MatrixSynapse/synapse/rest/media/v1/preview_url_resource.py

325 lines
13 KiB
Python

# Copyright 2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# 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.
from .base_resource import BaseMediaResource
from synapse.api.errors import Codes
from twisted.web.resource import Resource
from twisted.web.server import NOT_DONE_YET
from twisted.internet import defer
from lxml import html
from urlparse import urlparse, urlunparse
from synapse.util.stringutils import random_string
from synapse.util.caches.expiringcache import ExpiringCache
from synapse.http.client import SpiderHttpClient
from synapse.http.server import request_handler, respond_with_json, respond_with_json_bytes
import os
import re
import ujson as json
import logging
logger = logging.getLogger(__name__)
class PreviewUrlResource(BaseMediaResource):
isLeaf = True
def __init__(self, hs, filepaths):
BaseMediaResource.__init__(self, hs, filepaths)
self.client = SpiderHttpClient(hs)
self.cache = ExpiringCache(
cache_name = "url_previews",
clock = self.clock,
expiry_ms = 60*60*1000, # don't spider URLs more often than once an hour
)
self.cache.start()
def render_GET(self, request):
self._async_render_GET(request)
return NOT_DONE_YET
@request_handler
@defer.inlineCallbacks
def _async_render_GET(self, request):
try:
# XXX: if get_user_by_req fails, what should we do in an async render?
requester = yield self.auth.get_user_by_req(request)
url = request.args.get("url")[0]
if self.cache:
og = self.cache.get(url)
respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
return
# TODO: keep track of whether there's an ongoing request for this preview
# and block and return their details if there is one.
media_info = yield self._download_url(url, requester.user)
logger.debug("got media_info of '%s'" % media_info)
if self._is_media(media_info['media_type']):
dims = yield self._generate_local_thumbnails(
media_info['filesystem_id'], media_info
)
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'],
}
if dims:
og["og:image:width"] = dims['width']
og["og:image:height"] = dims['height']
else:
logger.warn("Couldn't get dims for %s" % url)
# define our OG response for this media
elif self._is_html(media_info['media_type']):
# TODO: somehow stop a big HTML tree from exploding synapse's RAM
try:
tree = html.parse(media_info['filename'])
og = yield self._calc_og(tree, media_info, requester)
except UnicodeDecodeError:
# XXX: evil evil bodge
file = open(media_info['filename'])
body = file.read()
file.close()
tree = html.fromstring(body.decode('utf-8','ignore'))
og = yield self._calc_og(tree, media_info, requester)
else:
logger.warn("Failed to find any OG data in %s", url)
og = {}
if self.cache:
self.cache[url] = og
logger.warn(og);
respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
except:
# XXX: if we don't explicitly respond here, the request never returns.
# isn't this what server.py's wrapper is meant to be doing for us?
respond_with_json(
request,
500,
{
"error": "Internal server error",
"errcode": Codes.UNKNOWN,
},
send_cors=True
)
raise
@defer.inlineCallbacks
def _calc_og(self, tree, media_info, requester):
# suck our tree into lxml and define our OG response.
# if we see any image URLs in the OG response, then spider them
# (although the client could choose to do this by asking for previews of those URLs to avoid DoSing the server)
# "og:type" : "article"
# "og:url" : "https://twitter.com/matrixdotorg/status/684074366691356672"
# "og:title" : "Matrix on Twitter"
# "og:image" : "https://pbs.twimg.com/profile_images/500400952029888512/yI0qtFi7_400x400.png"
# "og:description" : "Synapse 0.12 is out! Lots of polishing, performance & bugfixes: /sync API, /r0 prefix, fulltext search, 3PID invites https://t.co/5alhXLLEGP"
# "og:site_name" : "Twitter"
# or:
# "og:type" : "video",
# "og:url" : "https://www.youtube.com/watch?v=LXDBoHyjmtw",
# "og:site_name" : "YouTube",
# "og:video:type" : "application/x-shockwave-flash",
# "og:description" : " ",
# "og:title" : "RemoteJam - Matrix team hack for Disrupt Europe Hackathon",
# "og:image" : "https://i.ytimg.com/vi/LXDBoHyjmtw/maxresdefault.jpg",
# "og:video:url" : "http://www.youtube.com/v/LXDBoHyjmtw?version=3&autohide=1",
# "og:video:width" : "1280"
# "og:video:height" : "720",
# "og:video:secure_url": "https://www.youtube.com/v/LXDBoHyjmtw?version=3&autohide=1",
og = {}
for tag in tree.xpath("//*/meta[starts-with(@property, 'og:')]"):
og[tag.attrib['property']] = tag.attrib['content']
# TODO: grab article: meta tags too, e.g.:
# <meta property="article:publisher" content="https://www.facebook.com/thethudonline" />
# <meta property="article:author" content="https://www.facebook.com/thethudonline" />
# <meta property="article:tag" content="baby" />
# <meta property="article:section" content="Breaking News" />
# <meta property="article:published_time" content="2016-03-31T19:58:24+00:00" />
# <meta property="article:modified_time" content="2016-04-01T18:31:53+00:00" />
if 'og:title' not in og:
