providers/saml: fix handle Accept: application/xml for SAML Metadata endpoint (#12483)

authentik/providers/saml/api/providers.py

@@ -16,6 +16,7 @@
 from rest_framework.fields import CharField, FileField, SerializerMethodField
 from rest_framework.parsers import MultiPartParser
 from rest_framework.permissions import AllowAny
+from rest_framework.renderers import BaseRenderer, JSONRenderer
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.serializers import PrimaryKeyRelatedField, ValidationError
@@ -38,6 +39,16 @@
 LOGGER = get_logger()
 
 
+class RawXMLDataRenderer(BaseRenderer):
+    """Renderer to allow application/xml as value for 'Accept' in the metadata endpoint."""
+
+    media_type = "application/xml"
+    format = "xml"
+
+    def render(self, data, accepted_media_type=None, renderer_context=None):
+        return data
+
+
 class SAMLProviderSerializer(ProviderSerializer):
     """SAMLProvider Serializer"""
 
@@ -238,9 +249,21 @@ class SAMLProviderViewSet(UsedByMixin, ModelViewSet):
                 ],
                 description="Optionally force the metadata to only include one binding.",
             ),
+            # Explicitly excluded, because otherwise spectacular automatically
+            # add it when using multiple renderer_classes
+            OpenApiParameter(
+                name="format",
+                exclude=True,
+                required=False,
+            ),
         ],
     )
-    @action(methods=["GET"], detail=True, permission_classes=[AllowAny])
+    @action(
+        methods=["GET"],
+        detail=True,
+        permission_classes=[AllowAny],
+        renderer_classes=[JSONRenderer, RawXMLDataRenderer],
+    )
     def metadata(self, request: Request, pk: int) -> Response:
         """Return metadata as XML string"""
         # We don't use self.get_object() on purpose as this view is un-authenticated
@@ -258,9 +281,9 @@ def metadata(self, request: Request, pk: int) -> Response:
                     f'attachment; filename="{provider.name}_authentik_meta.xml"'
                 )
                 return response
-            return Response({"metadata": metadata})
+            return Response({"metadata": metadata}, content_type="application/json")
         except Provider.application.RelatedObjectDoesNotExist:
-            return Response({"metadata": ""})
+            return Response({"metadata": ""}, content_type="application/json")
 
     @permission_required(
         None,

authentik/providers/saml/tests/test_api.py

@@ -104,6 +104,22 @@ def test_metadata_download(self):
         )
         self.assertEqual(200, response.status_code)
         self.assertIn("Content-Disposition", response)
+        # Test download with Accept: application/xml
+        response = self.client.get(
+            reverse("authentik_api:samlprovider-metadata", kwargs={"pk": provider.pk})
+            + "?download",
+            HTTP_ACCEPT="application/xml",
+        )
+        self.assertEqual(200, response.status_code)
+        self.assertIn("Content-Disposition", response)
+
+        response = self.client.get(
+            reverse("authentik_api:samlprovider-metadata", kwargs={"pk": provider.pk})
+            + "?download",
+            HTTP_ACCEPT="application/xml;charset=UTF-8",
+        )
+        self.assertEqual(200, response.status_code)
+        self.assertIn("Content-Disposition", response)
 
     def test_metadata_invalid(self):
         """Test metadata export (invalid)"""
@@ -121,6 +137,11 @@ def test_metadata_invalid(self):
             reverse("authentik_api:samlprovider-metadata", kwargs={"pk": "abc"}),
         )
         self.assertEqual(404, response.status_code)
+        response = self.client.get(
+            reverse("authentik_api:samlprovider-metadata", kwargs={"pk": provider.pk}),
+            HTTP_ACCEPT="application/invalid-mime-type",
+        )
+        self.assertEqual(406, response.status_code)
 
     def test_import_success(self):
         """Test metadata import (success case)"""

schema.yml

@@ -22090,6 +22090,9 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/SAMLMetadata'
+            application/xml:
+              schema:
+                $ref: '#/components/schemas/SAMLMetadata'
           description: ''
         '404':
           description: Provider has no application assigned