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fix assorted redirect, unicode and screenscraping bugs

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This commit is contained in:
Matthew Hodgson 2016-04-01 02:17:48 +01:00
parent 683e564815
commit c60b751694
1 changed files with 89 additions and 71 deletions
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60
synapse/rest/media/v1/preview_url_resource.py
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@ -74,15 +74,7 @@ class PreviewUrlResource(BaseMediaResource):
elif self._is_html(media_info['media_type']):
# TODO: somehow stop a big HTML tree from exploding synapse's RAM
# XXX: can't work out how to make lxml ignore UTF8 decoding errors
# so slurp as a string at this point.
file = open(media_info['filename'])
body = file.read()
file.close()
# FIXME: we shouldn't be forcing utf-8 if the page isn't actually utf-8...
tree = html.fromstring(body.decode('utf-8','ignore'))
# tree = html.parse(media_info['filename'])
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
# (although the client could choose to do this by asking for previews of those URLs to avoid DoSing the server)
@ -112,11 +104,17 @@ class PreviewUrlResource(BaseMediaResource):
for tag in tree.xpath("//*/meta[starts-with(@property, 'og:')]"):
og[tag.attrib['property']] = tag.attrib['content']
if not og:
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
if 'og:image' not in og:
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
@ -126,32 +124,43 @@ class PreviewUrlResource(BaseMediaResource):
images = big_images if big_images else images
if images:
base = list(urlparse(media_info['uri']))
src = list(urlparse(images[0].attrib['src']))
if not src[0] and not src[1]:
src[0] = base[0]
src[1] = base[1]
if not src[2].startswith('/'):
src[2] = re.sub(r'/[^/]+$', '/', base[2]) + src[2]
og['og:image'] = urlunparse(src)
og['og:image'] = self._rebase_url(images[0].attrib['src'], media_info['uri'])
if 'og:description' not in og:
meta_description = tree.xpath("//*/meta[@name='description']/@content");
if meta_description:
og['og:description'] = meta_description[0]
else:
text_nodes = tree.xpath("//h1/text() | //h2/text() | //h3/text() | //p/text() | //div/text() | //span/text() | //a/text()")
# text_nodes = tree.xpath("//h1/text() | //h2/text() | //h3/text() | //p/text() | //div/text()")
text = ''
for text_node in text_nodes:
if len(text) < 1024:
if len(text) < 500:
text += text_node + ' '
else:
break
text = re.sub(r'[\t ]+', ' ', text)
text = re.sub(r'[\t \r\n]*[\r\n]+', '\n', text)
text = text.strip()[:1024]
text = text.strip()[:500]
og['og:description'] = text if text else None
# TODO: extract a favicon?
# TODO: turn any OG media URLs into mxc URLs to capture and thumbnail them too
# TODO: store our OG details in a cache (and expire them when stale)
# TODO: delete the content to stop diskfilling, as we only ever cared about its OG
return og
try:
tree = html.parse(media_info['filename'])
og = _calc_og()
except UnicodeDecodeError:
# XXX: evil evil bodge
file = open(media_info['filename'])
body = file.read()
file.close()
tree = html.fromstring(body.decode('utf-8','ignore'))
og = _calc_og()
else:
logger.warn("Failed to find any OG data in %s", url)
og = {}
@ -173,6 +182,15 @@ class PreviewUrlResource(BaseMediaResource):
)
raise
def _rebase_url(self, url, base):
base = list(urlparse(base))
url = list(urlparse(url))
if not url[0] and not url[1]:
url[0] = base[0]
url[1] = base[1]
if not url[2].startswith('/'):
url[2] = re.sub(r'/[^/]+$', '/', base[2]) + url[2]
return urlunparse(url)
@defer.inlineCallbacks
def _download_url(self, url, user):
@ -223,7 +241,7 @@ class PreviewUrlResource(BaseMediaResource):
download_name = None
yield self.store.store_local_media(
media_id=fname,
media_id=file_id,
media_type=media_type,
time_now_ms=self.clock.time_msec(),
upload_name=download_name,