Be more lenient when parsing the version for oEmbed responses. (#11065)

changelog.d/11065.misc

+Be more lenient when parsing oEmbed response versions.

mypy.ini

@@ -90,6 +90,7 @@ files =
   tests/rest/client/test_login.py,
   tests/rest/client/test_auth.py,
   tests/rest/media/v1/test_filepath.py,
+  tests/rest/media/v1/test_oembed.py,
   tests/storage/test_state.py,
   tests/storage/test_user_directory.py,
   tests/util/test_itertools.py,

synapse/rest/media/v1/oembed.py

@@ -17,7 +17,6 @@ from typing import TYPE_CHECKING, List, Optional
 
 import attr
 
-from synapse.http.client import SimpleHttpClient
 from synapse.types import JsonDict
 from synapse.util import json_decoder
 
@@ -48,7 +47,7 @@ class OEmbedProvider:
     requesting/parsing oEmbed content.
     """
 
-    def __init__(self, hs: "HomeServer", client: SimpleHttpClient):
+    def __init__(self, hs: "HomeServer"):
         self._oembed_patterns = {}
         for oembed_endpoint in hs.config.oembed.oembed_patterns:
             api_endpoint = oembed_endpoint.api_endpoint
@@ -69,7 +68,6 @@ class OEmbedProvider:
             # Iterate through each URL pattern and point it to the endpoint.
             for pattern in oembed_endpoint.url_patterns:
                 self._oembed_patterns[pattern] = api_endpoint
-        self._client = client
 
     def get_oembed_url(self, url: str) -> Optional[str]:
         """
@@ -139,10 +137,11 @@ class OEmbedProvider:
             # oEmbed responses *must* be UTF-8 according to the spec.
             oembed = json_decoder.decode(raw_body.decode("utf-8"))
 
-            # Ensure there's a version of 1.0.
-            oembed_version = oembed["version"]
-            if oembed_version != "1.0":
-                raise RuntimeError(f"Invalid version: {oembed_version}")
+            # The version is a required string field, but not always provided,
+            # or sometimes provided as a float. Be lenient.
+            oembed_version = oembed.get("version", "1.0")
+            if oembed_version != "1.0" and oembed_version != 1:
+                raise RuntimeError(f"Invalid oEmbed version: {oembed_version}")
 
             # Ensure the cache age is None or an int.
             cache_age = oembed.get("cache_age")

synapse/rest/media/v1/preview_url_resource.py

@@ -140,7 +140,7 @@ class PreviewUrlResource(DirectServeJsonResource):
         self.primary_base_path = media_repo.primary_base_path
         self.media_storage = media_storage
 
-        self._oembed = OEmbedProvider(hs, self.client)
+        self._oembed = OEmbedProvider(hs)
 
         # We run the background jobs if we're the instance specified (or no
         # instance is specified, where we assume there is only one instance

tests/rest/media/v1/test_oembed.py

+#  Copyright 2021 The Matrix.org Foundation C.I.C.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+import json
+
+from twisted.test.proto_helpers import MemoryReactor
+
+from synapse.rest.media.v1.oembed import OEmbedProvider
+from synapse.server import HomeServer
+from synapse.types import JsonDict
+from synapse.util import Clock
+
+from tests.unittest import HomeserverTestCase
+
+
+class OEmbedTests(HomeserverTestCase):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer):
+        self.oembed = OEmbedProvider(homeserver)
+
+    def parse_response(self, response: JsonDict):
+        return self.oembed.parse_oembed_response(
+            "https://test", json.dumps(response).encode("utf-8")
+        )
+
+    def test_version(self):
+        """Accept versions that are similar to 1.0 as a string or int (or missing)."""
+        for version in ("1.0", 1.0, 1):
+            result = self.parse_response({"version": version, "type": "link"})
+            # An empty Open Graph response is an error, ensure the URL is included.
+            self.assertIn("og:url", result.open_graph_result)
+
+        # A missing version should be treated as 1.0.
+        result = self.parse_response({"type": "link"})
+        self.assertIn("og:url", result.open_graph_result)
+
+        # Invalid versions should be rejected.
+        for version in ("2.0", "1", 1.1, 0, None, {}, []):
+            result = self.parse_response({"version": version, "type": "link"})
+            # An empty Open Graph response is an error, ensure the URL is included.
+            self.assertEqual({}, result.open_graph_result)