Refactor media modules. (#15146)

* Removes the `v1` directory from `test.rest.media.v1`.
* Moves the non-REST code from `synapse.rest.media.v1` to `synapse.media`.
* Flatten the `v1` directory from `synapse.rest.media`,  but leave compatiblity
  with 3rd party media repositories and spam checkers.

6 files changed, 2142 insertions, 0 deletions

diff --git a/tests/media/__init__.py b/tests/media/__init__.py
new file mode 100644
index 0000000000..68910cbf5b
--- /dev/null
+++ b/tests/media/__init__.py
@@ -0,0 +1,13 @@
+#  Copyright 2023 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.
diff --git a/tests/media/test_base.py b/tests/media/test_base.py
new file mode 100644
index 0000000000..66498c744d
--- /dev/null
+++ b/tests/media/test_base.py
@@ -0,0 +1,38 @@
+# Copyright 2019 New Vector Ltd
+#
+# 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.
+
+from synapse.media._base import get_filename_from_headers
+
+from tests import unittest
+
+
+class GetFileNameFromHeadersTests(unittest.TestCase):
+    # input -> expected result
+    TEST_CASES = {
+        b"inline; filename=abc.txt": "abc.txt",
+        b'inline; filename="azerty"': "azerty",
+        b'inline; filename="aze%20rty"': "aze%20rty",
+        b'inline; filename="aze"rty"': 'aze"rty',
+        b'inline; filename="azer;ty"': "azer;ty",
+        b"inline; filename*=utf-8''foo%C2%A3bar": "foo£bar",
+    }
+
+    def tests(self) -> None:
+        for hdr, expected in self.TEST_CASES.items():
+            res = get_filename_from_headers({b"Content-Disposition": [hdr]})
+            self.assertEqual(
+                res,
+                expected,
+                f"expected output for {hdr!r} to be {expected} but was {res}",
+            )
diff --git a/tests/media/test_filepath.py b/tests/media/test_filepath.py
new file mode 100644
index 0000000000..95e3b83d5a
--- /dev/null
+++ b/tests/media/test_filepath.py
@@ -0,0 +1,595 @@
+# 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 inspect
+import os
+from typing import Iterable
+
+from synapse.media.filepath import MediaFilePaths, _wrap_with_jail_check
+
+from tests import unittest
+
+
+class MediaFilePathsTestCase(unittest.TestCase):
+    def setUp(self) -> None:
+        super().setUp()
+
+        self.filepaths = MediaFilePaths("/media_store")
+
+    def test_local_media_filepath(self) -> None:
+        """Test local media paths"""
+        self.assertEqual(
+            self.filepaths.local_media_filepath_rel("GerZNDnDZVjsOtardLuwfIBg"),
+            "local_content/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+        self.assertEqual(
+            self.filepaths.local_media_filepath("GerZNDnDZVjsOtardLuwfIBg"),
+            "/media_store/local_content/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_local_media_thumbnail(self) -> None:
+        """Test local media thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.local_media_thumbnail_rel(
+                "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg", "scale"
+            ),
+            "local_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+        self.assertEqual(
+            self.filepaths.local_media_thumbnail(
+                "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg", "scale"
+            ),
+            "/media_store/local_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+
+    def test_local_media_thumbnail_dir(self) -> None:
+        """Test local media thumbnail directory paths"""
+        self.assertEqual(
+            self.filepaths.local_media_thumbnail_dir("GerZNDnDZVjsOtardLuwfIBg"),
+            "/media_store/local_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_remote_media_filepath(self) -> None:
+        """Test remote media paths"""
+        self.assertEqual(
+            self.filepaths.remote_media_filepath_rel(
+                "example.com", "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            "remote_content/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+        self.assertEqual(
+            self.filepaths.remote_media_filepath(
+                "example.com", "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            "/media_store/remote_content/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_remote_media_thumbnail(self) -> None:
+        """Test remote media thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.remote_media_thumbnail_rel(
+                "example.com",
+                "GerZNDnDZVjsOtardLuwfIBg",
+                800,
+                600,
+                "image/jpeg",
+                "scale",
+            ),
+            "remote_thumbnail/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+        self.assertEqual(
+            self.filepaths.remote_media_thumbnail(
+                "example.com",
+                "GerZNDnDZVjsOtardLuwfIBg",
+                800,
+                600,
+                "image/jpeg",
+                "scale",
+            ),
+            "/media_store/remote_thumbnail/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+
+    def test_remote_media_thumbnail_legacy(self) -> None:
+        """Test old-style remote media thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.remote_media_thumbnail_rel_legacy(
+                "example.com", "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg"
+            ),
+            "remote_thumbnail/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg",
+        )
+
+    def test_remote_media_thumbnail_dir(self) -> None:
+        """Test remote media thumbnail directory paths"""
+        self.assertEqual(
+            self.filepaths.remote_media_thumbnail_dir(
+                "example.com", "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            "/media_store/remote_thumbnail/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_url_cache_filepath(self) -> None:
+        """Test URL cache paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_filepath_rel("2020-01-02_GerZNDnDZVjsOtar"),
+            "url_cache/2020-01-02/GerZNDnDZVjsOtar",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_filepath("2020-01-02_GerZNDnDZVjsOtar"),
+            "/media_store/url_cache/2020-01-02/GerZNDnDZVjsOtar",
+        )
+
+    def test_url_cache_filepath_legacy(self) -> None:
+        """Test old-style URL cache paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_filepath_rel("GerZNDnDZVjsOtardLuwfIBg"),
+            "url_cache/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_filepath("GerZNDnDZVjsOtardLuwfIBg"),
+            "/media_store/url_cache/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_url_cache_filepath_dirs_to_delete(self) -> None:
+        """Test URL cache cleanup paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_filepath_dirs_to_delete(
+                "2020-01-02_GerZNDnDZVjsOtar"
+            ),
+            ["/media_store/url_cache/2020-01-02"],
+        )
+
+    def test_url_cache_filepath_dirs_to_delete_legacy(self) -> None:
+        """Test old-style URL cache cleanup paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_filepath_dirs_to_delete(
+                "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            [
+                "/media_store/url_cache/Ge/rZ",
+                "/media_store/url_cache/Ge",
+            ],
+        )
+
+    def test_url_cache_thumbnail(self) -> None:
+        """Test URL cache thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_rel(
+                "2020-01-02_GerZNDnDZVjsOtar", 800, 600, "image/jpeg", "scale"
+            ),
+            "url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar/800-600-image-jpeg-scale",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail(
+                "2020-01-02_GerZNDnDZVjsOtar", 800, 600, "image/jpeg", "scale"
+            ),
+            "/media_store/url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar/800-600-image-jpeg-scale",
+        )
+
+    def test_url_cache_thumbnail_legacy(self) -> None:
+        """Test old-style URL cache thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_rel(
+                "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg", "scale"
+            ),
+            "url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail(
+                "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg", "scale"
+            ),
+            "/media_store/url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+
+    def test_url_cache_thumbnail_directory(self) -> None:
+        """Test URL cache thumbnail directory paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_directory_rel(
+                "2020-01-02_GerZNDnDZVjsOtar"
+            ),
+            "url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_directory("2020-01-02_GerZNDnDZVjsOtar"),
+            "/media_store/url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar",
+        )
+
+    def test_url_cache_thumbnail_directory_legacy(self) -> None:
+        """Test old-style URL cache thumbnail directory paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_directory_rel(
+                "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            "url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_directory("GerZNDnDZVjsOtardLuwfIBg"),
+            "/media_store/url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_url_cache_thumbnail_dirs_to_delete(self) -> None:
+        """Test URL cache thumbnail cleanup paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_dirs_to_delete(
+                "2020-01-02_GerZNDnDZVjsOtar"
+            ),
+            [
+                "/media_store/url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar",
+                "/media_store/url_cache_thumbnails/2020-01-02",
+            ],
+        )
+
+    def test_url_cache_thumbnail_dirs_to_delete_legacy(self) -> None:
+        """Test old-style URL cache thumbnail cleanup paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_dirs_to_delete(
+                "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            [
+                "/media_store/url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+                "/media_store/url_cache_thumbnails/Ge/rZ",
+                "/media_store/url_cache_thumbnails/Ge",
+            ],
+        )
+
+    def test_server_name_validation(self) -> None:
+        """Test validation of server names"""
+        self._test_path_validation(
+            [
+                "remote_media_filepath_rel",
+                "remote_media_filepath",
+                "remote_media_thumbnail_rel",
+                "remote_media_thumbnail",
+                "remote_media_thumbnail_rel_legacy",
+                "remote_media_thumbnail_dir",
+            ],
+            parameter="server_name",
+            valid_values=[
+                "matrix.org",
+                "matrix.org:8448",
+                "matrix-federation.matrix.org",
+                "matrix-federation.matrix.org:8448",
+                "10.1.12.123",
+                "10.1.12.123:8448",
+                "[fd00:abcd::ffff]",
+                "[fd00:abcd::ffff]:8448",
+            ],
+            invalid_values=[
+                "/matrix.org",
+                "matrix.org/..",
+                "matrix.org\x00",
+                "",
+                ".",
+                "..",
+                "/",
+            ],
+        )
+
+    def test_file_id_validation(self) -> None:
+        """Test validation of local, remote and legacy URL cache file / media IDs"""
+        # File / media IDs get split into three parts to form paths, consisting of the
+        # first two characters, next two characters and rest of the ID.
