diff options
Diffstat (limited to 'synapse/rest/media/v1/preview_url_resource.py')
| -rw-r--r-- | synapse/rest/media/v1/preview_url_resource.py | 256 |
1 files changed, 78 insertions, 178 deletions
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py index 0f051d4041..f108da05db 100644 --- a/synapse/rest/media/v1/preview_url_resource.py +++ b/synapse/rest/media/v1/preview_url_resource.py @@ -22,7 +22,7 @@ import re import shutil import sys import traceback -from typing import TYPE_CHECKING, Any, Dict, Generator, Iterable, Optional, Union +from typing import TYPE_CHECKING, Dict, Generator, Iterable, Optional, Union from urllib import parse as urlparse import attr @@ -43,6 +43,8 @@ from synapse.logging.context import make_deferred_yieldable, run_in_background from synapse.metrics.background_process_metrics import run_as_background_process from synapse.rest.media.v1._base import get_filename_from_headers from synapse.rest.media.v1.media_storage import MediaStorage +from synapse.rest.media.v1.oembed import OEmbedError, OEmbedProvider +from synapse.types import JsonDict from synapse.util import json_encoder from synapse.util.async_helpers import ObservableDeferred from synapse.util.caches.expiringcache import ExpiringCache @@ -71,65 +73,44 @@ OG_TAG_VALUE_MAXLEN = 1000 ONE_HOUR = 60 * 60 * 1000 -# A map of globs to API endpoints. -_oembed_globs = { - # Twitter. - "https://publish.twitter.com/oembed": [ - "https://twitter.com/*/status/*", - "https://*.twitter.com/*/status/*", - "https://twitter.com/*/moments/*", - "https://*.twitter.com/*/moments/*", - # Include the HTTP versions too. - "http://twitter.com/*/status/*", - "http://*.twitter.com/*/status/*", - "http://twitter.com/*/moments/*", - "http://*.twitter.com/*/moments/*", - ], -} -# Convert the globs to regular expressions. -_oembed_patterns = {} -for endpoint, globs in _oembed_globs.items(): - for glob in globs: - # Convert the glob into a sane regular expression to match against. The - # rules followed will be slightly different for the domain portion vs. - # the rest. - # - # 1. The scheme must be one of HTTP / HTTPS (and have no globs). - # 2. The domain can have globs, but we limit it to characters that can - # reasonably be a domain part. - # TODO: This does not attempt to handle Unicode domain names. - # 3. Other parts allow a glob to be any one, or more, characters. - results = urlparse.urlparse(glob) - - # Ensure the scheme does not have wildcards (and is a sane scheme). - if results.scheme not in {"http", "https"}: - raise ValueError("Insecure oEmbed glob scheme: %s" % (results.scheme,)) - - pattern = urlparse.urlunparse( - [ - results.scheme, - re.escape(results.netloc).replace("\\*", "[a-zA-Z0-9_-]+"), - ] - + [re.escape(part).replace("\\*", ".+") for part in results[2:]] - ) - _oembed_patterns[re.compile(pattern)] = endpoint +@attr.s(slots=True, frozen=True, auto_attribs=True) +class MediaInfo: + """ + Information parsed from downloading media being previewed. + """ -@attr.s(slots=True) -class OEmbedResult: - # Either HTML content or URL must be provided. - html = attr.ib(type=Optional[str]) - url = attr.ib(type=Optional[str]) - title = attr.ib(type=Optional[str]) - # Number of seconds to cache the content. - cache_age = attr.ib(type=int) + # The Content-Type header of the response. + media_type: str + # The length (in bytes) of the downloaded media. + media_length: int + # The media filename, according to the server. This is parsed from the + # returned headers, if possible. + download_name: Optional[str] + # The time of the preview. + created_ts_ms: int + # Information from the media storage provider about where the file is stored + # on disk. + filesystem_id: str + filename: str + # The URI being previewed. + uri: str + # The HTTP response code. + response_code: int + # The timestamp (in milliseconds) of when this preview expires. + expires: int + # The ETag header of the response. + etag: Optional[str] -class OEmbedError(Exception): - """An error occurred processing the oEmbed object.""" +class PreviewUrlResource(DirectServeJsonResource): + """ + Generating