// Discordgo - Discord bindings for Go // Available at https://github.com/bwmarrin/discordgo // Copyright 2015-2016 Bruce Marriner . All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // This file contains code related to Discord voice suppport package discordgo import ( "encoding/binary" "encoding/json" "fmt" "net" "strconv" "strings" "sync" "time" "github.com/gorilla/websocket" "golang.org/x/crypto/nacl/secretbox" ) // ------------------------------------------------------------------------------------------------ // Code related to both VoiceConnection Websocket and UDP connections. // ------------------------------------------------------------------------------------------------ // A VoiceConnection struct holds all the data and functions related to a Discord Voice Connection. type VoiceConnection struct { sync.RWMutex Debug bool // If true, print extra logging -- DEPRECATED LogLevel int Ready bool // If true, voice is ready to send/receive audio UserID string GuildID string ChannelID string deaf bool mute bool speaking bool reconnecting bool // If true, voice connection is trying to reconnect OpusSend chan []byte // Chan for sending opus audio OpusRecv chan *Packet // Chan for receiving opus audio wsConn *websocket.Conn wsMutex sync.Mutex udpConn *net.UDPConn session *Session sessionID string token string endpoint string // Used to send a close signal to goroutines close chan struct{} // Used to allow blocking until connected connected chan bool // Used to pass the sessionid from onVoiceStateUpdate // sessionRecv chan string UNUSED ATM op4 voiceOP4 op2 voiceOP2 voiceSpeakingUpdateHandlers []VoiceSpeakingUpdateHandler } // VoiceSpeakingUpdateHandler type provides a function definition for the // VoiceSpeakingUpdate event type VoiceSpeakingUpdateHandler func(vc *VoiceConnection, vs *VoiceSpeakingUpdate) // Speaking sends a speaking notification to Discord over the voice websocket. // This must be sent as true prior to sending audio and should be set to false // once finished sending audio. // b : Send true if speaking, false if not. func (v *VoiceConnection) Speaking(b bool) (err error) { v.log(LogDebug, "called (%t)", b) type voiceSpeakingData struct { Speaking bool `json:"speaking"` Delay int `json:"delay"` } type voiceSpeakingOp struct { Op int `json:"op"` // Always 5 Data voiceSpeakingData `json:"d"` } if v.wsConn == nil { return fmt.Errorf("no VoiceConnection websocket") } data := voiceSpeakingOp{5, voiceSpeakingData{b, 0}} v.wsMutex.Lock() err = v.wsConn.WriteJSON(data) v.wsMutex.Unlock() v.Lock() defer v.Unlock() if err != nil { v.speaking = false v.log(LogError, "Speaking() write json error, %s", err) return } v.speaking = b return } // ChangeChannel sends Discord a request to change channels within a Guild // !!! NOTE !!! This function may be removed in favour of just using ChannelVoiceJoin func (v *VoiceConnection) ChangeChannel(channelID string, mute, deaf bool) (err error) { v.log(LogInformational, "called") data := voiceChannelJoinOp{4, voiceChannelJoinData{&v.GuildID, &channelID, mute, deaf}} v.wsMutex.Lock() err = v.session.wsConn.WriteJSON(data) v.wsMutex.Unlock() if err != nil { return } v.ChannelID = channelID v.deaf = deaf v.mute = mute v.speaking = false return } // Disconnect disconnects from this voice channel and closes the websocket // and udp connections to Discord. func (v *VoiceConnection) Disconnect() (err error) { // Send a OP4 with a nil channel to disconnect v.Lock() if v.sessionID != "" { data := voiceChannelJoinOp{4, voiceChannelJoinData{&v.GuildID, nil, true, true}} v.session.wsMutex.Lock() err = v.session.wsConn.WriteJSON(data) v.session.wsMutex.Unlock() v.sessionID = "" } v.Unlock() // Close websocket and udp connections v.Close() v.log(LogInformational, "Deleting VoiceConnection %s", v.GuildID) v.session.Lock() delete(v.session.VoiceConnections, v.GuildID) v.session.Unlock() return } // Close closes the voice ws and udp connections func (v *VoiceConnection) Close() { v.log(LogInformational, "called") v.Lock() defer v.Unlock() v.Ready = false v.speaking = false if v.close != nil { v.log(LogInformational, "closing v.close") close(v.close) v.close = nil } if v.udpConn != nil { v.log(LogInformational, "closing udp") err := v.udpConn.Close() if err != nil { v.log(LogError, "error closing udp connection, %s", err) } v.udpConn = nil } if v.wsConn != nil { v.log(LogInformational, "sending close frame") // To cleanly close a connection, a client should send a close // frame and wait for the server to close the connection. v.wsMutex.Lock() err := v.wsConn.