add some code to make sure we sent datagram before we try to receive it (#24615)

* add some code to make sure we sent datagram before we try to receive it. #17681

* use synchronous send with timeout instead of task to avoid race condition

2 files changed, 18 insertions, 7 deletions

diff --git a/src/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs b/src/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs
index fba1acd298..8c0b57c04c 100644
--- a/src/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs
+++ b/src/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs
@@ -2707,7 +2707,7 @@ namespace System.Net.Sockets.Tests
             private IPAddress _connectTo;
             private Socket _serverSocket;
 
-            public SocketUdpClient(ITestOutputHelper output, Socket serverSocket, IPAddress connectTo, int port, bool redundant = true)
+            public SocketUdpClient(ITestOutputHelper output, Socket serverSocket, IPAddress connectTo, int port, bool redundant = true, bool sendNow = true)
             {
                 _output = output;
 
@@ -2715,14 +2715,18 @@ namespace System.Net.Sockets.Tests
                 _port = port;
                 _serverSocket = serverSocket;
 
-                Task.Run(() => ClientSend(null, redundant));
+                if (sendNow)
+                {
+                    Task.Run(() => ClientSend(redundant));
+                }
             }
 
-            private void ClientSend(object state, bool redundant)
+            public void ClientSend(bool redundant = true, int timeout = 3)
             {
                 try
                 {
                     Socket socket = new Socket(_connectTo.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
+                    socket.SendTimeout = timeout * 1000;
 
                     for (int i = 0; i < (redundant ? TestSettings.UDPRedundancy : 1); i++)
                     {
@@ -2733,8 +2737,9 @@ namespace System.Net.Sockets.Tests
                         socket.SendToAsync(e);
                     }
                 }
-                catch (SocketException)
+                catch (SocketException e)
                 {
+                    _output.WriteLine("Send to {0} {1} failed: {2}", _connectTo, _port, e.ToString());
                     _serverSocket.Dispose(); // Cancels the test
                 }
             }
@@ -2755,10 +2760,12 @@ namespace System.Net.Sockets.Tests
         {
             using (Socket serverSocket = new Socket(SocketType.Dgram, ProtocolType.Udp))
             {
-                serverSocket.ReceiveTimeout = 500;
+                serverSocket.ReceiveTimeout = 1000;
                 int port = serverSocket.BindToAnonymousPort(listenOn);
 
-                SocketUdpClient client = new SocketUdpClient(_log, serverSocket, connectTo, port);
+                SocketUdpClient client = new SocketUdpClient(_log, serverSocket, connectTo, port, sendNow: false);
+
+                client.ClientSend();
 
                 EndPoint receivedFrom = new IPEndPoint(connectTo, port);
                 int received = serverSocket.ReceiveFrom(new byte[1], ref receivedFrom);
diff --git a/src/System.Net.Sockets/tests/FunctionalTests/System.Net.Sockets.Tests.csproj b/src/System.Net.Sockets/tests/FunctionalTests/System.Net.Sockets.Tests.csproj
index 088fd2ba4d..f3feef4441 100644
--- a/src/System.Net.Sockets/tests/FunctionalTests/System.Net.Sockets.Tests.csproj
+++ b/src/System.Net.Sockets/tests/FunctionalTests/System.Net.Sockets.Tests.csproj
@@ -3,6 +3,7 @@
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
   <PropertyGroup>
     <ProjectGuid>{8CBA022C-635F-4C8D-9D29-CD8AAC68C8E6}</ProjectGuid>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='netstandard-Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='netstandard-Release|AnyCPU'" />
@@ -97,6 +98,9 @@
     <Compile Include="$(CommonTestPath)\System\Diagnostics\Tracing\TestEventListener.cs">
       <Link>Common\System\Diagnostics\Tracing\TestEventListener.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)\System\Net\Logging\NetEventSource.Common.cs">
+      <Link>Common\System\Net\Logging\NetEventSource.Common.cs</Link>
+    </Compile>
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="$(CommonTestPath)\System\Diagnostics\RemoteExecutorConsoleApp\RemoteExecutorConsoleApp.csproj">
@@ -108,4 +112,4 @@
     <EmbeddedResource Include="Resources\$(AssemblyName).rd.xml" />
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
-</Project>
\ No newline at end of file
+</Project>