URL previews is a complicated task which many potential pitfalls. + See docs/development/url_previews.md for discussion of the design and + algorithm followed in this module. + """ -class PreviewUrlResource(DirectServeJsonResource): isLeaf = True def __init__( @@ -157,6 +138,8 @@ class PreviewUrlResource(DirectServeJsonResource): self.primary_base_path = media_repo.primary_base_path self.media_storage = media_storage + self._oembed = OEmbedProvider(hs, self.client) + # We run the background jobs if we're the instance specified (or no # instance is specified, where we assume there is only one instance # serving media). @@ -275,18 +258,17 @@ class PreviewUrlResource(DirectServeJsonResource): logger.debug("got media_info of '%s'", media_info) - if _is_media(media_info["media_type"]): - file_id = media_info["filesystem_id"] + if _is_media(media_info.media_type): + file_id = media_info.filesystem_id dims = await self.media_repo._generate_thumbnails( - None, file_id, file_id, media_info["media_type"], url_cache=True + None, file_id, file_id, media_info.media_type, url_cache=True ) og = { - "og:description": media_info["download_name"], - "og:image": "mxc://%s/%s" - % (self.server_name, media_info["filesystem_id"]), - "og:image:type": media_info["media_type"], - "matrix:image:size": media_info["media_length"], + "og:description": media_info.download_name, + "og:image": f"mxc://{self.server_name}/{media_info.filesystem_id}", + "og:image:type": media_info.media_type, + "matrix:image:size": media_info.media_length, } if dims: @@ -296,14 +278,14 @@ class PreviewUrlResource(DirectServeJsonResource): logger.warning("Couldn't get dims for %s" % url) # define our OG response for this media - elif _is_html(media_info["media_type"]): + elif _is_html(media_info.media_type): # TODO: somehow stop a big HTML tree from exploding synapse's RAM - with open(media_info["filename"], "rb") as file: + with open(media_info.filename, "rb") as file: body = file.read() - encoding = get_html_media_encoding(body, media_info["media_type"]) - og = decode_and_calc_og(body, media_info["uri"], encoding) + encoding = get_html_media_encoding(body, media_info.media_type) + og = decode_and_calc_og(body, media_info.uri, encoding) # pre-cache the image for posterity # FIXME: it might be cleaner to use the same flow as the main /preview_url @@ -311,14 +293,14 @@ class PreviewUrlResource(DirectServeJsonResource): # just rely on the caching on the master request to speed things up. if "og:image" in og and og["og:image"]: image_info = await self._download_url( - _rebase_url(og["og:image"], media_info["uri"]), user + _rebase_url(og["og:image"], media_info.uri), user ) - if _is_media(image_info["media_type"]): + if _is_media(image_info.media_type): # TODO: make sure we don't choke on white-on-transparent images - file_id = image_info["filesystem_id"] + file_id = image_info.filesystem_id dims = await self.media_repo._generate_thumbnails( - None, file_id, file_id, image_info["media_type"], url_cache=True + None, file_id, file_id, image_info.media_type, url_cache=True ) if dims: og["og:image:width"] = dims["width"] @@ -326,12 +308,11 @@ class PreviewUrlResource(DirectServeJsonResource): else: logger.warning("Couldn't get dims for %s", og["og:image"]) - og["og:image"] = "mxc://%s/%s" % ( - self.server_name, - image_info["filesystem_id"], - ) - og["og:image:type"] = image_info["media_type"] - og["matrix:image:size"] = image_info["media_length"] + og[ + "og:image" + ] = f"mxc://{self.server_name}/{image_info.filesystem_id}" + og["og:image:type"] = image_info.media_type + og["matrix:image:size"] = image_info.media_length else: del og["og:image"] else: @@ -357,98 +338,17 @@ class PreviewUrlResource(DirectServeJsonResource): # store OG in history-aware DB cache await self.store.store_url_cache( url, - media_info["response_code"], - media_info["etag"], - media_info["expires"] + media_info["created_ts"], + media_info.response_code, + media_info.etag, + media_info.expires + media_info.created_ts_ms, jsonog, - media_info["filesystem_id"], - media_info["created_ts"], + media_info.filesystem_id, + media_info.created_ts_ms, ) return