[SocketException]: New Constructor with string? for SocketException

src/libraries/Common/src/System/Net/Sockets/SocketExceptionFactory.Unix.cs

@@ -0,0 +1,21 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace System.Net.Sockets
+{
+    internal static partial class SocketExceptionFactory
+    {
+        public static SocketException CreateSocketException(int socketError, EndPoint endPoint)
+        {
+            int nativeErr = (int)socketError;
+
+            // If an interop error was not found, then don't invoke Info().RawErrno as that will fail with assert.
+            if (SocketErrorPal.TryGetNativeErrorForSocketError((SocketError)socketError, out Interop.Error interopErr))
+            {
+                nativeErr = interopErr.Info().RawErrno;
+            }
+
+            return new SocketException(socketError, CreateMessage(nativeErr, endPoint));
+        }
+    }
+}

src/libraries/Common/src/System/Net/Sockets/SocketExceptionFactory.Windows.cs

@@ -0,0 +1,14 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace System.Net.Sockets
+{
+    internal static partial class SocketExceptionFactory
+    {
+        public static SocketException CreateSocketException(int socketError, EndPoint endPoint)
+        {
+            // Windows directly maps socketError to native error code.
+            return new SocketException(socketError, CreateMessage(socketError, endPoint));
+        }
+    }
+}

src/libraries/Common/src/System/Net/Sockets/SocketExceptionFactory.cs

@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.InteropServices;
+
+namespace System.Net.Sockets
+{
+    internal static partial class SocketExceptionFactory
+    {
+        private static string CreateMessage(int nativeSocketError, EndPoint endPoint)
+        {
+            return Marshal.GetPInvokeErrorMessage(nativeSocketError) + " " + endPoint.ToString();
+        }
+    }
+}

src/libraries/System.Net.Primitives/ref/System.Net.Primitives.cs

@@ -471,6 +471,7 @@ public partial class SocketException : System.ComponentModel.Win32Exception
     {
         public SocketException() { }
         public SocketException(int errorCode) { }
+        public SocketException(int errorCode, string? message) { }
         protected SocketException(System.Runtime.Serialization.SerializationInfo serializationInfo, System.Runtime.Serialization.StreamingContext streamingContext) { }
         public override int ErrorCode { get { throw null; } }
         public override string Message { get { throw null; } }

src/libraries/System.Net.Primitives/src/System/Net/SocketException.cs

@@ -30,12 +30,23 @@ public SocketException(int errorCode) : this((SocketError)errorCode)
             // but that's the least bad option right now.
         }
 
+        /// <summary>Initializes a new instance of the <see cref='System.Net.Sockets.SocketException'/> class with the specified error code and optional message.</summary>
+        public SocketException(int errorCode, string? message) : this((SocketError)errorCode, message)
+        {
+        }
+
         /// <summary>Creates a new instance of the <see cref='System.Net.Sockets.SocketException'/> class with the specified error code as SocketError.</summary>
         internal SocketException(SocketError socketError) : base(GetNativeErrorForSocketError(socketError))
         {
             _errorCode = socketError;
         }
 
+        /// <summary>Initializes a new instance of the <see cref='System.Net.Sockets.SocketException'/> class with the specified error code as SocketError and optional message.</summary>
+        internal SocketException(SocketError socketError, string? message) : base(GetNativeErrorForSocketError(socketError), message)
+        {
+            _errorCode = socketError;
+        }
+
         public override string Message => base.Message;
 
         public SocketError SocketErrorCode => _errorCode;

src/libraries/System.Net.Primitives/tests/FunctionalTests/SocketExceptionTest.cs

@@ -0,0 +1,34 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Net.Sockets;
+using Xunit;
+
+namespace System.Net.Primitives.Functional.Tests
+{
+    public static class SocketExceptionTest
+    {
+        [Fact]
+        public static void Create_AllErrorCodes_Success()
+        {
+            foreach (SocketError error in Enum.GetValues(typeof(SocketError)))
+            {
+                SocketException e = new SocketException((int)error);
+                Assert.Equal(error, e.SocketErrorCode);
+                Assert.Null(e.InnerException);
+                Assert.NotNull(e.Message);
+            }
+        }
+
+        [Fact]
+        public static void Create_ExceptionWithMessage_Success()
+        {
+            const string message = "Hello World";
+            SocketException e = new SocketException((int)SocketError.AccessDenied, message);
+            Assert.Equal(SocketError.AccessDenied, e.SocketErrorCode);
+            Assert.Null(e.InnerException);
+            Assert.Equal(message, e.Message);
+            Assert.Contains(message, e.ToString());
+        }
+    }
+}

src/libraries/System.Net.Primitives/tests/FunctionalTests/System.Net.Primitives.Functional.Tests.csproj

