3 files changed, 47 insertions, 16 deletions
diff --git a/bot/cogs/token_remover.py b/bot/cogs/token_remover.py
index d55e079e9..ef979f222 100644
--- a/bot/cogs/token_remover.py
+++ b/bot/cogs/token_remover.py
@@ -4,7 +4,7 @@ import logging
 import re
 import typing as t
 
-from discord import Colour, Message
+from discord import Colour, Message, NotFound
 from discord.ext.commands import Cog
 
 from bot import utils
@@ -63,6 +63,10 @@ class TokenRemover(Cog):
 
         See: https://discordapp.com/developers/docs/reference#snowflakes
         """
+        # Ignore DMs; can't delete messages in there anyway.
+        if not msg.guild or msg.author.bot:
+            return
+
         found_token = self.find_token_in_message(msg)
         if found_token:
             await self.take_action(msg, found_token)
@@ -79,7 +83,13 @@ class TokenRemover(Cog):
     async def take_action(self, msg: Message, found_token: Token) -> None:
         """Remove the `msg` containing the `found_token` and send a mod log message."""
         self.mod_log.ignore(Event.message_delete, msg.id)
-        await msg.delete()
+
+        try:
+            await msg.delete()
+        except NotFound:
+            log.debug(f"Failed to remove token in message {msg.id}: message already deleted.")
+            return
+
         await msg.channel.send(DELETION_MESSAGE_TEMPLATE.format(mention=msg.author.mention))
 
         log_message = self.format_log_message(msg, found_token)
@@ -112,9 +122,6 @@ class TokenRemover(Cog):
     @classmethod
     def find_token_in_message(cls, msg: Message) -> t.Optional[Token]:
         """Return a seemingly valid token found in `msg` or `None` if no token is found."""
-        if msg.author.bot:
-            return
-
         # Use finditer rather than search to guard against method calls prematurely returning the
         # token check (e.g. `message.channel.send` also matches our token pattern)
         for match in TOKEN_RE.finditer(msg.content):
diff --git a/bot/cogs/webhook_remover.py b/bot/cogs/webhook_remover.py
index 1b5c3f821..543869215 100644
--- a/bot/cogs/webhook_remover.py
+++ b/bot/cogs/webhook_remover.py
@@ -1,7 +1,7 @@
 import logging
 import re
 
-from discord import Colour, Message
+from discord import Colour, Message, NotFound
 from discord.ext.commands import Cog
 
 from bot.bot import Bot
@@ -35,7 +35,13 @@ class WebhookRemover(Cog):
         """Delete `msg` and send a warning that it contained the Discord webhook `redacted_url`."""
         # Don't log this, due internal delete, not by user. Will make different entry.
         self.mod_log.ignore(Event.message_delete, msg.id)
-        await msg.delete()
+
+        try:
+            await msg.delete()
+        except NotFound:
+            log.debug(f"Failed to remove webhook in message {msg.id}: message already deleted.")
+            return
+
         await msg.channel.send(ALERT_MESSAGE_TEMPLATE.format(user=msg.author.mention))
 
         message = (
@@ -59,6 +65,10 @@ class WebhookRemover(Cog):
     @Cog.listener()
     async def on_message(self, msg: Message) -> None:
         """Check if a Discord webhook URL is in `message`."""
+        # Ignore DMs; can't delete messages in there anyway.
+        if not msg.guild or msg.author.bot:
+            return
+
         matches = WEBHOOK_URL_RE.search(msg.content)
         if matches:
             await self.delete_and_respond(msg, matches[1] + "xxx")
diff --git a/tests/bot/cogs/test_token_remover.py b/tests/bot/cogs/test_token_remover.py
index a10124d2d..3349caa73 100644
--- a/tests/bot/cogs/test_token_remover.py
+++ b/tests/bot/cogs/test_token_remover.py
@@ -3,7 +3,7 @@ from re import Match
 from unittest import mock
 from unittest.mock import MagicMock
 
-from discord import Colour
+from discord import Colour, NotFound
 
 from bot import constants
 from bot.cogs import token_remover
@@ -121,15 +121,16 @@ class TokenRemoverTests(unittest.IsolatedAsyncioTestCase):
         find_token_in_message.assert_called_once_with(self.msg)
         take_action.assert_not_awaited()
 
-    @autospec("bot.cogs.token_remover", "TOKEN_RE")
-    def test_find_token_ignores_bot_messages(self, token_re):
-        """The token finder should ignore messages authored by bots."""
-        self.msg.author.bot = True
+    @autospec(TokenRemover, "find_token_in_message")
+    async def test_on_message_ignores_dms_bots(self, find_token_in_message):
+        """Shouldn't parse a message if it is a DM or authored by a bot."""
+        cog = TokenRemover(self.bot)
+        dm_msg = MockMessage(guild=None)
+        bot_msg = MockMessage(author=MagicMock(bot=True))
 
-        return_value = TokenRemover.find_token_in_message(self.msg)
-
-        self.assertIsNone(return_value)
-        token_re.finditer.assert_not_called()
+        for msg in (dm_msg, bot_msg):
+            await cog.on_message(msg)
+            find_token_in_message.assert_not_called()
 
     @autospec("bot.cogs.token_remover", "TOKEN_RE")
     def test_find_token_no_matches(self, token_re):
@@ -281,6 +282,19 @@ class TokenRemoverTests(unittest.IsolatedAsyncioTestCase):
             channel_id=constants.Channels.mod_alerts
         )
 
+    @mock.patch.object(TokenRemover, "mod_log", new_callable=mock.PropertyMock)
+    async def test_take_action_delete_failure(self, mod_log_property):
+        """Shouldn't send any messages if the token message can't be deleted."""
+        cog = TokenRemover(self.bot)
+        mod_log_property.return_value = mock.create_autospec(ModLog, spec_set=True, instance=True)
+        self.msg.delete.side_effect = NotFound(MagicMock(), MagicMock())
+
+        token = mock.create_autospec(Token, spec_set=True, instance=True)
+        await cog.take_action(self.msg, token)
+
+        self.msg.delete.assert_called_once_with()
+        self.msg.channel.send.assert_not_awaited()
+
 
 class TokenRemoverExtensionTests(unittest.TestCase):
     """Tests for the token_remover extension."""