_search= queries now correctly escaped, fixes #651

Queries with reserved words or characters according to the SQLite
FTS5 query language could cause errors.

Queries are now escaped like so:

    dog cat => "dog" "cat"

datasette/plugins.py

@@ -8,6 +8,7 @@ DEFAULT_PLUGINS = (
     "datasette.publish.now",
     "datasette.publish.cloudrun",
     "datasette.facets",
+    "datasette.sql_functions",
 )
 
 pm = pluggy.PluginManager("datasette")

datasette/sql_functions.py

@@ -0,0 +1,7 @@
+from datasette import hookimpl
+from datasette.utils import escape_fts
+
+
+@hookimpl
+def prepare_connection(conn):
+    conn.create_function("escape_fts", 1, escape_fts)

datasette/utils/__init__.py

@@ -758,6 +758,20 @@ def format_bytes(bytes):
         return "{:.1f} {}".format(current, unit)
 
 
+_escape_fts_re = re.compile(r'\s+|(".*?")')
+
+
+def escape_fts(query):
+    # If query has unbalanced ", add one at end
+    if query.count('"') % 2:
+        query += '"'
+    bits = _escape_fts_re.split(query)
+    bits = [b for b in bits if b and b != '""']
+    return " ".join(
+        '"{}"'.format(bit) if not bit.startswith('"') else bit for bit in bits
+    )
+
+
 class RequestParameters(dict):
     def get(self, name, default=None):
         "Return first value in the list, if available"

datasette/views/table.py

@@ -361,7 +361,7 @@ class TableView(RowTableShared):
                 # Simple ?_search=xxx
                 search = search_args["_search"]
                 where_clauses.append(
-                    "{fts_pk} in (select rowid from {fts_table} where {fts_table} match :search)".format(
+                    "{fts_pk} in (select rowid from {fts_table} where {fts_table} match escape_fts(:search))".format(
                         fts_table=escape_sqlite(fts_table), fts_pk=escape_sqlite(fts_pk)
                     )
                 )
@@ -375,7 +375,7 @@ class TableView(RowTableShared):
                         raise DatasetteError("Cannot search by that column", status=400)
 
                     where_clauses.append(
-                        "rowid in (select rowid from {fts_table} where {search_col} match :search_{i})".format(
+                        "rowid in (select rowid from {fts_table} where {search_col} match escape_fts(:search_{i}))".format(
                             fts_table=escape_sqlite(fts_table),
                             search_col=escape_sqlite(search_col),
                             i=i,

tests/test_api.py

@@ -947,6 +947,11 @@ def test_sortable_columns_metadata(app_client):
                 [2, "terry dog", "sara weasel", "puma"],
             ],
         ),
+        (
+            # Special keyword shouldn't break FTS query
+            "/fixtures/searchable.json?_search=AND",
+            [],
+        ),
         (
             "/fixtures/searchable.json?_search=weasel",
             [[2, "terry dog", "sara weasel", "puma"]],

tests/test_utils.py

@@ -388,3 +388,21 @@ def test_path_with_format(path, format, extra_qs, expected):
 )
 def test_format_bytes(bytes, expected):
     assert expected == utils.format_bytes(bytes)
+
+
+@pytest.mark.parametrize(
+    "query,expected",
+    [
+        ("dog", '"dog"'),
+        ("cat,", '"cat,"'),
+        ("cat dog", '"cat" "dog"'),
+        # If a phrase is already double quoted, leave it so
+        ('"cat dog"', '"cat dog"'),
+        ('"cat dog" fish', '"cat dog" "fish"'),
+        # Sensibly handle unbalanced double quotes
+        ('cat"', '"cat"'),
+        ('"cat dog" "fish', '"cat dog" "fish"'),
+    ],
+)
+def test_escape_fts(query, expected):
+    assert expected == utils.escape_fts(query)