app/webhooks.py

   1 """
   2 This is the webhook server that interfaces with Google's WebSub (formerly pubsubhubbub) server. This is its own server, so it can live on a different host than the frontend.
   3 """
   4
   5 #TODO: fold update-websub.py into this?
   6
   7 import time
   8 import sqlite3
   9 from flask import Flask, request
  10 from urllib.parse import parse_qs
  11
  12 from common import *
  13
  14 app = Flask(__name__)
  15
  16 @app.route('/websub/v1/<int:timestamp>/<nonce>/<subject>/<sig>', methods=["GET"])
  17 def websub(timestamp, nonce, subject, sig):
  18     mode = request.args.get('hub.mode', '')
  19     topic = request.args.get('hub.topic', '')
  20     challenge = request.args.get('hub.challenge', '')
  21     until = int(request.args.get('hub.lease_seconds', '0'))
  22
  23     channel_id = parse_qs(topic.split('?')[1]).get('channel_id', [''])[0]  # TODO: support playlists # XXX: can raise indexerror
  24     if not channel_id:
  25         return '', 400
  26
  27     if time.time() - timestamp > int(cf['websub']['lease']):
  28         return '', 400
  29     # TODO: implement hmac check: return '',400 unless hmac_sha1_hex("$timestamp/$nonce", $HMACKEY) eq $sig
  30
  31     if mode != "subscribe":
  32         return '', 200
  33         # Note: channels are not purged from the websub dbtable.
  34
  35     with sqlite3.connect(cf['global']['database']) as conn:
  36         c = conn.cursor()
  37         c.execute("""
  38                 INSERT OR REPLACE INTO websub (channel_id, subscribed_until)
  39                            VALUES (?, datetime(?, 'unixepoch'))
  40         """, (channel_id, time.time()+until))
  41     return challenge, 200
  42
  43 @app.route('/websub/v1/<int:timestamp>/<nonce>/<subject>/<sig>', methods=["POST"])
  44 def websub_post(timestamp, nonce, subject, sig):
  45         # TODO: implement hmac check: return '',400 unless hmac_sha1_hex("$timestamp/$nonce", $HMACKEY) eq $sig
  46         # todo: # say 400 and exit unless hmac_sha1_hex($body, $HMACKEY) eq $ENV{X-Hub-Signature }
  47
  48     with sqlite3.connect(cf['global']['database']) as conn:
  49         c = conn.cursor()
  50         ok = update_channel(conn, request.data)
  51         if not ok:
  52             with open('/tmp/websub-subscriptions.err', 'a') as f:
  53                 f.write(f"<!-- {time.ctime()} ({int(time.time())}) -->\n{xmlfeed}\n")
  54     return '', 200
  55
  56 if __name__ == '__main__':
  57     app.run(debug=True)