Use partial messages in Streams cog to avoid potential leakage (#4742)

* Use partial messages in Streams cog to avoid leakage

* Stop trying to save bot object to Config...

* Put guild id as part of message data

* Fix AttributeError

* Pass bot object to stream classes in commands

* ugh

* Another place we use this class in

* more...

redbot/cogs/streams/streams.py

@@ -209,6 +209,7 @@ class Streams(commands.Cog):
         await self.maybe_renew_twitch_bearer_token()
         token = (await self.bot.get_shared_api_tokens("twitch")).get("client_id")
         stream = TwitchStream(
+            _bot=self.bot,
             name=channel_name,
             token=token,
             bearer=self.ttv_bearer_cache.get("access_token", None),
@@ -224,21 +225,25 @@ class Streams(commands.Cog):
         apikey = await self.bot.get_shared_api_tokens("youtube")
         is_name = self.check_name_or_id(channel_id_or_name)
         if is_name:
-            stream = YoutubeStream(name=channel_id_or_name, token=apikey, config=self.config)
+            stream = YoutubeStream(
+                _bot=self.bot, name=channel_id_or_name, token=apikey, config=self.config
+            )
         else:
-            stream = YoutubeStream(id=channel_id_or_name, token=apikey, config=self.config)
+            stream = YoutubeStream(
+                _bot=self.bot, id=channel_id_or_name, token=apikey, config=self.config
+            )
         await self.check_online(ctx, stream)
 
     @commands.command()
     async def smashcast(self, ctx: commands.Context, channel_name: str):
         """Check if a smashcast channel is live."""
-        stream = HitboxStream(name=channel_name)
+        stream = HitboxStream(_bot=self.bot, name=channel_name)
         await self.check_online(ctx, stream)
 
     @commands.command()
     async def picarto(self, ctx: commands.Context, channel_name: str):
         """Check if a Picarto channel is live."""
-        stream = PicartoStream(name=channel_name)
+        stream = PicartoStream(_bot=self.bot, name=channel_name)
         await self.check_online(ctx, stream)
 
     async def check_online(
@@ -396,19 +401,22 @@ class Streams(commands.Cog):
             is_yt = _class.__name__ == "YoutubeStream"
             is_twitch = _class.__name__ == "TwitchStream"
             if is_yt and not self.check_name_or_id(channel_name):
-                stream = _class(id=channel_name, token=token, config=self.config)
+                stream = _class(_bot=self.bot, id=channel_name, token=token, config=self.config)
             elif is_twitch:
                 await self.maybe_renew_twitch_bearer_token()
                 stream = _class(
+                    _bot=self.bot,
                     name=channel_name,
                     token=token.get("client_id"),
                     bearer=self.ttv_bearer_cache.get("access_token", None),
                 )
             else:
                 if is_yt:
-                    stream = _class(name=channel_name, token=token, config=self.config)
+                    stream = _class(
+                        _bot=self.bot, name=channel_name, token=token, config=self.config
+                    )
                 else:
-                    stream = _class(name=channel_name, token=token)
+                    stream = _class(_bot=self.bot, name=channel_name, token=token)
             try:
                 exists = await self.check_exists(stream)
             except InvalidTwitchCredentials:
@@ -714,14 +722,23 @@ class Streams(commands.Cog):
             await asyncio.sleep(await self.config.refresh_timer())
 
     async def _send_stream_alert(
-        self, stream, channel: discord.TextChannel, embed: discord.Embed, content: str = None
+        self,
+        stream,
+        channel: discord.TextChannel,
+        embed: discord.Embed,
+        content: str = None,
+        *,
+        is_schedule: bool = False,
     ):
         m = await channel.send(
             content,
             embed=embed,
             allowed_mentions=discord.AllowedMentions(roles=True, everyone=True),
         )
-        stream._messages_cache.append(m)
+        message_data = {"guild": m.guild.id, "channel": m.channel.id, "message": m.id}
+        if is_schedule:
+            message_data["is_schedule"] = True
+        stream.messages.append(message_data)
 
