Can't use VoiceConnection when the bot is moved to another vc by a User

[colecrouter]

Ran into a situation where when playing a sound, if the bot was moved to another voice channel, it seemingly gets stuck in limbo. Running Disconnect() just crashes. s.VoiceConnections[e.GuildID] seems to just flat out return nil every time (for me at least).

I was able to sorta get around this by storing the VoiceConnection* as a global, then setting a custom error handler for dgvoice:

dgvoice.OnError = func(str string, err error) {
	vc.Disconnect()
}

then setting up an event handler for voiceStateUpdate:

if e.UserID == "bot-id" {
	if e.BeforeUpdate != nil {
		vc, _ = s.ChannelVoiceJoin(e.GuildID, e.ChannelID, false, false)
		vc.Disconnect()
	}
	return
}

This also requires #833 in order to work, or some manual work keeping track of the bot's previous voice channel.

Basically, if it detects the bot being moved (e.BeforeUpdate != nil) then it reconnects to the same channel manually, bringing it out of "limbo". Then it just disconnects.

Obviously this isn't the end of the world, but it's a pretty rough fix. Does anyone have any better approaches? My ideas are:

• Add some "fromAnotherChannel" property to VoiceStateUpdate, then it's at least a bit easier for users to define their wanted behavior
• Add a separate "voiceChannelMoved` event to make it even a little bit more easy
• Ideally, somehow have VoiceConnection* update itself when moved

Thoughts?

[nonnonstop]

I'm having same issue.

When I moved the bot to another VC, I got the following log.

...
2021/03/07 18:56:55 [DG2] voice.go:354:wsListen() received 4014 manual disconnection
2021/03/07 18:56:55 [DG2] voice.go:167:Close() called
2021/03/07 18:56:55 [DG2] voice.go:176:Close() closing v.close
2021/03/07 18:56:55 [DG2] voice.go:182:Close() closing udp
...

This log is output from voice.go

discordgo/voice.go

Lines 351 to 368 in 37088ae

	// 4014 indicates a manual disconnection by someone in the guild;
	// we shouldn't reconnect.
	if websocket.IsCloseError(err, 4014) {
	v.log(LogInformational, "received 4014 manual disconnection")
	// Abandon the voice WS connection
	v.Lock()
	v.wsConn = nil
	v.Unlock()
	v.session.Lock()
	delete(v.session.VoiceConnections, v.GuildID)
	v.session.Unlock()
	v.Close()
	return
	}

I found the same issue at Rapptz/discord.py#5904.
Maybe the connection check is still needed when the client receives 4014 error.

[qaisjp]

storing the VoiceConnection* as a global, then setting a custom error handler for dgvoice:

dgvoice.OnError = func(str string, err error) {
	vc.Disconnect()
}

Btw, as a general Go tip, you need not store it as a global.

If you have something like this:

type MyBot struct {
	d *discordgo.Session
	vc *discordgo.VoiceConnection
}

func (b *MyBot) onError(str string, err error) {
	b.vc.Disconnect()
}

You can assign a method "bound" to this struct like this:

func main() {
	bot := &MyBot{}
	// assign some things inside bot
	dgvoice.OnError = bot.onError
}