+        valid_file_ids = [
+            "GerZNDnDZVjsOtardLuwfIBg",
+            # Unexpected, but produces an acceptable path:
+            "GerZN",  # "N" becomes the last directory
+        ]
+        invalid_file_ids = [
+            "/erZNDnDZVjsOtardLuwfIBg",
+            "Ge/ZNDnDZVjsOtardLuwfIBg",
+            "GerZ/DnDZVjsOtardLuwfIBg",
+            "GerZ/..",
+            "G\x00rZNDnDZVjsOtardLuwfIBg",
+            "Ger\x00NDnDZVjsOtardLuwfIBg",
+            "GerZNDnDZVjsOtardLuwfIBg\x00",
+            "",
+            "Ge",
+            "GerZ",
+            "GerZ.",
+            "..rZNDnDZVjsOtardLuwfIBg",
+            "Ge..NDnDZVjsOtardLuwfIBg",
+            "GerZ..",
+            "GerZ/",
+        ]
+
+        self._test_path_validation(
+            [
+                "local_media_filepath_rel",
+                "local_media_filepath",
+                "local_media_thumbnail_rel",
+                "local_media_thumbnail",
+                "local_media_thumbnail_dir",
+                # Legacy URL cache media IDs
+                "url_cache_filepath_rel",
+                "url_cache_filepath",
+                # `url_cache_filepath_dirs_to_delete` is tested below.
+                "url_cache_thumbnail_rel",
+                "url_cache_thumbnail",
+                "url_cache_thumbnail_directory_rel",
+                "url_cache_thumbnail_directory",
+                "url_cache_thumbnail_dirs_to_delete",
+            ],
+            parameter="media_id",
+            valid_values=valid_file_ids,
+            invalid_values=invalid_file_ids,
+        )
+
+        # `url_cache_filepath_dirs_to_delete` ignores what would be the last path
+        # component, so only the first 4 characters matter.
+        self._test_path_validation(
+            [
+                "url_cache_filepath_dirs_to_delete",
+            ],
+            parameter="media_id",
+            valid_values=valid_file_ids,
+            invalid_values=[
+                "/erZNDnDZVjsOtardLuwfIBg",
+                "Ge/ZNDnDZVjsOtardLuwfIBg",
+                "G\x00rZNDnDZVjsOtardLuwfIBg",
+                "Ger\x00NDnDZVjsOtardLuwfIBg",
+                "",
+                "Ge",
+                "..rZNDnDZVjsOtardLuwfIBg",
+                "Ge..NDnDZVjsOtardLuwfIBg",
+            ],
+        )
+
+        self._test_path_validation(
+            [
+                "remote_media_filepath_rel",
+                "remote_media_filepath",
+                "remote_media_thumbnail_rel",
+                "remote_media_thumbnail",
+                "remote_media_thumbnail_rel_legacy",
+                "remote_media_thumbnail_dir",
+            ],
+            parameter="file_id",
+            valid_values=valid_file_ids,
+            invalid_values=invalid_file_ids,
+        )
+
+    def test_url_cache_media_id_validation(self) -> None:
+        """Test validation of URL cache media IDs"""
+        self._test_path_validation(
+            [
+                "url_cache_filepath_rel",
+                "url_cache_filepath",
+                # `url_cache_filepath_dirs_to_delete` only cares about the date prefix
+                "url_cache_thumbnail_rel",
+                "url_cache_thumbnail",
+                "url_cache_thumbnail_directory_rel",
+                "url_cache_thumbnail_directory",
+                "url_cache_thumbnail_dirs_to_delete",
+            ],
+            parameter="media_id",
+            valid_values=[
+                "2020-01-02_GerZNDnDZVjsOtar",
+                "2020-01-02_G",  # Unexpected, but produces an acceptable path
+            ],
+            invalid_values=[
+                "2020-01-02",
+                "2020-01-02-",
+                "2020-01-02-.",
+                "2020-01-02-..",
+                "2020-01-02-/",
+                "2020-01-02-/GerZNDnDZVjsOtar",
+                "2020-01-02-GerZNDnDZVjsOtar/..",
+                "2020-01-02-GerZNDnDZVjsOtar\x00",
+            ],
+        )
+
+    def test_content_type_validation(self) -> None:
+        """Test validation of thumbnail content types"""
+        self._test_path_validation(
+            [
+                "local_media_thumbnail_rel",
+                "local_media_thumbnail",
+                "remote_media_thumbnail_rel",
+                "remote_media_thumbnail",
+                "remote_media_thumbnail_rel_legacy",
+                "url_cache_thumbnail_rel",
+                "url_cache_thumbnail",
+            ],
+            parameter="content_type",
+            valid_values=[
+                "image/jpeg",
+            ],
+            invalid_values=[
+                "",  # ValueError: not enough values to unpack
+                "image/jpeg/abc",  # ValueError: too many values to unpack
+                "image/jpeg\x00",
+            ],
+        )
+
+    def test_thumbnail_method_validation(self) -> None:
+        """Test validation of thumbnail methods"""
+        self._test_path_validation(
+            [
+                "local_media_thumbnail_rel",
+                "local_media_thumbnail",
+                "remote_media_thumbnail_rel",
+                "remote_media_thumbnail",
+                "url_cache_thumbnail_rel",
+                "url_cache_thumbnail",
+            ],
+            parameter="method",
+            valid_values=[
+                "crop",
+                "scale",
+            ],
+            invalid_values=[
+                "/scale",
+                "scale/..",
+                "scale\x00",
+                "/",
+            ],
+        )
+
+    def _test_path_validation(
+        self,
+        methods: Iterable[str],
+        parameter: str,
+        valid_values: Iterable[str],
+        invalid_values: Iterable[str],
+    ) -> None:
+        """Test that the specified methods validate the named parameter as expected
+
+        Args:
+            methods: The names of `MediaFilePaths` methods to test
+            parameter: The name of the parameter to test
+            valid_values: A list of parameter values that are expected to be accepted
+            invalid_values: A list of parameter values that are expected to be rejected
+
+        Raises:
+            AssertionError: If a value was accepted when it should have failed
+                validation.
+            ValueError: If a value failed validation when it should have been accepted.
+        """
+        for method in methods:
+            get_path = getattr(self.filepaths, method)
+
+            parameters = inspect.signature(get_path).parameters
+            kwargs = {
+                "server_name": "matrix.org",
+                "media_id": "GerZNDnDZVjsOtardLuwfIBg",
+                "file_id": "GerZNDnDZVjsOtardLuwfIBg",
+                "width": 800,
+                "height": 600,
+                "content_type": "image/jpeg",
+                "method": "scale",
+            }
+
+            if get_path.__name__.startswith("url_"):
+                kwargs["media_id"] = "2020-01-02_GerZNDnDZVjsOtar"
+
+            kwargs = {k: v for k, v in kwargs.items() if k in parameters}
+            kwargs.pop(parameter)
+
+            for value in valid_values:
+                kwargs[parameter] = value
+                get_path(**kwargs)
+                # No exception should be raised
+
+            for value in invalid_values:
+                with self.assertRaises(ValueError):
+                    kwargs[parameter] = value
+                    path_or_list = get_path(**kwargs)
+                    self.fail(
+                        f"{value!r} unexpectedly passed validation: "
+                        f"{method} returned {path_or_list!r}"
+                    )
+
+
+class MediaFilePathsJailTestCase(unittest.TestCase):
+    def _check_relative_path(self, filepaths: MediaFilePaths, path: str) -> None:
+        """Passes a relative path through the jail check.
+
+        Args:
+            filepaths: The `MediaFilePaths` instance.
+            path: A path relative to the media store directory.
+
+        Raises:
+            ValueError: If the jail check fails.
+        """
+
+        @_wrap_with_jail_check(relative=True)
+        def _make_relative_path(self: MediaFilePaths, path: str) -> str:
+            return path
+
+        _make_relative_path(filepaths, path)
+
+    def _check_absolute_path(self, filepaths: MediaFilePaths, path: str) -> None:
+        """Passes an absolute path through the jail check.
