store these values now, because Django's login cycle won't preserve them.
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        try:
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            self.request.session[SESSION_KEY_SAML_REQUEST] = source[
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                SESSION_KEY_SAML_REQUEST
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            ]
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        except (KeyError, MultiValueDictKeyError):
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            return bad_request_message(
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                self.request, "The SAML request payload is missing."
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            )
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        self.request.session[SESSION_KEY_RELAY_STATE] = source.get(
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            SESSION_KEY_RELAY_STATE, ""
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        )
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        try:
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            self.provider.processor.can_handle(self.request)
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            params = self.provider.processor.generate_response()
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            self.request.session[SESSION_KEY_PARAMS] = params
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        except CannotHandleAssertion as exc:
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            LOGGER.info(exc)
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            did_you_mean_link = self.request.build_absolute_uri(
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                reverse(
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                    "passbook_providers_saml:saml-login-initiate",
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                    kwargs={"application": application},
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                )
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            )
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            did_you_mean_message = (
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                f" Did you mean to go <a href='{did_you_mean_link}'>here</a>?"
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            )
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            return bad_request_message(
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                self.request, mark_safe(str(exc) + did_you_mean_message)
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            )
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        return redirect(
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            reverse(
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                "passbook_providers_saml:saml-login-authorize",
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                kwargs={"application": application},
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            )
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        )
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    @method_decorator(csrf_exempt)
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    def dispatch(self, *args, **kwargs):
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        return super().dispatch(*args, **kwargs)
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    @method_decorator(csrf_exempt)
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    def get(self, request: HttpRequest, application: str) -> HttpResponse:
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        """Handle REDIRECT bindings"""
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        return self.handler(request.GET, application)
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    @method_decorator(csrf_exempt)
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    def post(self, request: HttpRequest, application: str) -> HttpResponse:
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        """Handle POST Bindings"""
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        return self.handler(request.POST, application)
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class InitiateLoginView(AccessRequiredView):
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    """IdP-initiated Login"""
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    def get(self, request: HttpRequest, application: str) -> HttpResponse:
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        """Initiates an IdP-initiated link to a simple SP resource/target URL."""
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        self.provider.processor.is_idp_initiated = True
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        self.provider.processor.init_deep_link(request)
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        params = self.provider.processor.generate_response()
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        request.session[SESSION_KEY_PARAMS] = params
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        return redirect(
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            reverse(
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                "passbook_providers_saml:saml-login-authorize",
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                kwargs={"application": application},
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            )
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        )
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class AuthorizeView(AccessRequiredView):
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    """Ask the user for authorization to continue to the SP.
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    Presents a SAML 2.0 Assertion for POSTing back to the Service Provider."""
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    def get(self, request: HttpRequest, application: str) -> HttpResponse:
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        """Handle get request, i.e. render form"""
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        # User access gets checked in dispatch
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        # Otherwise we generate the IdP initiated session
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        try:
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            # application.skip_authorization is set so we directly redirect the user
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            if self.provider.application.skip_authorization:
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                LOGGER.debug("skipping authz", application=self.provider.application)
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                return self.post(request, application)
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            return render(
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                request,
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                "saml/idp/login.html",
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                {"provider": self.provider, "title": "Authorize Application",},
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            )
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        except KeyError:
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            return bad_request_message(request, "Missing SAML Payload")
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    # pylint: disable=unused-argument
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    def post(self, request: HttpRequest, application: str) -> HttpResponse:
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        """Handle post request, return back to ACS"""
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        # User access gets checked in dispatch
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        # we get here when skip_authorization is True, and after the user accepted
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        # the authorization form
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        # Log Application Authorization
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        Event.new(
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            EventAction.AUTHORIZE_APPLICATION,
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            authorized_application=self.provider.application,
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            skipped_authorization=self.provider.application.skip_authorization,
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        ).from_http(self.request)
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        self.request.session.pop(SESSION_KEY_SAML_REQUEST, None)
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        self.request.session.pop(SESSION_KEY_SAML_RESPONSE, None)
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        self.request.session.pop(SESSION_KEY_RELAY_STATE, None)
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        response: SAMLResponseParams = self.request.session.pop(SESSION_KEY_PARAMS)
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        return render(
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            self.request,
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            "saml/idp/autosubmit_form.html",
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            {
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                "url": response.acs_url,
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                "attrs": {
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                    "ACSUrl": response.acs_url,
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                    SESSION_KEY_SAML_RESPONSE: response.saml_response,
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                    SESSION_KEY_RELAY_STATE: response.relay_state,
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                },
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            },
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        )
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@method_decorator(csrf_exempt, name="dispatch")
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class LogoutView(AccessRequiredView):
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    """Allows a non-SAML 2.0 URL to log out the user and
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    returns a standard logged-out page. (SalesForce and others use this method,
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    though it's technically not SAML 2.0)."""
