zilencer: Fix server/register failing to check if server is deactivated.

A deactivated server shouldn't be updated like that - we want to return
an error.

zerver/tests/test_push_notifications.py

@@ -4258,6 +4258,16 @@ class PushBouncerSignupTest(ZulipTestCase):
             status_code=401,
         )
 
+        # Now try to do a request to server/register again. Normally, this updates
+        # the server's registration details. But the server is deactivated, so it
+        # should return the corresponding error.
+        result = self.client_post("/api/v1/remotes/server/register", request)
+        self.assert_json_error(
+            result,
+            "The mobile push notification service registration for your server has been deactivated",
+            status_code=401,
+        )
+
     def test_push_signup_invalid_host(self) -> None:
         zulip_org_id = str(uuid.uuid4())
         zulip_org_key = get_random_string(64)

zilencer/views.py

@@ -31,7 +31,11 @@ from corporate.lib.stripe import (
 )
 from corporate.models import CustomerPlan, get_current_plan_by_customer
 from zerver.decorator import require_post
-from zerver.lib.exceptions import JsonableError, RemoteRealmServerMismatchError
+from zerver.lib.exceptions import (
+    JsonableError,
+    RemoteRealmServerMismatchError,
+    RemoteServerDeactivatedError,
+)
 from zerver.lib.push_notifications import (
     InvalidRemotePushDeviceTokenError,
     UserPushIdentityCompat,
@@ -149,12 +153,15 @@ def register_remote_server(
         else:
             if not constant_time_compare(remote_server.api_key, zulip_org_key):
                 raise InvalidZulipServerKeyError(zulip_org_id)
-            else:
-                remote_server.hostname = hostname
-                remote_server.contact_email = contact_email
-                if new_org_key is not None:
-                    remote_server.api_key = new_org_key
-                remote_server.save()
+
+            if remote_server.deactivated:
+                raise RemoteServerDeactivatedError
+
+            remote_server.hostname = hostname
+            remote_server.contact_email = contact_email
+            if new_org_key is not None:
+                remote_server.api_key = new_org_key
+            remote_server.save()
 
     return json_success(request, data={"created": created})