+
+        Args:
+            filepaths: The `MediaFilePaths` instance.
+            path: A path relative to the media store directory.
+
+        Raises:
+            ValueError: If the jail check fails.
+        """
+
+        @_wrap_with_jail_check(relative=False)
+        def _make_absolute_path(self: MediaFilePaths, path: str) -> str:
+            return os.path.join(self.base_path, path)
+
+        _make_absolute_path(filepaths, path)
+
+    def test_traversal_inside(self) -> None:
+        """Test the jail check for paths that stay within the media directory."""
+        # Despite the `../`s, these paths still lie within the media directory and it's
+        # expected for the jail check to allow them through.
+        # These paths ought to trip the other checks in place and should never be
+        # returned.
+        filepaths = MediaFilePaths("/media_store")
+        path = "url_cache/2020-01-02/../../GerZNDnDZVjsOtar"
+        self._check_relative_path(filepaths, path)
+        self._check_absolute_path(filepaths, path)
+
+    def test_traversal_outside(self) -> None:
+        """Test that the jail check fails for paths that escape the media directory."""
+        filepaths = MediaFilePaths("/media_store")
+        path = "url_cache/2020-01-02/../../../GerZNDnDZVjsOtar"
+        with self.assertRaises(ValueError):
+            self._check_relative_path(filepaths, path)
+        with self.assertRaises(ValueError):
+            self._check_absolute_path(filepaths, path)
+
+    def test_traversal_reentry(self) -> None:
+        """Test the jail check for paths that exit and re-enter the media directory."""
+        # These paths lie outside the media directory if it is a symlink, and inside
+        # otherwise. Ideally the check should fail, but this proves difficult.
+        # This test documents the behaviour for this edge case.
+        # These paths ought to trip the other checks in place and should never be
+        # returned.
+        filepaths = MediaFilePaths("/media_store")
+        path = "url_cache/2020-01-02/../../../media_store/GerZNDnDZVjsOtar"
+        self._check_relative_path(filepaths, path)
+        self._check_absolute_path(filepaths, path)
+
+    def test_symlink(self) -> None:
+        """Test that a symlink does not cause the jail check to fail."""
+        media_store_path = self.mktemp()
+
+        # symlink the media store directory
+        os.symlink("/mnt/synapse/media_store", media_store_path)
+
+        # Test that relative and absolute paths don't trip the check
+        # NB: `media_store_path` is a relative path
+        filepaths = MediaFilePaths(media_store_path)
+        self._check_relative_path(filepaths, "url_cache/2020-01-02/GerZNDnDZVjsOtar")
+        self._check_absolute_path(filepaths, "url_cache/2020-01-02/GerZNDnDZVjsOtar")
+
+        filepaths = MediaFilePaths(os.path.abspath(media_store_path))
+        self._check_relative_path(filepaths, "url_cache/2020-01-02/GerZNDnDZVjsOtar")
+        self._check_absolute_path(filepaths, "url_cache/2020-01-02/GerZNDnDZVjsOtar")
+
+    def test_symlink_subdirectory(self) -> None:
+        """Test that a symlinked subdirectory does not cause the jail check to fail."""
+        media_store_path = self.mktemp()
+        os.mkdir(media_store_path)
+
+        # symlink `url_cache/`
+        os.symlink(
+            "/mnt/synapse/media_store_url_cache",
+            os.path.join(media_store_path, "url_cache"),
+        )
+
+        # Test that relative and absolute paths don't trip the check
+        # NB: `media_store_path` is a relative path
+        filepaths = MediaFilePaths(media_store_path)
+        self._check_relative_path(filepaths, "url_cache/2020-01-02/GerZNDnDZVjsOtar")
+        self._check_absolute_path(filepaths, "url_cache/2020-01-02/GerZNDnDZVjsOtar")
+
+        filepaths = MediaFilePaths(os.path.abspath(media_store_path))
+        self._check_relative_path(filepaths, "url_cache/2020-01-02/GerZNDnDZVjsOtar")
+        self._check_absolute_path(filepaths, "url_cache/2020-01-02/GerZNDnDZVjsOtar")
diff --git a/tests/media/test_html_preview.py b/tests/media/test_html_preview.py
new file mode 100644
index 0000000000..e7da75db3e
--- /dev/null
+++ b/tests/media/test_html_preview.py
@@ -0,0 +1,542 @@
+# Copyright 2014-2016 OpenMarket Ltd
+#
+# 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.
+
+from synapse.media.preview_html import (
+    _get_html_media_encodings,
+    decode_body,
+    parse_html_to_open_graph,
+    summarize_paragraphs,
+)
+
+from tests import unittest
+
+try:
+    import lxml
+except ImportError:
+    lxml = None
+
+
+class SummarizeTestCase(unittest.TestCase):
+    if not lxml:
+        skip = "url preview feature requires lxml"
+
+    def test_long_summarize(self) -> None:
+        example_paras = [
+            """Tromsø (Norwegian pronunciation: [ˈtrʊmsœ] ( listen); Northern Sami:
+            Romsa; Finnish: Tromssa[2] Kven: Tromssa) is a city and municipality in
+            Troms county, Norway. The administrative centre of the municipality is
+            the city of Tromsø. Outside of Norway, Tromso and Tromsö are
+            alternative spellings of the city.Tromsø is considered the northernmost
+            city in the world with a population above 50,000. The most populous town
+            north of it is Alta, Norway, with a population of 14,272 (2013).""",
+            """Tromsø lies in Northern Norway. The municipality has a population of
+            (2015) 72,066, but with an annual influx of students it has over 75,000
+            most of the year. It is the largest urban area in Northern Norway and the
+            third largest north of the Arctic Circle (following Murmansk and Norilsk).
+            Most of Tromsø, including the city centre, is located on the island of
+            Tromsøya, 350 kilometres (217 mi) north of the Arctic Circle. In 2012,
+            Tromsøya had a population of 36,088. Substantial parts of the urban area
+            are also situated on the mainland to the east, and on parts of Kvaløya—a
+            large island to the west. Tromsøya is connected to the mainland by the Tromsø
+            Bridge and the Tromsøysund Tunnel, and to the island of Kvaløya by the
+            Sandnessund Bridge. Tromsø Airport connects the city to many destinations
+            in Europe. The city is warmer than most other places located on the same
+            latitude, due to the warming effect of the Gulf Stream.""",
+            """The city centre of Tromsø contains the highest number of old wooden
+            houses in Northern Norway, the oldest house dating from 1789. The Arctic
+            Cathedral, a modern church from 1965, is probably the most famous landmark
+            in Tromsø. The city is a cultural centre for its region, with several
+            festivals taking place in the summer. Some of Norway's best-known
+             musicians, Torbjørn Brundtland and Svein Berge of the electronica duo
+             Röyksopp and Lene Marlin grew up and started their careers in Tromsø.
+             Noted electronic musician Geir Jenssen also hails from Tromsø.""",
+        ]
+
+        desc = summarize_paragraphs(example_paras, min_size=200, max_size=500)
+
+        self.assertEqual(
+            desc,
+            "Tromsø (Norwegian pronunciation: [ˈtrʊmsœ] ( listen); Northern Sami:"
+            " Romsa; Finnish: Tromssa[2] Kven: Tromssa) is a city and municipality in"
+            " Troms county, Norway. The administrative centre of the municipality is"
+            " the city of Tromsø. Outside of Norway, Tromso and Tromsö are"
+            " alternative spellings of the city.Tromsø is considered the northernmost"
+            " city in the world with a population above 50,000. The most populous town"
+            " north of it is Alta, Norway, with a population of 14,272 (2013).",
+        )
+
+        desc = summarize_paragraphs(example_paras[1:], min_size=200, max_size=500)
+
+        self.assertEqual(
+            desc,
+            "Tromsø lies in Northern Norway. The municipality has a population of"
+            " (2015) 72,066, but with an annual influx of students it has over 75,000"
+            " most of the year. It is the largest urban area in Northern Norway and the"
+            " third largest north of the Arctic Circle (following Murmansk and Norilsk)."