@@ -25,7 +25,7 @@
     <Compile Include="LoggingTest.cs" />
     <Compile Include="RequestCachePolicyTest.cs" />
     <Compile Include="CookieContainerAddTest.cs" />
-    <Compile Include="$(CommonTestPath)System\Diagnostics\Tracing\TestEventListener.cs"
-             Link="Common\System\Diagnostics\Tracing\TestEventListener.cs" />
+    <Compile Include="$(CommonTestPath)System\Diagnostics\Tracing\TestEventListener.cs" Link="Common\System\Diagnostics\Tracing\TestEventListener.cs" />
+    <Compile Include="SocketExceptionTest.cs" />
   </ItemGroup>
 </Project>

src/libraries/System.Net.Sockets/src/System.Net.Sockets.csproj

@@ -78,8 +78,8 @@
              Link="Common\System\Net\Internals\IPEndPointExtensions.cs" />
     <Compile Include="$(CommonPath)System\Net\Internals\IPAddressExtensions.cs"
              Link="Common\System\Net\Internals\IPAddressExtensions.cs" />
-    <Compile Include="$(CommonPath)System\Net\Internals\SocketExceptionFactory.cs"
-             Link="Common\System\Net\Internals\SocketExceptionFactory.cs" />
+    <Compile Include="$(CommonPath)System\Net\Sockets\SocketExceptionFactory.cs"
+             Link="Common\System\Net\Sockets\SocketExceptionFactory.cs" />
     <Compile Include="$(CommonPath)System\Net\Sockets\ProtocolFamily.cs"
              Link="Common\System\Net\Sockets\ProtocolFamily.cs" />
     <Compile Include="$(CommonPath)System\Net\Sockets\ProtocolType.cs"
@@ -100,6 +100,8 @@
              Link="Common\System\Net\SocketAddressPal.Windows.cs" />
     <Compile Include="$(CommonPath)System\Net\SocketProtocolSupportPal.Windows.cs"
              Link="Common\System\Net\SocketProtocolSupportPal.Windows" />
+    <Compile Include="$(CommonPath)System\Net\Sockets\SocketExceptionFactory.Windows.cs"
+             Link="Common\System\Net\Sockets\SocketExceptionFactory.Windows.cs" />
     <!-- Interop -->
     <Compile Include="$(CommonPath)Interop\Windows\Interop.Libraries.cs"
              Link="Common\Interop\Windows\Interop.Libraries.cs" />
@@ -278,6 +280,8 @@
              Link="Common\Interop\Unix\System.Native\Interop.Pipe.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Write.cs"
              Link="Common\Interop\Unix\System.Native\Interop.Write.cs" />
+    <Compile Include="$(CommonPath)System\Net\Sockets\SocketExceptionFactory.Unix.cs"
+             Link="Common\System\Net\Sockets\SocketExceptionFactory.Unix.cs" />
   </ItemGroup>
   <ItemGroup>
     <Reference Include="Microsoft.Win32.Primitives" />

src/libraries/System.Net.Sockets/tests/FunctionalTests/Connect.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Runtime.InteropServices;
 using Xunit;
 using Xunit.Abstractions;
 using Xunit.Sdk;
@@ -218,6 +219,28 @@ public ConnectApm(ITestOutputHelper output) : base(output) {}
     public sealed class ConnectTask : Connect<SocketHelperTask>
     {
         public ConnectTask(ITestOutputHelper output) : base(output) {}
+
+        [OuterLoop]
+        [Fact]
+        public static void Connect_ThrowSocketException_Success()
+        {
+            using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
+            {
+                int anonymousPort = socket.BindToAnonymousPort(IPAddress.Loopback);
+                IPEndPoint ep = new IPEndPoint(IPAddress.Loopback, anonymousPort);
+                Assert.ThrowsAsync<SocketException>(() => socket.ConnectAsync(ep));
+                try
+                {
+                    socket.Connect(ep);
+                    Assert.Fail("Socket Connect should throw SocketException in this case.");
+                }
+                catch (SocketException ex)
+                {
+                    Assert.Contains(Marshal.GetPInvokeErrorMessage(ex.NativeErrorCode), ex.Message);
+                    Assert.Contains(ep.ToString(), ex.Message);
+                }
+            }
+        }
     }
 
     public sealed class ConnectEap : Connect<SocketHelperEap>