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    # pylint: disable=unused-argument
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    def get(self, request: HttpRequest, application: str) -> HttpResponse:
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        """Perform logout"""
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        logout(request)
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        redirect_url = request.GET.get("redirect_to", "")
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        try:
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            URL_VALIDATOR(redirect_url)
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        except ValidationError:
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            pass
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        else:
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            return redirect(redirect_url)
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        return render(request, "saml/idp/logged_out.html")
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@method_decorator(csrf_exempt, name="dispatch")
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class SLOLogout(AccessRequiredView):
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    """Receives a SAML 2.0 LogoutRequest from a Service Provider,
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    logs out the user and returns a standard logged-out page."""
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    # pylint: disable=unused-argument
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    def post(self, request: HttpRequest, application: str) -> HttpResponse:
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        """Perform logout"""
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        request.session[SESSION_KEY_SAML_REQUEST] = request.POST[
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            SESSION_KEY_SAML_REQUEST
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        ]
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        # TODO: Parse SAML LogoutRequest from POST data, similar to login_process().
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        # TODO: Modify the base processor to handle logouts?
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        # TODO: Combine this with login_process(), since they are so very similar?
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        # TODO: Format a LogoutResponse and return it to the browser.
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        # XXX: For now, simply log out without validating the request.
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        logout(request)
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        return render(request, "saml/idp/logged_out.html")
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class DescriptorDownloadView(AccessRequiredView):
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    """Replies with the XML Metadata IDSSODescriptor."""
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    @staticmethod
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    def get_metadata(request: HttpRequest, provider: SAMLProvider) -> str:
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        """Return rendered XML Metadata"""
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        entity_id = provider.issuer
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        slo_url = request.build_absolute_uri(
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            reverse(
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                "passbook_providers_saml:saml-logout",
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                kwargs={"application": provider.application.slug},
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            )
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        )
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        sso_post_url = request.build_absolute_uri(
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            reverse(
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                "passbook_providers_saml:saml-login",
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                kwargs={"application": provider.application.slug},
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            )
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        )
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        pubkey = strip_pem_header(
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            provider.signing_kp.certificate_data.replace("\r", "")
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        ).replace("\n", "")
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        subject_format = provider.processor.subject_format
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        ctx = {
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            "entity_id": entity_id,
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            "cert_public_key": pubkey,
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            "slo_url": slo_url,
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            # Currently, the same endpoint accepts POST and REDIRECT
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            "sso_post_url": sso_post_url,
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            "sso_redirect_url": sso_post_url,
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            "subject_format": subject_format,
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        }
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        return render_to_string("saml/xml/metadata.xml", ctx)
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    # pylint: disable=unused-argument
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    def get(self, request: HttpRequest, application: str) -> HttpResponse:
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        """Replies with the XML Metadata IDSSODescriptor."""
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        try:
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            metadata = DescriptorDownloadView.get_metadata(request, self.provider)
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        except Provider.application.RelatedObjectDoesNotExist:  # pylint: disable=no-member
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            return bad_request_message(
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                request, "Provider is not assigned to an application."
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            )
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        else:
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            response = HttpResponse(metadata, content_type="application/xml")
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            response[
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                "Content-Disposition"
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            ] = f'attachment; filename="{self.provider.name}_passbook_meta.xml"'
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            return response
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