+            " Most of Tromsø, including the city centre, is located on the island of"
+            " Tromsøya, 350 kilometres (217 mi) north of the Arctic Circle. In 2012,"
+            " Tromsøya had a population of 36,088. Substantial parts of the urban…",
+        )
+
+    def test_short_summarize(self) -> None:
+        example_paras = [
+            "Tromsø (Norwegian pronunciation: [ˈtrʊmsœ] ( listen); Northern Sami:"
+            " Romsa; Finnish: Tromssa[2] Kven: Tromssa) is a city and municipality in"
+            " Troms county, Norway.",
+            "Tromsø lies in Northern Norway. The municipality has a population of"
+            " (2015) 72,066, but with an annual influx of students it has over 75,000"
+            " most of the year.",
+            "The city centre of Tromsø contains the highest number of old wooden"
+            " houses in Northern Norway, the oldest house dating from 1789. The Arctic"
+            " Cathedral, a modern church from 1965, is probably the most famous landmark"
+            " in Tromsø.",
+        ]
+
+        desc = summarize_paragraphs(example_paras, min_size=200, max_size=500)
+
+        self.assertEqual(
+            desc,
+            "Tromsø (Norwegian pronunciation: [ˈtrʊmsœ] ( listen); Northern Sami:"
+            " Romsa; Finnish: Tromssa[2] Kven: Tromssa) is a city and municipality in"
+            " Troms county, Norway.\n"
+            "\n"
+            "Tromsø lies in Northern Norway. The municipality has a population of"
+            " (2015) 72,066, but with an annual influx of students it has over 75,000"
+            " most of the year.",
+        )
+
+    def test_small_then_large_summarize(self) -> None:
+        example_paras = [
+            "Tromsø (Norwegian pronunciation: [ˈtrʊmsœ] ( listen); Northern Sami:"
+            " Romsa; Finnish: Tromssa[2] Kven: Tromssa) is a city and municipality in"
+            " Troms county, Norway.",
+            "Tromsø lies in Northern Norway. The municipality has a population of"
+            " (2015) 72,066, but with an annual influx of students it has over 75,000"
+            " most of the year."
+            " The city centre of Tromsø contains the highest number of old wooden"
+            " houses in Northern Norway, the oldest house dating from 1789. The Arctic"
+            " Cathedral, a modern church from 1965, is probably the most famous landmark"
+            " in Tromsø.",
+        ]
+
+        desc = summarize_paragraphs(example_paras, min_size=200, max_size=500)
+        self.assertEqual(
+            desc,
+            "Tromsø (Norwegian pronunciation: [ˈtrʊmsœ] ( listen); Northern Sami:"
+            " Romsa; Finnish: Tromssa[2] Kven: Tromssa) is a city and municipality in"
+            " Troms county, Norway.\n"
+            "\n"
+            "Tromsø lies in Northern Norway. The municipality has a population of"
+            " (2015) 72,066, but with an annual influx of students it has over 75,000"
+            " most of the year. The city centre of Tromsø contains the highest number"
+            " of old wooden houses in Northern Norway, the oldest house dating from"
+            " 1789. The Arctic Cathedral, a modern church from…",
+        )
+
+
+class OpenGraphFromHtmlTestCase(unittest.TestCase):
+    if not lxml:
+        skip = "url preview feature requires lxml"
+
+    def test_simple(self) -> None:
+        html = b"""
+        <html>
+        <head><title>Foo</title></head>
+        <body>
+        Some text.
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(og, {"og:title": "Foo", "og:description": "Some text."})
+
+    def test_comment(self) -> None:
+        html = b"""
+        <html>
+        <head><title>Foo</title></head>
+        <body>
+        <!-- HTML comment -->
+        Some text.
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(og, {"og:title": "Foo", "og:description": "Some text."})
+
+    def test_comment2(self) -> None:
+        html = b"""
+        <html>
+        <head><title>Foo</title></head>
+        <body>
+        Some text.
+        <!-- HTML comment -->
+        Some more text.
+        <p>Text</p>
+        More text
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(
+            og,
+            {
+                "og:title": "Foo",
+                "og:description": "Some text.\n\nSome more text.\n\nText\n\nMore text",
+            },
+        )
+
+    def test_script(self) -> None:
+        html = b"""
+        <html>
+        <head><title>Foo</title></head>
+        <body>
+        <script> (function() {})() </script>
+        Some text.
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(og, {"og:title": "Foo", "og:description": "Some text."})
+
+    def test_missing_title(self) -> None:
+        html = b"""
+        <html>
+        <body>
+        Some text.
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(og, {"og:title": None, "og:description": "Some text."})
+
+        # Another variant is a title with no content.
+        html = b"""
+        <html>
+        <head><title></title></head>
+        <body>
+        <h1>Title</h1>
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(og, {"og:title": "Title", "og:description": "Title"})
+
+    def test_h1_as_title(self) -> None:
+        html = b"""
+        <html>
+        <meta property="og:description" content="Some text."/>
+        <body>
+        <h1>Title</h1>
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(og, {"og:title": "Title", "og:description": "Some text."})
+
+    def test_empty_description(self) -> None:
+        """Description tags with empty content should be ignored."""
+        html = b"""
+        <html>
+        <meta property="og:description" content=""/>
+        <meta property="og:description"/>
+        <meta name="description" content=""/>
+        <meta name="description"/>
+        <meta name="description" content="Finally!"/>
+        <body>
+        <h1>Title</h1>
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(og, {"og:title": "Title", "og:description": "Finally!"})
+
+    def test_missing_title_and_broken_h1(self) -> None:
+        html = b"""
+        <html>
+        <body>
+        <h1><a href="foo"/></h1>
+        Some text.
+        </body>
+        </html>
+        """
+
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+
+        self.assertEqual(og, {"og:title": None, "og:description": "Some text."})
+
+    def test_empty(self) -> None:
+        """Test a body with no data in it."""
+        html = b""
+        tree = decode_body(html, "http://example.com/test.html")
+        self.assertIsNone(tree)
+
+    def test_no_tree(self) -> None:
+        """A valid body with no tree in it."""
+        html = b"\x00"
+        tree = decode_body(html, "http://example.com/test.html")
+        self.assertIsNone(tree)
+
+    def test_xml(self) -> None:
+        """Test decoding XML and ensure it works properly."""
+        # Note that the strip() call is important to ensure the xml tag starts
+        # at the initial byte.
+        html = b"""
+        <?xml version="1.0" encoding="UTF-8"?>
+
+        <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+        <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+        <head><title>Foo</title></head><body>Some text.</body></html>
+        """.strip()
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+        self.assertEqual(og, {"og:title": "Foo", "og:description": "Some text."})
+
+    def test_invalid_encoding(self) -> None:
+        """An invalid character encoding should be ignored and treated as UTF-8, if possible."""
+        html = b"""
+        <html>
+        <head><title>Foo</title></head>
+        <body>
+        Some text.
+        </body>
+        </html>
+        """
+        tree = decode_body(html, "http://example.com/test.html", "invalid-encoding")
+        og = parse_html_to_open_graph(tree)
+        self.assertEqual(og, {"og:title": "Foo", "og:description": "Some text."})
+
+    def test_invalid_encoding2(self) -> None:
+        """A body which doesn't match the sent character encoding."""
+        # Note that this contains an invalid UTF-8 sequence in the title.
+        html = b"""
+        <html>
+        <head><title>\xff\xff Foo</title></head>
+        <body>
+        Some text.
+        </body>
+        </html>
+        """
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+        self.assertEqual(og, {"og:title": "ÿÿ Foo", "og:description": "Some text."})
+
+    def test_windows_1252(self) -> None:
+        """A body which uses cp1252, but doesn't declare that."""
+        html = b"""
+        <html>
+        <head><title>\xf3</title></head>
+        <body>
+        Some text.
+        </body>
+        </html>
+        """
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+        self.assertEqual(og, {"og:title": "ó", "og:description": "Some text."})
+
+    def test_twitter_tag(self) -> None:
+        """Twitter card tags should be used if nothing else is available."""
+        html = b"""
+        <html>
+        <meta name="twitter:card" content="summary">
+        <meta name="twitter:description" content="Description">
+        <meta name="twitter:site" content="@matrixdotorg">
+        </html>
+        """
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+        self.assertEqual(
+            og,
+            {
+                "og:title": None,
+                "og:description": "Description",
+                "og:site_name": "@matrixdotorg",
+            },
+        )
+
+        # But they shouldn't override Open Graph values.
+        html = b"""
+        <html>
+        <meta name="twitter:card" content="summary">
+        <meta name="twitter:description" content="Description">
+        <meta property="og:description" content="Real Description">
+        <meta name="twitter:site" content="@matrixdotorg">
+        <meta property="og:site_name" content="matrix.org">
+        </html>
+        """
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+        self.assertEqual(
+            og,
+            {
+                "og:title": None,
+                "og:description": "Real Description",
+                "og:site_name": "matrix.org",
+            },
+        )
+
+    def test_nested_nodes(self) -> None:
+        """A body with some nested nodes. Tests that we iterate over children
+        in the right order (and don't reverse the order of the text)."""
