Validate regex when adding to the filter_token filter

1 files changed, 13 insertions, 0 deletions

diff --git a/bot/exts/filters/filter_lists.py b/bot/exts/filters/filter_lists.py
index ee5bd89f3..d3e6393d3 100644
--- a/bot/exts/filters/filter_lists.py
+++ b/bot/exts/filters/filter_lists.py
@@ -1,3 +1,4 @@
+import re
 from typing import Optional
 
 from discord import Colour, Embed
@@ -72,6 +73,18 @@ class FilterLists(Cog):
         elif list_type == "FILE_FORMAT" and not content.startswith("."):
             content = f".{content}"
 
+        # If it's a filter token, validate the passed regex
+        elif list_type == "FILTER_TOKEN":
+            try:
+                _ = re.compile(content)
+            except re.error:
+                await ctx.message.add_reaction("❌")
+                await ctx.send(
+                    f"{ctx.author.mention} that's not a valid regex! "
+                    "You may have forgotten to escape part of the regex."
+                )
+                return
+
         # Try to add the item to the database
         log.trace(f"Trying to add the {content} item to the {list_type} {allow_type}")
         payload = {