Added UDP keepalives and latency

src/Discord.Net.WebSocket/Audio/AudioClient.Events.cs

@@ -23,6 +23,12 @@ namespace Discord.Audio
             remove { _latencyUpdatedEvent.Remove(value); }
         }
         private readonly AsyncEvent<Func<int, int, Task>> _latencyUpdatedEvent = new AsyncEvent<Func<int, int, Task>>();
+        public event Func<int, int, Task> UdpLatencyUpdated
+        {
+            add { _udpLatencyUpdatedEvent.Add(value); }
+            remove { _udpLatencyUpdatedEvent.Remove(value); }
+        }
+        private readonly AsyncEvent<Func<int, int, Task>> _udpLatencyUpdatedEvent = new AsyncEvent<Func<int, int, Task>>();
         public event Func<ulong, AudioInStream, Task> StreamCreated
         {
             add { _streamCreatedEvent.Add(value); }

src/Discord.Net.WebSocket/Audio/AudioClient.cs

@@ -11,6 +11,7 @@ using System.Linq;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Collections.Generic;
 
 namespace Discord.Audio
 {
@@ -34,10 +35,11 @@ namespace Discord.Audio
         private readonly ConnectionManager _connection;
         private readonly SemaphoreSlim _stateLock;
         private readonly ConcurrentQueue<long> _heartbeatTimes;
+        private readonly ConcurrentQueue<KeyValuePair<ulong, int>> _keepaliveTimes;
         private readonly ConcurrentDictionary<uint, ulong> _ssrcMap;
         private readonly ConcurrentDictionary<ulong, StreamPair> _streams;
 
-        private Task _heartbeatTask;
+        private Task _heartbeatTask, _keepaliveTask;
         private long _lastMessageTime;
         private string _url, _sessionId, _token;
         private ulong _userId;
@@ -46,6 +48,7 @@ namespace Discord.Audio
         public SocketGuild Guild { get; }
         public DiscordVoiceAPIClient ApiClient { get; private set; }
         public int Latency { get; private set; }
+        public int UdpLatency { get; private set; }
         public ulong ChannelId { get; internal set; }
         internal byte[] SecretKey { get; private set; }
 
@@ -72,6 +75,7 @@ namespace Discord.Audio
             _connection.Connected += () => _connectedEvent.InvokeAsync();
             _connection.Disconnected += (ex, recon) => _disconnectedEvent.InvokeAsync(ex);
             _heartbeatTimes = new ConcurrentQueue<long>();
+            _keepaliveTimes = new ConcurrentQueue<KeyValuePair<ulong, int>>();
             _ssrcMap = new ConcurrentDictionary<uint, ulong>();
             _streams = new ConcurrentDictionary<ulong, StreamPair>();
             
@@ -83,6 +87,7 @@ namespace Discord.Audio
             };
 
             LatencyUpdated += async (old, val) => await _audioLogger.DebugAsync($"Latency = {val} ms").ConfigureAwait(false);
+            UdpLatencyUpdated += async (old, val) => await _audioLogger.DebugAsync($"UDP Latency = {val} ms").ConfigureAwait(false);
         }
 
         internal async Task StartAsync(string url, ulong userId, string sessionId, string token) 
@@ -119,6 +124,10 @@ namespace Discord.Audio
             if (heartbeatTask != null)
                 await heartbeatTask.ConfigureAwait(false);
             _heartbeatTask = null;
+            var keepaliveTask = _keepaliveTask;
+            if (keepaliveTask != null)
+                await keepaliveTask.ConfigureAwait(false);
+            _keepaliveTask = null;
 
             long time;
             while (_heartbeatTimes.TryDequeue(out time)) { }
@@ -242,6 +251,7 @@ namespace Discord.Audio
 
                             SecretKey = data.SecretKey;
                             await ApiClient.SendSetSpeaking(false).ConfigureAwait(false);
+                            _keepaliveTask = RunKeepaliveAsync(5000, _connection.CancelToken);
 
                             var _ = _connection.CompleteAsync();
                         }
@@ -283,6 +293,8 @@ namespace Discord.Audio
             }
         }
         private async Task ProcessPacketAsync(byte[] packet)
+        {
+            try
             {
                 if (_connection.State == ConnectionState.Connecting)
                 {
@@ -309,21 +321,46 @@ namespace Discord.Audio
                 }
                 else if (_connection.State == ConnectionState.Connected)
                 {
-                uint ssrc;
+                    if (packet.Length == 8)
-                ulong userId;
+                    {
-                StreamPair pair;
+                        await _audioLogger.DebugAsync("Received Keepalive").ConfigureAwait(false);
 
