258 lines
		
	
	
		
			9.4 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			258 lines
		
	
	
		
			9.4 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 HttpResponse, HttpResponseBadRequest, HttpRequest
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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.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
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from passbook.lib.mixins import CSRFExemptMixin
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from passbook.lib.utils.template import render_to_string
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from passbook.policies.engine import PolicyEngine
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from passbook.providers.saml import exceptions
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from passbook.providers.saml.models import SAMLProvider
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LOGGER = get_logger()
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URL_VALIDATOR = URLValidator(schemes=("http", "https"))
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def _generate_response(request: HttpRequest, provider: SAMLProvider):
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    """Generate a SAML response using processor_instance and return it in the proper Django
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    response."""
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    try:
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        provider.processor.init_deep_link(request, "")
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        ctx = provider.processor.generate_response()
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        ctx["remote"] = provider
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        ctx["is_login"] = True
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    except exceptions.UserNotAuthorized:
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        return render(request, "saml/idp/invalid_user.html")
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    return render(request, "saml/idp/login.html", ctx)
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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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            self._provider = get_object_or_404(SAMLProvider, pk=application.provider_id)
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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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        return policy_engine.passing
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    def dispatch(self, request, *args, **kwargs):
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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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                {
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                    "title": _("You don't have access to this application"),
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                    "is_login": True,
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                },
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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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    @method_decorator(csrf_exempt)
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    def dispatch(self, request, application):
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        if request.method == "POST":
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            source = request.POST
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        else:
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            source = request.GET
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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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            request.session["SAMLRequest"] = source["SAMLRequest"]
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        except (KeyError, MultiValueDictKeyError):
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            return HttpResponseBadRequest("the SAML request payload is missing")
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        request.session["RelayState"] = source.get("RelayState", "")
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        return redirect(
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            reverse(
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                "passbook_providers_saml:saml-login-process",
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                kwargs={"application": application},
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            )
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        )
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class RedirectToSPView(AccessRequiredView):
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    """Return autosubmit form"""
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    def get(self, request, acs_url, saml_response, relay_state):
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        """Return autosubmit form"""
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        return render(
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            request,
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            "core/autosubmit_form.html",
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            {
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                "url": acs_url,
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                "attrs": {"SAMLResponse": saml_response, "RelayState": relay_state},
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            },
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        )
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class LoginProcessView(AccessRequiredView):
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    """Processor-based login continuation.
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    Presents a SAML 2.0 Assertion for POSTing back to the Service Provider."""
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    # pylint: disable=unused-argument
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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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        if self.provider.application.skip_authorization:
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            ctx = self.provider.processor.generate_response()
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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=True,
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            ).from_http(request)
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            return RedirectToSPView.as_view()(
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                request=request,
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                acs_url=ctx["acs_url"],
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                saml_response=ctx["saml_response"],
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                relay_state=ctx["relay_state"],
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            )
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        try:
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            return _generate_response(request, self.provider)
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        except exceptions.CannotHandleAssertion as exc:
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            LOGGER.debug(exc)
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        return HttpResponseBadRequest()
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    # pylint: disable=unused-argument
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    def post(self, request, 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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        if request.POST.get("ACSUrl", None):
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            # User accepted request
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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=False,
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            ).from_http(request)
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            return RedirectToSPView.as_view()(
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                request=request,
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                acs_url=request.POST.get("ACSUrl"),
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                saml_response=request.POST.get("SAMLResponse"),
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                relay_state=request.POST.get("RelayState"),
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            )
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        try:
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            return _generate_response(request, self.provider)
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        except exceptions.CannotHandleAssertion as exc:
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            LOGGER.debug(exc)
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        return HttpResponseBadRequest()
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class LogoutView(CSRFExemptMixin, 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, application):
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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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class SLOLogout(CSRFExemptMixin, 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, application):
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        """Perform logout"""
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        request.session["SAMLRequest"] = request.POST["SAMLRequest"]
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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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    def get(self, request, application):
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        """Replies with the XML Metadata IDSSODescriptor."""
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        entity_id = self.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": application},
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            )
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        )
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        sso_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": application},
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            )
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        )
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        pubkey = strip_pem_header(self.provider.signing_cert.replace("\r", "")).replace(
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            "\n", ""
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        )
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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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            "sso_url": sso_url,
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        }
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        metadata = render_to_string("saml/xml/metadata.xml", ctx)
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        response = HttpResponse(metadata, content_type="application/xml")
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        response["Content-Disposition"] = (
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            'attachment; filename="' '%s_passbook_meta.xml"' % self.provider.name
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        )
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        return response
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class InitiateLoginView(AccessRequiredView):
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    """IdP-initiated Login"""
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    # pylint: disable=unused-argument
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    def get(self, request, application):
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        """Initiates an IdP-initiated link to a simple SP resource/target URL."""
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        self.provider.processor.init_deep_link(request, "")
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        self.provider.processor.is_idp_initiated = True
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        return _generate_response(request, self.provider)
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