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#
# This file is licensed under the Affero General Public License (AGPL) version 3.
#
# Copyright 2020-2021 The Matrix.org Foundation C.I.C.
# Copyright 2016 OpenMarket Ltd
# Copyright (C) 2023 New Vector, Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# See the GNU Affero General Public License for more details:
# <https://www.gnu.org/licenses/agpl-3.0.html>.
#
# Originally licensed under the Apache License, Version 2.0:
# <http://www.apache.org/licenses/LICENSE-2.0>.
#
# [This file includes modifications made by New Vector Limited]
#
#
import re
from typing import TYPE_CHECKING
from synapse.http.server import respond_with_json_bytes
from synapse.http.servlet import RestServlet, parse_integer, parse_string
from synapse.http.site import SynapseRequest
from synapse.media.media_storage import MediaStorage
if TYPE_CHECKING:
from synapse.media.media_repository import MediaRepository
from synapse.server import HomeServer
class PreviewUrlResource(RestServlet):
"""
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.
"""
PATTERNS = [re.compile("/_matrix/media/(r0|v3|v1)/preview_url$")]
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
assert self.media_repo.url_previewer is not None
self.url_previewer = self.media_repo.url_previewer
async def on_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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