diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index e52c86c798..13d1a6d2ed 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -26,6 +26,7 @@ import traceback
from typing import Dict, Optional
from urllib import parse as urlparse
+import attr
from canonicaljson import json
from twisted.internet import defer
@@ -56,6 +57,65 @@ _content_type_match = re.compile(r'.*; *charset="?(.*?)"?(;|$)', flags=re.I)
OG_TAG_NAME_MAXLEN = 50
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
+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)
+
+
+class OEmbedError(Exception):
+ """An error occurred processing the oEmbed object."""
+
class PreviewUrlResource(DirectServeJsonResource):
isLeaf = True
@@ -99,7 +159,7 @@ class PreviewUrlResource(DirectServeJsonResource):
cache_name="url_previews",
clock=self.clock,
# don't spider URLs more often than once an hour
- expiry_ms=60 * 60 * 1000,
+ expiry_ms=ONE_HOUR,
)
if self._worker_run_media_background_jobs:
@@ -310,6 +370,87 @@ class PreviewUrlResource(DirectServeJsonResource):
return jsonog.encode("utf8")
+ def _get_oembed_url(self, url: str) -> Optional[str]:
+ """
+ Check whether the URL should be downloaded as oEmbed content instead.
+
+ Params:
+ 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.
+
+ Params:
+ 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, user):
# TODO: we should probably honour robots.txt... except in practice
# we're most likely being explicitly triggered by a human rather than a
@@ -319,54 +460,90 @@ class PreviewUrlResource(DirectServeJsonResource):
file_info = FileInfo(server_name=None, file_id=file_id, url_cache=True)
- with self.media_storage.store_into_file(file_info) as (f, fname, finish):
+ # If this URL can be accessed via oEmbed, use that instead.
+ url_to_download = url
+ oembed_url = self._get_oembed_url(url)
+ if oembed_url:
+ # The result might be a new URL to download, or it might be HTML content.
try:
- logger.debug("Trying to get preview for url '%s'", url)
- length, headers, uri, code = await self.client.get_file(
- url,
- output_stream=f,
- max_size=self.max_spider_size,
- headers={"Accept-Language": self.url_preview_accept_language},
- )
- except SynapseError:
- # Pass SynapseErrors through directly, so that the servlet
- # handler will return a SynapseError to the client instead of
- # blank data or a 500.
- raise
- except DNSLookupError:
- # DNS lookup returned no results
- # Note: This will also be the case if one of the resolved IP
- # addresses is blacklisted
- raise SynapseError(
- 502,
- "DNS resolution failure during URL preview generation",
- Codes.UNKNOWN,
- )
- except Exception as e:
- # FIXME: pass through 404s and other error messages nicely
- logger.warning("Error downloading %s: %r", url, e)
+ oembed_result = await self._get_oembed_content(oembed_url, url)
+ if oembed_result.url:
+ url_to_download = oembed_result.url
+ elif oembed_result.html:
+ url_to_download = None
+ except OEmbedError:
+ # If an error occurs, try doing a normal preview.
+ pass
- raise SynapseError(
- 500,
- "Failed to download content: %s"
- % (traceback.format_exception_only(sys.exc_info()[0], e),),
- Codes.UNKNOWN,
- )
- await finish()
+ if url_to_download:
+ with self.media_storage.store_into_file(file_info) as (f, fname, finish):
+ try:
+ logger.debug("Trying to get preview for url '%s'", url_to_download)
+ length, headers, uri, code = await self.client.get_file(
+ url_to_download,
+ output_stream=f,
+ max_size=self.max_spider_size,
+ headers={"Accept-Language": self.url_preview_accept_language},
+ )
+ except SynapseError:
+ # Pass SynapseErrors through directly, so that the servlet
+ # handler will return a SynapseError to the client instead of
+ # blank data or a 500.
+ raise
+ except DNSLookupError:
+ # DNS lookup returned no results
+ # Note: This will also be the case if one of the resolved IP
+ # addresses is blacklisted
+ raise SynapseError(
+ 502,
+ "DNS resolution failure during URL preview generation",
+ Codes.UNKNOWN,
+ )
+ except Exception as e:
+ # FIXME: pass through 404s and other error messages nicely
+ logger.warning("Error downloading %s: %r", url_to_download, e)
+
+ raise SynapseError(
+ 500,
+ "Failed to download content: %s"
+ % (traceback.format_exception_only(sys.exc_info()[0], e),),
+ Codes.UNKNOWN,
+ )
+ await finish()
+
+ if b"Content-Type" in headers:
+ media_type = headers[b"Content-Type"][0].decode("ascii")
+ else:
+ media_type = "application/octet-stream"
+
+ download_name = get_filename_from_headers(headers)
+
+ # FIXME: we should calculate a proper expiration based on the
+ # Cache-Control and Expire headers. But for now, assume 1 hour.
+ expires = ONE_HOUR
+ etag = headers["ETag"][0] if "ETag" in headers else None
+ else:
+ html_bytes = oembed_result.html.encode("utf-8") # type: ignore
+ with self.media_storage.store_into_file(file_info) as (f, fname, finish):
+ f.write(html_bytes)
+ await finish()
+
+ media_type = "text/html"
+ download_name = oembed_result.title
+ length = len(html_bytes)
+ # If a specific cache age was not given, assume 1 hour.
+ expires = oembed_result.cache_age or ONE_HOUR
+ uri = oembed_url
+ code = 200
+ etag = None
try:
- if b"Content-Type" in headers:
- media_type = headers[b"Content-Type"][0].decode("ascii")
- else:
- media_type = "application/octet-stream"
time_now_ms = self.clock.time_msec()
- download_name = get_filename_from_headers(headers)
-
await self.store.store_local_media(
media_id=file_id,
media_type=media_type,
- time_now_ms=self.clock.time_msec(),
+ time_now_ms=time_now_ms,
upload_name=download_name,
media_length=length,
user_id=user,
@@ -389,10 +566,8 @@ class PreviewUrlResource(DirectServeJsonResource):
"filename": fname,
"uri": uri,
"response_code": code,
- # FIXME: we should calculate a proper expiration based on the
- # Cache-Control and Expire headers. But for now, assume 1 hour.
- "expires": 60 * 60 * 1000,
- "etag": headers["ETag"][0] if "ETag" in headers else None,
+ "expires": expires,
+ "etag": etag,
}
def _start_expire_url_cache_data(self):
@@ -449,7 +624,7 @@ class PreviewUrlResource(DirectServeJsonResource):
# These may be cached for a bit on the client (i.e., they
# may have a room open with a preview url thing open).
# So we wait a couple of days before deleting, just in case.
- expire_before = now - 2 * 24 * 60 * 60 * 1000
+ expire_before = now - 2 * 24 * ONE_HOUR
media_ids = await self.store.get_url_cache_media_before(expire_before)
removed_media = []
|
