Use join_policy API instead of joinable

The API is now under
 /groups/$group_id/setting/m.join_policy

and expects a JSON blob of the shape

```json
{
  "m.join_policy": {
    "type": "invite"
  }
}
```

where "invite" could alternatively be "open".

7 files changed, 58 insertions, 23 deletions

diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 5a6b63350b..0f7f656824 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -860,9 +860,9 @@ class TransportLayerClient(object):
     @log_function
     def set_group_joinable(self, destination, group_id, requester_user_id,
                            content):
-        """Sets whether a group is joinable without an invite or knock
+        """Sets the join policy for a group
         """
-        path = PREFIX + "/groups/%s/joinable" % (group_id,)
+        path = PREFIX + "/groups/%s/setting/m.join_policy" % (group_id,)
 
         return self.client.post_json(
             destination=destination,
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index 107deb4e1e..a52d3948f4 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -1125,10 +1125,10 @@ class FederationGroupsBulkPublicisedServlet(BaseFederationServlet):
         defer.returnValue((200, resp))
 
 
-class FederationGroupsJoinableServlet(BaseFederationServlet):
+class FederationGroupsSettingJoinPolicyServlet(BaseFederationServlet):
     """Sets whether a group is joinable without an invite or knock
     """
-    PATH = "/groups/(?P<group_id>[^/]*)/joinable$"
+    PATH = "/groups/(?P<group_id>[^/]*)/setting/m.join_policy$"
 
     @defer.inlineCallbacks
     def on_POST(self, origin, content, query, group_id):
@@ -1136,7 +1136,7 @@ class FederationGroupsJoinableServlet(BaseFederationServlet):
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
 
-        new_content = yield self.handler.set_group_joinable(
+        new_content = yield self.handler.set_group_join_policy(
             group_id, requester_user_id, content
         )
 
@@ -1191,7 +1191,7 @@ GROUP_SERVER_SERVLET_CLASSES = (
     FederationGroupsSummaryUsersServlet,
     FederationGroupsAddRoomsServlet,
     FederationGroupsAddRoomsConfigServlet,
-    FederationGroupsJoinableServlet,
+    FederationGroupsSettingJoinPolicyServlet,
 )
 
 
diff --git a/synapse/groups/groups_server.py b/synapse/groups/groups_server.py
index 25cbfb1691..70781e1854 100644
--- a/synapse/groups/groups_server.py
+++ b/synapse/groups/groups_server.py
@@ -207,20 +207,24 @@ class GroupsServerHandler(object):
         defer.returnValue({})
 
     @defer.inlineCallbacks
-    def set_group_joinable(self, group_id, requester_user_id, content):
-        """Sets whether a group is joinable without an invite or knock
+    def set_group_join_policy(self, group_id, requester_user_id, content):
+        """Sets the group join policy.
+
+        Currently supported policies are:
+         - "invite": an invite must be received and accepted in order to join.
+         - "open": anyone can join.
         """
         yield self.check_group_is_ours(
             group_id, requester_user_id, and_exists=True, and_is_admin=requester_user_id
         )
 
-        is_joinable = content.get('joinable')
-        if is_joinable is None:
+        join_policy = _parse_join_policy_from_contents(content)
+        if join_policy is None:
             raise SynapseError(
-                400, "No value specified for 'joinable'"
+                400, "No value specified for 'm.join_policy'"
             )
 
-        yield self.store.set_group_joinable(group_id, is_joinable=is_joinable)
+        yield self.store.set_group_join_policy(group_id, join_policy=join_policy)
 
         defer.returnValue({})
 
@@ -854,6 +858,31 @@ class GroupsServerHandler(object):
         })
 
 
+def _parse_join_policy_from_contents(content):
+    """Given a content for a request, return the specified join policy or None
+    """
+
+    join_policy_dict = content.get("m.join_policy")
+    if join_policy_dict:
+        return _parse_join_policy_dict(join_policy_dict)
+    else:
+        return None
+
+
+def _parse_join_policy_dict(join_policy_dict):
+    """Given a dict for the "m.join_policy" config return the join policy specified
+    """
+    join_policy_type = join_policy_dict.get("type")
+    if not join_policy_type:
+        return True
+
+    if join_policy_type not in ("invite", "open"):
+        raise SynapseError(
+            400, "Synapse only supports 'invite'/'open' join rule"
+        )
+    return join_policy_type
+
+
 def _parse_visibility_from_contents(content):
     """Given a content for a request parse out whether the entity should be
     public or not
diff --git a/synapse/handlers/groups_local.py b/synapse/handlers/groups_local.py
index c9671b9046..5f7b0ff305 100644
--- a/synapse/handlers/groups_local.py
+++ b/synapse/handlers/groups_local.py
@@ -91,7 +91,7 @@ class GroupsLocalHandler(object):
     get_group_role = _create_rerouter("get_group_role")
     get_group_roles = _create_rerouter("get_group_roles")
 
