realm: Add wildcard_mention_policy setting.

We add a new wildcard_mention_policy setting to handle wildcard
mentions in large streams, with a wide range of policies available to
organizations.

We set the default to the safe option for preventing accidental spam:
only stream administrators being able to use wildcard mentions in
large streams.

templates/zerver/api/changelog.md

@@ -10,6 +10,11 @@ below features are supported.
 
 ## Changes in Zulip 4.0
 
+**Feature level 34**
+
+* [`POST /register`](/api/register-queue): Added a new `wildcard_mention_policy`
+  setting for controlling who can use wildcard mentions in large streams.
+
 **Feature level 33**
 
 * Markdown code blocks now have a `data-code-language` attribute

version.py

@@ -29,7 +29,7 @@ DESKTOP_WARNING_VERSION = "5.2.0"
 #
 # Changes should be accompanied by documentation explaining what the
 # new level means in templates/zerver/api/changelog.md.
-API_FEATURE_LEVEL = 33
+API_FEATURE_LEVEL = 34
 
 # Bump the minor PROVISION_VERSION to indicate that folks should provision
 # only when going from an old version of the code to a newer version. Bump

zerver/migrations/0303_realm_wildcard_mention_policy.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.2.14 on 2020-09-04 16:28
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('zerver', '0302_case_insensitive_stream_name_index'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='realm',
+            name='wildcard_mention_policy',
+            field=models.PositiveSmallIntegerField(default=4),
+        ),
+    ]

zerver/models.py

@@ -256,6 +256,27 @@ class Realm(models.Model):
         PRIVATE_MESSAGE_POLICY_DISABLED,
     ]
 
+    # Global policy for who is allowed to use wildcard mentions in
+    # streams with a large number of subscribers.  Anyone can use
+    # wildcard mentions in small streams regardless of this setting.
+    WILDCARD_MENTION_POLICY_EVERYONE = 1
+    WILDCARD_MENTION_POLICY_MEMBERS = 2
+    WILDCARD_MENTION_POLICY_FULL_MEMBERS = 3
+    WILDCARD_MENTION_POLICY_STREAM_ADMINS = 4
+    WILDCARD_MENTION_POLICY_ADMINS = 5
+    WILDCARD_MENTION_POLICY_NOBODY = 6
+    wildcard_mention_policy: int = models.PositiveSmallIntegerField(
+        default=WILDCARD_MENTION_POLICY_STREAM_ADMINS,
+    )
+    WILDCARD_MENTION_POLICY_TYPES = [
+        WILDCARD_MENTION_POLICY_EVERYONE,
+        WILDCARD_MENTION_POLICY_MEMBERS,
+        WILDCARD_MENTION_POLICY_FULL_MEMBERS,
+        WILDCARD_MENTION_POLICY_STREAM_ADMINS,
+        WILDCARD_MENTION_POLICY_ADMINS,
+        WILDCARD_MENTION_POLICY_NOBODY,
+    ]
+
     # Who in the organization has access to users' actual email
     # addresses.  Controls whether the UserProfile.email field is the
     # same as UserProfile.delivery_email, or is instead garbage.
@@ -419,6 +440,7 @@ class Realm(models.Model):
         user_group_edit_policy=int,
         default_code_block_language=(str, type(None)),
         message_content_delete_limit_seconds=int,
+        wildcard_mention_policy=int,
     )
 
     DIGEST_WEEKDAY_VALUES = [0, 1, 2, 3, 4, 5, 6]

zerver/openapi/zulip.yaml

@@ -6792,6 +6792,24 @@ paths:
 
