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# Copyright 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.
from typing import TYPE_CHECKING
from synapse.http.server import (
DirectServeJsonResource,
respond_with_json,
respond_with_json_bytes,
)
from synapse.http.servlet import parse_integer, parse_string
from synapse.http.site import SynapseRequest
from synapse.media.media_storage import MediaStorage
from synapse.media.url_previewer import UrlPreviewer
if TYPE_CHECKING:
from synapse.media.media_repository import MediaRepository
from synapse.server import HomeServer
class PreviewUrlResource(DirectServeJsonResource):
"""
The `GET /_matrix/media/r0/preview_url` endpoint provides a generic preview API
for URLs which outputs Open Graph (https://ogp.me/) responses (with some Matrix
specific additions).
This does have trade-offs compared to other designs:
* Pros:
* Simple and flexible; can be used by any clients at any point
* Cons:
* If each homeserver provides one of these independently, all the homeservers in a
room may needlessly DoS the target URI
* The URL metadata must be stored somewhere, rather than just using Matrix
itself to store the media.
* Matrix cannot be used to distribute the metadata between homeservers.
"""
isLeaf = True
def __init__(
self,
hs: "HomeServer",
media_repo: "MediaRepository",
media_storage: MediaStorage,
):
super().__init__()
self.auth = hs.get_auth()
self.clock = hs.get_clock()
self.media_repo = media_repo
self.media_storage = media_storage
self._url_previewer = UrlPreviewer(hs, media_repo, media_storage)
async def _async_render_OPTIONS(self, request: SynapseRequest) -> None:
request.setHeader(b"Allow", b"OPTIONS, GET")
respond_with_json(request, 200, {}, send_cors=True)
async def _async_render_GET(self, request: SynapseRequest) -> None:
# XXX: if get_user_by_req fails, what should we do in an async render?
requester = await self.auth.get_user_by_req(request)
url = parse_string(request, "url", required=True)
ts = parse_integer(request, "ts")
if ts is None:
ts = self.clock.time_msec()
og = await self._url_previewer.preview(url, requester.user, ts)
respond_with_json_bytes(request, 200, og, send_cors=True)
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