Relax Socket.DualMode exception behavior (#50585)

Stop throwing from Socket.DualMode getter for IPV4 sockets, return false instead.
dotnet · May 11, 2021 · 753b764 · 753b764
1 parent d2c744f
commit 753b764
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Showing 2 changed files with 10 additions and 6 deletions.
diff --git a/src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.cs b/src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.cs
@@ -725,7 +725,7 @@ public bool DualMode
             {
                 if (AddressFamily != AddressFamily.InterNetworkV6)
                 {
-                    throw new NotSupportedException(SR.net_invalidversion);
+                    return false;
                 }
                 return ((int)GetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.IPv6Only)! == 0);
             }

diff --git a/src/libraries/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs b/src/libraries/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs
@@ -52,15 +52,19 @@ public void NormalConstructor_DualModeConfgiureable()
         }
 
         [Fact]
-        public void IPv4Constructor_DualModeThrows()
+        public void IPv4Constructor_DualMode_GetterReturnsFalse()
         {
             using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
             {
-                Assert.Throws<NotSupportedException>(() =>
-                {
-                    Assert.False(socket.DualMode);
-                });
+                Assert.False(socket.DualMode);
+            }
+        }
 
+        [Fact]
+        public void IPv4Constructor_DualMode_SetterThrows()
+        {
+            using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
+            {
                 Assert.Throws<NotSupportedException>(() =>
                 {
                     socket.DualMode = true;