-                if (!RTPReadStream.TryReadSsrc(packet, 0, out ssrc))
+                        ulong value = 
+                            ((ulong)packet[0] >> 0) |
+                            ((ulong)packet[1] >> 8) |
+                            ((ulong)packet[2] >> 16) |
+                            ((ulong)packet[3] >> 24) |
+                            ((ulong)packet[4] >> 32) |
+                            ((ulong)packet[5] >> 40) |
+                            ((ulong)packet[6] >> 48) |
+                            ((ulong)packet[7] >> 56);
+
+                        while (_keepaliveTimes.TryDequeue(out var pair))
+                        {
+                            if (pair.Key == value)
+                            {
+                                int latency = (int)(Environment.TickCount - pair.Value);
+                                int before = UdpLatency;
+                                UdpLatency = latency;
+
+                                await _udpLatencyUpdatedEvent.InvokeAsync(before, latency).ConfigureAwait(false);
+                                break;
+                            }
+                        }
+                    }
+                    else
+                    {                        
+                        if (!RTPReadStream.TryReadSsrc(packet, 0, out var ssrc))
                         {
                             await _audioLogger.DebugAsync($"Malformed Frame").ConfigureAwait(false);
                             return;
                         }
-                if (!_ssrcMap.TryGetValue(ssrc, out userId))
+                        if (!_ssrcMap.TryGetValue(ssrc, out var userId))
                         {
                             await _audioLogger.DebugAsync($"Unknown SSRC {ssrc}").ConfigureAwait(false);
                             return;
                         }
-                if (!_streams.TryGetValue(userId, out pair))
+                        if (!_streams.TryGetValue(userId, out var pair))
                         {
                             await _audioLogger.DebugAsync($"Unknown User {userId}").ConfigureAwait(false);
                             return;
@@ -340,6 +377,13 @@ namespace Discord.Audio
                         //await _audioLogger.DebugAsync($"Received {packet.Length} bytes from user {userId}").ConfigureAwait(false);
                     }
                 }
+            }
+            catch (Exception ex)
+            {
+                await _audioLogger.WarningAsync($"Failed to process UDP packet", ex).ConfigureAwait(false);
+                return;
+            }
+        }
 
         private async Task RunHeartbeatAsync(int intervalMillis, CancellationToken cancelToken)
         {
@@ -366,7 +410,7 @@ namespace Discord.Audio
                     }
                     catch (Exception ex)
                     {
-                        await _audioLogger.WarningAsync("Heartbeat Errored", ex).ConfigureAwait(false);
+                        await _audioLogger.WarningAsync("Failed to send heartbeat", ex).ConfigureAwait(false);
                     }
 
                     await Task.Delay(intervalMillis, cancelToken).ConfigureAwait(false);
@@ -382,6 +426,40 @@ namespace Discord.Audio
                 await _audioLogger.ErrorAsync("Heartbeat Errored", ex).ConfigureAwait(false);
             }
         }
+        private async Task RunKeepaliveAsync(int intervalMillis, CancellationToken cancelToken)
+        {
+            var packet = new byte[8];
+            try
+            {
+                await _audioLogger.DebugAsync("Keepalive Started").ConfigureAwait(false);
+                while (!cancelToken.IsCancellationRequested)
+                {
+                    var now = Environment.TickCount;
+
+                    try
+                    {
+                        ulong value = await ApiClient.SendKeepaliveAsync().ConfigureAwait(false);
+                        if (_keepaliveTimes.Count < 12) //No reply for 60 Seconds
+                            _keepaliveTimes.Enqueue(new KeyValuePair<ulong, int>(value, now));
+                    }
+                    catch (Exception ex)
+                    {
+                        await _audioLogger.WarningAsync("Failed to send keepalive", ex).ConfigureAwait(false);
+                    }
+                    
+                    await Task.Delay(intervalMillis, cancelToken).ConfigureAwait(false);
+                }
+                await _audioLogger.DebugAsync("Keepalive Stopped").ConfigureAwait(false);
+            }
+            catch (OperationCanceledException)
+            {
+                await _audioLogger.DebugAsync("Keepalive Stopped").ConfigureAwait(false);
+            }
+            catch (Exception ex)
+            {
+                await _audioLogger.ErrorAsync("Keepalive Errored", ex).ConfigureAwait(false);
+            }
+        }
 
         internal void Dispose(bool disposing)
         {

src/Discord.Net.WebSocket/DiscordVoiceApiClient.cs

@@ -42,6 +42,7 @@ namespace Discord.Audio
         private CancellationTokenSource _connectCancelToken;
         private IUdpSocket _udp;
         private bool _isDisposed;
+        private ulong _nextKeepalive;
 
         public ulong GuildId { get; }
         internal IWebSocketClient WebSocketClient { get; }
@@ -227,6 +228,21 @@ namespace Discord.Audio
             await SendAsync(packet, 0, 70).ConfigureAwait(false);
             await _sentDiscoveryEvent.InvokeAsync().ConfigureAwait(false);
         }
+        public async Task<ulong> SendKeepaliveAsync()
+        {
+            var value = _nextKeepalive++;
+            var packet = new byte[8];
+            packet[0] = (byte)(value >> 0);
+            packet[1] = (byte)(value >> 8);
+            packet[2] = (byte)(value >> 16);
+            packet[3] = (byte)(value >> 24);
+            packet[4] = (byte)(value >> 32);
+            packet[5] = (byte)(value >> 40);
+            packet[6] = (byte)(value >> 48);
+            packet[7] = (byte)(value >> 56);
+            await SendAsync(packet, 0, 8).ConfigureAwait(false);
+            return value;
+        }
 
         public void SetUdpEndpoint(string ip, int port)
         {