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")) v.wsMutex.Unlock() if err != nil { v.log(LogError, "error closing websocket, %s", err) } // TODO: Wait for Discord to actually close the connection. time.Sleep(1 * time.Second) v.log(LogInformational, "closing websocket") err = v.wsConn.Close() if err != nil { v.log(LogError, "error closing websocket, %s", err) } v.wsConn = nil } } // AddHandler adds a Handler for VoiceSpeakingUpdate events. func (v *VoiceConnection) AddHandler(h VoiceSpeakingUpdateHandler) { v.Lock() defer v.Unlock() v.voiceSpeakingUpdateHandlers = append(v.voiceSpeakingUpdateHandlers, h) } // VoiceSpeakingUpdate is a struct for a VoiceSpeakingUpdate event. type VoiceSpeakingUpdate struct { UserID string `json:"user_id"` SSRC int `json:"ssrc"` Speaking bool `json:"speaking"` } // ------------------------------------------------------------------------------------------------ // Unexported Internal Functions Below. // ------------------------------------------------------------------------------------------------ // A voiceOP4 stores the data for the voice operation 4 websocket event // which provides us with the NaCl SecretBox encryption key type voiceOP4 struct { SecretKey [32]byte `json:"secret_key"` Mode string `json:"mode"` } // A voiceOP2 stores the data for the voice operation 2 websocket event // which is sort of like the voice READY packet type voiceOP2 struct { SSRC uint32 `json:"ssrc"` Port int `json:"port"` Modes []string `json:"modes"` HeartbeatInterval time.Duration `json:"heartbeat_interval"` IP string `json:"ip"` } // WaitUntilConnected waits for the Voice Connection to // become ready, if it does not become ready it returns an err func (v *VoiceConnection) waitUntilConnected() error { v.log(LogInformational, "called") i := 0 for { v.RLock() ready := v.Ready v.RUnlock() if ready { return nil } if i > 10 { return fmt.Errorf("timeout waiting for voice") } time.Sleep(1 * time.Second) i++ } } // Open opens a voice connection. This should be called // after VoiceChannelJoin is used and the data VOICE websocket events // are captured. func (v *VoiceConnection) open() (err error) { v.log(LogInformational, "called") v.Lock() defer v.Unlock() // Don't open a websocket if one is already open if v.wsConn != nil { v.log(LogWarning, "refusing to overwrite non-nil websocket") return } // TODO temp? loop to wait for the SessionID i := 0 for { if v.sessionID != "" { break } if i > 20 { // only loop for up to 1 second total return fmt.Errorf("did not receive voice Session ID in time") } time.Sleep(50 * time.Millisecond) i++ } // Connect to VoiceConnection Websocket vg := "wss://" + strings.TrimSuffix(v.endpoint, ":80") v.log(LogInformational, "connecting to voice endpoint %s", vg) v.wsConn, _, err = websocket.DefaultDialer.Dial(vg, nil) if err != nil { v.log(LogWarning, "error connecting to voice endpoint %s, %s", vg, err) v.log(LogDebug, "voice struct: %#v\n", v) return } type voiceHandshakeData struct { ServerID string `json:"server_id"` UserID string `json:"user_id"` SessionID string `json:"session_id"` Token string `json:"token"` } type voiceHandshakeOp struct { Op int `json:"op"` // Always 0 Data voiceHandshakeData `json:"d"` } data := voiceHandshakeOp{0, voiceHandshakeData{v.GuildID, v.UserID, v.sessionID, v.token}} err = v.wsConn.WriteJSON(data) if err != nil { v.log(LogWarning, "error sending init packet, %s", err) return } v.close = make(chan struct{}) go v.wsListen(v.wsConn, v.close) // add loop/check for Ready bool here? // then return false if not ready? // but then wsListen will also err. return } // wsListen listens on the voice websocket for messages and passes them // to the voice event handler. This is automatically called by the Open func func (v *VoiceConnection) wsListen(wsConn *websocket.Conn, close <-chan struct{}) { v.log(LogInformational, "called") for { _, message, err := v.wsConn.ReadMessage() if err != nil { // 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 } // Detect if we have been closed manually. If a Close() has already // happened, the websocket we are listening on will be different to the // current session. v.RLock() sameConnection := v.wsConn == wsConn v.RUnlock() if sameConnection { v.log(LogError, "voice endpoint %s websocket closed unexpectantly, %s", v.endpoint, err) // Start reconnect goroutine then exit. go v.reconnect() } return } // Pass received message to voice event handler select { case <-close: return default: go v.onEvent(message) } } } // wsEvent handles any voice websocket events. This is only called by the // wsListen() function. func (v *VoiceConnection) onEvent(message []byte) { v.log(LogDebug, "received: %s", string(message)) var e Event if err := json.Unmarshal(message, &e); err != nil { v.log(LogError, "unmarshall error, %s", err) return } switch e.Operation { case 2: // READY if err := json.Unmarshal(e.RawData, &v.op2); err != nil { v.log(LogError, "OP2 unmarshall error, %s, %s", err, string(e.RawData)) return } // Start the voice websocket heartbeat to keep the connection alive go v.wsHeartbeat(v.wsConn, v.close, v.op2.HeartbeatInterval) // TODO monitor a chan/bool to verify this was successful // Start the UDP connection err := v.udpOpen() if err != nil { v.log(LogError, "error opening udp connection, %s", err) return } // Start the opusSender. // TODO: Should we allow 48000/960 values to be user defined? if v.OpusSend == nil { v.OpusSend = make(chan []byte, 2) } go v.opusSender(v.udpConn, v.close, v.OpusSend, 48000, 960) // Start the opusReceiver if !v.deaf { if v.OpusRecv == nil { v.OpusRecv = make(chan *Packet, 2) } go v.opusReceiver(v.udpConn, v.close, v.OpusRecv) } return case 3: // HEARTBEAT response // add code to use this to track latency? return case 4: // udp encryption secret key v.Lock() defer v.Unlock() v.op4 = voiceOP4{} if err := json.Unmarshal(e.RawData, &v.op4); err != nil { v.log(LogError, "OP4 unmarshall error, %s, %s", err, string(e.RawData)) return } return case 5: if len(v.voiceSpeakingUpdateHandlers) == 0 { return } voiceSpeakingUpdate := &VoiceSpeakingUpdate{} if err := json.Unmarshal(e.RawData, voiceSpeakingUpdate); err != nil { v.log(LogError, "OP5 unmarshall error, %s, %s", err, string(e.RawData)) return } for _, h := range v.voiceSpeakingUpdateHandlers { h(v, voiceSpeakingUpdate) } default: v.log(LogDebug, "unknown voice operation, %d, %s", e.Operation, string(e.RawData)) } return } type voiceHeartbeatOp struct { Op int `json:"op"` // Always 3 Data int `json:"d"` } // NOTE :: When a guild voice server changes how do we shut this down // properly, so a new connection can be setup without fuss? // // wsHeartbeat sends regular heartbeats to voice Discord so it knows the client // is still connected. If you do not send these heartbeats Discord will // disconnect the websocket connection after a few seconds. func (v *VoiceConnection) wsHeartbeat(wsConn *websocket.Conn, close <-chan struct{}, i time.Duration) { if close == nil || wsConn == nil { return } var err error ticker := time.NewTicker(i * time.Millisecond) defer ticker.Stop() for { v.log(LogDebug, "sending heartbeat packet") v.wsMutex.Lock() err = wsConn.WriteJSON(voiceHeartbeatOp{3, int(time.Now().Unix())}) v.wsMutex.Unlock() if err != nil { v.log(LogError, "error sending heartbeat to voice endpoint %s, %s", v.endpoint, err) return } select { case <-ticker.C: // continue loop and send heartbeat case <-close: return } } } // ------------------------------------------------------------------------------------------------ // Code related to the VoiceConnection UDP connection // ------------------------------------------------------------------------------------------------ type voiceUDPData struct { Address string `json:"address"` // Public IP of machine running this code Port uint16 `json:"port"` // UDP Port of machine running this code Mode string `json:"mode"` // always "xsalsa20_poly1305" } type voiceUDPD struct { Protocol string `json:"protocol"` // Always "udp" ? Data voiceUDPData `json:"data"` } type voiceUDPOp struct { Op int `json:"op"` // Always 1 Data voiceUDPD `json:"d"` } // udpOpen