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refactor calc_og; spider image URLs; fix xpath; add a (broken) expiringcache; loads of other fixes

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This commit is contained in:
Matthew Hodgson 2016-04-02 00:35:49 +01:00
parent c60b751694
commit 5fd07da764
1 changed files with 121 additions and 81 deletions
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146
synapse/rest/media/v1/preview_url_resource.py
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@ -20,6 +20,7 @@ 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
@ -36,6 +37,12 @@ class PreviewUrlResource(BaseMediaResource):
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)
@ -50,6 +57,11 @@ class PreviewUrlResource(BaseMediaResource):
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.
@ -74,9 +86,46 @@ class PreviewUrlResource(BaseMediaResource):
elif self._is_html(media_info['media_type']):
# TODO: somehow stop a big HTML tree from exploding synapse's RAM
def _calc_og():
# suck it up into lxml and define our OG response.
# if we see any URLs in the OG response, then spider them
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"
@ -104,35 +153,59 @@ class PreviewUrlResource(BaseMediaResource):
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 if title else None
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[@itemprop='image']/@content");
if meta_image:
og['og:image'] = self._rebase_url(meta_image[0], media_info['uri'])
else:
images = [ i for i in tree.xpath("//img") if 'src' in i.attrib ]
big_images = [ i for i in images if (
'width' in i.attrib and 'height' in i.attrib and
i.attrib['width'] > 64 and i.attrib['height'] > 64
)]
big_images = big_images.sort(key=lambda i: (-1 * int(i.attrib['width']) * int(i.attrib['height'])))
images = big_images if big_images else images
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
)
og["og:image"] = "mxc://%s/%s" % (self.server_name, image_info['filesystem_id'])
og["og:image:type"] = image_info['media_type']
og["og:image:width"] = dims['width']
og["og:image:height"] = dims['height']
else:
del og["og:image"]
if 'og:description' not in og:
meta_description = tree.xpath("//*/meta[@name='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("//h1/text() | //h2/text() | //h3/text() | //p/text() | //div/text()")
# 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:
@ -144,49 +217,16 @@ class PreviewUrlResource(BaseMediaResource):
text = text.strip()[:500]
og['og:description'] = text if text else None
# TODO: extract a favicon?
# TODO: turn any OG media URLs into mxc URLs to capture and thumbnail them too
# TODO: store our OG details in a cache (and expire them when stale)
# TODO: delete the content to stop diskfilling, as we only ever cared about its OG
return og
try:
tree = html.parse(media_info['filename'])
og = _calc_og()
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 = _calc_og()
else:
logger.warn("Failed to find any OG data in %s", 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
# 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] and not url[1]:
url[0] = base[0]
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]