+        html = b"""
+        <a href="somewhere">Welcome <b>the bold <u>and underlined text <svg>
+        with a cheeky SVG</svg></u> and <strong>some</strong> tail text</b></a>
+        """
+        tree = decode_body(html, "http://example.com/test.html")
+        og = parse_html_to_open_graph(tree)
+        self.assertEqual(
+            og,
+            {
+                "og:title": None,
+                "og:description": "Welcome\n\nthe bold\n\nand underlined text\n\nand\n\nsome\n\ntail text",
+            },
+        )
+
+
+class MediaEncodingTestCase(unittest.TestCase):
+    def test_meta_charset(self) -> None:
+        """A character encoding is found via the meta tag."""
+        encodings = _get_html_media_encodings(
+            b"""
+        <html>
+        <head><meta charset="ascii">
+        </head>
+        </html>
+        """,
+            "text/html",
+        )
+        self.assertEqual(list(encodings), ["ascii", "utf-8", "cp1252"])
+
+        # A less well-formed version.
+        encodings = _get_html_media_encodings(
+            b"""
+        <html>
+        <head>< meta charset = ascii>
+        </head>
+        </html>
+        """,
+            "text/html",
+        )
+        self.assertEqual(list(encodings), ["ascii", "utf-8", "cp1252"])
+
+    def test_meta_charset_underscores(self) -> None:
+        """A character encoding contains underscore."""
+        encodings = _get_html_media_encodings(
+            b"""
+        <html>
+        <head><meta charset="Shift_JIS">
+        </head>
+        </html>
+        """,
+            "text/html",
+        )
+        self.assertEqual(list(encodings), ["shift_jis", "utf-8", "cp1252"])
+
+    def test_xml_encoding(self) -> None:
+        """A character encoding is found via the meta tag."""
+        encodings = _get_html_media_encodings(
+            b"""
+        <?xml version="1.0" encoding="ascii"?>
+        <html>
+        </html>
+        """,
+            "text/html",
+        )
+        self.assertEqual(list(encodings), ["ascii", "utf-8", "cp1252"])
+
+    def test_meta_xml_encoding(self) -> None:
+        """Meta tags take precedence over XML encoding."""
+        encodings = _get_html_media_encodings(
+            b"""
+        <?xml version="1.0" encoding="ascii"?>
+        <html>
+        <head><meta charset="UTF-16">
+        </head>
+        </html>
+        """,
+            "text/html",
+        )
+        self.assertEqual(list(encodings), ["utf-16", "ascii", "utf-8", "cp1252"])
+
+    def test_content_type(self) -> None:
+        """A character encoding is found via the Content-Type header."""
+        # Test a few variations of the header.
+        headers = (
+            'text/html; charset="ascii";',
+            "text/html;charset=ascii;",
+            'text/html;  charset="ascii"',
+            "text/html; charset=ascii",
+            'text/html; charset="ascii;',
+            'text/html; charset=ascii";',
+        )
+        for header in headers:
+            encodings = _get_html_media_encodings(b"", header)
+            self.assertEqual(list(encodings), ["ascii", "utf-8", "cp1252"])
+
+    def test_fallback(self) -> None:
+        """A character encoding cannot be found in the body or header."""
+        encodings = _get_html_media_encodings(b"", "text/html")
+        self.assertEqual(list(encodings), ["utf-8", "cp1252"])
+
+    def test_duplicates(self) -> None:
+        """Ensure each encoding is only attempted once."""
+        encodings = _get_html_media_encodings(
+            b"""
+        <?xml version="1.0" encoding="utf8"?>
+        <html>
+        <head><meta charset="UTF-8">
+        </head>
+        </html>
+        """,
+            'text/html; charset="UTF_8"',
+        )
+        self.assertEqual(list(encodings), ["utf-8", "cp1252"])
+
+    def test_unknown_invalid(self) -> None:
+        """A character encoding should be ignored if it is unknown or invalid."""
+        encodings = _get_html_media_encodings(
+            b"""
+        <html>
+        <head><meta charset="invalid">
+        </head>
+        </html>
+        """,
+            'text/html; charset="invalid"',
+        )
+        self.assertEqual(list(encodings), ["utf-8", "cp1252"])
diff --git a/tests/media/test_media_storage.py b/tests/media/test_media_storage.py
new file mode 100644
index 0000000000..870047d0f2
--- /dev/null
+++ b/tests/media/test_media_storage.py
@@ -0,0 +1,792 @@
+# Copyright 2018-2021 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 os
+import shutil
+import tempfile
+from binascii import unhexlify
+from io import BytesIO
+from typing import Any, BinaryIO, ClassVar, Dict, List, Optional, Tuple, Union
+from unittest.mock import Mock
+from urllib import parse
+
+import attr
+from parameterized import parameterized, parameterized_class
+from PIL import Image as Image
+from typing_extensions import Literal
+
+from twisted.internet import defer
+from twisted.internet.defer import Deferred
+from twisted.test.proto_helpers import MemoryReactor
+
+from synapse.api.errors import Codes
+from synapse.events import EventBase
+from synapse.events.spamcheck import load_legacy_spam_checkers
+from synapse.http.types import QueryParams
+from synapse.logging.context import make_deferred_yieldable
+from synapse.media._base import FileInfo
+from synapse.media.filepath import MediaFilePaths
+from synapse.media.media_storage import MediaStorage, ReadableFileWrapper
+from synapse.media.storage_provider import FileStorageProviderBackend
+from synapse.module_api import ModuleApi
+from synapse.rest import admin
+from synapse.rest.client import login
+from synapse.server import HomeServer
+from synapse.types import JsonDict, RoomAlias
+from synapse.util import Clock
+
+from tests import unittest
+from tests.server import FakeChannel, FakeSite, make_request
+from tests.test_utils import SMALL_PNG
+from tests.utils import default_config
+
+
+class MediaStorageTests(unittest.HomeserverTestCase):
+    needs_threadpool = True
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.test_dir = tempfile.mkdtemp(prefix="synapse-tests-")
+        self.addCleanup(shutil.rmtree, self.test_dir)
+
+        self.primary_base_path = os.path.join(self.test_dir, "primary")
+        self.secondary_base_path = os.path.join(self.test_dir, "secondary")
+
+        hs.config.media.media_store_path = self.primary_base_path
+
+        storage_providers = [FileStorageProviderBackend(hs, self.secondary_base_path)]
+
+        self.filepaths = MediaFilePaths(self.primary_base_path)
+        self.media_storage = MediaStorage(
+            hs, self.primary_base_path, self.filepaths, storage_providers
+        )
+
+    def test_ensure_media_is_in_local_cache(self) -> None:
+        media_id = "some_media_id"
+        test_body = "Test\n"
+
+        # First we create a file that is in a storage provider but not in the
+        # local primary media store
+        rel_path = self.filepaths.local_media_filepath_rel(media_id)
+        secondary_path = os.path.join(self.secondary_base_path, rel_path)
+
+        os.makedirs(os.path.dirname(secondary_path))
+
+        with open(secondary_path, "w") as f:
+            f.write(test_body)
+
+        # Now we run ensure_media_is_in_local_cache, which should copy the file
+        # to the local cache.
+        file_info = FileInfo(None, media_id)
+
+        # This uses a real blocking threadpool so we have to wait for it to be
+        # actually done :/
+        x = defer.ensureDeferred(
+            self.media_storage.ensure_media_is_in_local_cache(file_info)
+        )
+
+        # Hotloop until the threadpool does its job...
+        self.wait_on_thread(x)
+
+        local_path = self.get_success(x)
+
+        self.assertTrue(os.path.exists(local_path))
+
+        # Asserts the file is under the expected local cache directory
+        self.assertEqual(
+            os.path.commonprefix([self.primary_base_path, local_path]),
+            self.primary_base_path,
+        )
+
+        with open(local_path) as f:
+            body = f.read()
+
+        self.assertEqual(test_body, body)
+
+
+@attr.s(auto_attribs=True, slots=True, frozen=True)
+class _TestImage:
+    """An image for testing thumbnailing with the expected results
+
+    Attributes:
+        data: The raw image to thumbnail
+        content_type: The type of the image as a content type, e.g. "image/png"
+        extension: The extension associated with the format, e.g. ".png"
+        expected_cropped: The expected bytes from cropped thumbnailing, or None if
+            test should just check for success.
+        expected_scaled: The expected bytes from scaled thumbnailing, or None if
+            test should just check for a valid image returned.
+        expected_found: True if the file should exist on the server, or False if
+            a 404/400 is expected.
+        unable_to_thumbnail: True if we expect the thumbnailing to fail (400), or
+            False if the thumbnailing should succeed or a normal 404 is expected.
