fix: Connection deadlock when trying to Send and Disconnect (#1872)

src/Discord.Net.WebSocket/DiscordSocketApiClient.cs

@@ -188,9 +188,9 @@ namespace Discord.API
             catch { }
 
             if (ex is GatewayReconnectException)
-                await WebSocketClient.DisconnectAsync(4000);
+                await WebSocketClient.DisconnectAsync(4000).ConfigureAwait(false);
             else
-            await WebSocketClient.DisconnectAsync().ConfigureAwait(false);
+                await WebSocketClient.DisconnectAsync().ConfigureAwait(false);
 
             ConnectionState = ConnectionState.Disconnected;
         }

src/Discord.Net.WebSocket/Net/DefaultWebSocketClient.cs

@@ -108,11 +108,11 @@ namespace Discord.Net.WebSockets
         }
         private async Task DisconnectInternalAsync(int closeCode = 1000, bool isDisposing = false)
         {
+            _isDisconnecting = true;
+
             try { _disconnectTokenSource.Cancel(false); }
             catch { }
 
-            _isDisconnecting = true;
-
             if (_client != null)
             {
                 if (!isDisposing)
@@ -166,7 +166,14 @@ namespace Discord.Net.WebSockets
 
         public async Task SendAsync(byte[] data, int index, int count, bool isText)
         {
-            await _lock.WaitAsync().ConfigureAwait(false);
+            try
+            {
+                await _lock.WaitAsync(_cancelToken).ConfigureAwait(false);
+            }
+            catch (TaskCanceledException)
+            {
+                return;
+            }
             try
             {
                 if (_client == null) return;
@@ -201,7 +208,7 @@ namespace Discord.Net.WebSockets
             {
                 while (!cancelToken.IsCancellationRequested)
                 {
-                    WebSocketReceiveResult socketResult = await _client.ReceiveAsync(buffer, CancellationToken.None).ConfigureAwait(false);
+                    WebSocketReceiveResult socketResult = await _client.ReceiveAsync(buffer, cancelToken).ConfigureAwait(false);
                     byte[] result;
                     int resultCount;