opens a UDP connection to the voice server and completes the // initial required handshake. This connection is left open in the session // and can be used to send or receive audio. This should only be called // from voice.wsEvent OP2 func (v *VoiceConnection) udpOpen() (err error) { v.Lock() defer v.Unlock() if v.wsConn == nil { return fmt.Errorf("nil voice websocket") } if v.udpConn != nil { return fmt.Errorf("udp connection already open") } if v.close == nil { return fmt.Errorf("nil close channel") } if v.endpoint == "" { return fmt.Errorf("empty endpoint") } host := v.op2.IP + ":" + strconv.Itoa(v.op2.Port) addr, err := net.ResolveUDPAddr("udp", host) if err != nil { v.log(LogWarning, "error resolving udp host %s, %s", host, err) return } v.log(LogInformational, "connecting to udp addr %s", addr.String()) v.udpConn, err = net.DialUDP("udp", nil, addr) if err != nil { v.log(LogWarning, "error connecting to udp addr %s, %s", addr.String(), err) return } // Create a 70 byte array and put the SSRC code from the Op 2 VoiceConnection event // into it. Then send that over the UDP connection to Discord sb := make([]byte, 70) binary.BigEndian.PutUint32(sb, v.op2.SSRC) _, err = v.udpConn.Write(sb) if err != nil { v.log(LogWarning, "udp write error to %s, %s", addr.String(), err) return } // Create a 70 byte array and listen for the initial handshake response // from Discord. Once we get it parse the IP and PORT information out // of the response. This should be our public IP and PORT as Discord // saw us. rb := make([]byte, 70) rlen, _, err := v.udpConn.ReadFromUDP(rb) if err != nil { v.log(LogWarning, "udp read error, %s, %s", addr.String(), err) return } if rlen < 70 { v.log(LogWarning, "received udp packet too small") return fmt.Errorf("received udp packet too small") } // Loop over position 4 through 20 to grab the IP address // Should never be beyond position 20. var ip string for i := 4; i < 20; i++ { if rb[i] == 0 { break } ip += string(rb[i]) } // Grab port from position 68 and 69 port := binary.BigEndian.Uint16(rb[68:70]) // Take the data from above and send it back to Discord to finalize // the UDP connection handshake. data := voiceUDPOp{1, voiceUDPD{"udp", voiceUDPData{ip, port, "xsalsa20_poly1305"}}} v.wsMutex.Lock() err = v.wsConn.WriteJSON(data) v.wsMutex.Unlock() if err != nil { v.log(LogWarning, "udp write error, %#v, %s", data, err) return } // start udpKeepAlive go v.udpKeepAlive(v.udpConn, v.close, 5*time.Second) // TODO: find a way to check that it fired off okay return } // udpKeepAlive sends a udp packet to keep the udp connection open // This is still a bit of a "proof of concept" func (v *VoiceConnection) udpKeepAlive(udpConn *net.UDPConn, close <-chan struct{}, i time.Duration) { if udpConn == nil || close == nil { return } var err error var sequence uint64 packet := make([]byte, 8) ticker := time.NewTicker(i) defer ticker.Stop() for { binary.LittleEndian.PutUint64(packet, sequence) sequence++ _, err = udpConn.Write(packet) if err != nil { v.log(LogError, "write error, %s", err) return } select { case <-ticker.C: // continue loop and send keepalive case <-close: return } } } // opusSender will listen on the given channel and send any // pre-encoded opus audio to Discord. Supposedly. func (v *VoiceConnection) opusSender(udpConn *net.UDPConn, close <-chan struct{}, opus <-chan []byte, rate, size int) { if udpConn == nil || close == nil { return } // VoiceConnection is now ready to receive audio packets // TODO: this needs reviewed as I think there must be a better way. v.Lock() v.Ready = true v.Unlock() defer func() { v.Lock() v.Ready = false v.Unlock() }() var sequence uint16 var timestamp uint32 var recvbuf []byte var ok bool udpHeader := make([]byte, 12) var nonce [24]byte // build the parts that don't change in the udpHeader udpHeader[0] = 0x80 udpHeader[1] = 0x78 binary.BigEndian.PutUint32(udpHeader[8:], v.op2.SSRC) // start a send loop that loops until buf chan is closed ticker := time.NewTicker(time.Millisecond * time.Duration(size/(rate/1000))) defer ticker.Stop() for { // Get data from chan. If chan is closed, return. select { case <-close: return case recvbuf, ok = <-opus: if !ok { return } // else, continue loop } v.RLock() speaking := v.speaking v.RUnlock() if !speaking { err := v.Speaking(true) if err != nil { v.log(LogError, "error sending speaking packet, %s", err) } } // Add sequence and timestamp to udpPacket binary.BigEndian.PutUint16(udpHeader[2:], sequence) binary.BigEndian.PutUint32(udpHeader[4:], timestamp) // encrypt the opus data copy(nonce[:], udpHeader) v.RLock() sendbuf := secretbox.Seal(udpHeader, recvbuf, &nonce, &v.op4.SecretKey) v.RUnlock() // block here until we're exactly at the right time :) // Then send rtp audio packet to Discord over UDP select { case <-close: return case <-ticker.C: // continue } _, err := udpConn.Write(sendbuf) if err != nil { v.log(LogError, "udp write error, %s", err) v.log(LogDebug, "voice struct: %#v\n", v) return } if (sequence) == 0xFFFF { sequence = 0 } else { sequence++ } if (timestamp + uint32(size)) >= 0xFFFFFFFF { timestamp = 0 } else { timestamp += uint32(size) } } } // A Packet contains the headers and content of a received voice packet. type Packet struct { SSRC uint32 Sequence uint16 Timestamp uint32 Type []byte Opus []byte PCM []int16 } // opusReceiver listens on the UDP socket for incoming packets // and sends them across the given channel // NOTE :: This function may change names later. func (v *VoiceConnection) opusReceiver(udpConn *net.UDPConn, close <-chan struct{}, c chan *Packet) { if udpConn == nil || close == nil { return } recvbuf := make([]byte, 1024) var nonce [24]byte for { rlen, err := udpConn.Read(recvbuf) if err != nil { // Detect if we have been closed manually. If a Close() has already // happened, the udp connection we are listening on will be different // to the current session. v.RLock() sameConnection := v.udpConn == udpConn v.RUnlock() if sameConnection { v.log(LogError, "udp read error, %s, %s", v.endpoint, err) v.log(LogDebug, "voice struct: %#v\n", v) go v.reconnect() } return } select { case <-close: return default: // continue loop } // For now, skip anything except audio. if rlen < 12 || (recvbuf[0] != 0x80 && recvbuf[0] != 0x90) { continue } // build a audio packet struct p := Packet{} p.Type = recvbuf[0:2] p.Sequence = binary.BigEndian.Uint16(recvbuf[2:4]) p.Timestamp = binary.BigEndian.Uint32(recvbuf[4:8]) p.SSRC = binary.BigEndian.Uint32(recvbuf[8:12]) // decrypt opus data copy(nonce[:], recvbuf[0:12]) p.Opus, _ = secretbox.Open(nil, recvbuf[12:rlen], &nonce, &v.op4.SecretKey) if len(p.Opus) > 8 && recvbuf[0] == 0x90 { // Extension bit is set, first 8 bytes is the extended header p.Opus = p.Opus[8:] } if c != nil { select { case c <- &p: case <-close: return } } } } // Reconnect will close down a voice connection then immediately try to // reconnect to that session. // NOTE : This func is messy and a WIP while I find what works. // It will be cleaned up once a proven stable option is flushed out. // aka: this is ugly shit code, please don't judge too harshly. func (v *VoiceConnection) reconnect() { v.log(LogInformational, "called") v.Lock() if v.reconnecting { v.log(LogInformational, "already reconnecting to channel %s, exiting", v.ChannelID) v.Unlock() return } v.reconnecting = true v.Unlock() defer func() { v.reconnecting = false }() // Close any currently open connections v.Close() wait := time.Duration(1) for { <-time.After(wait * time.Second) wait *= 2 if wait > 600 { wait = 600 } if v.session.DataReady == false || v.session.wsConn == nil { v.log(LogInformational, "cannot reconnect to channel %s with unready session", v.ChannelID) continue } v.log(LogInformational, "trying to reconnect to channel %s", v.ChannelID) _, err := v.session.ChannelVoiceJoin(v.GuildID, v.ChannelID, v.mute, v.deaf) if err == nil { v.log(LogInformational, "successfully reconnected to channel %s", v.ChannelID) return } v.log(LogInformational, "error reconnecting to channel %s, %s", v.ChannelID, err) // if the reconnect above didn't work lets just send a disconnect // packet to reset things. // Send a OP4 with a nil channel to disconnect data := voiceChannelJoinOp{4, voiceChannelJoinData{&v.GuildID, nil, true, true}} v.session.wsMutex.Lock() err = v.session.wsConn.WriteJSON(data) v.session.wsMutex.Unlock() if err != nil { v.log(LogError, "error sending disconnect packet, %s", err) } } }