From 06e12b837f24c7b5463f59bbb71745417a63895d Mon Sep 17 00:00:00 2001
From: Mikhail Filippov <Mikhail.Filippov@jetbrains.com>
Date: Mon, 25 Apr 2016 16:06:31 +0300
Subject: [PATCH] Socket.AcceptAsync shouldn't create new socket if
 SocketAsyncEventArgs.AcceptSocket isn't null

---
 mcs/class/System/System.Net.Sockets/Socket.cs | 18 ++--
 mcs/class/System/System_test.dll.sources      |  1 +
 .../SocketAcceptAsyncTest.cs                  | 82 +++++++++++++++++++
 3 files changed, 95 insertions(+), 6 deletions(-)
 create mode 100644 mcs/class/System/Test/System.Net.Sockets/SocketAcceptAsyncTest.cs

diff --git a/mcs/class/System/System.Net.Sockets/Socket.cs b/mcs/class/System/System.Net.Sockets/Socket.cs
index 0f1c977a71d..b41d204ace8 100644
--- a/mcs/class/System/System.Net.Sockets/Socket.cs
+++ b/mcs/class/System/System.Net.Sockets/Socket.cs
@@ -991,16 +991,20 @@ namespace System.Net.Sockets
 
 		static IOAsyncCallback BeginAcceptCallback = new IOAsyncCallback (ares => {
 			SocketAsyncResult sockares = (SocketAsyncResult) ares;
-			Socket socket = null;
-
+			Socket acc_socket = null;
 			try {
-				socket = sockares.socket.Accept ();
+				if (sockares.AcceptSocket == null) {
+					acc_socket = sockares.socket.Accept ();
+				} else {
+					acc_socket = sockares.AcceptSocket;
+					sockares.socket.Accept (acc_socket);
+				}
+
 			} catch (Exception e) {
 				sockares.Complete (e);
 				return;
 			}
-
-			sockares.Complete (socket);
+			sockares.Complete (acc_socket);
 		});
 
 		public IAsyncResult BeginAccept (int receiveSize, AsyncCallback callback, object state)
@@ -3427,7 +3431,9 @@ namespace System.Net.Sockets
 		void InitSocketAsyncEventArgs (SocketAsyncEventArgs e, AsyncCallback callback, object state, SocketOperation operation)
 		{
 			e.socket_async_result.Init (this, callback, state, operation);
-
+			if (e.AcceptSocket != null) {
+				e.socket_async_result.AcceptSocket = e.AcceptSocket;
+			}
 			e.current_socket = this;
 			e.SetLastOperation (SocketOperationToSocketAsyncOperation (operation));
 			e.SocketError = SocketError.Success;
diff --git a/mcs/class/System/System_test.dll.sources b/mcs/class/System/System_test.dll.sources
index 7d07dd75041..6ec32758faf 100644
--- a/mcs/class/System/System_test.dll.sources
+++ b/mcs/class/System/System_test.dll.sources
@@ -247,6 +247,7 @@ System.Net.Sockets/MulticastOptionTest.cs
 System.Net.Sockets/NetworkStreamTest.cs
 System.Net.Sockets/TcpClientTest.cs
 System.Net.Sockets/TcpListenerTest.cs
+System.Net.Sockets/SocketAcceptAsyncTest.cs
 System.Net.Sockets/SocketTest.cs
 System.Net.Sockets/SocketAsyncEventArgsTest.cs
 System.Net.Sockets/SocketConnectAsyncTest.cs
diff --git a/mcs/class/System/Test/System.Net.Sockets/SocketAcceptAsyncTest.cs b/mcs/class/System/Test/System.Net.Sockets/SocketAcceptAsyncTest.cs
new file mode 100644
index 00000000000..6866ff58513
--- /dev/null
+++ b/mcs/class/System/Test/System.Net.Sockets/SocketAcceptAsyncTest.cs
@@ -0,0 +1,82 @@
+using System;
+using System.Threading;
+using System.Net;
+using System.Net.Sockets;
+using NUnit.Framework;
+
+namespace MonoTests.System.Net.Sockets
+{
+	[TestFixture]
+	public class SocketAcceptAsyncTest
+	{
+		private Socket _listenSocket;
+		private Socket _clientSocket;
+		private Socket _serverSocket;
+		private Socket _acceptedSocket;
+		private ManualResetEvent _readyEvent;
+		private ManualResetEvent _mainEvent;
+
+		[TestFixtureSetUp]
+		public void SetUp()
+		{
+			_readyEvent = new ManualResetEvent(false);
+			_mainEvent = new ManualResetEvent(false);
+
+			ThreadPool.QueueUserWorkItem(_ => StartListen());
+			if (!_readyEvent.WaitOne(1500))
+				throw new TimeoutException();
+
+			_clientSocket = new Socket(
+				AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+			_clientSocket.Connect(_listenSocket.LocalEndPoint);
+			_clientSocket.NoDelay = true;
+		}
+
+		[TestFixtureTearDown]
+		public void TearDown()
+		{
+			if (_acceptedSocket != null)
+				_acceptedSocket.Close();
+			if (_listenSocket != null)
+				_listenSocket.Close();
+			_readyEvent.Close();
+			_mainEvent.Close();
+		}
+
+		private void StartListen()
+		{
+			_listenSocket = new Socket(
+				AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+			_listenSocket.Bind(new IPEndPoint(IPAddress.Loopback, 0));
+			_listenSocket.Listen(1);
+
+			_serverSocket = new Socket(
+				AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+
+      var async = new SocketAsyncEventArgs();
+			async.AcceptSocket = _serverSocket;
+			async.Completed += (s, e) => OnAccepted(e);
+
+			_readyEvent.Set();
+
+			if (!_listenSocket.AcceptAsync(async))
+				OnAccepted(async);
+		}
+
+		private void OnAccepted(SocketAsyncEventArgs e)
+		{
+			_acceptedSocket = e.AcceptSocket;
+			_mainEvent.Set();
+		}
+
+		[Test]
+		[Category("Test")]
+		public void AcceptAsyncShouldUseAcceptSocketFromEventArgs()
+		{
+			if (!_mainEvent.WaitOne(1500))
+				throw new TimeoutException();
+			Assert.AreEqual(_serverSocket, _acceptedSocket);
+			_mainEvent.Reset();
+		}
+	}
+}
-- 
2.25.1