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