diff options
| -rw-r--r-- | changelog.d/11767.bugfix | 1 | ||||
| -rw-r--r-- | synapse/rest/media/v1/preview_html.py | 31 | ||||
| -rw-r--r-- | synapse/rest/media/v1/preview_url_resource.py | 224 | ||||
| -rw-r--r-- | tests/rest/media/v1/test_html_preview.py (renamed from tests/test_preview.py) | 34 | ||||
| -rw-r--r-- | tests/rest/media/v1/test_url_preview.py | 81 | ||||
| -rw-r--r-- | tests/server.py | 2 |
6 files changed, 299 insertions, 74 deletions
diff --git a/changelog.d/11767.bugfix b/changelog.d/11767.bugfix new file mode 100644 index 0000000000..3e344747f4 --- /dev/null +++ b/changelog.d/11767.bugfix @@ -0,0 +1 @@ +Fix a long-standing bug when previewing Reddit URLs which do not contain an image. diff --git a/synapse/rest/media/v1/preview_html.py b/synapse/rest/media/v1/preview_html.py index 30b067dd42..872a9e72e8 100644 --- a/synapse/rest/media/v1/preview_html.py +++ b/synapse/rest/media/v1/preview_html.py @@ -321,14 +321,33 @@ def _iterate_over_text( def rebase_url(url: str, base: str) -> str: - base_parts = list(urlparse.urlparse(base)) + """ + Resolves a potentially relative `url` against an absolute `base` URL. + + For example: + + >>> rebase_url("subpage", "https://example.com/foo/") + 'https://example.com/foo/subpage' + >>> rebase_url("sibling", "https://example.com/foo") + 'https://example.com/sibling' + >>> rebase_url("/bar", "https://example.com/foo/") + 'https://example.com/bar' + >>> rebase_url("https://alice.com/a/", "https://example.com/foo/") + 'https://alice.com/a' + """ + base_parts = urlparse.urlparse(base) + # Convert the parsed URL to a list for (potential) modification. url_parts = list(urlparse.urlparse(url)) - if not url_parts[0]: # fix up schema - url_parts[0] = base_parts[0] or "http" - if not url_parts[1]: # fix up hostname - url_parts[1] = base_parts[1] + # Add a scheme, if one does not exist. + if not url_parts[0]: + url_parts[0] = base_parts.scheme or "http" + # Fix up the hostname, if this is not a data URL. + if url_parts[0] != "data" and not url_parts[1]: + url_parts[1] = base_parts.netloc + # If the path does not start with a /, nest it under the base path's last + # directory. if not url_parts[2].startswith("/"): - url_parts[2] = re.sub(r"/[^/]+$", "/", base_parts[2]) + url_parts[2] + url_parts[2] = re.sub(r"/[^/]+$", "/", base_parts.path) + url_parts[2] return urlparse.urlunparse(url_parts) diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py index e8881bc870..efd84ced8f 100644 --- a/synapse/rest/media/v1/preview_url_resource.py +++ b/synapse/rest/media/v1/preview_url_resource.py @@ -21,8 +21,9 @@ import re import shutil import sys import traceback -from typing import TYPE_CHECKING, Iterable, Optional, Tuple +from typing import TYPE_CHECKING, BinaryIO, Iterable, Optional, Tuple from urllib import parse as urlparse +from urllib.request import urlopen import attr @@ -71,6 +72,17 @@ IMAGE_CACHE_EXPIRY_MS = 2 * ONE_DAY @attr.s(slots=True, frozen=True, auto_attribs=True) +class DownloadResult: + length: int + uri: str + response_code: int + media_type: str + download_name: Optional[str] + expires: int + etag: Optional[str] + + +@attr.s(slots=True, frozen=True, auto_attribs=True) class MediaInfo: """ Information parsed from downloading media being previewed. @@ -256,7 +268,7 @@ class PreviewUrlResource(DirectServeJsonResource): if oembed_url: url_to_download = oembed_url - media_info = await self._download_url(url_to_download, user) + media_info = await self._handle_url(url_to_download, user) logger.debug("got media_info of '%s'", media_info) @@ -297,7 +309,9 @@ class PreviewUrlResource(DirectServeJsonResource): oembed_url = self._oembed.autodiscover_from_html(tree) og_from_oembed: JsonDict = {} if oembed_url: - oembed_info = await self._download_url(oembed_url, user) + oembed_info = await