diff options
Diffstat (limited to 'synapse/rest/media')
| -rw-r--r-- | synapse/rest/media/v1/oembed.py | 26 | ||||
| -rw-r--r-- | synapse/rest/media/v1/preview_url_resource.py | 112 |
2 files changed, 100 insertions, 38 deletions
diff --git a/synapse/rest/media/v1/oembed.py b/synapse/rest/media/v1/oembed.py index e04671fb95..6d7e1f9064 100644 --- a/synapse/rest/media/v1/oembed.py +++ b/synapse/rest/media/v1/oembed.py @@ -96,6 +96,32 @@ class OEmbedProvider: # No match. return None + def autodiscover_from_html(self, tree: "etree.Element") -> Optional[str]: + """ + Search an HTML document for oEmbed autodiscovery information. + + Args: + tree: The parsed HTML body. + + Returns: + The URL to use for oEmbed information, or None if no URL was found. + """ + # Search for link elements with the proper rel and type attributes. + for tag in tree.xpath( + "//link[@rel='alternate'][@type='application/json+oembed']" + ): + if "href" in tag.attrib: + return tag.attrib["href"] + + # Some providers (e.g. Flickr) use alternative instead of alternate. + for tag in tree.xpath( + "//link[@rel='alternative'][@type='application/json+oembed']" + ): + if "href" in tag.attrib: + return tag.attrib["href"] + + return None + def parse_oembed_response(self, url: str, raw_body: bytes) -> OEmbedResult: """ Parse the oEmbed response into an Open Graph response. diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py index 044f44a397..1fe0fc8aa9 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, Dict, Generator, Iterable, Optional, Union +from typing import TYPE_CHECKING, Dict, Generator, Iterable, Optional, Tuple, Union from urllib import parse as urlparse import attr @@ -296,22 +296,32 @@ class PreviewUrlResource(DirectServeJsonResource): body = file.read() encoding = get_html_media_encoding(body, media_info.media_type) - og = decode_and_calc_og(body, media_info.uri, encoding) - - await self._precache_image_url(user, media_info, og) - - elif oembed_url and _is_json(media_info.media_type): - # Handle an oEmbed response. - with open(media_info.filename, "rb") as file: - body = file.read() - - oembed_response = self._oembed.parse_oembed_response(url, body) - og = oembed_response.open_graph_result - - # Use the cache age from the oEmbed result, instead of the HTTP response. - if oembed_response.cache_age is not None: - expiration_ms = oembed_response.cache_age + tree = decode_body(body, encoding) + if tree is not None: + # Check if this HTML document points to oEmbed information and + # defer to that. + oembed_url = self._oembed.autodiscover_from_html(tree) + og = {} + if oembed_url: + oembed_info = await self._download_url(oembed_url, user) + og, expiration_ms = await self._handle_oembed_response( + url, oembed_info, expiration_ms + ) + + # If there was no oEmbed URL (or oEmbed parsing failed), attempt + # to generate the Open Graph information from the HTML. + if not oembed_url or not og: + og = _calc_og(tree, media_info.uri) + + await self._precache_image_url(user, media_info, og) + else: + og = {} + elif oembed_url: + # Handle the oEmbed information. + og, expiration_ms = await self._handle_oembed_response( + url, media_info, expiration_ms + ) await self._precache_image_url(user, media_info, og) else: @@ -479,6 +489,39 @@ class PreviewUrlResource(DirectServeJsonResource): else: del og["og:image"] + async def _handle_oembed_response( + self, url: str, media_info: MediaInfo, expiration_ms: int + ) -> Tuple[JsonDict, int]: + """ + Parse the downloaded oEmbed info. + + Args: + url: The URL which is being previewed (not the one which was + requested). + media_info: The media being previewed. + expiration_ms: The length of time, in milliseconds, the media is valid for. + + Returns: + A tuple of: + The Open Graph dictionary, if the oEmbed info can be parsed. + The (possibly updated) length of time, in milliseconds, the media is valid for. + """ + # If JSON was not returned, there's nothing to do. + if not _is_json(media_info.media_type): + return {}, expiration_ms + + with open(media_info.filename, "rb") as file: + body = file.read() + + oembed_response = self._oembed.parse_oembed_response(url, body) + open_graph_result = oembed_response.open_graph_result + + # Use the cache age from the oEmbed result, if one was given. + if open_graph_result and oembed_response.cache_age is not None: + expiration_ms = oembed_response.cache_age + + return open_graph_result, expiration_ms + def _start_expire_url_cache_data(self) -> Deferred: return run_as_background_process( "expire_url_cache_data", self._expire_url_cache_data @@ -631,26 +674,22 @@ def get_html_media_encoding(body: bytes, content_type: str) -> str: return "utf-8" -def decode_and_calc_og( - body: bytes, media_uri: str, request_encoding: Optional[str] = None -) -> JsonDict: +def decode_body( + body: bytes, request_encoding: Optional[str] = None +) -> Optional["etree.Element"]: """ - Calculate metadata for an HTML document. - - This uses lxml to parse the HTML document into the OG response. If errors - occur during processing of the document, an empty response is returned. + This uses lxml to parse the HTML document. Args: body: The HTML document, as bytes. - media_url: The URI used to download the body. request_encoding: The character encoding of the body, as a string. Returns: - The OG response as a dictionary. + The parsed HTML body, or None if an error occurred during processed. """ # If there's no body, nothing useful is going to be found. if not body: - return {} + return None from lxml import etree @@ -662,25 +701,22 @@ def decode_and_calc_og( parser = etree.HTMLParser(recover=True, encoding="utf-8") except Exception as e: logger.warning("Unable to create HTML parser: %s" % (e,)) - return {} - - def _attempt_calc_og(body_attempt: Union[bytes, str]) -> Dict[str, Optional[str]]: - # Attempt to parse the body. If this fails, log and return no metadata. - tree = etree.fromstring(body_attempt, parser) - - # The data was successfully parsed, but no tree was found. - if tree is None: - return {} + return None - return _calc_og(tree, media_uri) + def _attempt_decode_body( + body_attempt: Union[bytes, str] + ) -> Optional["etree.Element"]: + # Attempt to parse the body. Returns None if the body was successfully + # parsed, but no tree was found. + return etree.fromstring(body_attempt, parser) # Attempt to parse the body. If this fails, log and return no metadata. try: - return _attempt_calc_og(body) + return _attempt_decode_body(body) except UnicodeDecodeError: # blindly try decoding the body as utf-8, which seems to fix # the charset mismatches on https://google.com - return _attempt_calc_og(body.decode("utf-8", "ignore")) + return _attempt_decode_body(body.decode("utf-8", "ignore")) def _calc_og(tree: "etree.Element", media_uri: str) -> Dict[str, Optional[str]]: |