Redactions: only remove the keys that are specced for removal

lib/models/event.js

@@ -21,6 +21,7 @@ limitations under the License.
  * @module models/event
  */
 
+var utils = require("../utils");
 
 /**
  * Enum for event statuses.
@@ -202,7 +203,19 @@ module.exports.MatrixEvent.prototype = {
             this.event.unsigned = {};
         }
         this.event.unsigned.redacted_because = redaction_event;
-        this.event.content = {};
+
+        for (var key in utils.keys(this.event)) {
+            if (!_REDACT_KEEP_KEY_MAP[key]) {
+                delete this.event[key];
+            }
+        }
+
+        var keeps = _REDACT_KEEP_CONTENT_MAP[this.getType()] || {};
+        for (var key in utils.keys(this.event.content)) {
+            if (!keeps[key]) {
+                delete this.event.content[key];
+            }
+        }
     },
 
     /**
@@ -214,3 +227,40 @@ module.exports.MatrixEvent.prototype = {
         return Boolean(this.getUnsigned().redacted_because);
     },
 };
+
+
+/* http://matrix.org/docs/spec/r0.0.1/client_server.html#redactions says:
+ *
+ * the server should strip off any keys not in the following list:
+ *    event_id
+ *    type
+ *    room_id
+ *    user_id
+ *    state_key
+ *    prev_state
+ *    content
+ *    [we keep 'unsigned' as well, since that is created by the local server]
+ *
+ * The content object should also be stripped of all keys, unless it is one of one of the following event types:
+ *    m.room.member allows key membership
+ *    m.room.create allows key creator
+ *    m.room.join_rules allows key join_rule
+ *    m.room.power_levels allows keys ban, events, events_default, kick, redact, state_default, users, users_default.
+ *    m.room.aliases allows key aliases
+ */
+// a map giving the keys we keep when an event is redacted
+var _REDACT_KEEP_KEY_MAP = [
+    'event_id', 'type', 'room_id', 'user_id', 'state_key', 'prev_state', 'content', 'unsigned',
+].reduce(function(ret, val) { ret[val] = 1; return ret}, {});
+
+// a map from event type to the .content keys we keep when an event is redacted
+var _REDACT_KEEP_CONTENT_MAP = {
+    'm.room.member': {'membership': 1},
+    'm.room.create': {'creator': 1},
+    'm.room.join_rules': {'join_rule': 1},
+    'm.room.power_levels': {'ban': 1, 'events': 1, 'events_default': 1,
+                            'kick': 1, 'redact': 1, 'state_default': 1,
+                            'users': 1, 'users_default': 1,
+                           },
+    'm.room.aliases': {'aliases': 1},
+};