+    """
+
+    data: bytes
+    content_type: bytes
+    extension: bytes
+    expected_cropped: Optional[bytes] = None
+    expected_scaled: Optional[bytes] = None
+    expected_found: bool = True
+    unable_to_thumbnail: bool = False
+
+
+@parameterized_class(
+    ("test_image",),
+    [
+        # small png
+        (
+            _TestImage(
+                SMALL_PNG,
+                b"image/png",
+                b".png",
+                unhexlify(
+                    b"89504e470d0a1a0a0000000d4948445200000020000000200806"
+                    b"000000737a7af40000001a49444154789cedc101010000008220"
+                    b"ffaf6e484001000000ef0610200001194334ee0000000049454e"
+                    b"44ae426082"
+                ),
+                unhexlify(
+                    b"89504e470d0a1a0a0000000d4948445200000001000000010806"
+                    b"0000001f15c4890000000d49444154789c636060606000000005"
+                    b"0001a5f645400000000049454e44ae426082"
+                ),
+            ),
+        ),
+        # small png with transparency.
+        (
+            _TestImage(
+                unhexlify(
+                    b"89504e470d0a1a0a0000000d49484452000000010000000101000"
+                    b"00000376ef9240000000274524e5300010194fdae0000000a4944"
+                    b"4154789c636800000082008177cd72b60000000049454e44ae426"
+                    b"082"
+                ),
+                b"image/png",
+                b".png",
+                # Note that we don't check the output since it varies across
+                # different versions of Pillow.
+            ),
+        ),
+        # small lossless webp
+        (
+            _TestImage(
+                unhexlify(
+                    b"524946461a000000574542505650384c0d0000002f0000001007"
+                    b"1011118888fe0700"
+                ),
+                b"image/webp",
+                b".webp",
+            ),
+        ),
+        # an empty file
+        (
+            _TestImage(
+                b"",
+                b"image/gif",
+                b".gif",
+                expected_found=False,
+                unable_to_thumbnail=True,
+            ),
+        ),
+    ],
+)
+class MediaRepoTests(unittest.HomeserverTestCase):
+    test_image: ClassVar[_TestImage]
+    hijack_auth = True
+    user_id = "@test:user"
+
+    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
+        self.fetches: List[
+            Tuple[
+                "Deferred[Tuple[bytes, Tuple[int, Dict[bytes, List[bytes]]]]]",
+                str,
+                str,
+                Optional[QueryParams],
+            ]
+        ] = []
+
+        def get_file(
+            destination: str,
+            path: str,
+            output_stream: BinaryIO,
+            args: Optional[QueryParams] = None,
+            retry_on_dns_fail: bool = True,
+            max_size: Optional[int] = None,
+            ignore_backoff: bool = False,
+        ) -> "Deferred[Tuple[int, Dict[bytes, List[bytes]]]]":
+            """A mock for MatrixFederationHttpClient.get_file."""
+
+            def write_to(
+                r: Tuple[bytes, Tuple[int, Dict[bytes, List[bytes]]]]
+            ) -> Tuple[int, Dict[bytes, List[bytes]]]:
+                data, response = r
+                output_stream.write(data)
+                return response
+
+            d: Deferred[Tuple[bytes, Tuple[int, Dict[bytes, List[bytes]]]]] = Deferred()
+            self.fetches.append((d, destination, path, args))
+            # Note that this callback changes the value held by d.
+            d_after_callback = d.addCallback(write_to)
+            return make_deferred_yieldable(d_after_callback)
+
+        # Mock out the homeserver's MatrixFederationHttpClient
+        client = Mock()
+        client.get_file = get_file
+
+        self.storage_path = self.mktemp()
+        self.media_store_path = self.mktemp()
+        os.mkdir(self.storage_path)
+        os.mkdir(self.media_store_path)
+
+        config = self.default_config()
+        config["media_store_path"] = self.media_store_path
+        config["max_image_pixels"] = 2000000
+
+        provider_config = {
+            "module": "synapse.media.storage_provider.FileStorageProviderBackend",
+            "store_local": True,
+            "store_synchronous": False,
+            "store_remote": True,
+            "config": {"directory": self.storage_path},
+        }
+        config["media_storage_providers"] = [provider_config]
+
+        hs = self.setup_test_homeserver(config=config, federation_http_client=client)
+
+        return hs
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        media_resource = hs.get_media_repository_resource()
+        self.download_resource = media_resource.children[b"download"]
+        self.thumbnail_resource = media_resource.children[b"thumbnail"]
+        self.store = hs.get_datastores().main
+        self.media_repo = hs.get_media_repository()
+
+        self.media_id = "example.com/12345"
+
+    def _req(
+        self, content_disposition: Optional[bytes], include_content_type: bool = True
+    ) -> FakeChannel:
+        channel = make_request(
+            self.reactor,
+            FakeSite(self.download_resource, self.reactor),
+            "GET",
+            self.media_id,
+            shorthand=False,
+            await_result=False,
+        )
+        self.pump()
+
+        # We've made one fetch, to example.com, using the media URL, and asking
+        # the other server not to do a remote fetch
+        self.assertEqual(len(self.fetches), 1)
+        self.assertEqual(self.fetches[0][1], "example.com")
+        self.assertEqual(
+            self.fetches[0][2], "/_matrix/media/r0/download/" + self.media_id
+        )
+        self.assertEqual(self.fetches[0][3], {"allow_remote": "false"})
+
+        headers = {
+            b"Content-Length": [b"%d" % (len(self.test_image.data))],
+        }
+
+        if include_content_type:
+            headers[b"Content-Type"] = [self.test_image.content_type]
+
+        if content_disposition:
+            headers[b"Content-Disposition"] = [content_disposition]
+
+        self.fetches[0][0].callback(
+            (self.test_image.data, (len(self.test_image.data), headers))
+        )
+
+        self.pump()
+        self.assertEqual(channel.code, 200)
+
+        return channel
+
+    def test_handle_missing_content_type(self) -> None:
+        channel = self._req(
+            b"inline; filename=out" + self.test_image.extension,
+            include_content_type=False,
+        )
+        headers = channel.headers
+        self.assertEqual(channel.code, 200)
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Type"), [b"application/octet-stream"]
+        )
+
+    def test_disposition_filename_ascii(self) -> None:
+        """
+        If the filename is filename=<ascii> then Synapse will decode it as an
+        ASCII string, and use filename= in the response.
+        """
+        channel = self._req(b"inline; filename=out" + self.test_image.extension)
+
+        headers = channel.headers
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Type"), [self.test_image.content_type]
+        )
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Disposition"),
+            [b"inline; filename=out" + self.test_image.extension],
+        )
+
+    def test_disposition_filenamestar_utf8escaped(self) -> None:
+        """
+        If the filename is filename=*utf8''<utf8 escaped> then Synapse will
+        correctly decode it as the UTF-8 string, and use filename* in the
+        response.
+        """
+        filename = parse.quote("\u2603".encode()).encode("ascii")
+        channel = self._req(
+            b"inline; filename*=utf-8''" + filename + self.test_image.extension
+        )
+
+        headers = channel.headers
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Type"), [self.test_image.content_type]
+        )
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Disposition"),
+            [b"inline; filename*=utf-8''" + filename + self.test_image.extension],
+        )
+
+    def test_disposition_none(self) -> None:
+        """
+        If there is no filename, one isn't passed on in the Content-Disposition
+        of the request.
+        """
+        channel = self._req(None)
+
+        headers = channel.headers
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Type"), [self.test_image.content_type]
+        )
+        self.assertEqual(headers.getRawHeaders(b"Content-Disposition"), None)
+
+    def test_thumbnail_crop(self) -> None:
+        """Test that a cropped remote thumbnail is available."""
+        self._test_thumbnail(
+            "crop",
+            self.test_image.expected_cropped,
+            expected_found=self.test_image.expected_found,
+            unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+        )
+
+    def test_thumbnail_scale(self) -> None:
+        """Test that a scaled remote thumbnail is available."""
+        self._test_thumbnail(
+            "scale",
+            self.test_image.expected_scaled,
+            expected_found=self.test_image.expected_found,
+            unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+        )
+
+    def test_invalid_type(self) -> None:
+        """An invalid thumbnail type is never available."""
+        self._test_thumbnail(
+            "invalid",
+            None,
+            expected_found=False,
+            unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+        )
+
+    @unittest.override_config(
+        {"thumbnail_sizes": [{"width": 32, "height": 32, "method": "scale"}]}
+    )
+    def test_no_thumbnail_crop(self) -> None:
+        """
+        Override the config to generate only scaled thumbnails, but request a cropped one.
+        """
+        self._test_thumbnail(
+            "crop",
+            None,
+            expected_found=False,
+            unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+        )
+
+    @unittest.override_config(
+        {"thumbnail_sizes": [{"width": 32, "height": 32, "method": "crop"}]}
+    )
+    def test_no_thumbnail_scale(self) -> None:
+        """
+        Override the config to generate only cropped thumbnails, but request a scaled one.