# do some basic spidering of the HTML
title = tree.xpath("(//title)[1] | (//h1)[1] | (//h2)[1] | (//h3)[1]")
og['og:title'] = title[0].text.strip() if title else None
if 'og:image' not in og:
# TODO: extract a favicon failing all else
meta_image = tree.xpath("//*/meta[translate(@itemprop, 'IMAGE', 'image')='image']/@content");
if meta_image:
og['og:image'] = self._rebase_url(meta_image[0], media_info['uri'])
else:
# TODO: consider inlined CSS styles as well as width & height attribs
images = tree.xpath("//img[@src][number(@width)>10][number(@height)>10]")
images = sorted(images, key=lambda i: (-1 * int(i.attrib['width']) * int(i.attrib['height'])))
if not images:
images = tree.xpath("//img[@src]")
if images:
og['og:image'] = self._rebase_url(images[0].attrib['src'], media_info['uri'])
# pre-cache the image for posterity
if 'og:image' in og and og['og:image']:
image_info = yield self._download_url(og['og:image'], requester.user)
if self._is_media(image_info['media_type']):
# TODO: make sure we don't choke on white-on-transparent images
dims = yield self._generate_local_thumbnails(
image_info['filesystem_id'], image_info
)
if dims:
og["og:image:width"] = dims['width']
og["og:image:height"] = dims['height']
else:
logger.warn("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']
else:
del og["og:image"]
if 'og:description' not in og:
meta_description = tree.xpath("//*/meta[translate(@name, 'DESCRIPTION', 'description')='description']/@content");
if meta_description:
og['og:description'] = meta_description[0]
else:
# text_nodes = tree.xpath("//h1/text() | //h2/text() | //h3/text() | //p/text() | //div/text() | //span/text() | //a/text()")
text_nodes = tree.xpath("//text()[not(ancestor::header | ancestor::nav | ancestor::aside | " +
"ancestor::footer | ancestor::script | ancestor::style)]" +
"[ancestor::body]")
text = ''
for text_node in text_nodes:
if len(text) < 500:
text += text_node + ' '
else:
break
text = re.sub(r'[\t ]+', ' ', text)
text = re.sub(r'[\t \r\n]*[\r\n]+', '\n', text)
text = text.strip()[:500]
og['og:description'] = text if text else None
# TODO: persist a cache mapping { url, etag } -> { og, mxc of url (if we bother keeping it around), age }
# TODO: delete the url downloads to stop diskfilling, as we only ever cared about its OG
defer.returnValue(og);
def _rebase_url(self, url, base):
base = list(urlparse(base))
url = list(urlparse(url))
if not url[0]:
url[0] = base[0] or "http"
if not url[1]:
url[1] = base[1]
if not url[2].startswith('/'):
url[2] = re.sub(r'/[^/]+$', '/', base[2]) + url[2]
return urlunparse(url)
@defer.inlineCallbacks
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
# bot, so are we really a robot?
# XXX: horrible duplication with base_resource's _download_remote_file()
file_id = random_string(24)
fname = self.filepaths.local_media_filepath(file_id)
self._makedirs(fname)
try:
with open(fname, "wb") as f:
logger.debug("Trying to get url '%s'" % url)
length, headers, uri = yield self.client.get_file(
url, output_stream=f, max_size=self.max_spider_size,
)
# FIXME: pass through 404s and other error messages nicely
media_type = headers["Content-Type"][0]
time_now_ms = self.clock.time_msec()
content_disposition = headers.get("Content-Disposition", None)
if content_disposition:
_, params = cgi.parse_header(content_disposition[0],)
download_name = None
# First check if there is a valid UTF-8 filename
download_name_utf8 = params.get("filename*", None)
if download_name_utf8:
if download_name_utf8.lower().startswith("utf-8''"):
download_name = download_name_utf8[7:]
# If there isn't check for an ascii name.
if not download_name:
download_name_ascii = params.get("filename", None)
if download_name_ascii and is_ascii(download_name_ascii):
download_name = download_name_ascii
if download_name:
download_name = urlparse.unquote(download_name)
try:
download_name = download_name.decode("utf-8")
except UnicodeDecodeError:
download_name = None
else:
download_name = None
yield self.store.store_local_media(
media_id=file_id,
media_type=media_type,
time_now_ms=self.clock.time_msec(),
upload_name=download_name,
media_length=length,
user_id=user,
)
except:
os.remove(fname)
raise
defer.returnValue({
"media_type": media_type,
"media_length": length,
"download_name": download_name,
"created_ts": time_now_ms,
"filesystem_id": file_id,
"filename": fname,
"uri": uri,
})
def _is_media(self, content_type):
if content_type.lower().startswith("image/"):
return True
def _is_html(self, content_type):
content_type = content_type.lower()
if (content_type.startswith("text/html") or
content_type.startswith("application/xhtml")):
return True