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synthesise basig OG metadata from pages lacking it

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This commit is contained in:
Matthew Hodgson 2016-03-31 14:15:09 +01:00
parent 0d3d7de6fc
commit bb9a2ca87c
1 changed files with 47 additions and 0 deletions
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47
synapse/rest/media/v1/preview_url_resource.py
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@ -23,6 +23,7 @@ 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
@ -70,6 +71,7 @@ class PreviewUrlResource(BaseMediaResource):
# 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
tree = html.parse(media_info['filename'])
# suck it up into lxml and define our OG response.
@ -82,17 +84,58 @@ class PreviewUrlResource(BaseMediaResource):
# "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']
if not 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
images = tree.xpath("//img")
big_images = [ i for i in images if (
'width' in i and 'height' in i and
i.attrib['width'] > 64 and i.attrib['height'] > 64
)] or images
og['og:image'] = images[0].attrib['src'] if images else None
text_nodes = tree.xpath("//h1/text() | //h2/text() | //h3/text() | //p/text() | //div/text() | //span/text() | //a/text()")
text = ''
for text_node in text_nodes:
if len(text) < 1024:
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]
og['og:description'] = text if text else None
# 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
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.
@ -111,6 +154,10 @@ class PreviewUrlResource(BaseMediaResource):
@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)