-    set_group_joinable = _create_rerouter("set_group_joinable")
+    set_group_join_policy = _create_rerouter("set_group_join_policy")
 
     @defer.inlineCallbacks
     def get_group_summary(self, group_id, requester_user_id):
diff --git a/synapse/rest/client/v2_alpha/groups.py b/synapse/rest/client/v2_alpha/groups.py
index aa94130e57..8faaa1d6a0 100644
--- a/synapse/rest/client/v2_alpha/groups.py
+++ b/synapse/rest/client/v2_alpha/groups.py
@@ -402,13 +402,13 @@ class GroupInvitedUsersServlet(RestServlet):
         defer.returnValue((200, result))
 
 
-class GroupJoinableServlet(RestServlet):
-    """Set whether a group is joinable without an invite
+class GroupSettingJoinPolicyServlet(RestServlet):
+    """Set group join policy
     """
-    PATTERNS = client_v2_patterns("/groups/(?P<group_id>[^/]*)/joinable$")
+    PATTERNS = client_v2_patterns("/groups/(?P<group_id>[^/]*)/setting/m.join_policy$")
 
     def __init__(self, hs):
-        super(GroupJoinableServlet, self).__init__()
+        super(GroupSettingJoinPolicyServlet, self).__init__()
         self.auth = hs.get_auth()
         self.groups_handler = hs.get_groups_local_handler()
 
@@ -419,7 +419,7 @@ class GroupJoinableServlet(RestServlet):
 
         content = parse_json_object_from_request(request)
 
-        result = yield self.groups_handler.set_group_joinable(
+        result = yield self.groups_handler.set_group_join_policy(
             group_id,
             requester_user_id,
             content,
@@ -765,7 +765,7 @@ def register_servlets(hs, http_server):
     GroupInvitedUsersServlet(hs).register(http_server)
     GroupUsersServlet(hs).register(http_server)
     GroupRoomServlet(hs).register(http_server)
-    GroupJoinableServlet(hs).register(http_server)
+    GroupSettingJoinPolicyServlet(hs).register(http_server)
     GroupCreateServlet(hs).register(http_server)
     GroupAdminRoomsServlet(hs).register(http_server)
     GroupAdminRoomsConfigServlet(hs).register(http_server)
diff --git a/synapse/storage/group_server.py b/synapse/storage/group_server.py
index 96553d4fb1..db66ea1eb0 100644
--- a/synapse/storage/group_server.py
+++ b/synapse/storage/group_server.py
@@ -30,16 +30,16 @@ _DEFAULT_ROLE_ID = ""
 
 
 class GroupServerStore(SQLBaseStore):
-    def set_group_joinable(self, group_id, is_joinable):
+    def set_group_join_policy(self, group_id, join_policy):
         return self._simple_update_one(
             table="groups",
             keyvalues={
                 "group_id": group_id,
             },
             updatevalues={
-                "is_joinable": is_joinable,
+                "join_policy": join_policy,
             },
-            desc="set_group_joinable",
+            desc="set_group_join_policy",
         )
 
     def get_group(self, group_id):
diff --git a/synapse/storage/schema/delta/48/groups_joinable.sql b/synapse/storage/schema/delta/48/groups_joinable.sql
index ace7d0a723..ab3b00286d 100644
--- a/synapse/storage/schema/delta/48/groups_joinable.sql
+++ b/synapse/storage/schema/delta/48/groups_joinable.sql
@@ -13,4 +13,10 @@
  * limitations under the License.
  */
 
-ALTER TABLE groups ADD COLUMN is_joinable SMALLINT DEFAULT 0 NOT NULL;
+/* 
+ * This isn't a real ENUM because sqlite doesn't support it
+ * and we use a default of NULL for inserted rows and interpret
+ * NULL at the python store level as necessary so that existing
+ * rows are given the correct default policy.
+ */
+ALTER TABLE groups ADD COLUMN join_policy TEXT DEFAULT NULL;