self._handle_url( + oembed_url, user, allow_data_urls=True + ) ( og_from_oembed, author_name, @@ -367,7 +381,135 @@ class PreviewUrlResource(DirectServeJsonResource): return jsonog.encode("utf8") - async def _download_url(self, url: str, user: UserID) -> MediaInfo: + async def _download_url(self, url: str, output_stream: BinaryIO) -> DownloadResult: + """ + Fetches a remote URL and parses the headers. + + Args: + url: The URL to fetch. + output_stream: The stream to write the content to. + + Returns: + A tuple of: + Media length, URL downloaded, the HTTP response code, + the media type, the downloaded file name, the number of + milliseconds the result is valid for, the etag header. + """ + + try: + logger.debug("Trying to get preview for url '%s'", url) + length, headers, uri, code = await self.client.get_file( + url, + output_stream=output_stream, + 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) + + raise SynapseError( + 500, + "Failed to download content: %s" + % (traceback.format_exception_only(sys.exc_info()[0], e),), + Codes.UNKNOWN, + ) + + 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[b"ETag"][0].decode("ascii") if b"ETag" in headers else None + + return DownloadResult( + length, uri, code, media_type, download_name, expires, etag + ) + + async def _parse_data_url( + self, url: str, output_stream: BinaryIO + ) -> DownloadResult: + """ + Parses a data: URL. + + Args: + url: The URL to parse. + output_stream: The stream to write the content to. + + Returns: + A tuple of: + Media length, URL downloaded, the HTTP response code, + the media type, the downloaded file name, the number of + milliseconds the result is valid for, the etag header. + """ + + try: + logger.debug("Trying to parse data url '%s'", url) + with urlopen(url) as url_info: + # TODO Can this be more efficient. + output_stream.write(url_info.read()) + except Exception as e: + logger.warning("Error parsing data: URL %s: %r", url, e) + + raise SynapseError( + 500, + "Failed to parse data URL: %s" + % (traceback.format_exception_only(sys.exc_info()[0], e),), + Codes.UNKNOWN, + ) + + return DownloadResult( + # Read back the length that has been written. + length=output_stream.tell(), + uri=url, + # If it was parsed, consider this a 200 OK. + response_code=200, + # urlopen shoves the media-type from the data URL into the content type + # header object. + media_type=url_info.headers.get_content_type(), + # Some features are not supported by data: URLs. + download_name=None, + expires=ONE_HOUR, + etag=None, + ) + + async def _handle_url( + self, url: str, user: UserID, allow_data_urls: bool = False + ) -> MediaInfo: + """ + Fetches content from a URL and parses the result to generate a MediaInfo. + + It uses the media storage provider to persist the fetched content and + stores the mapping into the database. + + Args: + url: The URL to fetch. + user: The user who ahs requested this URL. + allow_data_urls: True if data URLs should be allowed. + + Returns: + A MediaInfo object describing the fetched content. + """ + # 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? @@ -377,61 +519,27 @@ 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): - 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) - - raise SynapseError( - 500, - "Failed to download content: %s" - % (traceback.format_exception_only(sys.exc_info()[0], e),), - Codes.UNKNOWN, - ) - await finish() + if url.startswith("data:"): + if not allow_data_urls: + raise SynapseError( + 500, "Previewing of data: URLs is forbidden", Codes.UNKNOWN + ) - if b"Content-Type" in headers: - media_type = headers[b"Content-Type"][0].decode("ascii") + download_result = await self._parse_data_url(url, f) else: - media_type = "application/octet-stream" + download_result = await self._download_url(url, f) - 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[b"ETag"][0].decode("ascii") if