remote_server: Handle invalid server uuid being given authing to API.

get_remote_server_by_uuid (called in validate_api_key) raises
ValidationError when given an invalid UUID due to how Django handles
UUIDField. We don't want that exception and prefer the ordinary
DoesNotExist exception to be raised.

zerver/tests/test_push_notifications.py

@@ -241,6 +241,20 @@ class PushBouncerNotificationTest(BouncerTestCase):
 
         del self.API_KEYS[self.server_uuid]
 
+        self.API_KEYS["invalid_uuid"] = "invalid"
+        result = self.uuid_post(
+            "invalid_uuid",
+            endpoint,
+            dict(user_id=user_id, token_kind=token_kind, token=token),
+            subdomain="zulip",
+        )
+        self.assert_json_error(
+            result,
+            "Zulip server auth failure: invalid_uuid is not registered -- did you run `manage.py register_server`?",
+            status_code=401,
+        )
+        del self.API_KEYS["invalid_uuid"]
+
         credentials_uuid = str(uuid.uuid4())
         credentials = "{}:{}".format(credentials_uuid, "invalid")
         api_auth = "Basic " + base64.b64encode(credentials.encode()).decode()

zilencer/models.py

@@ -3,6 +3,7 @@ from typing import List, Tuple
 from uuid import UUID
 
 from django.conf import settings
+from django.core.exceptions import ValidationError
 from django.db import models
 
 from analytics.models import BaseCount
@@ -12,7 +13,10 @@ from zerver.models import AbstractPushDeviceToken, AbstractRealmAuditLog
 
 
 def get_remote_server_by_uuid(uuid: str) -> "RemoteZulipServer":
-    return RemoteZulipServer.objects.get(uuid=uuid)
+    try:
+        return RemoteZulipServer.objects.get(uuid=uuid)
+    except ValidationError:
+        raise RemoteZulipServer.DoesNotExist()
 
 
 class RemoteZulipServer(models.Model):