index: Catch query parsing errors.

Tantivy's query parser can throw errors if the syntax of the query is
invalid.

There is a more lenient query parser[1] in the works but until then
catch query parser errors and return an error response to the user.

[1] https://github.com/tantivy-search/tantivy/issues/5

pantalaimon/daemon.py

@@ -32,6 +32,7 @@ from pantalaimon.client import (InvalidLimit, InvalidOrderByError, PanClient,
                                 UnknownRoomError)
 from pantalaimon.log import logger
 from pantalaimon.store import ClientInfo, PanStore
+from pantalaimon.index import InvalidQueryError
 from pantalaimon.thread_messages import (AcceptSasMessage, CancelSasMessage,
                                          CancelSendingMessage,
                                          ConfirmSasMessage, DaemonResponse,
@@ -943,7 +944,7 @@ class ProxyDaemon:
                 },
                 status=400,
             )
-        except (InvalidOrderByError, InvalidLimit) as e:
+        except (InvalidOrderByError, InvalidLimit, InvalidQueryError) as e:
             return web.json_response(
                 {
                     "errcode": "M_INVALID_PARAM",

pantalaimon/index.py

@@ -29,6 +29,10 @@ from peewee import (SQL, DateTimeField, ForeignKeyField, Model, SqliteDatabase,
 from pantalaimon.store import use_database
 
 
+class InvalidQueryError(Exception):
+    pass
+
+
 class DictField(TextField):
     def python_value(self, value):  # pragma: no cover
         return json.loads(value)
@@ -284,12 +288,17 @@ class Searcher:
         # This currently supports only a single room since the query parser
         # doesn't seem to work with multiple room fields here.
         if room:
-            search_term = "{} AND room:{}".format(
+            query_string = "{} AND room:{}".format(
                 search_term,
                 sanitize_room_id(room)
             )
+        else:
+            query_string = search_term
 
-        query = queryparser.parse_query(search_term)
+        try:
+            query = queryparser.parse_query(query_string)
+        except ValueError:
+            raise InvalidQueryError(f"Invalid search term: {search_term}")
 
         if order_by_recent:
             collector = tantivy.TopDocs(max_results,