Fix the problem of reconnecting when moved to another VC

[nonnonstop]

Fixes #849.

Description

When the bot was moved to another vc, the connection was disconnected with 4014 Disconnected.

• 4014 error when moving bot to another voice channel Rapptz/discord.py#5904
• Voice WebSocket Connection closed with 4014 when switching voice channels discord/discord-api-docs#2450
• https://github.com/discordjs/guide/blob/main/guide/voice/voice-connections.md#handling-disconnects

Then, VOICE_SERVER_UPDATE is received after 4014 Disconnected.

2022/10/30 14:47:23 [DG2] voice.go:356:wsListen() received 4014 manual disconnection
2022/10/30 14:47:23 [DG2] voice.go:167:Close() called
2022/10/30 14:47:23 [DG2] voice.go:176:Close() closing v.close
2022/10/30 14:47:23 [DG2] voice.go:182:Close() closing udp
2022/10/30 14:47:23 [DG3] wsapi.go:547:onEvent() Op: 0, Seq: 6, Type: VOICE_STATE_UPDATE, Data: [hidden]
2022/10/30 14:47:23 [DG3] wsapi.go:547:onEvent() Op: 0, Seq: 7, Type: VOICE_SERVER_UPDATE, Data: {"token":"[hidden]","guild_id":"[hidden]","endpoint":"brazil7541.discord.media:443"}
2022/10/30 14:47:23 [DG2] wsapi.go:763:onVoiceServerUpdate() called

However, the VoiceConnection has been deleted when the VOICE_SERVER_UPDATE is received due to the following code. (L364)

discordgo/voice.go

Lines 355 to 370 in afab840

	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
	}

Since the VoiceConnection does not exist, onVoiceServerUpdate does not reconnect.

discordgo/wsapi.go

Lines 761 to 772 in afab840

	func (s *Session) onVoiceServerUpdate(st *VoiceServerUpdate) {
	s.log(LogInformational, "called")
	s.RLock()
	voice, exists := s.VoiceConnections[st.GuildID]
	s.RUnlock()
	// If no VoiceConnection exists, just skip this
	if !exists {
	return
	}

This is the cause of #849.

How to fix

Delay the time between receiving 4014 Disconnected and deleting the connection.
If VOICE_SERVER_UPDATE is received during that time, the connection is not deleted.

2022/10/30 15:17:13 [DG2] voice.go:356:wsListen() received 4014 manual disconnection
2022/10/30 15:17:13 [DG3] wsapi.go:547:onEvent() Op: 0, Seq: 7, Type: VOICE_SERVER_UPDATE, Data: {"token":"[hidden]","guild_id":"[hidden]","endpoint":"brazil2241.discord.media:443"}
2022/10/30 15:17:13 [DG2] wsapi.go:763:onVoiceServerUpdate() called
2022/10/30 15:17:13 [DG2] voice.go:167:Close() called
2022/10/30 15:17:13 [DG2] voice.go:176:Close() closing v.close
2022/10/30 15:17:13 [DG2] voice.go:182:Close() closing udp
2022/10/30 15:17:13 [DG2] voice.go:280:open() called
2022/10/30 15:17:13 [DG2] voice.go:306:open() connecting to voice endpoint wss://brazil2241.discord.media:443
2022/10/30 15:17:13 [DG2] voice.go:348:wsListen() called
2022/10/30 15:17:13 [DG3] voice.go:417:onEvent() received: {"op":8,"d":{"v":1,"heartbeat_interval":55000}}
2022/10/30 15:17:13 [DG3] voice.go:494:onEvent() unknown voice operation, 8, {"v":1,"heartbeat_interval":55000}
2022/10/30 15:17:14 [DG2] voice.go:372:wsListen() successfully reconnected due to code 4014

If not (e.g. kicked by admin), the connection is deleted.

2022/10/30 15:18:24 [DG2] voice.go:356:wsListen() received 4014 manual disconnection
2022/10/30 15:18:29 [DG2] voice.go:376:wsListen() disconnect due to code 4014
2022/10/30 15:18:29 [DG2] voice.go:167:Close() called
2022/10/30 15:18:29 [DG2] voice.go:176:Close() closing v.close
2022/10/30 15:18:29 [DG2] voice.go:182:Close() closing udp

[FedorLap2006]

LGTM, however I'm not fully sure about this for based retry solution

P.S. Thanks for fixing such longstanding issue!

[FedorLap2006]

Sorry for a long wait.

[FedorLap2006]

LGTM.

P.S. About the To Do comment. I've marked this loop, since we will probably replace it with a proper solution, using our event system, sometime in the future, alongisde other unrefactored stuff.

[FedorLap2006]

Anyhow, thank you for your work and patience.