Add a push notification module to handle mobile client notifications

(imported from commit 3061a6e2d845226d3dce5bb262deb3a896e54f07)

zerver/lib/push_notifications.py

@@ -0,0 +1,70 @@
+from __future__ import absolute_import
+
+from zerver.models import UserProfile, AppleDeviceToken
+from zerver.lib.timestamp import timestamp_to_datetime
+from zerver.decorator import statsd_increment
+
+from apnsclient import Session, Connection, Message, APNs
+
+from django.conf import settings
+
+import base64, binascii, logging
+
+# Maintain a long-lived Session object to avoid having to re-SSL-handshake
+# for each request
+session = Session()
+connection = session.get_connection(settings.APNS_SANDBOX, cert_file=settings.APNS_CERT_FILE)
+
+
+def num_push_devices_for_user(user_profile):
+    return AppleDeviceToken.objects.filter(user=user_profile).count()
+
+# We store the token as b64, but apns-client wants hex strings
+def b64_to_hex(data):
+    return binascii.hexlify(base64.b64decode(data))
+
+def hex_to_b64(data):
+    return base64.b64encode(binascii.unhexlify(data))
+
+# Send a push notification to the desired clients
+# extra_data is a dict that will be passed to the
+# mobile app
+@statsd_increment("apple_push_notification")
+def send_apple_push_notification(user, alert, **extra_data):
+    # Sends a push notifications to all the PushClients
+    # Only Apple Push Notifications clients are supported at the moment
+    tokens = [b64_to_hex(device.token) for device in AppleDeviceToken.objects.filter(user=user)]
+
+    logging.info("Sending apple push notification to devices: %s" % (tokens,))
+    message = Message(tokens, alert=alert, **extra_data)
+
+    apns_client = APNs(connection)
+    ret = apns_client.send(message)
+    if not ret:
+       logging.warning("Failed to send push notification for clients %s" % (tokens,))
+       return
+
+    for token, reason in ret.failed.items():
+        code, errmsg = reason
+        logging.warning("Failed to deliver APNS notification to %s, reason: %s" % (token, errmsg))
+
+    # Check failures not related to devices.
+    for code, errmsg in ret.errors:
+        logging.warning("Unknown error when delivering APNS: %s" %  (errmsg,))
+
+    if ret.needs_retry():
+        # TODO handle retrying by potentially scheduling a background job
+        # or re-queueing
+        logging.warning("APNS delivery needs a retry but ignoring")
+
+# NOTE: This is used by the check_apns_tokens manage.py command. Do not call it otherwise, as the
+# feedback() call can take up to 15s
+def check_apns_feedback():
+    apns_client = APNs(connection, tail_timeout=20)
+
+    for token, since in apns_client.feedback():
+        since_date = timestamp_to_datetime(since)
+        logging.info("Found unavailable token %s, unavailable since %s" % (token, since_date))
+
+        AppleDeviceToken.objects.filter(token=hex_to_b64(token), last_updates__lt=since_date).delete()
+    logging.info("Finished checking feedback for stale tokens")