diff --git a/synapse/rest/media/download_resource.py b/synapse/rest/media/download_resource.py
new file mode 100644
index 0000000000..8f270cf4cc
--- /dev/null
+++ b/synapse/rest/media/download_resource.py
@@ -0,0 +1,75 @@
+# Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2020-2021 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 logging
+from typing import TYPE_CHECKING
+
+from synapse.http.server import (
+ DirectServeJsonResource,
+ set_corp_headers,
+ set_cors_headers,
+)
+from synapse.http.servlet import parse_boolean
+from synapse.http.site import SynapseRequest
+from synapse.media._base import parse_media_id, respond_404
+
+if TYPE_CHECKING:
+ from synapse.media.media_repository import MediaRepository
+ from synapse.server import HomeServer
+
+logger = logging.getLogger(__name__)
+
+
+class DownloadResource(DirectServeJsonResource):
+ isLeaf = True
+
+ def __init__(self, hs: "HomeServer", media_repo: "MediaRepository"):
+ super().__init__()
+ self.media_repo = media_repo
+ self.server_name = hs.hostname
+
+ async def _async_render_GET(self, request: SynapseRequest) -> None:
+ set_cors_headers(request)
+ set_corp_headers(request)
+ request.setHeader(
+ b"Content-Security-Policy",
+ b"sandbox;"
+ b" default-src 'none';"
+ b" script-src 'none';"
+ b" plugin-types application/pdf;"
+ b" style-src 'unsafe-inline';"
+ b" media-src 'self';"
+ b" object-src 'self';",
+ )
+ # Limited non-standard form of CSP for IE11
+ request.setHeader(b"X-Content-Security-Policy", b"sandbox;")
+ request.setHeader(
+ b"Referrer-Policy",
+ b"no-referrer",
+ )
+ server_name, media_id, name = parse_media_id(request)
+ if server_name == self.server_name:
+ await self.media_repo.get_local_media(request, media_id, name)
+ else:
+ allow_remote = parse_boolean(request, "allow_remote", default=True)
+ if not allow_remote:
+ logger.info(
+ "Rejecting request for remote media %s/%s due to allow_remote",
+ server_name,
+ media_id,
+ )
+ respond_404(request)
+ return
+
+ await self.media_repo.get_remote_media(request, server_name, media_id, name)
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