app/webhooks/__init__.py

   1 """
   2 This is the webhook server that interfaces with Google's WebSub (formerly
   3 pubsubhubbub) server. This can be run either as a module on the main frontend,
   4 or as its own server, so it can live on a different host than the frontend.
   5 """
   6
   7 import time
   8 import sqlite3
   9 from flask import Flask, Blueprint, request
  10 from urllib.parse import parse_qs, urlparse
  11
  12 from ..common.common import *
  13
  14 frontend = Blueprint('webhooks', __name__)
  15
  16 def app():
  17     app = Flask(__name__)
  18     app.register_blueprint(frontend)
  19     return app
  20
  21 @frontend.route('/websub')
  22 def index():
  23     return '', 204 # No Content
  24
  25 @frontend.route('/websub/v1/<int:timestamp>/<nonce>/<subject>/<sig>', methods=["GET"])
  26 def websub(timestamp, nonce, subject, sig):
  27     hmackey = cf['websub']['hmac_key']
  28     mode = request.args.get('hub.mode', '')
  29     topic = request.args.get('hub.topic', '')
  30     challenge = request.args.get('hub.challenge', '')
  31     until = int(request.args.get('hub.lease_seconds', '0'))
  32
  33     if sig != websub_url_hmac(hmackey, subject, timestamp, nonce):
  34         return '', 400
  35
  36     if time.time() - timestamp > int(cf['websub']['lease']):
  37         return '', 400
  38
  39     if mode != "subscribe":
  40         return '', 200
  41         # Note: channels are not purged from the websub dbtable.
  42
  43     with sqlite3.connect(cf['global']['database']) as conn:
  44         c = conn.cursor()
  45         c.execute("""
  46                 INSERT OR REPLACE INTO websub (channel_id, subscribed_until)
  47                            VALUES (?, datetime(?, 'unixepoch'))
  48         """, (subject, time.time()+until))
  49     return challenge, 200
  50
  51 @frontend.route('/websub/v1/<int:timestamp>/<nonce>/<subject>/<sig>', methods=["POST"])
  52 def websub_post(timestamp, nonce, subject, sig):
  53     lease = cf['websub']['lease']
  54     hmackey = cf['websub']['hmac_key']
  55     hub_signature = request.headers.get('X-Hub-Signature').replace("sha1=", "")
  56
  57     if sig != websub_url_hmac(hmackey, subject, timestamp, nonce):
  58         return '', 400
  59     if hub_signature != websub_body_hmac(hmackey, request.data):
  60         return '', 400
  61
  62     with sqlite3.connect(cf['global']['database']) as conn:
  63         c = conn.cursor()
  64         try:
  65             update_channel(conn, request.data, from_webhook=True)
  66         except Exception as e:
  67             with open('/tmp/websub-subscriptions.err', 'ab') as f:
  68                 f.write(f"<!-- {time.ctime()} ({int(time.time())}) -->\n".encode('ascii'))
  69                 f.write(request.data + b"\n")
  70             raise e
  71     return '', 200
  72
  73 if __name__ == '__main__':
  74     app().run(debug=True)