     async def check_streams(self):
         to_remove = []
@@ -744,19 +761,25 @@ class Streams(commands.Cog):
                     to_remove.append(stream)
                     continue
                 except OfflineStream:
-                    if not stream._messages_cache:
+                    if not stream.messages:
                         continue
-                    for message in stream._messages_cache:
-                        if await self.bot.cog_disabled_in_guild(self, message.guild):
+
+                    for msg_data in stream.iter_messages():
+                        partial_msg = msg_data["partial_message"]
+                        if partial_msg is None:
                             continue
-                        autodelete = await self.config.guild(message.guild).autodelete()
-                        if autodelete:
+                        if await self.bot.cog_disabled_in_guild(self, partial_msg.guild):
+                            continue
+                        if not await self.config.guild(partial_msg.guild).autodelete():
+                            continue
+
                         with contextlib.suppress(discord.NotFound):
-                                await message.delete()
-                    stream._messages_cache.clear()
+                            await partial_msg.delete()
+
+                    stream.messages.clear()
                     await self.save_streams()
                 else:
-                    if stream._messages_cache:
+                    if stream.messages:
                         continue
                     for channel_id in stream.channels:
                         channel = self.bot.get_channel(channel_id)
@@ -772,7 +795,7 @@ class Streams(commands.Cog):
                             continue
                         if is_schedule:
                             # skip messages and mentions
-                            await self._send_stream_alert(stream, channel, embed)
+                            await self._send_stream_alert(stream, channel, embed, is_schedule=True)
                             await self.save_streams()
                             continue
                         await set_contextual_locales_from_guild(self.bot, channel.guild)
@@ -874,17 +897,6 @@ class Streams(commands.Cog):
             _class = getattr(_streamtypes, raw_stream["type"], None)
             if not _class:
                 continue
-            raw_msg_cache = raw_stream["messages"]
-            raw_stream["_messages_cache"] = []
-            for raw_msg in raw_msg_cache:
-                chn = self.bot.get_channel(raw_msg["channel"])
-                if chn is not None:
-                    try:
-                        msg = await chn.fetch_message(raw_msg["message"])
-                    except discord.HTTPException:
-                        pass
-                    else:
-                        raw_stream["_messages_cache"].append(msg)
             token = await self.bot.get_shared_api_tokens(_class.token_name)
             if token:
                 if _class.__name__ == "TwitchStream":
@@ -894,6 +906,7 @@ class Streams(commands.Cog):
                     if _class.__name__ == "YoutubeStream":
                         raw_stream["config"] = self.config
                     raw_stream["token"] = token
+            raw_stream["_bot"] = self.bot
             streams.append(_class(**raw_stream))
 
         return streams

redbot/cogs/streams/streamtypes.py

@@ -58,10 +58,11 @@ class Stream:
     token_name: ClassVar[Optional[str]] = None
 
     def __init__(self, **kwargs):
+        self._bot = kwargs.pop("_bot")
         self.name = kwargs.pop("name", None)
         self.channels = kwargs.pop("channels", [])
         # self.already_online = kwargs.pop("already_online", False)
-        self._messages_cache = kwargs.pop("_messages_cache", [])
+        self.messages = kwargs.pop("messages", [])
         self.type = self.__class__.__name__
 
     async def is_online(self):
@@ -70,14 +71,24 @@ class Stream:
     def make_embed(self):
         raise NotImplementedError()
 
+    def iter_messages(self):
+        for msg_data in self.messages:
+            data = msg_data.copy()
+            # "guild" key might not exist for old config data (available since GH-4742)
+            if guild_id := msg_data.get("guild"):
+                guild = self._bot.get_guild(guild_id)
+                channel = guild and guild.get_channel(msg_data["channel"])
+            else:
+                channel = self._bot.get_channel(msg_data["channel"])
+            if channel is not None:
+                data["partial_message"] = channel.get_partial_message(data["message"])
+            yield data
+
     def export(self):
         data = {}
         for k, v in self.__dict__.items():
             if not k.startswith("_"):
                 data[k] = v
-        data["messages"] = []
-        for m in self._messages_cache:
-            data["messages"].append({"channel": m.channel.id, "message": m.id})
         return data
 
     def __repr__(self):
@@ -211,17 +222,21 @@ class YoutubeStream(Stream):
                 embed.timestamp = start_time
                 is_schedule = True
             else:
-                # repost message
+                # delete the message(s) about the stream schedule
                 to_remove = []
-                for message in self._messages_cache:
-                    if message.embeds[0].description is discord.Embed.Empty:
+                for msg_data in self.iter_messages():
+                    if not msg_data.get("is_schedule", False):
                         continue
-                    with contextlib.suppress(Exception):
-                        autodelete = await self._config.guild(message.guild).autodelete()
+                    partial_msg = msg_data["partial_message"]
+                    if partial_msg is not None:
+                        autodelete = await self._config.guild(partial_msg.guild).autodelete()
                         if autodelete:
-                            await message.delete()
-                    to_remove.append(message.id)
-                self._messages_cache = [x for x in self._messages_cache if x.id not in to_remove]
+                            with contextlib.suppress(discord.NotFound):
+                                await partial_msg.delete()
+                    to_remove.append(msg_data["message"])
+                self.messages = [
+                    data for data in self.messages if data["message"] not in to_remove
+                ]
         embed.set_author(name=channel_title)
         embed.set_image(url=rnd(thumbnail))
         embed.colour = 0x9255A5