From f47c1b500e4cb9895ae5b34c7050c577aa9fb187 Mon Sep 17 00:00:00 2001
From: Anton Firszov <Anton.Firszov@microsoft.com>
Date: Tue, 2 Feb 2021 13:48:41 +0100
Subject: [PATCH] Respect offset in Socket.ReceiveMessageFrom(saea) on Windows
 (#47642)

Fixes #47637, and adds ReceiveSent_UDP_Success test to both ReceiveFrom and ReceiveMessageFrom
---
 .../Net/Sockets/SocketAsyncEventArgs.Windows.cs    |  2 +-
 .../tests/FunctionalTests/ReceiveFrom.cs           | 42 ++++++++++++++++++++++
 .../tests/FunctionalTests/ReceiveMessageFrom.cs    |  6 ++--
 3 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketAsyncEventArgs.Windows.cs b/src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketAsyncEventArgs.Windows.cs
index def3414..8e99813 100644
--- a/src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketAsyncEventArgs.Windows.cs
+++ b/src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketAsyncEventArgs.Windows.cs
@@ -563,7 +563,7 @@ namespace System.Net.Sockets
                     Debug.Assert(_singleBufferHandleState == SingleBufferHandleState.None);
                     _singleBufferHandleState = SingleBufferHandleState.InProcess;
 
-                    _wsaRecvMsgWSABufferArrayPinned[0].Pointer = (IntPtr)bufferPtr;
+                    _wsaRecvMsgWSABufferArrayPinned[0].Pointer = (IntPtr)bufferPtr + _offset;
                     _wsaRecvMsgWSABufferArrayPinned[0].Length = _count;
                     wsaRecvMsgWSABufferArray = _wsaRecvMsgWSABufferArrayPinned;
                     wsaRecvMsgWSABufferCount = 1;
diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/ReceiveFrom.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/ReceiveFrom.cs
index ce8e3f9..e686dd4 100644
--- a/src/libraries/System.Net.Sockets/tests/FunctionalTests/ReceiveFrom.cs
+++ b/src/libraries/System.Net.Sockets/tests/FunctionalTests/ReceiveFrom.cs
@@ -84,6 +84,48 @@ namespace System.Net.Sockets.Tests
         }
 
         [Theory]
+        [InlineData(false)]
+        [InlineData(true)]
+        public async Task ReceiveSent_UDP_Success(bool ipv4)
+        {
+            const int Offset = 10;
+            const int DatagramSize = 256;
+            const int DatagramsToSend = 16;
+
+            IPAddress address = ipv4 ? IPAddress.Loopback : IPAddress.IPv6Loopback;
+            using Socket receiver = new Socket(address.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
+            using Socket sender = new Socket(address.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
+
+            ConfigureNonBlocking(sender);
+            ConfigureNonBlocking(receiver);
+
+            receiver.BindToAnonymousPort(address);
+            sender.BindToAnonymousPort(address);
+
+            byte[] sendBuffer = new byte[DatagramSize];
+            var receiveInternalBuffer = new byte[DatagramSize + Offset];
+            var emptyBuffer = new byte[Offset];
+            ArraySegment<byte> receiveBuffer = new ArraySegment<byte>(receiveInternalBuffer, Offset, DatagramSize);
+
+            Random rnd = new Random(0);
+
+            IPEndPoint remoteEp = new IPEndPoint(ipv4 ? IPAddress.Any : IPAddress.IPv6Any, 0);
+
+            for (int i = 0; i < DatagramsToSend; i++)
+            {
+                rnd.NextBytes(sendBuffer);
+                sender.SendTo(sendBuffer, receiver.LocalEndPoint);
+
+                SocketReceiveFromResult result = await ReceiveFromAsync(receiver, receiveBuffer, remoteEp);
+
+                Assert.Equal(DatagramSize, result.ReceivedBytes);
+                AssertExtensions.SequenceEqual(emptyBuffer, new ReadOnlySpan<byte>(receiveInternalBuffer, 0, Offset));
+                AssertExtensions.SequenceEqual(sendBuffer, new ReadOnlySpan<byte>(receiveInternalBuffer, Offset, DatagramSize));
+                Assert.Equal(sender.LocalEndPoint, result.RemoteEndPoint);
+            }
+        }
+
+        [Theory]
         [InlineData(true)]
         [InlineData(false)]
         public async Task ClosedBeforeOperation_Throws_ObjectDisposedException(bool closeOrDispose)
diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/ReceiveMessageFrom.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/ReceiveMessageFrom.cs
index 49d95c3..a944380 100644
--- a/src/libraries/System.Net.Sockets/tests/FunctionalTests/ReceiveMessageFrom.cs
+++ b/src/libraries/System.Net.Sockets/tests/FunctionalTests/ReceiveMessageFrom.cs
@@ -52,10 +52,9 @@ namespace System.Net.Sockets.Tests
         [Theory]
         [InlineData(false)]
         [InlineData(true)]
-        public async Task ReceiveSentMessages_UDP_Success(bool ipv4)
+        public async Task ReceiveSent_UDP_Success(bool ipv4)
         {
-            // [ActiveIssue("https://github.com/dotnet/runtime/issues/47637")]
-            int Offset = UsesSync || !PlatformDetection.IsWindows ? 10 : 0;
+            const int Offset = 10;
             const int DatagramSize = 256;
             const int DatagramsToSend = 16;
 
@@ -74,6 +73,7 @@ namespace System.Net.Sockets.Tests
             var receiveInternalBuffer = new byte[DatagramSize + Offset];
             var emptyBuffer = new byte[Offset];
             ArraySegment<byte> receiveBuffer = new ArraySegment<byte>(receiveInternalBuffer, Offset, DatagramSize);
+
             Random rnd = new Random(0);
 
             IPEndPoint remoteEp = new IPEndPoint(ipv4 ? IPAddress.Any : IPAddress.IPv6Any, 0);
-- 
2.7.4