Add rate limiting for Pushover notifications

CHANGELOG.md

@@ -12,6 +12,7 @@ All notable changes to this project will be documented in this file.
 - Change Zulip onboarding, ask for the zuliprc file (#202)
 - Add a section in Docs about running self-hosted instances
 - Add experimental Dockerfile and docker-compose.yml
+- Add rate limiting for Pushover notifications (6 notifications / user / minute)
 
 ## Bug Fixes
 - Fix unwanted HTML escaping in SMS and WhatsApp notifications

hc/api/models.py

@@ -931,6 +931,13 @@ class TokenBucket(models.Model):
         # 6 messages for a single recipient per minute:
         return TokenBucket.authorize(value, 6, 60)
 
+    @staticmethod
+    def authorize_pushover(user_key):
+        salted_encoded = (user_key + settings.SECRET_KEY).encode()
+        value = "po-%s" % hashlib.sha1(salted_encoded).hexdigest()
+        # 6 messages for a single user key per minute:
+        return TokenBucket.authorize(value, 6, 60)
+
     @staticmethod
     def authorize_sudo_code(user):
         value = "sudo-%d" % user.id

hc/api/tests/test_notify.py

@@ -2,7 +2,7 @@
 
 from datetime import timedelta as td
 import json
-from unittest.mock import patch, Mock
+from unittest.mock import patch
 
 from django.core import mail
 from django.utils.timezone import now
@@ -492,33 +492,6 @@ class NotifyTestCase(BaseTestCase):
         n = Notification.objects.first()
         self.assertEqual(n.error, 'Received status code 403 with a message: "Nice try"')
 
-    @patch("hc.api.transports.requests.request")
-    def test_pushover(self, mock_post):
-        self._setup_data("po", "123|0")
-        mock_post.return_value.status_code = 200
-
-        self.channel.notify(self.check)
-        assert Notification.objects.count() == 1
-
-        args, kwargs = mock_post.call_args
-        payload = kwargs["data"]
-        self.assertIn("DOWN", payload["title"])
-
-    @patch("hc.api.transports.requests.request")
-    def test_pushover_up_priority(self, mock_post):
-        self._setup_data("po", "123|0|2", status="up")
-        mock_post.return_value.status_code = 200
-
-        self.channel.notify(self.check)
-        assert Notification.objects.count() == 1
-
-        args, kwargs = mock_post.call_args
-        payload = kwargs["data"]
-        self.assertIn("UP", payload["title"])
-        self.assertEqual(payload["priority"], 2)
-        self.assertIn("retry", payload)
-        self.assertIn("expire", payload)
-
     @patch("hc.api.transports.requests.request")
     def test_victorops(self, mock_post):
         self._setup_data("victorops", "123")

hc/api/tests/test_notify_pushover.py

@@ -0,0 +1,65 @@
+# coding: utf-8
+
+from datetime import timedelta as td
+from unittest.mock import patch
+
+from django.test.utils import override_settings
+from django.utils.timezone import now
+from hc.api.models import Channel, Check, Notification, TokenBucket
+from hc.test import BaseTestCase
+
+
+class NotifyTestCase(BaseTestCase):
+    def _setup_data(self, value, status="down", email_verified=True):
+        self.check = Check(project=self.project)
+        self.check.status = status
+        self.check.last_ping = now() - td(minutes=61)
+        self.check.save()
+
+        self.channel = Channel(project=self.project)
+        self.channel.kind = "po"
+        self.channel.value = value
+        self.channel.email_verified = email_verified
+        self.channel.save()
+        self.channel.checks.add(self.check)
+
+    @patch("hc.api.transports.requests.request")
+    def test_pushover(self, mock_post):
+        self._setup_data("123|0")
+        mock_post.return_value.status_code = 200
+
+        self.channel.notify(self.check)
+        assert Notification.objects.count() == 1
+
+        args, kwargs = mock_post.call_args
+        payload = kwargs["data"]
+        self.assertIn("DOWN", payload["title"])
+
+    @patch("hc.api.transports.requests.request")
+    def test_pushover_up_priority(self, mock_post):
+        self._setup_data("123|0|2", status="up")
+        mock_post.return_value.status_code = 200
+
+        self.channel.notify(self.check)
+        assert Notification.objects.count() == 1
+
+        args, kwargs = mock_post.call_args
+        payload = kwargs["data"]
+        self.assertIn("UP", payload["title"])
+        self.assertEqual(payload["priority"], 2)
+        self.assertIn("retry", payload)
+        self.assertIn("expire", payload)
+
+    @override_settings(SECRET_KEY="test-secret")
+    @patch("hc.api.transports.requests.request")
+    def test_it_obeys_rate_limit(self, mock_post):
+        self._setup_data("123|0")
+
+        # "c0ca..." is sha1("123test-secret")
+        obj = TokenBucket(value="po-c0ca2a9774952af32cabf86453f69e442c4ed0eb")
+        obj.tokens = 0
+        obj.save()
+
+        self.channel.notify(self.check)
+        n = Notification.objects.first()
+        self.assertEqual(n.error, "Rate limit exceeded")

hc/api/transports.py

@@ -358,20 +358,24 @@ class Pushover(HttpTransport):
     URL = "https://api.pushover.net/1/messages.json"
 
     def notify(self, check):
-        others = self.checks().filter(status="down").exclude(code=check.code)
-
-        # list() executes the query, to avoid DB access while
-        # rendering a template
-        ctx = {"check": check, "down_checks": list(others)}
-        text = tmpl("pushover_message.html", **ctx)
-        title = tmpl("pushover_title.html", **ctx)
-
         pieces = self.channel.value.split("|")
         user_key, prio = pieces[0], pieces[1]
         # The third element, if present, is the priority for "up" events
         if len(pieces) == 3 and check.status == "up":
             prio = pieces[2]
 
+        from hc.api.models import TokenBucket
+
+        if not TokenBucket.authorize_pushover(user_key):
+            return "Rate limit exceeded"
+
+        others = self.checks().filter(status="down").exclude(code=check.code)
+        # list() executes the query, to avoid DB access while
+        # rendering a template
+        ctx = {"check": check, "down_checks": list(others)}
+        text = tmpl("pushover_message.html", **ctx)
+        title = tmpl("pushover_title.html", **ctx)
+
         payload = {
             "token": settings.PUSHOVER_API_TOKEN,
             "user": user_key,