b"ETag" in headers else None + await finish() try: time_now_ms = self.clock.time_msec() await self.store.store_local_media( media_id=file_id, - media_type=media_type, + media_type=download_result.media_type, time_now_ms=time_now_ms, - upload_name=download_name, - media_length=length, + upload_name=download_result.download_name, + media_length=download_result.length, user_id=user, url_cache=url, ) @@ -444,16 +552,16 @@ class PreviewUrlResource(DirectServeJsonResource): raise return MediaInfo( - media_type=media_type, - media_length=length, - download_name=download_name, + media_type=download_result.media_type, + media_length=download_result.length, + download_name=download_result.download_name, created_ts_ms=time_now_ms, filesystem_id=file_id, filename=fname, - uri=uri, - response_code=code, - expires=expires, - etag=etag, + uri=download_result.uri, + response_code=download_result.response_code, + expires=download_result.expires, + etag=download_result.etag, ) async def _precache_image_url( @@ -474,8 +582,8 @@ class PreviewUrlResource(DirectServeJsonResource): # FIXME: it might be cleaner to use the same flow as the main /preview_url # request itself and benefit from the same caching etc. But for now we # just rely on the caching on the master request to speed things up. - image_info = await self._download_url( - rebase_url(og["og:image"], media_info.uri), user + image_info = await self._handle_url( + rebase_url(og["og:image"], media_info.uri), user, allow_data_urls=True ) if _is_media(image_info.media_type): diff --git a/tests/test_preview.py b/tests/rest/media/v1/test_html_preview.py index 46e02f483f..a4b57e3d1f 100644 --- a/tests/test_preview.py +++ b/tests/rest/media/v1/test_html_preview.py @@ -16,10 +16,11 @@ from synapse.rest.media.v1.preview_html import ( _get_html_media_encodings, decode_body, parse_html_to_open_graph, + rebase_url, summarize_paragraphs, ) -from . import unittest +from tests import unittest try: import lxml @@ -447,3 +448,34 @@ class MediaEncodingTestCase(unittest.TestCase): 'text/html; charset="invalid"', ) self.assertEqual(list(encodings), ["utf-8", "cp1252"]) + + +class RebaseUrlTestCase(unittest.TestCase): + def test_relative(self): + """Relative URLs should be resolved based on the context of the base URL.""" + self.assertEqual( + rebase_url("subpage", "https://example.com/foo/"), + "https://example.com/foo/subpage", + ) + self.assertEqual( + rebase_url("sibling", "https://example.com/foo"), + "https://example.com/sibling", + ) + self.assertEqual( + rebase_url("/bar", "https://example.com/foo/"), + "https://example.com/bar", + ) + + def test_absolute(self): + """Absolute URLs should not be modified.""" + self.assertEqual( + rebase_url("https://alice.com/a/", "https://example.com/foo/"), + "https://alice.com/a/", + ) + + def test_data(self): + """Data URLs should not be modified.""" + self.assertEqual( + rebase_url("data:,Hello%2C%20World%21", "https://example.com/foo/"), + "data:,Hello%2C%20World%21", + ) diff --git a/tests/rest/media/v1/test_url_preview.py b/tests/rest/media/v1/test_url_preview.py index 16e904f15b..53f6186213 100644 --- a/tests/rest/media/v1/test_url_preview.py +++ b/tests/rest/media/v1/test_url_preview.py @@ -12,9 +12,11 @@ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. +import base64 import json import os import re +from urllib.parse import urlencode from twisted.internet._resolver import HostResolution from twisted.internet.address import IPv4Address, IPv6Address @@ -23,6 +25,7 @@ from twisted.test.proto_helpers import AccumulatingProtocol from synapse.config.oembed import OEmbedEndpointConfig from synapse.rest.media.v1.preview_url_resource import IMAGE_CACHE_EXPIRY_MS +from synapse.types import JsonDict from synapse.util.stringutils import parse_and_validate_mxc_uri from tests