                           The policy for which users can add other users to streams in this
                           organization.
+                      realm_wildcard_mention_policy:
+                        type: integer
+                        description: |
+                          Present if `realm` is present in `fetch_event_types`.
+
+                          The policy for who can use wildcard mentions in large streams.
+
+                          * 1 => Any user can use wildcard mentions in large streams.
+                          * 2 => Only members can use wildcard mentions in large streams.
+                          * 3 => Only full members can use wildcard mentions in large streams.
+                          * 4 => Only stream and organization administrators can use wildcard mentions in large streams.
+                          * 5 => Only organization administrators can use wildcard mentions in large streams.
+                          * 6 => Nobody can use wildcard mentions in large streams.
+
+                          All users will receive a warning/reminder when using
+                          mentions in large streams, even when permitted to do so.
+
+                          **Changes**: New in Zulip 4.0 (feature level 33).
                       realm_default_language:
                         type: string
                         description: |

zerver/tests/test_events.py

@@ -1729,6 +1729,7 @@ class RealmPropertyActionTest(BaseAction):
             invite_to_stream_policy=[3, 2, 1],
             private_message_policy=[2, 1],
             user_group_edit_policy=[1, 2],
+            wildcard_mention_policy=[3, 2, 1],
             email_address_visibility=[Realm.EMAIL_ADDRESS_VISIBILITY_ADMINS],
             bot_creation_policy=[Realm.BOT_CREATION_EVERYONE],
             video_chat_provider=[

zerver/tests/test_home.py

@@ -196,6 +196,7 @@ class HomeTest(ZulipTestCase):
             "realm_users",
             "realm_video_chat_provider",
             "realm_waiting_period_threshold",
+            "realm_wildcard_mention_policy",
             "recent_private_conversations",
             "root_domain_uri",
             "save_stacktraces",

zerver/tests/test_realm.py

@@ -502,6 +502,18 @@ class RealmTest(ZulipTestCase):
         result = self.client_patch('/json/realm', req)
         self.assert_json_error(result, 'Invalid private_message_policy')
 
+    def test_change_wildcard_mention_policy(self) -> None:
+        # We need an admin user.
+        self.login('iago')
+        req = dict(wildcard_mention_policy = orjson.dumps(Realm.WILDCARD_MENTION_POLICY_EVERYONE).decode())
+        result = self.client_patch('/json/realm', req)
+        self.assert_json_success(result)
+
+        invalid_value = 10
+        req = dict(wildcard_mention_policy = orjson.dumps(invalid_value).decode())
+        result = self.client_patch('/json/realm', req)
+        self.assert_json_error(result, 'Invalid wildcard_mention_policy')
+
     def test_invalid_integer_attribute_values(self) -> None:
 
         integer_values = [key for key, value in Realm.property_types.items() if value is int]
@@ -518,6 +530,7 @@ class RealmTest(ZulipTestCase):
             user_group_edit_policy=10,
             private_message_policy=10,
             message_content_delete_limit_seconds=-10,
+            wildcard_mention_policy=10,
         )
 
         # We need an admin user.
@@ -719,6 +732,9 @@ class RealmAPITest(ZulipTestCase):
             invite_to_stream_policy=[Realm.POLICY_ADMINS_ONLY,
                                      Realm.POLICY_MEMBERS_ONLY,
                                      Realm.POLICY_FULL_MEMBERS_ONLY],
+            wildcard_mention_policy=[Realm.WILDCARD_MENTION_POLICY_EVERYONE,
+                                     Realm.WILDCARD_MENTION_POLICY_FULL_MEMBERS,
+                                     Realm.WILDCARD_MENTION_POLICY_ADMINS],
             bot_creation_policy=[1, 2],
             email_address_visibility=[Realm.EMAIL_ADDRESS_VISIBILITY_EVERYONE,
                                       Realm.EMAIL_ADDRESS_VISIBILITY_ADMINS,

zerver/views/realm.py

@@ -80,6 +80,8 @@ def update_realm(
             Realm.USER_GROUP_EDIT_POLICY_TYPES), default=None),
         private_message_policy: Optional[int]=REQ(validator=check_int_in(
             Realm.PRIVATE_MESSAGE_POLICY_TYPES), default=None),
+        wildcard_mention_policy: Optional[int]=REQ(validator=check_int_in(
+            Realm.WILDCARD_MENTION_POLICY_TYPES), default=None),
         email_address_visibility: Optional[int]=REQ(validator=check_int_in(
             Realm.EMAIL_ADDRESS_VISIBILITY_TYPES), default=None),
         default_twenty_four_hour_time: Optional[bool]=REQ(validator=check_bool, default=None),