Cannot reuse Unix Domain Socket on Windows

[sakno]

Description

On Linux, Socket.DisconnectAsync works fine and allows to reuse Socket object to connect again. On Windows, DisconnectAsync completes successfully. However, subsequent call of ConnectAsync fails with SocketException and SocketError.IsConnected error. At the same time, Socket.Connected property returns false.

Reproduction Steps

[Fact]
        public static async Task CannotReuseSocketRepro()
        {
            var path = new UnixDomainSocketEndPoint(Path.Combine(Path.GetTempPath(), Path.GetRandomFileName()));

            // server
            using var serverCts = new CancellationTokenSource();
            var server = RunServer(path, serverCts.Token);

            // client
            using (var clientSocket = new Socket(AddressFamily.Unix, SocketType.Stream, ProtocolType.Unspecified))
            {
                var buffer = new byte[512];
                await clientSocket.ConnectAsync(path);
                var count = await clientSocket.ReceiveAsync(buffer, SocketFlags.None);
                Equal("Hello", Encoding.UTF8.GetString(buffer, 0, count));
                await clientSocket.DisconnectAsync(reuseSocket: true);

                // on Linux the connection is successful here, on Windows - failure
                await clientSocket.ConnectAsync(path);
                count = await clientSocket.ReceiveAsync(buffer, SocketFlags.None);
                Equal("Hello", Encoding.UTF8.GetString(buffer, 0, count));
                await clientSocket.DisconnectAsync(reuseSocket: true);
            }

            serverCts.Cancel();
            await server;
        }

        private static async Task RunServer(UnixDomainSocketEndPoint endPoint, CancellationToken token)
        {
            using var serverSocket = new Socket(AddressFamily.Unix, SocketType.Stream, ProtocolType.Unspecified);
            serverSocket.Bind(endPoint);
            serverSocket.Listen();

            while (!token.IsCancellationRequested)
            {
                using var acceptedSocket = await serverSocket.AcceptAsync(token);
                await acceptedSocket.SendAsync(Encoding.UTF8.GetBytes("Hello"), SocketFlags.None, token);
                await acceptedSocket.DisconnectAsync(reuseSocket: false, token);
            }
        }

Expected behavior

Behavior on Linux and Windows must be identical.

Actual behavior

On Windows, it is not possible to call ConnectAsync on disconnected socket.

Regression?

No

Known Workarounds

Recreate socket on client side by the cost of allocation.

Configuration

.NET 6.0.301
Windows 10 Enterprise 20H2 (Build 1904.1706)

Other information

No response

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Issue Details

---

Description

On Linux, Socket.DisconnectAsync works fine and allows to reuse Socket object to connect again. On Windows, DisconnectAsync completes successfully. However, subsequent call of ConnectAsync fails with SocketException and SocketError.IsConnected error. At the same time, Socket.Connected property returns false.

Reproduction Steps

[Fact]
        public static async Task CannotReuseSocketRepro()
        {
            var path = new UnixDomainSocketEndPoint(Path.Combine(Path.GetTempPath(), Path.GetRandomFileName()));

            // server
            using var serverCts = new CancellationTokenSource();
            var server = RunServer(path, serverCts.Token);

            // client
            using (var clientSocket = new Socket(AddressFamily.Unix, SocketType.Stream, ProtocolType.Unspecified))
            {
                var buffer = new byte[512];
                await clientSocket.ConnectAsync(path);
                var count = await clientSocket.ReceiveAsync(buffer, SocketFlags.None);
                Equal("Hello", Encoding.UTF8.GetString(buffer, 0, count));
                await clientSocket.DisconnectAsync(reuseSocket: true);

                // on Linux the connection is successful here, on Windows - failure
                await clientSocket.ConnectAsync(path);
                count = await clientSocket.ReceiveAsync(buffer, SocketFlags.None);
                Equal("Hello", Encoding.UTF8.GetString(buffer, 0, count));
                await clientSocket.DisconnectAsync(reuseSocket: true);
            }

            serverCts.Cancel();
            await server;
        }

        private static async Task RunServer(UnixDomainSocketEndPoint endPoint, CancellationToken token)
        {
            using var serverSocket = new Socket(AddressFamily.Unix, SocketType.Stream, ProtocolType.Unspecified);
            serverSocket.Bind(endPoint);
            serverSocket.Listen();

            while (!token.IsCancellationRequested)
            {
                using var acceptedSocket = await serverSocket.AcceptAsync(token);
                await acceptedSocket.SendAsync(Encoding.UTF8.GetBytes("Hello"), SocketFlags.None, token);
                await acceptedSocket.DisconnectAsync(reuseSocket: false, token);
            }
        }

Expected behavior

Behavior on Linux and Windows must be identical.

Actual behavior

On Windows, it is not possible to call ConnectAsync on disconnected socket.

Regression?

No

Known Workarounds

Recreate socket on client side by the cost of allocation.

Configuration

.NET 6.0.301
Windows 10 Enterprise 20H2 (Build 1904.1706)

Other information

No response

Author:	sakno
Assignees:	-
Labels:	area-System.Net.Sockets
Milestone:	-

[karelz]

Triage: Would be nice to understand it and route it to appropriate team (us or Windows). Not high pri -> Future.