"""Handles inbound webmentions. TODO tests: * actor/attributedTo could be string URL * salmon rel via webfinger via author.name + domain """ import datetime import json import logging import urlparse import appengine_config from bs4 import BeautifulSoup import django_salmon from django_salmon import magicsigs, utils import feedparser from granary import as2, atom, microformats2 from httpsig.requests_auth import HTTPSignatureAuth import mf2py import mf2util from oauth_dropins.webutil import util import requests import webapp2 import activitypub import common import models class WebmentionHandler(webapp2.RequestHandler): """Handles inbound webmention, converts to ActivityPub or Salmon.""" def post(self): logging.info('Params: %s', self.request.params.items()) source = util.get_required_param(self, 'source') target = util.get_required_param(self, 'target') # fetch source page, convert to ActivityStreams resp = common.requests_get(source) mf2 = mf2py.parse(resp.text, url=resp.url) # logging.debug('Parsed mf2 for %s: %s', resp.url, json.dumps(mf2, indent=2)) entry = mf2util.find_first_entry(mf2, ['h-entry']) logging.info('First entry: %s', json.dumps(entry, indent=2)) source_obj = microformats2.json_to_object(entry) logging.info('Converted to AS: %s', json.dumps(source_obj, indent=2)) # fetch target page as AS object try: resp = common.requests_get(target, headers=activitypub.CONNEG_HEADER, log=True) except requests.HTTPError as e: if e.response.status_code // 100 == 4: return self.send_salmon(source_obj, target_url=target) raise if resp.headers.get('Content-Type').startswith('text/html'): return self.send_salmon(source_obj, target_resp=resp) # find actor's inbox target_obj = resp.json() inbox_url = target_obj.get('inbox') if not inbox_url: # TODO: test actor/attributedTo and not, with/without inbox actor = target_obj.get('actor') or target_obj.get('attributedTo') if isinstance(actor, dict): inbox_url = actor.get('inbox') actor = actor.get('url') if not inbox_url and not actor: self.abort(400, 'Target object has no actor or attributedTo URL') if not inbox_url: # fetch actor as AS object actor = common.requests_get(actor, parse_json=True, headers=activitypub.CONNEG_HEADER) inbox_url = actor.get('inbox') if not inbox_url: # TODO: probably need a way to save errors like this so that we can # return them if ostatus fails too. # self.abort(400, 'Target actor has no inbox') return self.send_salmon(source_obj, target_url=target) # convert to AS2 source_domain = urlparse.urlparse(source).netloc key = models.MagicKey.get_or_create(source_domain) source_activity = common.postprocess_as2(as2.from_as1(source_obj), key=key) # prepare HTTP Signature (required by Mastodon) # https://w3c.github.io/activitypub/#authorization-lds # https://tools.ietf.org/html/draft-cavage-http-signatures-07 # https://github.com/tootsuite/mastodon/issues/4906#issuecomment-328844846 acct = 'acct:me@%s' % source_domain auth = HTTPSignatureAuth(secret=key.private_pem(), key_id=acct, algorithm='rsa-sha256') # deliver source object to target actor's inbox. headers = { 'Content-Type': activitypub.CONTENT_TYPE_AS, # required for HTTP Signature # https://tools.ietf.org/html/draft-cavage-http-signatures-07#section-2.1.3 'Date': datetime.datetime.utcnow().strftime('%a, %d %b %Y %H:%M:%S GMT'), } resp = common.requests_post( urlparse.urljoin(target, inbox_url), json=source_activity, auth=auth, headers=headers, log=True) def send_salmon(self, source_obj, target_url=None, target_resp=None): # fetch target HTML page, extract Atom rel-alternate link if target_url: assert not target_resp target_resp = common.requests_get(target_url) else: assert target_resp # TODO: this could be different due to redirects target_url = target_resp.url parsed = BeautifulSoup(target_resp.content, from_encoding=target_resp.encoding) atom_url = parsed.find('link', rel='alternate', type=common.ATOM_CONTENT_TYPE) if not atom_url or not atom_url['href']: common.error(self, 'Target post %s has no Atom link' % target_resp.url, status=400) # fetch Atom target post, extract id and salmon endpoint feed = common.requests_get(atom_url['href']).text parsed = feedparser.parse(feed) logging.info('Parsed: %s', json.dumps(parsed, indent=2, default=lambda key: '-')) entry = parsed.entries[0] target_id = entry.id source_obj['inReplyTo'][0]['id'] = target_id # Mastodon (and maybe others?) require a rel-mentioned link to the # original post's author to make it show up as a reply: # app/services/process_interaction_service.rb # ...so add them as a tag, which atom renders as a rel-mention link. authors = entry.get('authors', None) if authors: url = entry.authors[0].get('href') if url: source_obj.setdefault('tags', []).append({'url': url}) logging.info('Discovering Salmon endpoint in %s', atom_url['href']) endpoint = django_salmon.discover_salmon_endpoint(feed) if not endpoint: # try webfinger parsed = urlparse.urlparse(target_url) # TODO: test missing email acct = entry.author_detail.get('email') or '@'.join( (entry.author_detail.name, parsed.netloc)) try: resp = common.requests_get( '%s://%s/.well-known/webfinger?resource=%s' % (parsed.scheme, parsed.netloc, acct), log=True) endpoint = django_salmon.get_salmon_replies_link(resp.json()) except requests.HTTPError as e: pass if not endpoint: common.error(self, 'No salmon endpoint found!', status=400) logging.info('Discovered Salmon endpoint %s', endpoint) # construct reply Atom object source_url = self.request.get('source') entry = atom.activity_to_atom({'object': source_obj}, xml_base=source_url) logging.info('Converted %s to Atom:\n%s', source_url, entry) # sign reply and wrap in magic envelope domain = urlparse.urlparse(source_url).netloc.split(':')[0] key = models.MagicKey.get_or_create(domain) logging.info('Using key for %s: %s', domain, key) magic_envelope = magicsigs.magic_envelope( entry, common.ATOM_CONTENT_TYPE, key) logging.info('Sending Salmon slap to %s', endpoint) common.requests_post( endpoint, data=common.XML_UTF8 + magic_envelope, log=True, headers={'Content-Type': common.MAGIC_ENVELOPE_CONTENT_TYPE}) app = webapp2.WSGIApplication([ ('/webmention', WebmentionHandler), ], debug=appengine_config.DEBUG)