fixed a bug about handling close handshake when PackageHandler is in use

Author: kerryjiang

src/WebSocket4Net/WebSocket.cs

@@ -24,6 +24,10 @@ public class WebSocket : EasyClient<WebSocketPackage>, IWebSocket
         private static readonly Encoding _utf8Encoding = new UTF8Encoding(false);
         private const string _magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
+        private TaskCompletionSource<WebSocketPackage> _closePackageReceivedTaskSource;
+
+        private bool _packageHandlerMode = false;
+
         public Uri Uri { get; private set; }
 
         public bool AutoPingEnabled { get; set; }
@@ -220,7 +224,11 @@ private void WriteHandshakeRequest(PipeWriter writer, string secKey)
             writer.Write("\r\n", _asciiEncoding);
         }
 
-        public new void StartReceive() => base.StartReceive();
+        public new void StartReceive()
+        {
+            base.StartReceive();
+            _packageHandlerMode = true;
+        }
 
         public new async ValueTask<WebSocketPackage> ReceiveAsync()
             => await ReceiveAsync(
@@ -229,6 +237,11 @@ private void WriteHandshakeRequest(PipeWriter writer, string secKey)
 
         internal async ValueTask<WebSocketPackage> ReceiveAsync(bool handleControlPackage, bool returnControlPackage)
         {
+            if (_packageHandlerMode)
+            {
+                throw new InvalidOperationException($"You cannot call the method {nameof(ReceiveAsync)} if you already setup the client to process packages by PackageHandler.");
+            }
+
             var package = await base.ReceiveAsync();
 
             if (package == null)
@@ -254,6 +267,15 @@ protected override async ValueTask OnPackageReceived(WebSocketPackage package)
         {
             if (package.OpCode != OpCode.Binary && package.OpCode != OpCode.Text)
             {
+                if (package.OpCode == OpCode.Close && _closePackageReceivedTaskSource is TaskCompletionSource<WebSocketPackage> closePackageReceivedTaskSource)
+                {
+                    if (Interlocked.CompareExchange(ref _closePackageReceivedTaskSource, null, closePackageReceivedTaskSource) == closePackageReceivedTaskSource)
+                    {
+                        closePackageReceivedTaskSource.SetResult(package);
+                        return;
+                    }
+                }
+
                 await HandleControlPackage(package);
                 return;
             }
@@ -349,14 +371,21 @@ public async ValueTask CloseAsync(CloseReason closeReason, string message = null
                 Reason = closeReason,
                 ReasonText = message
             };
+
+            var closePackageReceivedTaskSource = default(TaskCompletionSource<WebSocketPackage>);
+
+            if (_packageHandlerMode)
+            {
+                closePackageReceivedTaskSource = _closePackageReceivedTaskSource = new ();
+            }
 
             await SendAsync(_packageEncoder, package);
 
             State = WebSocketState.CloseSent;
 
-            var closeHandshakeResponse = await ReceiveAsync(
-                handleControlPackage: false,
-                returnControlPackage: true);
+            var closeHandshakeResponse = closePackageReceivedTaskSource != null
+                ? await closePackageReceivedTaskSource.Task
+                : await ReceiveAsync(handleControlPackage: false, returnControlPackage: true);
 
             if (closeHandshakeResponse.OpCode != OpCode.Close)
             {