+        """
+        self._test_thumbnail(
+            "scale",
+            None,
+            expected_found=False,
+            unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+        )
+
+    def test_thumbnail_repeated_thumbnail(self) -> None:
+        """Test that fetching the same thumbnail works, and deleting the on disk
+        thumbnail regenerates it.
+        """
+        self._test_thumbnail(
+            "scale",
+            self.test_image.expected_scaled,
+            expected_found=self.test_image.expected_found,
+            unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+        )
+
+        if not self.test_image.expected_found:
+            return
+
+        # Fetching again should work, without re-requesting the image from the
+        # remote.
+        params = "?width=32&height=32&method=scale"
+        channel = make_request(
+            self.reactor,
+            FakeSite(self.thumbnail_resource, self.reactor),
+            "GET",
+            self.media_id + params,
+            shorthand=False,
+            await_result=False,
+        )
+        self.pump()
+
+        self.assertEqual(channel.code, 200)
+        if self.test_image.expected_scaled:
+            self.assertEqual(
+                channel.result["body"],
+                self.test_image.expected_scaled,
+                channel.result["body"],
+            )
+
+        # Deleting the thumbnail on disk then re-requesting it should work as
+        # Synapse should regenerate missing thumbnails.
+        origin, media_id = self.media_id.split("/")
+        info = self.get_success(self.store.get_cached_remote_media(origin, media_id))
+        assert info is not None
+        file_id = info["filesystem_id"]
+
+        thumbnail_dir = self.media_repo.filepaths.remote_media_thumbnail_dir(
+            origin, file_id
+        )
+        shutil.rmtree(thumbnail_dir, ignore_errors=True)
+
+        channel = make_request(
+            self.reactor,
+            FakeSite(self.thumbnail_resource, self.reactor),
+            "GET",
+            self.media_id + params,
+            shorthand=False,
+            await_result=False,
+        )
+        self.pump()
+
+        self.assertEqual(channel.code, 200)
+        if self.test_image.expected_scaled:
+            self.assertEqual(
+                channel.result["body"],
+                self.test_image.expected_scaled,
+                channel.result["body"],
+            )
+
+    def _test_thumbnail(
+        self,
+        method: str,
+        expected_body: Optional[bytes],
+        expected_found: bool,
+        unable_to_thumbnail: bool = False,
+    ) -> None:
+        """Test the given thumbnailing method works as expected.
+
+        Args:
+            method: The thumbnailing method to use (crop, scale).
+            expected_body: The expected bytes from thumbnailing, or None if
+                test should just check for a valid image.
+            expected_found: True if the file should exist on the server, or False if
+                a 404/400 is expected.
+            unable_to_thumbnail: True if we expect the thumbnailing to fail (400), or
+                False if the thumbnailing should succeed or a normal 404 is expected.
+        """
+
+        params = "?width=32&height=32&method=" + method
+        channel = make_request(
+            self.reactor,
+            FakeSite(self.thumbnail_resource, self.reactor),
+            "GET",
+            self.media_id + params,
+            shorthand=False,
+            await_result=False,
+        )
+        self.pump()
+
+        headers = {
+            b"Content-Length": [b"%d" % (len(self.test_image.data))],
+            b"Content-Type": [self.test_image.content_type],
+        }
+        self.fetches[0][0].callback(
+            (self.test_image.data, (len(self.test_image.data), headers))
+        )
+        self.pump()
+
+        if expected_found:
+            self.assertEqual(channel.code, 200)
+
+            self.assertEqual(
+                channel.headers.getRawHeaders(b"Cross-Origin-Resource-Policy"),
+                [b"cross-origin"],
+            )
+
+            if expected_body is not None:
+                self.assertEqual(
+                    channel.result["body"], expected_body, channel.result["body"]
+                )
+            else:
+                # ensure that the result is at least some valid image
+                Image.open(BytesIO(channel.result["body"]))
+        elif unable_to_thumbnail:
+            # A 400 with a JSON body.
+            self.assertEqual(channel.code, 400)
+            self.assertEqual(
+                channel.json_body,
+                {
+                    "errcode": "M_UNKNOWN",
+                    "error": "Cannot find any thumbnails for the requested media ([b'example.com', b'12345']). This might mean the media is not a supported_media_format=(image/jpeg, image/jpg, image/webp, image/gif, image/png) or that thumbnailing failed for some other reason. (Dynamic thumbnails are disabled on this server.)",
+                },
+            )
+        else:
+            # A 404 with a JSON body.
+            self.assertEqual(channel.code, 404)
+            self.assertEqual(
+                channel.json_body,
+                {
+                    "errcode": "M_NOT_FOUND",
+                    "error": "Not found [b'example.com', b'12345']",
+                },
+            )
+
+    @parameterized.expand([("crop", 16), ("crop", 64), ("scale", 16), ("scale", 64)])
+    def test_same_quality(self, method: str, desired_size: int) -> None:
+        """Test that choosing between thumbnails with the same quality rating succeeds.
+
+        We are not particular about which thumbnail is chosen."""
+        self.assertIsNotNone(
+            self.thumbnail_resource._select_thumbnail(
+                desired_width=desired_size,
+                desired_height=desired_size,
+                desired_method=method,
+                desired_type=self.test_image.content_type,
+                # Provide two identical thumbnails which are guaranteed to have the same
+                # quality rating.
+                thumbnail_infos=[
+                    {
+                        "thumbnail_width": 32,
+                        "thumbnail_height": 32,
+                        "thumbnail_method": method,
+                        "thumbnail_type": self.test_image.content_type,
+                        "thumbnail_length": 256,
+                        "filesystem_id": f"thumbnail1{self.test_image.extension.decode()}",
+                    },
+                    {
+                        "thumbnail_width": 32,
+                        "thumbnail_height": 32,
+                        "thumbnail_method": method,
+                        "thumbnail_type": self.test_image.content_type,
+                        "thumbnail_length": 256,
+                        "filesystem_id": f"thumbnail2{self.test_image.extension.decode()}",
+                    },
+                ],
+                file_id=f"image{self.test_image.extension.decode()}",
+                url_cache=None,
+                server_name=None,
+            )
+        )
+
+    def test_x_robots_tag_header(self) -> None:
+        """
+        Tests that the `X-Robots-Tag` header is present, which informs web crawlers
+        to not index, archive, or follow links in media.
+        """
+        channel = self._req(b"inline; filename=out" + self.test_image.extension)
+
+        headers = channel.headers
+        self.assertEqual(
+            headers.getRawHeaders(b"X-Robots-Tag"),
+            [b"noindex, nofollow, noarchive, noimageindex"],
+        )
+
+    def test_cross_origin_resource_policy_header(self) -> None:
+        """
+        Test that the Cross-Origin-Resource-Policy header is set to "cross-origin"
+        allowing web clients to embed media from the downloads API.
+        """
+        channel = self._req(b"inline; filename=out" + self.test_image.extension)
+
+        headers = channel.headers
+
+        self.assertEqual(
+            headers.getRawHeaders(b"Cross-Origin-Resource-Policy"),
+            [b"cross-origin"],
+        )
+
+
+class TestSpamCheckerLegacy:
+    """A spam checker module that rejects all media that includes the bytes
+    `evil`.
+
+    Uses the legacy Spam-Checker API.
+    """
+
+    def __init__(self, config: Dict[str, Any], api: ModuleApi) -> None:
+        self.config = config
+        self.api = api
+
+    @staticmethod
+    def parse_config(config: Dict[str, Any]) -> Dict[str, Any]:
+        return config
+
+    async def check_event_for_spam(self, event: EventBase) -> Union[bool, str]:
+        return False  # allow all events
+
+    async def user_may_invite(
+        self,
+        inviter_userid: str,
+        invitee_userid: str,
+        room_id: str,
+    ) -> bool:
+        return True  # allow all invites
+
+    async def user_may_create_room(self, userid: str) -> bool:
+        return True  # allow all room creations
+
+    async def user_may_create_room_alias(
+        self, userid: str, room_alias: RoomAlias
+    ) -> bool:
+        return True  # allow all room aliases
+
+    async def user_may_publish_room(self, userid: str, room_id: str) -> bool:
+        return True  # allow publishing of all rooms
+
+    async def check_media_file_for_spam(
+        self, file_wrapper: ReadableFileWrapper, file_info: FileInfo
+    ) -> bool:
+        buf = BytesIO()
+        await file_wrapper.write_chunks_to(buf.write)
+
+        return b"evil" in buf.getvalue()
+
+
+class SpamCheckerTestCaseLegacy(unittest.HomeserverTestCase):
+    servlets = [
+        login.register_servlets,
+        admin.register_servlets,
+    ]
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.user = self.register_user("user", "pass")
+        self.tok = self.login("user", "pass")
+
+        # Allow for uploading and downloading to/from the media repo
+        self.media_repo = hs.get_media_repository_resource()
+        self.download_resource = self.media_repo.children[b"download"]
+        self.upload_resource = self.media_repo.children[b"upload"]
+
+        load_legacy_spam_checkers(hs)
+
+    def default_config(self) -> Dict[str, Any]:
+        config = default_config("test")
+
+        config.update(
+            {
+                "spam_checker": [
+                    {
+                        "module": TestSpamCheckerLegacy.__module__
+                        + ".TestSpamCheckerLegacy",
+                        "config": {},
+                    }
+                ]
+            }
+        )
+
+        return config
+
+    def test_upload_innocent(self) -> None:
+        """Attempt to upload some innocent data that should be allowed."""
