From 704239bca8ec1c7087f37cd6da31aece205c7d31 Mon Sep 17 00:00:00 2001
From: Chris Ross <Tratcher@Outlook.com>
Date: Tue, 11 Mar 2014 08:26:42 -0700
Subject: [PATCH] Allow zero length sends and receives.

---
 .../CommonWebSocket.cs                        |  4 +-
 .../WebSocketClientTests.cs                   | 63 +++++++++++++++++++
 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/src/Microsoft.Net.WebSockets/CommonWebSocket.cs b/src/Microsoft.Net.WebSockets/CommonWebSocket.cs
index b4315644b2..cbad809539 100644
--- a/src/Microsoft.Net.WebSockets/CommonWebSocket.cs
+++ b/src/Microsoft.Net.WebSockets/CommonWebSocket.cs
@@ -533,11 +533,11 @@ namespace Microsoft.Net.WebSockets
             {
                 throw new ArgumentNullException("buffer");
             }
-            if (buffer.Offset < 0 || buffer.Offset >= buffer.Array.Length)
+            if (buffer.Offset < 0 || buffer.Offset > buffer.Array.Length)
             {
                 throw new ArgumentOutOfRangeException("buffer.Offset", buffer.Offset, string.Empty);
             }
-            if (buffer.Count <= 0 || buffer.Count > buffer.Array.Length - buffer.Offset)
+            if (buffer.Count < 0 || buffer.Count > buffer.Array.Length - buffer.Offset)
             {
                 throw new ArgumentOutOfRangeException("buffer.Count", buffer.Count, string.Empty);
             }
diff --git a/test/Microsoft.Net.WebSockets.Test/WebSocketClientTests.cs b/test/Microsoft.Net.WebSockets.Test/WebSocketClientTests.cs
index f4c6b207fe..b0a9779c82 100644
--- a/test/Microsoft.Net.WebSockets.Test/WebSocketClientTests.cs
+++ b/test/Microsoft.Net.WebSockets.Test/WebSocketClientTests.cs
@@ -61,6 +61,38 @@ namespace Microsoft.Net.WebSockets.Test
             }
         }
 
+        [Fact]
+        public async Task SendEmptyData_Success()
+        {
+            using (HttpListener listener = new HttpListener())
+            {
+                listener.Prefixes.Add(ServerAddress);
+                listener.Start();
+                Task<HttpListenerContext> serverAccept = listener.GetContextAsync();
+
+                WebSocketClient client = new WebSocketClient();
+                Task<WebSocket> clientConnect = client.ConnectAsync(new Uri(ClientAddress), CancellationToken.None);
+
+                HttpListenerContext serverContext = await serverAccept;
+                Assert.True(serverContext.Request.IsWebSocketRequest);
+                HttpListenerWebSocketContext serverWebSocketContext = await serverContext.AcceptWebSocketAsync(null);
+
+                WebSocket clientSocket = await clientConnect;
+
+                byte[] orriginalData = new byte[0];
+                await clientSocket.SendAsync(new ArraySegment<byte>(orriginalData), WebSocketMessageType.Binary, true, CancellationToken.None);
+
+                byte[] serverBuffer = new byte[orriginalData.Length];
+                WebSocketReceiveResult result = await serverWebSocketContext.WebSocket.ReceiveAsync(new ArraySegment<byte>(serverBuffer), CancellationToken.None);
+                Assert.True(result.EndOfMessage);
+                Assert.Equal(orriginalData.Length, result.Count);
+                Assert.Equal(WebSocketMessageType.Binary, result.MessageType);
+                Assert.Equal(orriginalData, serverBuffer);
+
+                clientSocket.Dispose();
+            }
+        }
+
         [Fact]
         public async Task SendShortData_Success()
         {
@@ -220,6 +252,37 @@ namespace Microsoft.Net.WebSockets.Test
             }
         }
 
+        [Fact]
+        public async Task ReceiveEmptyData_Success()
+        {
+            using (HttpListener listener = new HttpListener())
+            {
+                listener.Prefixes.Add(ServerAddress);
+                listener.Start();
+                Task<HttpListenerContext> serverAccept = listener.GetContextAsync();
+
+                WebSocketClient client = new WebSocketClient();
+                Task<WebSocket> clientConnect = client.ConnectAsync(new Uri(ClientAddress), CancellationToken.None);
+
+                HttpListenerContext serverContext = await serverAccept;
+                Assert.True(serverContext.Request.IsWebSocketRequest);
+                HttpListenerWebSocketContext serverWebSocketContext = await serverContext.AcceptWebSocketAsync(null);
+
+                WebSocket clientSocket = await clientConnect;
+
+                byte[] orriginalData = Encoding.UTF8.GetBytes("Hello World");
+                await serverWebSocketContext.WebSocket.SendAsync(new ArraySegment<byte>(orriginalData), WebSocketMessageType.Binary, true, CancellationToken.None);
+
+                byte[] clientBuffer = new byte[0];
+                WebSocketReceiveResult result = await clientSocket.ReceiveAsync(new ArraySegment<byte>(clientBuffer), CancellationToken.None);
+                Assert.False(result.EndOfMessage);
+                Assert.Equal(0, result.Count);
+                Assert.Equal(WebSocketMessageType.Binary, result.MessageType);
+
+                clientSocket.Dispose();
+            }
+        }
+
         [Fact]
         public async Task ReceiveShortData_Success()
         {