import unittest @@ -142,6 +145,14 @@ class URLPreviewTests(unittest.HomeserverTestCase): def create_test_resource(self): return self.hs.get_media_repository_resource() + def _assert_small_png(self, json_body: JsonDict) -> None: + """Assert properties from the SMALL_PNG test image.""" + self.assertTrue(json_body["og:image"].startswith("mxc://")) + self.assertEqual(json_body["og:image:height"], 1) + self.assertEqual(json_body["og:image:width"], 1) + self.assertEqual(json_body["og:image:type"], "image/png") + self.assertEqual(json_body["matrix:image:size"], 67) + def test_cache_returns_correct_type(self): self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")] @@ -569,6 +580,66 @@ class URLPreviewTests(unittest.HomeserverTestCase): server.data, ) + def test_data_url(self): + """ + Requesting to preview a data URL is not supported. + """ + self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")] + + data = base64.b64encode(SMALL_PNG).decode() + + query_params = urlencode( + { + "url": f'<html><head><img src="data:image/png;base64,{data}" /></head></html>' + } + ) + + channel = self.make_request( + "GET", + f"preview_url?{query_params}", + shorthand=False, + ) + self.pump() + + self.assertEqual(channel.code, 500) + + def test_inline_data_url(self): + """ + An inline image (as a data URL) should be parsed properly. + """ + self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")] + + data = base64.b64encode(SMALL_PNG) + + end_content = ( + b"<html><head>" b'<img src="data:image/png;base64,%s" />' b"</head></html>" + ) % (data,) + + channel = self.make_request( + "GET", + "preview_url?url=http://matrix.org", + shorthand=False, + await_result=False, + ) + self.pump() + + client = self.reactor.tcpClients[0][2].buildProtocol(None) + server = AccumulatingProtocol() + server.makeConnection(FakeTransport(client, self.reactor)) + client.makeConnection(FakeTransport(server, self.reactor)) + client.dataReceived( + ( + b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n" + b'Content-Type: text/html; charset="utf8"\r\n\r\n' + ) + % (len(end_content),) + + end_content + ) + + self.pump() + self.assertEqual(channel.code, 200) + self._assert_small_png(channel.json_body) + def test_oembed_photo(self): """Test an oEmbed endpoint which returns a 'photo' type which redirects the preview to a new URL.""" self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")] @@ -626,10 +697,7 @@ class URLPreviewTests(unittest.HomeserverTestCase): self.assertEqual(channel.code, 200) body = channel.json_body self.assertEqual(body["og:url"], "http://twitter.com/matrixdotorg/status/12345") - self.assertTrue(body["og:image"].startswith("mxc://")) - self.assertEqual(body["og:image:height"], 1) - self.assertEqual(body["og:image:width"], 1) - self.assertEqual(body["og:image:type"], "image/png") + self._assert_small_png(body) def test_oembed_rich(self): """Test an oEmbed endpoint which returns HTML content via the 'rich' type.""" @@ -820,10 +888,7 @@ class URLPreviewTests(unittest.HomeserverTestCase): self.assertEqual( body["og:url"], "http://www.twitter.com/matrixdotorg/status/12345" ) - self.assertTrue(body["og:image"].startswith("mxc://")) - self.assertEqual(body["og:image:height"], 1) - self.assertEqual(body["og:image:width"], 1) - self.assertEqual(body["og:image:type"], "image/png") + self._assert_small_png(body) def _download_image(self): """Downloads an image into the URL cache. diff --git a/tests/server.py b/tests/server.py index a0cd14ea45..82990c2eb9 100644 --- a/tests/server.py +++ b/tests/server.py @@ -313,7 +313,7 @@ def make_request( req = request(channel, site) req.content = BytesIO(content) # Twisted expects to be at the end of the content when parsing the request. - req.content.seek(SEEK_END) + req.content.seek(0, SEEK_END) if access_token: req.requestHeaders.addRawHeader( |