+        self.helper.upload_media(
+            self.upload_resource, SMALL_PNG, tok=self.tok, expect_code=200
+        )
+
+    def test_upload_ban(self) -> None:
+        """Attempt to upload some data that includes bytes "evil", which should
+        get rejected by the spam checker.
+        """
+
+        data = b"Some evil data"
+
+        self.helper.upload_media(
+            self.upload_resource, data, tok=self.tok, expect_code=400
+        )
+
+
+EVIL_DATA = b"Some evil data"
+EVIL_DATA_EXPERIMENT = b"Some evil data to trigger the experimental tuple API"
+
+
+class SpamCheckerTestCase(unittest.HomeserverTestCase):
+    servlets = [
+        login.register_servlets,
+        admin.register_servlets,
+    ]
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.user = self.register_user("user", "pass")
+        self.tok = self.login("user", "pass")
+
+        # Allow for uploading and downloading to/from the media repo
+        self.media_repo = hs.get_media_repository_resource()
+        self.download_resource = self.media_repo.children[b"download"]
+        self.upload_resource = self.media_repo.children[b"upload"]
+
+        hs.get_module_api().register_spam_checker_callbacks(
+            check_media_file_for_spam=self.check_media_file_for_spam
+        )
+
+    async def check_media_file_for_spam(
+        self, file_wrapper: ReadableFileWrapper, file_info: FileInfo
+    ) -> Union[Codes, Literal["NOT_SPAM"], Tuple[Codes, JsonDict]]:
+        buf = BytesIO()
+        await file_wrapper.write_chunks_to(buf.write)
+
+        if buf.getvalue() == EVIL_DATA:
+            return Codes.FORBIDDEN
+        elif buf.getvalue() == EVIL_DATA_EXPERIMENT:
+            return (Codes.FORBIDDEN, {})
+        else:
+            return "NOT_SPAM"
+
+    def test_upload_innocent(self) -> None:
+        """Attempt to upload some innocent data that should be allowed."""
+        self.helper.upload_media(
+            self.upload_resource, SMALL_PNG, tok=self.tok, expect_code=200
+        )
+
+    def test_upload_ban(self) -> None:
+        """Attempt to upload some data that includes bytes "evil", which should
+        get rejected by the spam checker.
+        """
+
+        self.helper.upload_media(
+            self.upload_resource, EVIL_DATA, tok=self.tok, expect_code=400
+        )
+
+        self.helper.upload_media(
+            self.upload_resource,
+            EVIL_DATA_EXPERIMENT,
+            tok=self.tok,
+            expect_code=400,
+        )
diff --git a/tests/media/test_oembed.py b/tests/media/test_oembed.py
new file mode 100644
index 0000000000..c8bf8421da
--- /dev/null
+++ b/tests/media/test_oembed.py
@@ -0,0 +1,162 @@
+#  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 parameterized import parameterized
+
+from twisted.test.proto_helpers import MemoryReactor
+
+from synapse.media.oembed import OEmbedProvider, OEmbedResult
+from synapse.server import HomeServer
+from synapse.types import JsonDict
+from synapse.util import Clock
+
+from tests.unittest import HomeserverTestCase
+
+try:
+    import lxml
+except ImportError:
+    lxml = None
+
+
+class OEmbedTests(HomeserverTestCase):
+    if not lxml:
+        skip = "url preview feature requires lxml"
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.oembed = OEmbedProvider(hs)
+
+    def parse_response(self, response: JsonDict) -> OEmbedResult:
+        return self.oembed.parse_oembed_response(
+            "https://test", json.dumps(response).encode("utf-8")
+        )
+
+    def test_version(self) -> None:
+        """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})
+            # 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)
+
+    def test_cache_age(self) -> None:
+        """Ensure a cache-age is parsed properly."""
+        # Correct-ish cache ages are allowed.
+        for cache_age in ("1", 1.0, 1):
+            result = self.parse_response({"cache_age": cache_age})
+            self.assertEqual(result.cache_age, 1000)
+
+        # Invalid cache ages are ignored.
+        for cache_age in ("invalid", {}):
+            result = self.parse_response({"cache_age": cache_age})
+            self.assertIsNone(result.cache_age)
+
+        # Cache age is optional.
+        result = self.parse_response({})
+        self.assertIsNone(result.cache_age)
+
+    @parameterized.expand(
+        [
+            ("title", "title"),
+            ("provider_name", "site_name"),
+            ("thumbnail_url", "image"),
+        ],
+        name_func=lambda func, num, p: f"{func.__name__}_{p.args[0]}",
+    )
+    def test_property(self, oembed_property: str, open_graph_property: str) -> None:
+        """Test properties which must be strings."""
+        result = self.parse_response({oembed_property: "test"})
+        self.assertIn(f"og:{open_graph_property}", result.open_graph_result)
+        self.assertEqual(result.open_graph_result[f"og:{open_graph_property}"], "test")
+
+        result = self.parse_response({oembed_property: 1})
+        self.assertNotIn(f"og:{open_graph_property}", result.open_graph_result)
+
+    def test_author_name(self) -> None:
+        """Test the author_name property."""
+        result = self.parse_response({"author_name": "test"})
+        self.assertEqual(result.author_name, "test")
+
+        result = self.parse_response({"author_name": 1})
+        self.assertIsNone(result.author_name)
+
+    def test_rich(self) -> None:
+        """Test a type of rich."""
+        result = self.parse_response({"html": "test<img src='foo'>", "type": "rich"})
+        self.assertIn("og:description", result.open_graph_result)
+        self.assertIn("og:image", result.open_graph_result)
+        self.assertEqual(result.open_graph_result["og:description"], "test")
+        self.assertEqual(result.open_graph_result["og:image"], "foo")
+
+        result = self.parse_response({"type": "rich"})
+        self.assertNotIn("og:description", result.open_graph_result)
+
+        result = self.parse_response({"html": 1, "type": "rich"})
+        self.assertNotIn("og:description", result.open_graph_result)
+
+    def test_photo(self) -> None:
+        """Test a type of photo."""
+        result = self.parse_response({"url": "test", "type": "photo"})
+        self.assertIn("og:image", result.open_graph_result)
+        self.assertEqual(result.open_graph_result["og:image"], "test")
+
+        result = self.parse_response({"type": "photo"})
+        self.assertNotIn("og:image", result.open_graph_result)
+
+        result = self.parse_response({"url": 1, "type": "photo"})
+        self.assertNotIn("og:image", result.open_graph_result)
+
+    def test_video(self) -> None:
+        """Test a type of video."""
+        result = self.parse_response({"html": "test", "type": "video"})
+        self.assertIn("og:type", result.open_graph_result)
+        self.assertEqual(result.open_graph_result["og:type"], "video.other")
+        self.assertIn("og:description", result.open_graph_result)
+        self.assertEqual(result.open_graph_result["og:description"], "test")
+
+        result = self.parse_response({"type": "video"})
+        self.assertIn("og:type", result.open_graph_result)
+        self.assertEqual(result.open_graph_result["og:type"], "video.other")
+        self.assertNotIn("og:description", result.open_graph_result)
+
+        result = self.parse_response({"url": 1, "type": "video"})
+        self.assertIn("og:type", result.open_graph_result)
+        self.assertEqual(result.open_graph_result["og:type"], "video.other")
+        self.assertNotIn("og:description", result.open_graph_result)
+
+    def test_link(self) -> None:
+        """Test type of link."""
+        result = self.parse_response({"type": "link"})
+        self.assertIn("og:type", result.open_graph_result)
+        self.assertEqual(result.open_graph_result["og:type"], "website")
+
+    def test_title_html_entities(self) -> None:
+        """Test HTML entities in title"""
+        result = self.parse_response(
+            {"title": "Why JSON isn&#8217;t a Good Configuration Language"}
+        )
+        self.assertEqual(
+            result.open_graph_result["og:title"],
+            "Why JSON isn’t a Good Configuration Language",
+        )