diff --git a/synapse/rest/media/v1/oembed.py b/synapse/rest/media/v1/oembed.py
index 2e6706dbfa..e04671fb95 100644
--- a/synapse/rest/media/v1/oembed.py
+++ b/synapse/rest/media/v1/oembed.py
@@ -12,30 +12,32 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
-from typing import TYPE_CHECKING, Optional
+import urllib.parse
+from typing import TYPE_CHECKING, List, Optional
import attr
from synapse.http.client import SimpleHttpClient
+from synapse.types import JsonDict
+from synapse.util import json_decoder
if TYPE_CHECKING:
+ from lxml import etree
+
from synapse.server import HomeServer
logger = logging.getLogger(__name__)
-@attr.s(slots=True, auto_attribs=True)
+@attr.s(slots=True, frozen=True, auto_attribs=True)
class OEmbedResult:
- # Either HTML content or URL must be provided.
- html: Optional[str]
- url: Optional[str]
- title: Optional[str]
- # Number of seconds to cache the content.
- cache_age: int
-
-
-class OEmbedError(Exception):
- """An error occurred processing the oEmbed object."""
+ # The Open Graph result (converted from the oEmbed result).
+ open_graph_result: JsonDict
+ # Number of milliseconds to cache the content, according to the oEmbed response.
+ #
+ # This will be None if no cache-age is provided in the oEmbed response (or
+ # if the oEmbed response cannot be turned into an Open Graph response).
+ cache_age: Optional[int]
class OEmbedProvider:
@@ -81,75 +83,145 @@ class OEmbedProvider:
"""
for url_pattern, endpoint in self._oembed_patterns.items():
if url_pattern.fullmatch(url):
- return endpoint
+ # TODO Specify max height / width.
+
+ # Note that only the JSON format is supported, some endpoints want
+ # this in the URL, others want it as an argument.
+ endpoint = endpoint.replace("{format}", "json")
+
+ args = {"url": url, "format": "json"}
+ query_str = urllib.parse.urlencode(args, True)
+ return f"{endpoint}?{query_str}"
# No match.
return None
- async def get_oembed_content(self, endpoint: str, url: str) -> OEmbedResult:
+ def parse_oembed_response(self, url: str, raw_body: bytes) -> OEmbedResult:
"""
- Request content from an oEmbed endpoint.
+ Parse the oEmbed response into an Open Graph response.
Args:
- endpoint: The oEmbed API endpoint.
- url: The URL to pass to the API.
+ url: The URL which is being previewed (not the one which was
+ requested).
+ raw_body: The oEmbed response as JSON encoded as bytes.
Returns:
- An object representing the metadata returned.
-
- Raises:
- OEmbedError if fetching or parsing of the oEmbed information fails.
+ json-encoded Open Graph data
"""
- try:
- logger.debug("Trying to get oEmbed content for url '%s'", url)
-
- # Note that only the JSON format is supported, some endpoints want
- # this in the URL, others want it as an argument.
- endpoint = endpoint.replace("{format}", "json")
- result = await self._client.get_json(
- endpoint,
- # TODO Specify max height / width.
- args={"url": url, "format": "json"},
- )
+ try:
+ # oEmbed responses *must* be UTF-8 according to the spec.
+ oembed = json_decoder.decode(raw_body.decode("utf-8"))
# 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")
+ oembed_version = oembed["version"]
+ if oembed_version != "1.0":
+ raise RuntimeError(f"Invalid version: {oembed_version}")
# Ensure the cache age is None or an int.
- cache_age = result.get("cache_age")
+ cache_age = oembed.get("cache_age")
if cache_age:
- cache_age = int(cache_age)
+ cache_age = int(cache_age) * 1000
- oembed_result = OEmbedResult(None, None, result.get("title"), cache_age)
+ # The results.
+ open_graph_response = {
+ "og:url": url,
+ }
- # HTML content.
- if oembed_type == "rich":
- oembed_result.html = result.get("html")
- return oembed_result
+ # Use either title or author's name as the title.
+ title = oembed.get("title") or oembed.get("author_name")
+ if title:
+ open_graph_response["og:title"] = title
- if oembed_type == "photo":
- oembed_result.url = result.get("url")
- return oembed_result
+ # Use the provider name and as the site.
+ provider_name = oembed.get("provider_name")
+ if provider_name:
+ open_graph_response["og:site_name"] = provider_name
- # TODO Handle link and video types.
+ # If a thumbnail exists, use it. Note that dimensions will be calculated later.
+ if "thumbnail_url" in oembed:
+ open_graph_response["og:image"] = oembed["thumbnail_url"]
- if "thumbnail_url" in result:
- oembed_result.url = result.get("thumbnail_url")
- return oembed_result
+ # Process each type separately.
+ oembed_type = oembed["type"]
+ if oembed_type == "rich":
+ calc_description_and_urls(open_graph_response, oembed["html"])
+
+ elif oembed_type == "photo":
+ # If this is a photo, use the full image, not the thumbnail.
+ open_graph_response["og:image"] = oembed["url"]
- raise OEmbedError("Incompatible oEmbed information.")
+ elif oembed_type == "video":
+ open_graph_response["og:type"] = "video.other"
+ calc_description_and_urls(open_graph_response, oembed["html"])
+ open_graph_response["og:video:width"] = oembed["width"]
+ open_graph_response["og:video:height"] = oembed["height"]
- 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
+ elif oembed_type == "link":
+ open_graph_response["og:type"] = "website"
+
+ else:
+ raise RuntimeError(f"Unknown oEmbed type: {oembed_type}")
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
+ logger.warning(f"Error parsing oEmbed metadata from {url}: {e:r}")
+ open_graph_response = {}
+ cache_age = None
+
+ return OEmbedResult(open_graph_response, cache_age)
+
+
+def _fetch_urls(tree: "etree.Element", tag_name: str) -> List[str]:
+ results = []
+ for tag in tree.xpath("//*/" + tag_name):
+ if "src" in tag.attrib:
+ results.append(tag.attrib["src"])
+ return results
+
+
+def calc_description_and_urls(open_graph_response: JsonDict, html_body: str) -> None:
+ """
+ Calculate description for an HTML document.
+
+ This uses lxml to convert the HTML document into plaintext. If errors
+ occur during processing of the document, an empty response is returned.
+
+ Args:
+ open_graph_response: The current Open Graph summary. This is updated with additional fields.
+ html_body: The HTML document, as bytes.
+
+ Returns:
+ The summary
+ """
+ # If there's no body, nothing useful is going to be found.
+ if not html_body:
+ return
+
+ from lxml import etree
+
+ # Create an HTML parser. If this fails, log and return no metadata.
+ parser = etree.HTMLParser(recover=True, encoding="utf-8")
+
+ # Attempt to parse the body. If this fails, log and return no metadata.
+ tree = etree.fromstring(html_body, parser)
+
+ # The data was successfully parsed, but no tree was found.
+ if tree is None:
+ return
+
+ # Attempt to find interesting URLs (images, videos, embeds).
+ if "og:image" not in open_graph_response:
+ image_urls = _fetch_urls(tree, "img")
+ if image_urls:
+ open_graph_response["og:image"] = image_urls[0]
+
+ video_urls = _fetch_urls(tree, "video") + _fetch_urls(tree, "embed")
+ if video_urls:
+ open_graph_response["og:video"] = video_urls[0]
+
+ from synapse.rest.media.v1.preview_url_resource import _calc_description
+
+ description = _calc_description(tree)
+ if description:
+ open_graph_response["og:description"] = description
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