jsonog.encode("utf8") - def _get_oembed_url(self, url: str) -> Optional[str]: - """ - Check whether the URL should be downloaded as oEmbed content instead. - - Args: - url: The URL to check. - - Returns: - A URL to use instead or None if the original URL should be used. - """ - for url_pattern, endpoint in _oembed_patterns.items(): - if url_pattern.fullmatch(url): - return endpoint - - # No match. - return None - - async def _get_oembed_content(self, endpoint: str, url: str) -> OEmbedResult: - """ - Request content from an oEmbed endpoint. - - Args: - endpoint: The oEmbed API endpoint. - url: The URL to pass to the API. - - Returns: - An object representing the metadata returned. - - Raises: - OEmbedError if fetching or parsing of the oEmbed information fails. - """ - try: - logger.debug("Trying to get oEmbed content for url '%s'", url) - result = await self.client.get_json( - endpoint, - # TODO Specify max height / width. - # Note that only the JSON format is supported. - args={"url": url}, - ) - - # Ensure there's a version of 1.0. - if result.get("version") != "1.0": - raise OEmbedError("Invalid version: %s" % (result.get("version"),)) - - oembed_type = result.get("type") - - # Ensure the cache age is None or an int. - cache_age = result.get("cache_age") - if cache_age: - cache_age = int(cache_age) - - oembed_result = OEmbedResult(None, None, result.get("title"), cache_age) - - # HTML content. - if oembed_type == "rich": - oembed_result.html = result.get("html") - return oembed_result - - if oembed_type == "photo": - oembed_result.url = result.get("url") - return oembed_result - - # TODO Handle link and video types. - - if "thumbnail_url" in result: - oembed_result.url = result.get("thumbnail_url") - return oembed_result - - raise OEmbedError("Incompatible oEmbed information.") - - except OEmbedError as e: - # Trap OEmbedErrors first so we can directly re-raise them. - logger.warning("Error parsing oEmbed metadata from %s: %r", url, e) - raise - - except Exception as e: - # Trap any exception and let the code follow as usual. - # FIXME: pass through 404s and other error messages nicely - logger.warning("Error downloading oEmbed metadata from %s: %r", url, e) - raise OEmbedError() from e - - async def _download_url(self, url: str, user: str) -> Dict[str, Any]: + async def _download_url(self, url: str, user: str) -> MediaInfo: # TODO: we should probably honour robots.txt... except in practice # we're most likely being explicitly triggered by a human rather than a # bot, so are we really a robot? @@ -459,11 +359,11 @@ class PreviewUrlResource(DirectServeJsonResource): # If this URL can be accessed via oEmbed, use that instead. url_to_download: Optional[str] = url - oembed_url = self._get_oembed_url(url) + oembed_url = self._oembed.get_oembed_url(url) if oembed_url: # The result might be a new URL to download, or it might be HTML content. try: - oembed_result = await self._get_oembed_content(oembed_url, url) + oembed_result = await self._oembed.get_oembed_content(oembed_url, url) if oembed_result.url: url_to_download = oembed_result.url elif oembed_result.html: @@ -560,18 +460,18 @@ class PreviewUrlResource(DirectServeJsonResource): # therefore not expire it. raise - return { - "media_type": media_type, - "media_length": length, - "download_name": download_name, - "created_ts": time_now_ms, - "filesystem_id": file_id, - "filename": fname, - "uri": uri, - "response_code": code, - "expires": expires, - "etag": etag, - } + return MediaInfo( + media_type=media_type, + media_length=length, + download_name=download_name, + created_ts_ms=time_now_ms, + filesystem_id=file_id, + filename=fname, + uri=uri, + response_code=code, + expires=expires, + etag=etag, + ) def _start_expire_url_cache_data(self): return run_as_background_process( @@ -717,7 +617,7 @@ def get_html_media_encoding(body: bytes, content_type: str) -> str: def decode_and_calc_og( body: bytes, media_uri: str, request_encoding: Optional[str] = None -) -> Dict[str, Optional[str]]: +) -> JsonDict: """ Calculate metadata for an HTML document. |