Support MSC3916 by adding a federation /download endpoint

synapse/media/media_repository.py

@@ -53,10 +53,11 @@
     ThumbnailInfo,
     get_filename_from_headers,
     respond_404,
+    respond_with_multipart_responder,
     respond_with_responder,
 )
 from synapse.media.filepath import MediaFilePaths
-from synapse.media.media_storage import MediaStorage
+from synapse.media.media_storage import MediaStorage, MultipartResponder
 from synapse.media.storage_provider import StorageProviderWrapper
 from synapse.media.thumbnailer import Thumbnailer, ThumbnailError
 from synapse.media.url_previewer import UrlPreviewer
@@ -70,6 +71,7 @@
 if TYPE_CHECKING:
     from synapse.server import HomeServer
 
+
 logger = logging.getLogger(__name__)
 
 # How often to run the background job to update the "recently accessed"
@@ -422,6 +424,7 @@ async def get_local_media(
         media_id: str,
         name: Optional[str],
         max_timeout_ms: int,
+        federation: bool = False,
     ) -> None:
         """Responds to requests for local media, if exists, or returns 404.
 
@@ -433,6 +436,7 @@ async def get_local_media(
                 the filename in the Content-Disposition header of the response.
             max_timeout_ms: the maximum number of milliseconds to wait for the
                 media to be uploaded.
+            federation: whether the local media being fetched is for a federation request
 
         Returns:
             Resolves once a response has successfully been written to request
@@ -452,10 +456,17 @@ async def get_local_media(
 
         file_info = FileInfo(None, media_id, url_cache=bool(url_cache))
 
-        responder = await self.media_storage.fetch_media(file_info)
-        await respond_with_responder(
-            request, responder, media_type, media_length, upload_name
+        responder = await self.media_storage.fetch_media(
+            file_info, media_info, federation
         )
+        if federation:
+            # this really should be a Multipart responder but just in case
+            assert isinstance(responder, MultipartResponder)
+            await respond_with_multipart_responder(request, responder, media_info)
+        else:
+            await respond_with_responder(
+                request, responder, media_type, media_length, upload_name
+            )
 
     async def get_remote_media(
         self,

synapse/media/storage_provider.py

@@ -24,14 +24,16 @@
 import os
 import shutil
 from typing import TYPE_CHECKING, Callable, Optional
+from uuid import uuid4
 
 from synapse.config._base import Config
 from synapse.logging.context import defer_to_thread, run_in_background
 from synapse.logging.opentracing import start_active_span, trace_with_opname
 from synapse.util.async_helpers import maybe_awaitable
 
+from ..storage.databases.main.media_repository import LocalMedia
 from ._base import FileInfo, Responder
-from .media_storage import FileResponder
+from .media_storage import FileResponder, MultipartResponder
 
 logger = logging.getLogger(__name__)
 
@@ -55,13 +57,21 @@ async def store_file(self, path: str, file_info: FileInfo) -> None:
         """
 
     @abc.abstractmethod
-    async def fetch(self, path: str, file_info: FileInfo) -> Optional[Responder]:
+    async def fetch(
+        self,
+        path: str,
+        file_info: FileInfo,
+        media_info: Optional[LocalMedia] = None,
+        federation: bool = False,
+    ) -> Optional[Responder]:
         """Attempt to fetch the file described by file_info and stream it
         into writer.
 
         Args:
             path: Relative path of file in local cache
             file_info: The metadata of the file.
+            media_info: metadata of the media item
+            federation: Whether the requested media is for a federation request
 
         Returns:
             Returns a Responder if the provider has the file, otherwise returns None.
@@ -124,15 +134,23 @@ async def store() -> None:
             run_in_background(store)
 
     @trace_with_opname("StorageProviderWrapper.fetch")
-    async def fetch(self, path: str, file_info: FileInfo) -> Optional[Responder]:
+    async def fetch(
+        self,
+        path: str,
+        file_info: FileInfo,
+        media_info: Optional[LocalMedia] = None,
+        federation: bool = False,
+    ) -> Optional[Responder]:
         if file_info.url_cache:
             # Files in the URL preview cache definitely aren't stored here,
             # so avoid any potentially slow I/O or network access.
             return None
 
         # store_file is supposed to return an Awaitable, but guard
         # against improper implementations.
-        return await maybe_awaitable(self.backend.fetch(path, file_info))
+        return await maybe_awaitable(
+            self.backend.fetch(path, file_info, media_info, federation)
+        )
 
 
 class FileStorageProviderBackend(StorageProvider):
@@ -172,11 +190,23 @@ async def store_file(self, path: str, file_info: FileInfo) -> None:
             )
 
     @trace_with_opname("FileStorageProviderBackend.fetch")
-    async def fetch(self, path: str, file_info: FileInfo) -> Optional[Responder]:
+    async def fetch(
+        self,
+        path: str,
+        file_info: FileInfo,
+        media_info: Optional[LocalMedia] = None,
+        federation: bool = False,
+    ) -> Optional[Responder]:
         """See StorageProvider.fetch"""
 
         backup_fname = os.path.join(self.base_directory, path)
         if os.path.isfile(backup_fname):
+            if federation:
+                assert media_info is not None
+                boundary = uuid4().hex.encode("ascii")
+                return MultipartResponder(
+                    open(backup_fname, "rb"), media_info, boundary
+                )
             return FileResponder(open(backup_fname, "rb"))
 
         return None