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, urlparse
  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     # extract the first query parameter, which is either channel_id or playlist_id:
  24     channel_id = next(iter(parse_qs(urlparse(topic).query).values()), [None])[0]
  25
  26     if not channel_id:
  27         return '', 400
  28
  29     if time.time() - timestamp > int(cf['websub']['lease']):
  30         return '', 400
  31     # TODO: implement hmac check: return '',400 unless hmac_sha1_hex("$timestamp/$nonce", $HMACKEY) eq $sig
  32
  33     if mode != "subscribe":
  34         return '', 200
  35         # Note: channels are not purged from the websub dbtable.
  36
  37     with sqlite3.connect(cf['global']['database']) as conn:
  38         c = conn.cursor()
  39         c.execute("""
  40                 INSERT OR REPLACE INTO websub (channel_id, subscribed_until)
  41                            VALUES (?, datetime(?, 'unixepoch'))
  42         """, (channel_id, time.time()+until))
  43     return challenge, 200
  44
  45 @app.route('/websub/v1/<int:timestamp>/<nonce>/<subject>/<sig>', methods=["POST"])
  46 def websub_post(timestamp, nonce, subject, sig):
  47         # TODO: implement hmac check: return '',400 unless hmac_sha1_hex("$timestamp/$nonce", $HMACKEY) eq $sig
  48         # todo: # say 400 and exit unless hmac_sha1_hex($body, $HMACKEY) eq $ENV{X-Hub-Signature }
  49
  50     with sqlite3.connect(cf['global']['database']) as conn:
  51         c = conn.cursor()
  52         try:
  53             update_channel(conn, request.data)
  54         except:
  55             with open('/tmp/websub-subscriptions.err', 'a') as f:
  56                 f.write(f"<!-- {time.ctime()} ({int(time.time())}) -->\n{xmlfeed}\n")
  57     return '', 200
  58
  59 if __name__ == '__main__':
  60     app.run(debug=True)